Collegiate Papers - Abstract

2025

Operational optimisation of a bivalent heat pump-district heating compact
station
This thesis examines the operational optimisation of a bivalent heat pump district heating house station. The aim is to increase the heat pump coverage ratio and to identify the causes of and solutions to high-pressure faults. Analysis of the 2025 operating year shows a coverage ratio of 55.4 %. The key observation is that the coverage ratio decreases as the outside temperature rises, despite a simultaneous increase in the heat pump’s thermal output. To optimise the operating point, the reference variables and parameters of the PI controller for the heating circuit mixing valves are adjusted, and the target temperature in the heating circuit is lowered during evaporator defrost cycles and the energy supplier’s blocking hours. In addition, the heat pump’s cut-off temperature is reduced by five degrees Celsius, whilst the setpoint for drinking water heating is raised by ten degrees Celsius. Using a simulation programmed in Python, this leads to an increase in the heat pump coverage ratio to 73.05 %. At the same time, an increase in the heat pump’s operating hours of 27.88 % and a decrease in cycling frequency of 26.75 % are projected. The main cause of the high-pressure faults is identified as a minimum flow rate being not met. Furthermore, faulty temperature measurement leads to incorrect loading requirements for the storage tank. To resolve the fault, the circulation pump frequency is increased and the temperature sensors are calibrated.
Editor: Oskar Krajci
Tutor: Olaf Bartmuß SachsenEnergie, Dipl.-Ing. Michael Wördemann
Year: 2025

Economic Evaluation of Direct Supply Concepts with Renewable Energy Systems and Battery Storage: Development of a Simulation-Based Software Tool for Optimizing Operational Management and System Dimensioning
The transition of the energy system towards decentralised structures increases the relevance of industrial direct supply concepts, particularly in the context of falling feed-in tariffs. This thesis examines the techno-economic design and operational management of direct supply systems based on renewable energy sources. The aim is to identify cost-optimised system configurations while simultaneously optimising self-sufficiency and the share of energy consumed on-site. The analysis is conducted using mixed-integer linear optimisation implemented via the Flixopt framework. The model is based on an AC-coupled system that includes renewable energy sources, lithium iron phosphate battery storage, and grid components. Electricity supplied directly to the consumer is marketed through Power Purchase Agreements, while any surplus is fed into the day-ahead market under the market premium scheme in accordance with the Renewable Energy Sources Act. The residual load is met through grid procurement, with costs projected using an hourly price forward curve. The optimisation results are evaluated both under a static planning horizon with perfect foresight and under a dynamic planning horizon that takes into account future developments in loads, costs, and energy prices. Applying the model to a practical case study of electric bus charging infrastructure shows that a 7,000 kWp photovoltaic system, combined with a battery storage system with a capacity of 3,900 kWh, represents a cost-optimised solution, reducing electricity costs by 16 %. In this configuration, a self-sufficiency rate of 60 % and a self-consumption share of 32 % are achieved. The results illustrate that the combination of direct supply, storage integration and grid feed-in is essential for economic viability. The model developed in this thesis is transferable to other direct supply applications and provides a robust basis for designing efficient energy supply systems based on renewable energy sources.
Editor: Frederike Bäcker
Tutor: Valentin Heusgen - NaturStromProjekte GmbH, Dr.rer.nat. Peter Stange
Year: 2025

lnvestigation into district heating network operation in connection with
the partial collapse of the Carola Bridge in Dresden
The Dresden district heating network, operated by SachsenEnergie AG, supplies heat to Dresden Neustadt via two river crossings of the Elbe. Following the collapse of the Carola Bridge, the two defective DN 500 transmission pipelines were replaced by a temporary crossing consisting of two DN 400 pipelines routed across the Augustus Bridge. This structural modification resulted in a fundamental change of the hydraulic conditions within the district heating network.
The objective of this thesis is to analyze the altered supply situation, with a particular emphasis on the required heat input of the Combined Heat and Power Plant Nord to hydraulically support the Dresden Neustadt, and its dependence on other supply locations as well as the network load. Based on thermohydraulic simulations, the operational limits of the heat generation sites are determined and represented in operating maps.
The results indicate that several network components have been subjected to significantly increased loads since construction of the temporary crossing and, in some cases, to overload conditions. The developed operating maps enable an assessment of whether defined limit criteria, such as security of supply and acceptable component stress, are satisfied under specific operating conditions. On this basis, operational recommendations for adjusting the heat generation dispatch to reduce component stress are derived.
The analysis of reduced supply temperatures demonstrates that low temperature operation is feasible under low and medium network loads, whereas the current temperature regime remains hydraulically necessary at high network loads.
A future network model for the reference year 2028 shows that currently planned network reinforcements will hydraulically relieve the existing system. With the addition of these network reinforcements, the current generation strategy is no longer expected to cause the component overloads identified in this thesis.
Editor: Eric Wobst
Tutor: Benjamin Latta - SachsenEnergie, KTF, Jorin Günther - SachsenEnergie, KE, Dr.rer.nat. Peter Stange
Year: 2025

Comprehensive analysis and evaluation of energy recovery strategies in semiconductor manufacturing, with particular emphasis on technical, energy, economic and environmental aspects
This thesis addresses the comprehensive analysis and evaluation of energy monitoring strategies in semiconductor manufacturing. The analysis is conducted while considering technical, energetic, economic, and environmental aspects. Due to the high complexity of industrial semiconductor fabrication facilities and the strongly interconnected nature of supply and production processes, precise and systematic energy monitoring plays a crucial role. Only reliable measurement data enable transparent representation of energy flows, accurate characterization of load profiles, and the identification of energy efficiency potentials.
The thesis is based on the hypothesis that establishing a clearly defined energy monitoring strategy within a semiconductor fabrication facility can significantly increase energy transparency and support decision-making regarding energy efficiency improvements and energy recovery measures. The main objective of this work is the development and application of a structured planning methodology that enables the systematic integration of an energy monitoring strategy into the operational environment of semiconductor manufacturing. A particular focus is placed on the investigation of different energy monitoring strategies and on how the collected energy measurement
data can be further analyzed and visualized using complementary tools. In this context, various load and operating scenarios of semiconductor production are taken into account.
Following an initial classification of the energy demands in semiconductor manufacturing,
different measurement methods applied to the most energy-intensive systems within the facility environment are presented. Subsequently, several fundamental energy monitoring concepts are evaluated with regard to their suitability for semiconductor manufacturing using a multi-criteria decision analysis. Existing energy measurement data are analyzed with respect to key parameters such as production utilization and ambient temperature. Based on this data analysis and visualization, the energetic interactions within the system are illustrated. As a final step, methods for establishing energy baselines are presented, allowing the derivation of an integrative energy monitoring concept.
The results of this work demonstrate that the individual methodological steps presented can serve as a guideline for implementing an integrative energy monitoring concept in semiconductor manufacturing. Furthermore, the study shows how energy performance indicators can be derived from measurement data and which energy monitoring concepts are required to support this process. The developed approach for data visualization using dynamic Sankey diagrams enables the targeted evaluation of energy measurement data in order to illustrate energetic interactions under different load and operating scenarios. Based on these insights, simulations under varying load conditions can be performed to establish energy baselines that support system analysis. This data-driven approach facilitates informed decisions regarding energy efficiency measures and energy recovery,
ultimately contributing to a reduction in primary energy consumption and supporting more economical and sustainable semiconductor production.
Editor: Leo Niklas Schulze
Tutor: Tobias Saum - CRC, Dipl.-Wi.Ing. Laura Lehmann
Year: 2025

Automated generation of formal energy asset descriptions from various unstructured data sources
Heating, ventilation, and air-conditioning (HVAC) systems are among the main energy consumers. Although large amounts of operational and sensor data are continuously collected, their potential for analysis, optimization, and fault detection is hardly utilized. A major reason is the lack of consistent, machine-readable metadata that clearly describes the structure, function, and relationships of HVAC components, which in existing buildings is often fragmented across different sources. To leverage this information, formal representations in the form of knowledge graphs have been established. Ho wever, their creation is labor-intensive, and existing automation approaches have not been able to provide a complete overall representation of HVAC systems. The aim of this work is the automated integration of multiple independently generated knowledge graphs describing the same HVAC system. The goal is to combine the results of different inference methods, exploit redundancies, and identify semantic inconsistencies in order to generate a consistent overall representation of the system. This work thus addresses a previously little-studied aspect of automated HVAC system modeling. To tackle this research question, a rule- and heuristic-based approach is presented, combining the identificati on of equivalent entities (Entity Alignment) with the detection of conflicting statements (Conflict Detection). The knowledge graphs used are based on the Brick schema and were constructed to si mulate different automatic metadata inference methods such as Natural Language Processing (NLP), Computer Vision (CV), and Time Series Analysis (TSA). For this purpose, controlled test graphs with targeted, realistic distortions were generated. Evaluation on multiple realistic datasets shows promising results: Entity Alignment achieves an average F1-score of 0.86. For Conflict Detection, the average F1-score is 0.84 and rises to 0.89 when isolating upstream Entity Alignment errors, with consistently high precision. Overall, this work demonstrates that the systematic integration of multiple knowledge graphs is a promising approach to improving the quality of automatically generated HVAC models.
Editor: Hüseyin Tokul
Tutor: Dr. Matthias Eberlein - Fraunhofer IIS/EAS, Dr. Andreas Wilde - EA-Systems, MSc Hervé Pruvost, Dr.-Ing. Martin Knorr
Year: 2025

Commissioning of a PVT-WP test rig, implementation and comprehensive evaluation and analysis of test runs
This paper describes the commissioning of a combined PVT heat pump system at the Center for Energy Technology at TU Dresden, which was designed for student training. The system consists of four SOLINK photovoltaic-thermal collectors (PVT collectors). These serve as a heat source for a brine/water heat pump and can simultaneously cover part of the heat pump's electrical requirements. The heat pump charges a combination storage tank that supplies an artificial consumer with heating and domestic hot water. The heating load and domestic hot water profiles of a single-family home are simulated at this artificial consumer.
For this purpose, a calculation program is being developed to create load profiles based on the reference load profiles in accordance with VDI 4655, which should enable the simple creation of any load profiles. The regulation and control of the artificial consumer is implemented, and three variants of the heating load simulation are tested. By balancing the test setup, the measured values are validated, errors are identified, and optimization potential is identified.
Based on the measured values, an energetic and exergetic comparison of the PVT collectors with photovoltaic modules and solar thermal collectors is carried out. In addition, a method for the exergetic evaluation of the PVT heat pump system is presented.
Finally, optimization potentials are derived and recommendations for action are made.
Editor: Richard Michael Hempel
Tutor: Dipl.-Ing. Maximilian Beyer, Dipl.-Ing. Elisabeth Wudenka
Year: 2025

Training of reinforcement learning agents to control a building energy system
This thesis investigated the use of reinforcement learning algorithms for model predictive control of heating systems in private households. The aim was to reduce the energy consumption of space heating while maintaining thermal comfort. Given the high proportion of private households in final energy consumption in Germany, this topic is highly relevant.
A hardware-in-the-loop test bench was used for this purpose. This included a real heat pump and a device for mixing the flow temperature into the building. First, a corresponding simulation model was developed. This then served as a training environment for a reinforcement learning agent. The agent was gradually and systematically introduced to various disturbance variables and changing system conditions using a multi-stage curriculum. This served to increase stability and result quality while reducing training time. The aim was to improve robustness against variable boundary conditions and disturbances.
The results presented show that training with the documented structure can achieve a significant improvement in energy efficiency. In particular, by systematically lowering the flow temperature and operating the heat pump in a more favorable efficiency range, savings of up to 24.6% were achieved compared to classic heating curve control. At the same time, comfort criteria were reliably maintained. The agent's generalizability was improved in particular by training phases with varying weather conditions.
Subsequently, a cost-benefit analysis and the transferability of the learned control strategy to the realtest bench and potential sources of error, such as model simplifications and deviations in parameterization, were discussed. In addition, further approaches to increasing robustness are presented. Further improvement can be expected, in particular through domain randomization with regard to the heat pump model and the modeling of the building, as well as the consideration of partial observability. Overall, the work shows that the use of reinforcement learning in combination with a structured training concept can provide a powerful and robust control approach for heating systems. The results demonstrate high savings potential and underscore the suitability of the approach for future energyefficient and flexible building operation strategies.
Editor: Antonia Johanna Beatrice Spall
Tutor: Dipl.-Ing. Konstantin Wrede (EAS), Dipl.-Ing. Stephan Seidel (EAS), Dr.-Ing. Paul Seidel
Year: 2025

KUEHASystem: Development of a system concept for the retrofitting of the pilot project MFH-WOGETRA-1
This study investigates the energetic boundary conditions of an existing multi-family residential building with the objective of developing and evaluating alternative system concepts for integrating heat pumps into an existing district heating system, including summer space cooling via existing heating surfaces. Based on a thermal building model, heating and cooling loads as well as energy demands were calculated in accordance with relevant standards and compared with measured consumption data. An analysis of the existing heat emitters indicated suitable conditions for reducing system temperatures. Based on these findings, five system variants incorporating air-to-water and water-to-water heat pumps were modelled using the simulation software Polysun and compared with the existing district heating supply as a reference case. For the water-to-water heat pumps, the district heating return flow was used as an energy source, while space cooling was implemented through reversible heat pump operation, with the return flow additionally investigated as a potential heat sink. The assessment was carried out based on final energy consumption, economic performance, and operational greenhouse gas emissions. The results show that the space heating and domestic hot water demand can largely be met in all variants. Air-to-water heat pump configurations achieve the greatest emission reductions, whereas concepts utilizing the district heating return flow demonstrate significant system-level potential for reducing district heating supply temperatures and forward flow demand. Under the assumed energy prices, no economic advantage is achieved compared to the reference system; however, adapted tariff structures for energy extraction from the district heating return flow may improve economic performance. Overall, the results highlight the potential for reducing energy consumption and emissions while also revealing economic and modelling-related limitations of the investigated system concepts.
Editor: Micha Daniel Roder
Tutor: Prof. Dr.-Ing. André Kremonke, M. Eng. Manuel Kornmacher
Year: 2025

Development of simulation models for technical systems of an Urban Digital Twin
Many different factors influence the energy demand within a town or commune. The need for a sustainable energy supply means changes in the energy system and thus requires modeling of changes in the energy demand. This can be done through software solutions that analyze changes in energy consumption regarding different parameters. This paper supplements a pre-existing methodology for determining the energy need of the town Wittichenau by simulation models for technical systems. Multiple models were developed to describe different systems for heat and power generators and the load profiles of different energy needs. They were implemented in the programming language Python. The resulting simulation algorithm was used to determine the influence of specific factors on the energy need through a sensitivity analysis.
Editor: Jan Zschippang
Tutor: Dipl.-Wi.-Ing. Pauline Grun, Dr.-Ing. Paul Seidel
Year: 2025

Thermohydraulic modelling for MILP-based operational optimization of district heating systems
The grid of district heating systems is frequently neglected in standard optimization frameworks. The entire network is simplified as a single node preserving only the aggre- gate of incoming and outgoing heat flows. This thesis aims to find a thermohydraulic model which can be used in mixed-integer linear programming (MILP) and accurately represents the grid behavior. The model should incorporate three criteria: heat losses, pressure loss constraints of pipes, and transportation delays.
The literature analysis reveals that integrating all three criteria within MILP is challen- ging. No model has been found in the literature which solves all three criteria with MILP simultaneously. Therefore, known temperatures in the piping network are assumed to simplify the problem. Based on this assumption, a hydraulic model for MILP is developed to compute mass flows and pressure losses across pipes. This enables the optimization to respect pressure loss constraints. Additionally it’s possible to calculate pressures in the supply and return lines as well as the pressure difference between them. For theoretical investigations the hydraulic model is able to control the network pressure to reach the minimum allowable pressure difference at least at one node. The model was implemented in the Python framework flixOpt and validated against real-world heat distribution network measurements and simulation data.
Editor: Jonathan Gläßer
Tutor: Dr.rer.nat. Peter Stange, Dipl.-Ing. Vera Alieva
Year: 2025

Methodology for determining sustainable energy concepts for buildings
Editor: Jinjin Zhang
Tutor: Dr. Jochen Westhäuser - ECOMIND GmbH, Dipl.-Ing. Jens Kaiser
Year: 2025

Local energy planning - concept development and comparison of a local heating network with a decentralized heat supply
This thesis investigates under which technical and policy conditions a district heating network can contribute to the decarbonisation of heat supply in rural areas, and in which cases decentralised systems represent the more robust and cost-efficient option. The analysis focuses on the town of Wittichenau in the Lausitz region, where the transformation of the heating sector is gaining importance due to the ongoing structural change.
Based on the building-level data from the ZellSys project, the building stock is classified according to construction period, renovation status and the potential for using renewable energy. Representative building archetypes are derived and used as the basis for techno-economic optimisation of decentralised supply concepts using the flixOpt framework.
For the densely built historic town centre, a cost-optimised district heating network is designed using the GIS-based planning tool STEFaN. Three central heat generation concepts are evaluated. All concepts are assessed based on levelised cost of heat and operational CO₂ emissions.
To evaluate long-term viability, scenarios for 2025, 2035 and 2045 are considered, including declining heat demand due to demographic development and energy efficiency measures, as well as rising energy and CO₂ prices. This allows to analyse the performance of central solutions under changing demand and market conditions.
The optimisation results show that heat pump systems combined with photovoltaic generation achieve low heat generation costs and low CO₂ emissions. These decentralised solutions remain cost-stable even under varying electricity prices, making them economically and environmentally advantageous.
District heating concepts, in contrast, show high sensitivity to changes in heat demand. Decreasing loads lead to rising specific costs and reduced economic viability. Their feasibility strongly depends on high connection rates and stable heat consumption. Financial support schemes are therefore crucial, especially for centralised options.
Overall, the results indicate that a district heating network can contribute to decarbonisation in those parts of Wittichenau’s historic centre where decentralised systems face technical or regulatory constraints, such as heritage protection and higher temperature requirements. In the remaining areas, decentralised heat pump solutions represent the more cost-efficient and lower-emission pathway.
Editor: Julius Konstantin Brendel
Tutor: Dipl.-Wi.-Ing. Pauline Grun, Dr.-Ing. Paul Seidel, Dr.rer.nat. Peter Stange
Year: 2025

Simulation of the theoretical energy requirement for the treatment of cleanroom air and comparison with real energy consumption data (digital twin)
The energy demand of cleanroom air conditioning in semiconductor manufactoring is significant due to required high air volume flows, and it depends strongly on outdoor climate conditions. The aim of this thesis is to develop a simulation model for the central air handling unit of the cleanroom. The model should represent the energy demand under real operating conditions in a realistic way, and it should be useable to evaluate different operating strategies.
For this purpose, the system layout, measurement points, and control strategy are analyzed, and measuremnt data from representive winter and summer periods are evaluated. Based on this, a digital twin is implemented in Python as a grey box model. The heat exchangers are described using an Effectiveness NTU approach. The heat transfer coefficient is identified from measurement data, and its dependence on relevant parameters is represented by a regression model. Humidification is modeled as an adiabatic process and limited by boundary values. In summer operation, dehumidification by condensation is additionally considered.
The results show that the model reproduces the cleanroom air conditioning process chain in winter and summer operation in a generally realistic manner. The time profiles of relevant temperature and performance variables largely agree with measurement data. Larger deviations occur for humidification, because the real unit does not operate fully adiabatically. For the cooling coils, deviations appear on the water side, while the energetically relevant cooling provision is still reproduced in a plausible way.
In addition, sensitivity analyses are used to examine the heat exchanger capacity under varying boundary conditions and to identify capacity limits. Based on the validated model, selected operating strategies are also evaluated, including return air mixing and the setpoint control of absolut humidity. Overall, the model is suitable as a tool for simulation of energy demand and for evaluating operating strategies under variable boundary conditions.
Editor: Salah Habib
Tutor: Prof. Dr.-Ing. habil. Joachim Seifert, Dipl.-Ing. Lars Schinke, Dr.-Ing. Thomas Püschel - GlobalFoundries Inc. (GF), Dipl.-Ing. Michael Scharf - GlobalFoundries Inc.
Year: 2025

Modelling of batteries and electric vehicles in design and operational management optimization
Stationary battery storage systems and electric vehicles are steadily gaining importance in the optimization of design and operation of energy systems. However, the existing optimization framework, FlixOpt, only represents their specific characteristics to a limited extent. Against this background, this thesis develops and integrates extended models based on Mixed-Integer Linear Programming (MILP).
The battery model encompasses the dynamics of the State of Energy (SoE) and State of Health (SoH), efficiencies, self-discharge, as well as charging and discharging constraints. Furthermore, degradation effects and deviation penalties are modeled.
The electric vehicle model is based on the fundamental structure of the stationary battery storage system but has been adapted for mobile applications. The implementation constructs a topology of internal charging and discharging nodes that decouple the storage unit from the remaining energy system. Grid connection is subsequently established via location-specific interfaces that account for bidirectional energy flows and usage-dependent availability.
Functionality is validated using parameterized test scenarios. The results demonstrate a consistent reproduction of the implemented constraints and system interdependencies.
Finally, a complex case study demonstrates the utility of the models for investment decisions and the assessment of cost structures. Consequently, this thesis provides a robust foundation for the model-based planning and operation of battery-based energy systems.
Editor: Jun Ma
Tutor: Dr.rer.nat. Peter Stange
Year: 2025

Energy analysis of the Yados Green Factory during the commissioning phase
The present study describes and analyses the energy system of a factory in Hoyerswerda, Saxony, with the background of a climate‑friendly energy supply. First, the structure, boundary conditions, and operating modes of the system are outlined. This is followed by an energetic assessment that points out the overall function of the heating system as well as the interactions between its balance zones and components, thereby identifying existing problems. On this basis, concepts are developed to increase efficiency and to raise the self‑consumed share of the generated solar power.
The analysis in particular enables the identification of loss sources and the causes of inefficient operating states, from which concrete proposals for a more environmentally friendly operation are derived. The thesis thus provides a structured overview of the complex energy system and offers an external perspective on key challenges and potentials in its operation.
Editor: Arthur Schicht
Tutor: Dr.-Ing. Paul Seidel, Dipl.-Ing. Martin Altenburger, M.Eng. Benjamin Zabel - Yados GmbH
Year: 2025

Evaluation of the photovoltaic and solar radiation measurement data on the roof of the ZET
This work examines the measurement data from the photovoltaic system on the roof of the Zentrum für Energietechnik (Center for Energy Engineering) at the Dresden University of Technology, as well as the sensors installed to monitor the system.
To provide easy and clear access to the data in the future, two dashboards in the Grafana visualization tool will be expanded and adapted.
However, the focus of the work is on the plausibility check of the measurement data and the detailed evaluation of the yields and the performance of the system. Based on these analyses, statements about degradation are made. To enable a more precise evaluation, the system is divided into its three sub-systems, which are examined separately and then compared with each other.
Finally, recommendations for sensor inspection and maintenance are formulated. Various possibilities for the future energy use of the photovoltaic system after the end of the current feed-in tariff in 2030 are shown.
Editor: Anton Steinert
Tutor: Dipl.-Ing. Elisabeth Wudenka, Dipl.-Ing. Stefan Hoppe
Year: 2025

Conception of an energy management system across different sites and derivation of a key performance indicator system
This work examines with the development of a cross-site energy management system
(EnMS) for the company "Endress Hauser SICK GmbH+Co. KG", a manufacturer of gas flow
and dust measuring devices with three production sites. The goal is to analyze energy
consumption of the company and assess the requirements for certification according to
the standard DIN EN ISO 50001.
A GAP-analysis identifies existing deficits and develops solutions to meet the
requirements of the standard. A key finding of the study is the lack of suitable energy
performance indicators (EnPIs) for energy assessment, particularly considering the
different manufacturing processes and product portfolios. Despite the differences in
location profiles, a uniform structure of the EnMS with comparable indicators is being
pursued.
The energy analysis is based on data from the building automation system, conducted
measurement campaigns, and extrapolations. The largest energy consumers and their
influencing factors were determined. It is shown that the building infrastructure systems
account for the largest share of total consumption, while the formation of KPIs in the
manufacturing area is made more difficult by the high variety of variants and customer-specific requirements. This requires a compromise between accuracy and practical
implementation.
Additionally, a measurement concept is being developed to record energy consumption
and derive key figures. Two sites already have numerous measuring points, but their
functionality is limited. The GAP analysis shows that the main site already meets the
essential requirements of the standard and that these can largely be transferred to the
other locations. Full implementation of the EnMS requires investment in measurement
technology and additional personnel resources.
Editor: Pia Wetstein
Tutor: Dipl.-Ing. (FH) Bernhard Schindler - Endress+Hauser SICK GmbH+Co.KG (EHS), Prof. Dr.-Ing. Clemens Felsmann
Year: 2025

Layout of the cooling supply of consumers for air conditioning using district heating and lake water from the Lake Constance
In the context of growing demand for cooling concepts in urban areas, this study
examines the design and evaluation of a centralized cold supply systemusing the example
of a new hotel construction project inMeersburg. The objective is to analyze the technical,
economic, and ecological suitability of different supply concepts. Both compression and
absorption chillers are investigated. In addition to conventional cooling towers, the
potential integration of a planned anergy network is evaluated, and photovoltaic systems
are considered as an option for on-site electricity generation. Based on a cooling load
simulation, four supply concepts are systematically dimensioned and analyzed for
economic performance using the net present value method. An ecological assessment is
conducted using primary energy factors and CO₂ equivalents. The results reveal
significant differences in the specific cooling generation costs among the technologies
considered. A combination of a compression chiller with heat rejection via the anergy
network achieves the lowest CO₂ emissions and the lowest specific cooling costs,
estimated at 17 ct/kWh. The absorption chiller combined with the anergy network also
performs well at around 20 ct/kWh. In contrast, systems using conventional cooling
towers show considerably higher costs: 30 ct/kWh for the compression chiller and
approximately double that value for the absorption chiller. This is primarily due to their
reliance on district heating with low efficiency. The high energy demand of absorption
chillers further increases their CO₂ emissions. Overall, the findings demonstrate that
integrating an anergy network provides substantial cost advantages for both compression
and absorption cooling systems, representing the most economically attractive solutions
for the analyzed scenario.
Editor: Eva Harriehausen
Tutor: Dr. Marius Wöhler - Stadtwerke am See GmbH & Co. KG, Prof. Dr.-Ing. André Kremonke
Year: 2025

Application of a heat pump with zeotropic refrigerant mixtures
Editor: Paul Marten Rieche
Tutor: Dipl.-Ing. Michael Wördemann
Year: 2025

Design and optimisation of an innovative heat source system for brine-to-water heat pumps, consisting of ground collectors and photovoltaic-thermal modules (PVT)
In the canton of Zurich, 71 % of multi-family homes are currently heated with fossil fuels. To achieve Switzerland’s net-zero target by 2050, it is essential to replace these systems with low-emission technologies. Heat pumps have been identified as a key component in this transformation. However, the adoption of this technology remains limited, with its current utilization in only 19 % of multi-family homes. An analysis of multi-family homes equipped with heat pumps reveals that 71 % of these residential buildings utilize geothermal probes as a primary heat source. In 24 % of multi-family homes currently heated with fossil fuels, geothermal probes are not approved for reasons of groundwater protection alone. Air/water heat pumps constitute a simple alternative; however, they are not ideal in terms of noise emissions and winter electricity consumption.
This thesis focuses on the subject of heat pump systems and their simulation using Polysun software. A comprehensive analysis of five systems with diverse heat sources is conducted: ambient air, geothermal probes, shallow geothermal collectors, ice storage, and photovoltaic-thermal modules (PVT).
For these systems, the key components were firstly simulated in isolation, and the simulation results were compared with field data. This enabled the calibration of the models and the quantification of their uncertainties. Subsequently, the complete systems were subject to simulation. This analysis revealed greater uncertainties in the systems with PVT and shallow geothermal collectors. The other systems were modeled with a high degree of accuracy. (∆SP F_HP < 0.1)
All systems were then compared with each other in five reference scenarios. A multi- criteria evaluation method was established, which takes technical, economic, and eco- logical indicators into account. This enabled the systems examined to be ranked. The geothermal probe system emerged as the superior option due to its technical superiority, followed by the shallow geothermal collector system and the system with an air/water heat pump, which demonstrated superior economic value.
Motivated by the aforementioned market potential for heat source systems in loca- tions where geothermal probes are not possible, an innovative brine/water heat pump system, TerraSol, consisting of a PVT system and shallow geothermal collectors, was designed and optimized. Degrees of freedom in the dimensioning of PVT systems and shallow geothermal collectors and their interactive effects were identified and presented. The new system is therefore highly flexible and can be customized to suit individual projects. The typical available areas were identified for the canton of Zurich as an example. Compared to other systems, the TerraSol system achieves the second or third best values depending on the scenario and is therefore the best option after the geothermal probe and shallow geothermal collector systems, which have limited availability.
The Polysun templates developed in this thesis, in conjunction with the multi-criteria evaluation method, provide a reliable basis for selecting a heat generator system. Soltop intends to use this basis to further develop the TerraSol system and offer it as a system solution. Furthermore, the templates will be published in Polysun as company standards.
Editor: Friedrich Ohrt
Tutor: Prof. Dr.-Ing. André Kremonke, M. Eng. Manuel Kornmacher, M. Sc. Simon Büttgenbach - SOLTOP Energie AG
Year: 2025

Development of a utilisation concept to enable fulfilment of the greenhouse gas reduction required by RED III for the SachsenEnergie biomethan plant in Haßlau
In order to achieve climate goals, greenhouse gas emissions from energy production must be further reduced. This work examines strategies for reducing greenhouse gases in the production and use of biomethane, taking into account RED III in the production and use of biomethane. The aim is to achieve greenhouse gas reduction while ensuring economical plant operation and enabling the sustainable use of biomethane in accordance with German legislation. To determine the greenhouse gas balance, material and energy balances were created for different supply variants, which differ in terms of the composition of the substrate mixture and the power supply to the biogas plant and biogas upgrading plant. Based on the results, various variants of utilisation for biomethane were identified. These include the previous use within the framework of the Renewable Energy Sources Act and an expansion of the applicability to include heat supply for the city of Dresden. This will enable the energy supply in Dresden to be further decarbonised.
Editor: Katharina Becker
Tutor: Dipl.-Ing. Sven Wegeleben - SachsenEnergie, Ing. Rocco Reichel - SachsenEnergie, Prof. Dr.-Ing. Clemens Felsmann
Year: 2025

Development of a techno-economic evaluation method for suitability testing and optimization of cold heating networks in residential districts
Decarbonizing the heating sector is a key component in achieving climate protection targets. Since more than half of Germany’s final energy consumption is attributed to the provision of heating and cooling, innovative and renewable supply concepts are gaining increasing importance. Fifth-generation district heating and cooling networks (cold district heating networks) represent a promising solution, as they efficiently integrate renewable energy sources and can provide both heating and cooling services.
The objective of this study is the development of a techno-economic method that offers a sound decision-making basis for assessing the suitability of neighborhoods for cold district heating networks. For this purpose, a Key Performance Indicator (KPI) was designed, combining technical and economic criteria into a single dimensionless metric. The methodology is based on simulations of a cold district heating network for two case- study neighborhoods. In a subsequent sensitivity analysis, the influence of six parameters: floor area ratio, building distance, specific heat extraction rate, surface characteristics, building energy efficiency class, and regeneration rate on the levelized cost of heat was determined.
The results show that particularly a high floor area ratio, a high specific extraction rate, and a high specific heat demand have a significant impact on the resulting levelized cost of heat. Based on the findings of the sensitivity analysis, weighting factors and optimal reference values were derived, forming the foundation of the KPI. This KPI enables a comparative evaluation of different neighborhoods and can thus serve as a practice- oriented decision-making tool in early planning phases. In view of the ongoing energy transition, cold district heating networks are expected to gain increasing relevance, with the KPI contributing to strategic decision-making processes.
Editor: Leo Schmitz-Floeder
Tutor: M. Sc. Dominik Güther - TKI Chemnitz, Dr. Matthias Pohler - TKI Chemnitz, Dr.rer.nat. Peter Stange
Year: 2025

Thermal analysis of the heat transfer in the PCM heat exchanger of a thermally driven gas compression system
Phase Change Materials (PCMs) are valued in thermal energy storage for their high latent heat capacity, but their volume change during melting and solidification also offers potential for mechanical energy applications. A novel concept developed at Fraunhofer IFAM Dresden seeks to exploit this property by coupling PCM expansion and contraction to a piston for gas compression. Achieving rapid and repeatable phase transitions is crucial for system efficiency, motivating the integration of thermally conductive porous structures within the PCM to accelerate heat transfer while preserving usable volume for actuation.
This study employs COMSOL Multiphysics to model heat transfer in PCM-based heat exchangers during both charging and discharging cycles. The modeling framework is developed for two 3D geometries—cylindrical and plate-type—with an emphasis on transient thermal behavior, material property variation, and structural influence on melting/solidification rates. Due to persistent numerical instabilities and project time constraints, only the cylindrical configuration was advanced to partial analysis; the planned plate geometry is set up for only CAD model and comprehensive parametric investigations could not be completed. Model verification is performed through plausibility checks against energy balance calculation and mesh convergence studies, ensuring the physical consistency of the results obtained.
The completed simulations provide insight into the transient heat transfer characteristics of the cylindrical PCM heat exchanger and highlight key sensitivities to operating conditions and thermal conductivity enhancement strategies. While full comparative and parametric results are not achieved, the developed modeling approach establishes a foundation for future work aimed at optimizing geometry, materials, and operating conditions for cyclic PCM-driven gas compression systems.
Editor: Syed Arbab Ali Shah
Tutor: Dipl.-Ing. Torsten Seidel - IFAM, Dr.-Ing. Marcus Rohne - IFAM, Dipl.-Ing. Lars Schinke
Year: 2025

Implementation and application of a demand-side-management model in operational optimization
Driven by the advancing climate catastrophe, major efforts are being made to decar- bonize all areas of the energy industry. In the heating sector, one of the main focuses lies with sustainable district heating. As fluctuating renewable energy sources are in- creasingly being tapped for heat generation, demand side management is gaining in relevance alongside energy storage in order to adapt the load to the available heat generation. In addition, optimization is becoming more relevant in order to leverage efficiency potential in operational management.
This thesis develops a model for demand side management in operational management optimization in order to link these two relevant areas. The optimization model enables the most important characteristics of flexible loads to be modeled with low complexity, in particular the possibility of limiting the energy shift in time, incorporating energy losses, and taking comfort losses into account.
The model is then implemented in the FlixOpt optimization framework and used for optimization of the Schönau subnetwork of the Mannheim district heating system. The optimization results are compared with the optimization of a central energy storage. This reveals a comparatively large potential for cost and CO₂ reductions and shorter payback periods compared to the central storage. However, it also becomes apparent that precise parameterization of the model would involve considerable effort, which is why the significance of the optimization results is limited.
Overall, this work presents a powerful tool that offers many possibilities for opera- tional optimization, but is very demanding to use due to the parameterization effort involved.
Editor: Florian Keller
Tutor: Dr.rer.nat. Peter Stange, Dipl.-Ing. Vera Alieva
Year: 2025

Comparison of the refrigerants R32 and R290 with a view to economic efficiency and sustainability in their application
Economic efficiency and sustainability are central aspects for the planning of refrigeration technology. But in practice there is often a lack of time and/or money to run a detailed analysis, which is why only an empirical estimate is possible.
The refrigeration technology of a specific project is examined, with the refrigerants R32 and R290 being available for cooling. During the planning, different technical solutions occur for these two refrigerants. The paper first describes which technical, regulatory, and statutory requirements the refrigerants must fulfill. It shows afterwards which requirements refrigeration technology must meet in the specific project and the resulting technical solutions. These different variants are examined for their economic efficiency based on the VDI 2067. Furthermore, the climate impacts and greenhouse gas emissions caused by these variants are investigated for the aspect of sustainability.
The results of these examinations should show which solution is the most economical or rather the most sustainable in their application and if this knowledge can be used to draw any general conclusions for the application of these two refrigerants.
Editor: Steen Schlosser
Tutor: Udo Henke - Innius DÖ, Dr.-Ing. Paul Seidel
Year: 2025

Development of simplified methods for calculating frost formation and defrosting of air-to-water heat pumps for residential building
At temperatures around the freezing point of water, air-to-water heat pumps can show frost formation on the evaporator, which, together with the corresponding defrosting process, leads to an efficiency loss ∆𝐶𝑂𝑃. This project focuses on developing a method to determine ∆𝐶𝑂𝑃 within the scope of an annual simulation.
For this purpose, the dependencies of ∆𝐶𝑂𝑃 on the outdoor temperature 𝜗_A and relative humidity 𝜑_A are first analyzed within the scope of a literature review and then examined through experimental measurements in the Combined Energy Lab at TU Dresden. The measurement results show a strong dependence on 𝜗_A and 𝜑_A, which this project summarizes. Since deviations in frost formation and the defrosting behavior are observed, two system-specific methods are developed to determine the ∆𝐶𝑂𝑃 of the heat pump installed in the test setup. These methods are then applied and compared in an annual performance calculation.
Finally, this work recommends determining the ∆𝐶𝑂𝑃 in annual simulations using the presented interpolation method based on the measured data points and provides an outlook on potential further improvements.
Editor: Eric Wobst
Tutor: Dr.-Ing. Martin Knorr, Dipl.-Ing. Lars Schinke
Year: 2025

Validation of a thermal storage model and analysis of heat losses using DTS measurement data
As part of the research projects SPICE (temperature field measurement in large heat storage tanks of CHP-based district heating systems as a tool for increasing efficiency) and TWINopt (prediction of temperature field development in large heat storage tanks for integration into network simulation and operational optimization), fiber optic temperature measurement systems (Distributed Temperature Sensing, DTS) were used to continuously record the temporally and spatially resolved temperature distribution in large heat storage tanks. In addition to the DTS systems already in use, this study researched other commercial measuring devices that could be classified as potentially more suitable from a technical and economic point of view.
In the SPICE project, a numerical model was developed to simulate the temperature distribution in heat storage tanks, which is specially designed for 1-zone storage tanks. The model was validated using additional measurement data from defined operating conditions. In addition, the transferability to a 2-zone storage tank was investigated, using corresponding measurement data for comparable operating conditions.
To investigate the thermal losses, fiber optic cables were installed in the area of the foundation in addition to the temperature curves in the storage tank to enable continuous temperature recording with DTS systems there as well. Based on the temperature differences between the underside of the storage tank and the foundation, spatially resolved heat flux densities were calculated, which were used to develop an analytical model to simulate the heat losses via the base plate. The analysis included both historical and current measurement data. The temporal progressions of heat losses derived from this form the basis for the development of measures to reduce thermal losses and increase the energy efficiency of heat stores.
Editor: Thang Tran Xuan
Tutor: Dipl.-Ing. Bogdan Narusavicius, Dipl.-Math. Anja Matthees
Year: 2025

2024

Detection of generation plants based on a load profile (electricity) using intelligent algorithms (B2B)
This study examines the current relevance of existing standard load profiles, as defined by the German Association of Energy and Water Industries (BDEW), based on the load profiles (electricity) of companies with an annual consumption of more than 100 MWh. Additionally, using a clustering method, fuzzy-c-means, the study questions the feasibility of identifying standard load profiles in the commercial sector. The data basis for these companies is also characterized by an annual consumption of more than 100 MWh.
In the second part of the study, the possibility of detecting a PV system based on a given load profile is discussed. A combination of AI models is used to analyze relationships between load profiles and site-specific weather data from medium-sized companies, based on self-selected criteria. The prediction accuracy is examined, and limitations are highlighted.
Editor: Nicolai Steffen
Tutor: Carsten Welge - EnBW, Dr.rer.nat. Peter Stange
Year: 2024

Modelling of innovative substation (iHAST) concepts and their measurement data-based evaluation in an existing district heating network
Along with the european research project NeutralPath, an urban district consisting of multi-family homes with seven substations in the district heating network of the city Dresden has been modernized. The stations were structurally remodeled, networked, and supplemented with various storage units and decentralized electrical heat generators.
Based on measurement data, an energy profile with a focus on the drinking water side was developed, which is used to optimize the heat generators in the python-based optimization framework flixopt. Three of the five individual station concepts were investigated, parameterized, and mathematically modeled to approximate real-world behavior as closely as possible through energy balance optimization.
The goal of the optimization is not only to quantify cost and emission savings potential, but also to test the feasibility of adapted network operation modes in the secondary network. These range from temperature reductions outside of the heating season to the seasonal shutdown of self-sufficient network sections. Such measures require that the affected HASTs are supplied with sufficient and uninterrupted thermal energy for domestic hot water production via the electrical heat generators. In the long term, the station concepts are intended to serve as role models for efficient heat supply with sector integration and emission neutrality.
The evaluations demonstrate theoretical savings potential with optimized operational management, as well as the feasibility of planned grid operating curves. A concept with an air-water heat pump coupled with a photovoltaic system appears particularly advantageous. The increased yields in summer and the improved COP of the heat pump can result in significant savings in costs and emissions. The correct dimensioning of the buffer storage tanks has a significant impact on self-sufficient operational management, ensuring that solar supply is aligned with demand behavior.
Editor: Martin Wiesner
Tutor: Dipl.-Ing. Tiedo Behrends, Dr.rer.nat. Peter Stange, Dipl.-Ing. Johannes Löffler - DREWAG Stadtwerke Dresden GmbH
Year: 2024

Sustainability in building planning: criteria, verification procedures and instruments
According to the ISO 15392 standard, sustainable construction is defined as meeting technical and functional requirements while giving equal consideration to the three aspects of sustainability (economy, ecology and social). The need for sustainable building planning is based on the high greenhouse gas emissions of the construction sector both worldwide and in Germany.
Over time, evaluation systems have been developed to assess the sustainability of buildings. In Germany, the German Sustainable Building Council (DGNB) was created for private buildings and the Assessment System for Sustainable Building (BNB) for federal buildings. Both assessment systems set requirements for maintaining the ecological, economic, socio-cultural, technical and process-related quality of a building. These requirements can vary depending on the type of building and its life cycle.
Based on the two assessment systems, with a stronger focus on the DGNB, planning principles for the building services engineer were developed as part of this project work.
In addition, the use of simulations in the planning phase was assessed and compared with other verification methods such as measurements and calculations.
Editor: Ana Paula Alfonso Fretes
Tutor: Thomas Waurick - INNIUS GTD GmbH Dresden, Dipl.-Ing. Andrea Meinzenbach
Year: 2024

Calculations of excess heat in solar thermal systems and analysis of measures for their utilisation
In summer, the solar thermal system of a residential building usually provides more thermal energy than is required. In systems from Jenni Energietechnik AG, the heat from the solar thermal collectors is stored in a heat storage tank (Swiss Solartank®). The tank allows a maximum operating temperature of 95 ^oC. To protect the antifreeze in the collector fluid and the system components, stagnation operation as a result of an oversupply of thermal energy should be avoided. For this reason, the Jenni control unit ensures night-time re-cooling as soon as the limit of 80 ^oC is exceeded at the lowest temperature sensor of the storage tank. The pump of the collector circuit continues to operate at night so that excess heat is released via the collectors. Recooling reduces the temperature level in the tank to such an extent that a day with maximum solar radiation can follow without the required maximum operating temperature being exceeded.
When designing a solar thermal system, the excess heat generated in summer must be taken into account and it must be ensured that the necessary recooling can take place at night completely. For this reason, an Excel calculation tool was developed as part of this project work, which can be used to estimate the excess heat, depending on relevant influencing parameters, and which evaluates the recooling capability. In addition, the integration of a yield forecast into the control system of the solar thermal system is being discussed in order to optimise recooling operation. Strategies to deal with the surplus heat are discussed in case the night-time recooling of an existing system is not suﬃcient, or if the surplus heat should be utilised in a useful way.
Editor: Lisa Göllner
Tutor: Silvio Bezzola - Jenni Energietechnik, Dipl.-Ing. Elisabeth Wudenka
Year: 2024

Development of a concept for the energetic utilisation of waste heat potential in the Johannstadt campus area
The aim of the study is to determine the potential of waste heat sources at the Johannstadt campus and to analyze the possibilities of energy use both to cover the building’s own needs and to feed it into the district heating network. In the course of the basic investigation, the preferred concept development for two hydraulic systems operated all year round is determined. Other sources of waste heat are not considered, as they are assessed as unsuitable due to insuffi cient operating times, unsuitable load profles or insuffi cient output.
The evaluation of thermal-hydraulic measurements results in a base load level of waste heat of around 40 kW_th that can be decoupled. However, the systems under consideration indicate a strongly fuctuating load behavior, which depends on the utilization of the connected test stands and can reach peak values of up to 240 kW_th. The technical design therefore requires suitability for covering different partial load conditions.
On this basis, the option of proportionally covering the internal demand is primarily investigated. A technical feasibility study shows that it is possible to feed the waste heat into the return fow of the heating system with comparatively little effort. High return temperatures in winter at low outside temperatures are identifed as a challenge, which reduce the possibility of coupling the waste heat into the heating system.
The return feed concept requires the use of a heat pump to make the waste heat usable for energy generation. This results in a COP of 10 for the return fow boost due to the low temperature lift required. Operation as a high-temperature heat pump results in a COP of 2.7 to 4 for a return fow feed.
The economic analysis results in heat production costs of 6.3 to 7.6 ct/kWh for the concept for use for own consumption and 9.2 to 12.3 ct/kWh for the variants for feeding into the district heating network.
The concept for use for own consumption is recommended due to the suitable performance profle of the heat source and sink as well as an advantageous amortization period of 3 to 4 years. In addition, the technical and planning effort is comparatively low, which favors implementation.
Editor: Hendrik Martin
Tutor: Alexander Schneider - Sachsen Energie, Dr.-Ing. Sven Werdin, Dr.-Ing. Karin Rühling
Year: 2024

Systematic approach to testing degasification units in liquid circuits using selected examples
In liquid circulation systems, both dissolved and free gases pose a potential threat to the
operational safety, efficiency, and service life of technical systems. The targeted removal of these gases - particularly dissolved gases - through degassing systems is therefore an essential aspect of system optimization. Various methods and techniques are available for gas removal in liquid circuits. If the solubility limit of the gases is to be undershot in order to extract dissolved gases from the liquid, the use of degassers is required. For the standardized evaluation of degassing performance, the VDI Guideline 4708-2 was developed, which serves as the methodological basis of this study.
As part of this study, a standardized testing procedure for evaluating the performance of degassers was further developed and tested using two vacuum degassers (W11 and W12) at the “Degassing/Diffusion” laboratory test bench. An existing template for test execution as well as a Python script for data analysis were further developed to facilitate ease of use. Additionally, a database was implemented for the structured documentation and comparative evaluation of test results. Furthermore, various measurement methods for determining the gas content in liquids were analyzed and evaluated. The methods currently in use at the “Degassing/Diffusion” test bench - amperometric oxygen measurement and gas chromatography - proved to be the most suitable in terms of accuracy and economic efficiency.
The test results show that increasing the medium temperature leads to improved degassing performance. However, neither of the two tested degassers was able to fully meet the oxygen reduction targets defined in VDI 4708-2. Compared to previous studies, the performance values of degassers W11 and W12 were at the lower end of the spectrum.
The testing and evaluation procedure further developed in the course of this study enables a consistent and comparable assessment of degassing systems in the future.
Furthermore, alternative technologies such as membrane degassers or advanced vacuum degassers can be evaluated in comparison.
Editor: Max Müller
Tutor: Dr.-Ing. Karin Rühling, Ulrike Wagner - AGFW e.V.
Year: 2024

Development and test application of a tool for monitoring district heating systems
SachsenEnergie AG is working towards achieving climate neutrality by 2045, and as part of this effort, the Dresden district heating network is undergoing significant changes. The complexity of the existing network is increasing, for example, due to the expansion of decentralized heat generators, leading to a growing number of tasks. To address this, a digital tool has been developed for monitoring and analyzing the district heating network. The tool is based on the large number of measurement points from the EU “NeutralPath” project, which provided a significant amount of measurement data. The developed system differentiates between evaluative and descriptive methods to partially automate the analysis by linking causes and effects. The tool was tested on a model of the EU project area, and recommendations were made for extending it to the entire district heating network. This digital tool aims to simplify monitoring and analysis, supporting the transition to climate neutrality.
Editor: Max Hamann
Tutor: Dipl.-Ing. Jonas Schmidt - SachsenEnergie, Dipl.-Ing. Tiedo Behrends
Year: 2024

Empirical analysis of building-side load management in district heating networks
When operating a district heating network, large load fluctuations and high return temperatures are a major challenge, as they reduce the efficiency of the heat supply. In this thesis, the demand side management approach to deal with this problem is examined empirically in more detail. After analyzing two previous heating periods, various aspects and approaches of demand side management are discussed. Based on this, improvement measures are designed and their consequences estimated. Subsequently, these measures are implemented in a six-week test run and the results are compared with the measurement data from previous heating periods. The focus is on the changed load profile and its peak value, the energy consumption and the flow and return temperatures that occur.
The results show that staggered heating operation can both reduce the occurring peak loads and postpone them, while also reducing energy consumption. However, there is still a significant difference between Mondays, when significantly higher loads occur, and the other days of the week. The supply and return temperatures in the heating circuit can be reduced slightly for low outside temperatures, but they increase significantly for high outside temperatures. Overall, staggered heating operation is recommended, as the results are predominantly positive, but there is still potential for improvement.
Editor: Konrad Rottscholl
Tutor: Dipl.-Wi.Ing. Laura Lehmann
Year: 2024

Creation of a heat utilisation concept for the biogas plant in Dresden-Klotzsche including economic evaluation
One possible option for decarbonizing the electricity and heat supply is to replace fossil natural gas with fuel gases of biogenic origin. The use of biogas is very advantageous due to its good availability and the possibility of an efficient circular economy. In order to make the best possible use of the existing biogas plant in Dresden-Klotzsche, a series of key figures were drawn up in this work after a detailed presentation of the plant components, with the help of which various measures for optimizing the plant were evaluated from an energy and system technology point of view and at the same time comparisons with target figures (e.g. for the feeding-quantity) were made possible. From an economic point of view, the measures were checked by means of a profitability calculation. Consideration was also given to the future of the system.
It became clear that comparing the key figures with the accumulated experience of other plants can be very helpful for efficient operational management by the operating team. The investment calculation also provided evidence of clear economic advantages for some measures.
The investigation of the Dresden-Klotzsche biogas plant revealed promising advantages in the expansion of the plant to increase efficiency. These expansions allow the decarbonization of Saxony's electricity and district heating networks to be driven forward.
Editor: Saghi Vaziri
Tutor: Sven Wegeleben – SachsenEnergie AG, Steffen Füssel – SachsenEnergie AG
Year: 2024

Evaluation of serial housing construction (apartment buildings)
This thesis is dedicated to the topic of serial residential construction in the context of multi-family housing. The primary focus of this study is twofold: first, to examine the technical building equipment (TGA) employed in this field, and second, to assess the supply of apartments via prefabricated installation shafts. The present study commences with a comprehensive introduction to the components of serial residential construction and a historical overview. Subsequently, it delves into a select group of manufacturers, including the company Gropyus, which serves as a practical example of how serial installation solutions work. The legal framework conditions that specifically affect serial construction are also briefly described.
The primary focus of this work is the analysis of prefabricated installation shafts and their integration into the serial construction process. In particular, riser shafts and bathing cells from Gropyus serve as a case study. A specific construction project is selected for the purpose of evaluating the economic efficiency of prefabrication in comparison with conventional on-site installation methods. The analysis encompasses a meticulous examination of the planning phase, underpinned by the fee structure for architects and engineers, and the execution phase, substantiated by empirical data. The analysis places particular emphasis on cost and production structures, as well as construction time.
To further refine the findings, a comparative analysis is conducted between the two distinct construction methodologies employing well-defined comparison criteria. The central finding of the study indicates that the cost-effectiveness of prefabrication compared to on-site assembly is heavily dependent on project-specific factors. When evaluated against other criteria, such as construction time, flexibility, or quality, no general advanta-ges of either method could be identified. Instead, a customized, case-by-case assessment is imperative for identifying the most suitable method.
Editor: Manuel Haunschild
Tutor: Erik Weise (Fa. Gropyus Solutions GmbH)
Year: 2024

Possible applications, design and operation of baseboard heaters
This paper examines the potential applications, design and operation of baseboard heating systems as an efficient and sustainable heating solution for residential and commercial buildings. Highlighting the market overview and comparison of baseboard heating systems, including their history, technological developments and regulatory framework. In addition, the different types of baseboard heating systems, such as electric and water-based systems, are analyzed and their advantages and disadvantages are discussed. The work also focuses on the design and operation of baseboard heating systems, including hydraulic balancing, control technology and integration into existing heating systems. Special emphasis is placed on analyzing the design of baseboard heaters and their ability to achieve efficient heat distribution. Baseboard heating systems are an efficient and sustainable heating solution that can be used in both new buildings and renovations. The work provides a comprehensive overview of the possible applications, design and operation of baseboard heating systems and can serve as a basis for further research and applications in this area.
Editor: Stephan Beitlich
Tutor: Prof. Dr.-Ing. Clemens Felsmann
Year: 2024

Development of a model predictive control of a battery energy storage system in combination with PV generation and electrical load
In this diploma thesis, a multi-stage model-predictive operation management system was
developed for PV battery storage systems in the industrial sector. The aim of this development was to increase economic efficiency by reducing electricity procurement costs. To this end, the objectives of self-consumption optimisation and peak load capping were pursued, and a special feature of the development is the consideration of the full load hour-dependent structure of the grid charges. The developed operational management was analysed and evaluated by means of simulation-based investigations for an example location.The operational management was compared with the results of priority-based operational management and optimum peak load capping.The simulations were carried out with the commercial solver Gurobi and the open source solver HiGHS.The results show that the operational management is able to optimally combine both objectives. However, it also became clear that compliance with the specified peak load cannot always be guaranteed when the optimisation horizon is varied.The Gurobi solver proved to be significantly more efficient and delivered more reliable results than HiGHS.Realistic forecasts should be used for further investigations, as only perfect forecasts have been used to date.
Editor: Josua Palmstedt
Tutor: Manuel Kersic - TRICERA energy GmbH, Dr.rer.nat. Peter Stange
Year: 2024

Considerations on the energy efficiency of heating and ventilation systems in a non-residential building
Concepts to change the heat source of a church to renewable energy are developed. The church in question is heated by an air heater with a power of 100 kW and a community centre in the same building. The community centre is freshly renovated. It is designed to only require a flow temperature of 45 °C as per design data.
The church is being simulated with the help of a Beuken-model. An investigation is conducted to determine whether the flow temperature of the air heater can be lowered to such a degree that renewable energy, respectively a heat pump, can be used. This is the case under the condition that the present heating behaviour is changed and automated.
The four concepts presented each include a heat pump and a system of solar panels. The panels are favourable because of the orientation of the church and because of the wide roof. The heat sources of the heat pump are different in each concept.
Two of the concepts use the ground as a heat source. Both concepts have large investment costs but cannot make up for those costs in an increase in efficiency. This leads to high amortisation periods. The concepts with air respectively air and solar radiation as heat sources have lower investment costs and barely lower efficiency. This is the reason they have lower amortisation periods.
This project includes an Excel spreadsheet which calculates the results. The conditions are editable to accommodate future changes.
Editor: Hendrik Pohl
Tutor: Dr. Markus Müller, Dr.-Ing. Martin Knorr
Year: 2024

Use of direct electric heat generators in rural areas and small towns for sector coupling of electricity and heating grids
This thesis examines the possible uses of direct electric heat generators in rural heating networks. Both the marketing options on the spot market and on the balancing power market as weil as possible uses of locally generated electricity from renewable energies are examined. The study initially focuses on four heating networks operated by SachsenEnergie in Weigsdorf-Köblitz, Königswartha, Zeithain and Nünchritz, which are analyzed in more detail with regard to their future heat generation as described in transformation plans.
First of all, models are created for each of the four rural heating networks in which the heat generators are mapped. With the help of the investment and deployment optimization tool flixüpt, an optimization is then carried out in order to obtain a reference. ßy adding a direct electric heat generator, possible applications are derived in comparison with the reference. Various scenarios are considered in which the assumed costs for electricity procurement and the gaseous energy sources used are varied. lt is shown that the economic operation of a direct electric heat generator is a challenge due to the high costs of electricity procurement from the grid. Existing connection options to the mediumvoltage grid represent a clear advantage for the location.
Marketing as balancing power can facilitate economic operation, but it is crucial that the additional costs incurred for prequalification and marketing expenses are covered by revenues on the balancing power market. However, as this market is volatile, this marketing option carries an economic risk.
In addition, the knowledge gained will be extended to other existing and future heating networks in SachsenEnergie's supply area in the context of municipal heating planning. In addition, possible uses of surplus electricity from local renewable generation plants are being investigated. lt turns out that the technical potential for this use is available in the near future and that the use of surplus electricity from existing photovoltaic systems in particular represents an economically viable option under favorable integration conditions.
lt has been shown that usage is economically feasible under certain boundary conditions. This work thus provides a basis for considering the use of direct electric heat generators in heating networks. In addition, the models created offer a useful basis for the further planning of future heat generation in the four heating networks under consideration.
Editor: Daniel Raschke
Tutor: Alexander Schneider - SachsenEnergie AG, Prof. Dr.-Ing. Clemens Felsmann
Year: 2024

Development of a concept for managing measurement data in test benches
The collection of measurement data in test benches is imperative to ensure the functionality of machines and to facilitate the acquisition of further knowledge. Measured values are typically stored in files or relational databases. In recent years, there has been a proliferation of specialized time series databases that assign a time stamp to measurement points.
The present study investigates the potential for the structured storage and retrieval of measurement data from a heat pump test bench using these specialized databases. In this context, a comparative analysis is conducted between selected databases and potential data models with regard to their capacity to store time series and metadata. The integration of these databases into existing test benches is then examined through the presentation of implementation examples.
The results of this work demonstrate the efficacy of integrating a time series database within test benches and highlight the potential for structured queries and visualizations to facilitate further evaluation methods. However, challenges emerge in the integration of further evaluations and the enhancement of user-friendliness.
Editor: Parssa Feizi
Tutor: Dipl.-Ing. (FH) J. Jirschitzka - ILK, Dr.-Ing. Paul Seidel
Year: 2024

Validation of a 1D-passenger compartment simulation model for a fuel cell traction unit
In the present work the validation of a 1D-simulation model of the passenger compartment of a fuel cell train is carried out. The results of the simulation are therefore compared to the values measured at a test stand consisting of a 1:1 mockup of the passenger compartment of a regional train with 16 seats. The simulation model calculates the mean air temperature of the passenger compartment by balancing the occurring heat flows, as well as the mean radiant temperature of the enclosing surfaces via an area-related weighting of the surface temperatures. The combination of these values results in the operative temperature, which can be used as a simplified measure to assess the thermal comfort of the passengers. It therefore acts as a control variable for the climate control system consisting of an air conditioning unit and a surface heating and cooling system.
Since the operative temperature can be measured directly using a globe thermometer, the variable is also suitable as a reference value for validating the calculated mean radiant temperature. In order to be able to evaluate only the influence of the mean radiant temperature calculation, it is necessary to specify the measured air temperature in this case. Accordingly, the validation as well as the derivation of possible model adjustments is carried out separately for air temperature and mean radiant temperature.
The comparison of the results shows that the model underestimates the mean radiant temperature of the enclosing surfaces. By adapting the calculation, a significant improvement in the results and thus an increase in model quality can be achieved. Due to the measurement set-up, the air temperature can only be validated regarding the internal heat transfer. Consequently, some adjustments to the simulation model are necessary. In this case the comparison of the results already shows good agreement between the measured values and the calculation.
Editor: Till Mauksch
Tutor: Dipl.-Ing. Max Schott - HÖRMANN Vehicle Engineering GmbH, Dr.-Ing. Martin Knorr
Year: 2024

Considerations on hydraulic balancing using a practical example
The following text summarizes procedures and methods of hydronic balancing that are given in current standards. Legislative demands of the German Buildings Energy Act (GEG) and the procedure B of the specialist regulation of the German Central Association Plumbing, Heating and Air Conditioning (ZVHSK) are specified.
As part of an internship in an engineering office, a practical hydronic balancing was conducted for an exemplary object in Berlin. From this, insights and general recommendations for the overall approach and incremental conduction of a balancing, including all calculations and an inventory are derived. They could reduce the outlay for future projects or beginners in the thematic area.
Furthermore, the impact of a lack of hydronic balancing is illustrated by approximative calculation of an unbalanced circuit. Given that common planning software for calculation and dimensioning of piping does not provide information about a lack of balancing, a new calculation scheme is developed. This calculates the mass flow of unbalanced circuits in the exemplary object, which allows for inferences about the oversupply of the radiator and the additional power requirements in support of the mass flow.
Additionally, the capital and installation expenditure are evaluated for the exemplary object. Costs for different procedures, and expenditure of time for planning and installation are considered.
Editor: Jan Zschippang
Examiner Prof. Dr.-Ing. Clemens Felsmann, Prof. Dr.-Ing. André Kremonke
Year: 2024

Considerations on the integration of aquifer heat storage into the heat supply system
The ongoing transformation processes in the energy sector will further increase the volatility and seasonal load shifting in heat production in the future. In order to ensure an efficient and sustainable heat supply, the integration of thermal storage systems into existing infrastructures is becoming increasingly important. High-temperature aquifer heat storage systems (HT-ATES) offer considerable potential in this context, as they enable the efficient integration of renewable heat sources into the heat supply infrastructure by seasonally balancing heat production and demand. This technology is characterised by its high storage capacity as well as its cost-effective and efficient operation. They are also particularly suitable for use in urban areas due to their underground utilisation.
Despite their promising potential, HT-ATES have so far only been used to a limited extent. This study therefore analyses existing application examples in order to identify challenges and risks. It shows that a detailed consideration of the site-specific underground and above-ground conditions is essential. In addition, technical problems should be addressed at an early stage in order to ensure cost-effective operation. The characteristics of a suitable district heating network were analysed using the example of the Berlin ‘GeoSpeicher’ real-world laboratory and an outlook on the future development of district heating supply was provided. The results make it clear that a seasonal shift in heat demand is necessary to enable sufficient storage volumes. At the same time, a sufficiently large consumer structure is required, as the storage temperatures are significantly influenced by the requirements of the district heating network.
Based on a simplified modelling of the HT-ATES behaviour, two integration concepts were developed within the TRNSYS-TUD simulation environment and three scenarios were analysed with regard to maximum storage temperatures and the type of heat extraction. The results show that integration with an additional heat pump is the most efficient solution, even if direct heat extraction is technically possible at storage temperatures above 50 °C. The temperature difference between the cold and hot well is crucial for particularly efficient operation. Ideally, the cold well is cooled down to the natural ambient temperature in order to minimise heat losses and increase the overall efficiency.
To summarise, this study concludes that aquifer heat storage systems are a promising technology for sustainable energy supply and can therefore make an important contribution to the transformation process. Their future development requires further research and increased practical implementation.
Editor: Anna von Heimburg
Tutor: Dipl.-Ing. Kevin Bock, Dipl.-Wi.Ing. Laura Lehmann
Year: 2024

Development of a controller for hybrid heat generation systems
The present work investigates the possibilities of hybrid heat supply based on the use of a heat pump and a biomass generator, based on the trend of hybridization of heat supply in the building sector as well as the energy and cost-efficient use of energy sources. Based on a hydraulic diagram developed for a given model building, a control algorithm for a system-wide controller was developed. The system controller realizes the coordinated operation of a heat pump and a pellet boiler, which are connected to each other via a combination of series and parallel connections and linked via a buffer storage. The controller is based on the evaluation of the heat generator, which is based on minimizing the costs incurred.
Particular attention was paid to the integration of the pellet boiler. The biomass-based generator has technical boundary conditions that must be taken into account in the control algorithm. The extended control functionality was tested in detail within several simulation variants. For this purpose, the system controller was linked to the building simulation and the pellet boiler model and then tested analogously to the software-in- the-loop method.
The investigations included analyses of the efficiency values achieved by the generators and the operating costs incurred. The investigations showed, among other things, that the pellet boiler is the preferred heat generator, taking into account the environmental and boundary conditions, which covers the heat demand more cost-effectively. The electricity purchase price makes the use of the heat pump uneconomical compared to operating the pellet boiler with the associated pellet price per kWh. In addition, operating modes and influencing factors were determined under which the use of the pellet boiler is particularly efficient.
Editor: Luzie Mosig
Tutor: Prof. Dr.-Ing. habil. Joachim Seifert, Dr.-Ing. Martin Knorr, Dipl.-Ing. Maximilian Beyer
Year: 2024

Development of a scalable interface system with automated optimization of EEG systems
In recent years, the share of energy generated from renewable sources has steadily
increased. Consequently, the impact of weather on the electricity supplied to the grid
has grown, influencing electricity pricing — particularly in short-term markets — and
resulting in negative electricity prices. To address this issue, it is essential to adjust
controllable energy generation so that it feeds into the grid during periods of high
electricity prices and withholds energy when prices are low.
This thesis presents the development of an interface system designed to optimize the
feed-in compensation of EEG plants, with a particular focus on optimizing the operation
schedule of biogas plants. The optimization is based on electricity price forecasts,
which serve as the key boundary condition. The interface system, written in Python, is
intended to serve three main functions: retrieving data for optimization, interacting with
the optimization framework, and exporting the optimized scheduling data. Additionally,
a user interface is developed to facilitate user interaction.
The choice of an appropriate solver and optimization framework is guided by the creation
of a Pugh matrix, where relevant criteria are determined and weighted according to
their importance. As a result, the optimization framework FlixOpt and the solver
Gurobi were selected.
Next, the interface system is implemented, with the required classes defined and their
specifications established. This includes determining which constraints need to be
transferred for schedule optimization and how these constraints are formulated. Given
that up to 1000 power plants are anticipated to be integrated into the interface system,
a database is also set up to manage the data efficiently.
Finally, the system’s functionality is tested. For example, a real power plant is created
within the system, and its schedule is optimized for a week. The optimization results
and implementation procedure are compared to an existing optimization system. The
findings indicate that the interface system can perform the optimization efficiently and
generate higher revenues based on the optimized schedule. Additionally, when 1000
sample power plants (including faulty ones) were created within the interface system,
it demonstrated its capacity to function effectively under such conditions, with faulty
plants having no adverse impact on its performance.
Editor: Robin Böhm
Tutor: Martin Frohs - Sachsen Energie, Dr.rer.nat. Peter Stange
Year: 2024

Investigations into the design of clean rooms in microelectronics
The existing ventilation and air conditioning infrastructure in Infineon Dresden's Building 32 was analysed and an optimized supply situation for the clean rooms was developed as part of this internship project. The focus was on the thermal and volumetric flow load calculation as a basis for the further development and adaptation of the existing ventilation systems.
The analysis of the current supply situation revealed that the existing ventilation systems were no longer fully sufficient due to increased requirements resulting from new production facilities and structural changes. Maintaining the cleanliness class in accordance with ISO 14644 was a particular challenge. To ensure uniform air distribution and avoid the risk of contamination from neighboring areas, an overpressure concept was developed. This prevents the cleanrooms from drawing in air from adjacent areas and allowing particles or contaminants to enter.
Based on comprehensive thermal and volumetric load calculations, the necessary supply air and exhaust air capacity was determined in order to ensure stable and efficient air conditioning. The calculations showed that the air volumes needed to be adjusted to avoid underpressurisation. Both the process exhaust air and the internal heat loads were taken into account. Precise coordination of the supply air and exhaust air flows ensured that the desired pressure balance was maintained in the cleanroom.
Various measures were developed to optimise the ventilation system. These include the implementation of energy-efficient cross-flow heat exchangers, the integration of modern high-pressure humidification systems and the introduction of a central control unit to regulate the air flows as required. In addition, improved air balancing was carried out to ensure a stable indoor climate with constant temperature and humidity.
The calculations and planning carried out offer a long-term solution for the energy-efficient and standard-compliant air conditioning of clean rooms. The optimised system design creates a stable basis for future expansions and ensures reliable compliance with cleanliness and pressure requirements. The knowledge gained also provides valuable application examples for further infrastructure measures in the field of cleanroom technology.
Editor: Selin Sari
Tutor: Prof. Dr.-Ing. habil. Joachim Seifert, Dipl.-Ing. Lars Schinke, Klaus Ogiermann - Manager Process Dresden ATF
Year: 2024

Conception and evaluation of energy supply and energy saving measures for a football stadium
Oschatz Football Club is aiming to reduce its greenhouse gas emissions and become less dependent of energy suppliers. To this end, a feasibility study is being carried out to analyse both efficiency measures and the transformation of the energy system to integrate renewable energy.
The first step is to analyse the existing energy system in order to determine electricity and heat load profiles. The energy and cost savings from converting the existing floodlight system to LED technology are then calculated and potential photovoltaic systems on the roofs of the club buildings are simulated. The current energy supply via the electricity grid and a natural gas boiler is compared with three alternative supply options:

rooftop solar system with electric heating and thermal storage
rooftop solar system with air-to-water heat pump and storage tank
rooftop solar system with battery storage, air-to-water heat pump and storage tank.

The options are evaluated on the basis of energy consumption, environmental and economic aspects. As a result, Option 3 is recommended as the preferred option as it provides the greatest reduction in greenhouse gas emissions while being economically viable.
Editor: Laurin Schmid
Tutor: Clemens Schmitt - GICON®-Großmann Ingenieur Consult GmbH
Year: 2024

Evaluation of the practicability of optimization-based controls in heat supply of a residential complex with CHP and geothermal heat pump
In this thesis, the practicability of optimisation-based control systems in a heat supply
system for a 70-party residential complex is investigated using simulation. The energy
system consists of a combined heat and power unit, a brine-to-water heat pump, a
condensing boiler and two stratified storage tanks. At the beginning, the basic technical
knowledge in the areas of building automation, system technology and optimisation
is outlined, followed by a description of the optimisation and simulation model of the
system and its conventional system control. The OptiLink program is then designed
and implemented, which carries out the transfer of the optimisation results of the
energy node model into practical setpoint signals as automatically and generalised as
possible. Technical requirements for the system technology are taken into account and
the technical admissibility of the system status is checked in a parallel simulation. The
first approach examines the special case in which the interfaces of optimisation and
building automation differ. The performance specifications of the system schedule are
reduced to a storage setpoint temperature for integration into a rule-based control
system. In the second approach, the case is examined in which the interfaces between
the optimisation and the building automation correspond, i. h. the result variables of
the optimisation become the input variables of the building automation. The behaviour
of the real system with different control strategies is simulated by a final control model.
The validation shows that a lot of optimisation potential is lost with the first control
approach and that further investigations are necessary. The second control approach
proves that the performance specifications of the optimisation can be implemented
precisely. The control of the storage tank balancing pump works apart from deviations
due to an imperfect forecast of the optimisation model. This confirms that control using
OptiLink is significantly dependent on the quality of the optimisation model. In summary,
however, it can be stated that OptiLink can be used to transfer the optimisation-based
control into system signals in a generalised manner and in real time, taking into account
some practical requirements.
Editor: Richard Sturz
Tutor: Dipl.-Ing. Torsten Schwan - EA Systems Dresden GmbH, Dr.rer.nat. Peter Stange
Year: 2024

Investigations to optimize the reference pressure measurement - and evaluation in an extensive factory building
This work encompasses the investigation and optimization of reference pressure measurement in a building of a semiconductor factory. The objective of the work was to analyse the influences on a reference pressure pipe, given that these have a direct impact on the functionality of the systems connected to the pipe and can affect the control stability of these systems. As part of this work, the GlobalFoundries cleanroom and its ventilation system were described, with particular attention paid to the underlying mechanical and control aspects.
The analysis was based on the existing measurement system’s data, which were utilized to evaluate the issue of pressure fluctuations on windy days. To structure and analyze the data effectively, a visualization tool was developed, which provides an organized display of the data and enables detailed evaluation. This tool was instrumental in identifying and confirming the cause of pressure fluctuations within the systems.
In this investigation, the factors influencing the reference pressure pipe and the pressure measurement were analyzed in detail over various days throughout the year. Based on the findings, mechanical improvements were considered to mitigate the effects of wind on the existing reference pressure pipe. Additionally, optimization opportunities for the design of the reference pressure pipe and its inlet points were explored. Complementary to these measures, potential control engineering improvements to the measurement
devices were proposed.
Finally, a general solution approach was formulated, integrating the individual partial solutions to ensure a comprehensive optimization of the reference pressure measurement. The findings of the study were summarized, and an outlook on potential further research and optimization measures was provided.
Editor: Salah Habib
Tutor: Prof. Dr.-Ing. habil. Joachim Seifert, Dipl.-Ing. Lars Schinke, Dr.-Ing. Thomas Püschel – GlobalFoundris (GF®), Dipl.-Ing. Michael Scharf – GlobalFoundris (GF®)
Year: 2024

Optimization of the energy supply concept for a new housing estate
The aim of this thesis is to design an optimized energy concept for the supply of a new housing estate with 21 houses under construction on the basis of electricity from a photovoltaic system with an output of approx. 1 MWp. To this end, an optimization calculation is to be carried out using the flixOpt optimization framework and then evaluated.
For this purpose, the framework conditions of the project are first explained and possibilities and limitations are described. This is followed by the design of an energy concept, which includes centralized and decentralized battery storage systems. The overall energy concept also includes a local heat supply, a hydrogen storage pathway and the use of decentralized storage systems located in the individual houses. In addition, a decentralized heat supply for the houses via heat pumps should be an option. Data is then researched and calculated for the energy concept so that it can be modeled in flixOpt. In this process, load forecasts are made for the electricity and heating requirements of the new housing estate. Also an existing yield forecast for the PV system is compared with real generation data for the same. After allocating the costs incurred for investment, operation and energy, a cost optimization target is set for the district. Due to excessive calculation times, the problem is reduced with the help of logical considerations and calculations. Optimization calculations are then carried out using the developed model, evaluated and discussed. The results obtained are evaluated and recommendations are made for implementing the energy concept.
The final recommendation is to equip the resulting houses with air source heat pumps and, depending on the energy requirements, to check individually whether it makes sense to invest in a heat storage system. Further optimization calculations are to be carried out in the future in order to achieve more reliable results.
Editor: Justus Jonas Kerlin
Tutor: Dr.rer.nat. Peter Stange, Dipl.-Ing. Tiedo Behrends
Year: 2024

Analysis of the utilisation of condensation enthalpy in the exhaust air system in the drying section of paper machines
The paper industry is one of the most energy-intensive sectors of the economy and is facing major challenges due to climate change and new climate protection requirements. In particular, the drying of paper webs requires large amounts of energy, but at the same time offers considerable potential for energy savings through heat recovery. This study investigates how the enthalpy of condensation from the moist exhaust air of the drying section of paper machines can be utilised to increase energy efficiency.
In order to fulfil this aim, the process air system was analysed using an R&I flow diagram, and a measurement concept was developed to record the enthalpy flows. The process and measurement data (relative humidity and temperature) were transmitted in real time and processed for a digital energy balance model, which confirms the potential of heat recovery. The result shows that a large proportion of the energy used is contained in the exhaust air, which opens up opportunities for optimising process control.
Recommendations for further investigations include an extension of the measurement to other air flows and a fundamental review of the indoor climate system. Controlled humidity regulation could make the heating energy used to date available for vapour recovery in the future. Overall, this work contributes to the improvement of energy efficiency and sustainability in paper production.
Editor: Florian Günther
Tutor: Prof. Dr.-Ing. habil. Joachim Seifert, Dr. Hagen Hilse - GICON
Year: 2024

Analysis of a cellular energy system in suburban areas using the example of the town of Schwarzkollm
This thesis focuses on building-specific energy demand assessment using the example of the village of Schwarzkollm. The methodological approach is based on the aggregation of publicly available geodata in a geoinformation system in combination with local expert knowledge, whereby various energy -relevant parameters are integrated. The spatial visualisation of the results is carried out using a heat atlas as weil as heat and electrical energy heat maps. A central aspect of the work is the forecast of heat demand up to 2035, which takes into account demographic trends, vacancy dynamics and the renovation rate. The modelling is based on a multi-stage approach that integrates both statistical and empirical data. Finally, specific recommendations for action for the implementation of a sustainable energy system in Schwarzkollm are developed in the context of municipal energy planning. A critical analysis and further development of the concept study on local heating supply presented by Viessmann completes the investigation and identifies optimisation potential for practical implementation.
Editor: Jennifer Peine
Tutor: Dipl.-Wi.-Ing. Pauline Grun, Dr.-Ing. Paul Seidel, Michael Boch - "IGES" Interessengemeinschaft Energieversorgung Schwarzkollm
Year: 2024

Automated classification of technical building equipment data points based on time series
Decarbonizing the building sector is essential for achieving climate goals, particularly given the inefficient operation of many existing buildings. The use of software-based energy-saving applications such as energy monitoring, predictive maintenance, or digital twins requires detailed semantic descriptions of building energy systems. However, this information is often unavailable or must be collected manually, which is time-consuming and error-prone.
This study develops a comprehensive approach for metadata inference in HVAC systems, aimed at generating system knowledge graphs using machine learning. Two information sources - data point names and time series - were integrated to classify data point types and identify their functional and spatial relationships. For data point type classification, two methods were utilized: a time-series-based classification model and a neural language model that classifies data point names.
For functional relationships, a methodology was developed that relies exclusively on time- series analysis. Spatial relationships were identified using a neural language model functioning as a binary classifier. An ensemble learning approach was employed to improve the accuracy of data point type classification. The approach was evaluated using the open-source dataset MORTAR, demonstrating the feasibility and potential of this method for the semantic modeling of building energy systems.
The results demonstrate an F1 score of 99 % for datapoint type classification, with perfect classification across the five specific datapoint types. Classification of spatial relationships achieves 93%, although a notable challenge is the prevalence of false positives. Functional relationships are correctly identified at a rate of 79%, indicating challenges in this area. Nevertheless, issues remain regarding data diversity, the accuracy of relationship classification, and the extension to additional classes and components. This work highlights the feasibility of automated knowledge graph generation for building energy systems but underscores the need for further optimizations to enhance robustness and expand the application scope.
Editor: Hüseyin Tokul
Tutor: Dr. Andreas Wilde - EAS, Dr.rer.nat. Peter Stange
Year: 2024

Experimental investigation on a thermosyphon
A thermosyphon with a height of h_TS = 1800 mm was constructed at the Institut für Luft und Kältetechnik Dresden (ILK) for the experimental investigation on thermodynamic parameters of a thermosyphon. In order to simulate isothermal operation, the evaporator and condenser were connected to water circuits for the test. The modular evaporator was equipped with various modifications. These are a SiO₂ suspension, a coil spring and a stent. The recorded values were analysed using a script and compared with the reference measurement series on H₂O.
The suspension achieved a significant reduction in thermal resistance in the range Qp_e ≤ 200 W. The coil spring and the stent only slightly reduced the thermal resistance over the entire observed range. Furthermore, the formation of geyser cycles when using the suspension could only be observed at higher operating temperatures, while a spring suppressed them completely.
To investigate the effects of individual modifications, the evaporator was cut open and photographed after the series of measurements. In addition, the working fluids from the inner evaporator were also analysed for copper, iron and silicon using mass spectrometry.
Editor: Lukas Reinecke
Tutor: PD Dr.-Ing.habil. Matthias H. Buschmann - ILK Dresden gGmbH, Prof. Dr.-Ing. Clemens Felsmann, Dr.-Ing. Markus Rösler
Year: 2024

Analysis of energy flows and development of resulting optimisation proposals for the Dresden-Klotzsche fermentation plant
In recent years, the relevance of sustainable energy production and efficient waste management has increased significantly. In this context, biogas plants are of central importance, as they not only contribute to the production of renewable energy but are also an essential part of the circular economy. Although biowaste is already being industrially recycled on a large scale and the biogas produced in biogas plants already makes a reliable contribution to Germany's energy supply, there is still considerable untapped potential for optimizing waste streams and biogas use.
This paper analyses the current challenges and opportunities in the field of biogas plants in the context of waste and recycling management with the aim of demonstrating the diversity of optimization possibilities. The results presented are illustrated using the biowaste fermentation plant of MVV Umwelt GmbH. The focus of the study is on presenting the possibilities for increasing biomethane production and tapping further optimization potential through a detailed analysis of the operating processes. Particular attention is paid to the plant's heat supply. The evaluation of operating data and the modeling of the heating system are used to develop options for increasing the efficiency of the current operation and reducing the proportion of unused heat. Furthermore, alternative heat generators are included in the analysis, as they have the potential to reduce the biogas demand and thus increase biomethane production. The aim of this study is to identify measures that are suitable for increasing the efficiency and profitability of biogas plants and thus maximizing their contribution to the energy supply in terms of the circular economy.
Editor: Richard Michael Hempel
Tutor: Sven Böhler - MVV, Prof. Dr.-Ing. Clemens Felsmann, Dr.-Ing. Thomas Sander
Year: 2024

Expansion of a standardized evaluation routine for heat storage test series
The VKTES research project (development of comparative key figures for thermal energy storage systems) aims to develop key figures and methods which facilitate for engineers to make technical and economic comparisons between different thermal storage systems. These comparative key figures help manufacturers and planners to better assess the suitability of storage tanks for specific applications such as heating, domestic hot water heating or cooling. In addition, the determined comparative key figures are important for the design of heating and cooling systems, as they help to optimize energy consumption and ensure sustainable operation.
In this thesis, the evaluation routine for analyzing experiments on heat accumulators, which was originally developed in Cheng's student research project based on Excel VBA, is transferred to the Python programming language and extended. The aim of the new evaluation routine is to make the evaluation of the measurement data more efficient and automated. The tests were carried out on two storage heaters from Kermi GmbH with different volumes, with one loading and one unloading process being analyzed in each case. Furthermore, the existing Excel evaluation template from Cheng's student research project was expanded to calculate comparative key figures and display measured values graphically. In addition, a new Excel template was developed that contains extended diagrams for displaying measured values and enables a comparison of three experiments.
Detailed documentation of the Python script created is intended to ensure that the evaluations can be reproduced and understood by any user. The results of the new evaluation routine should, as in Cheng's work, provide a deeper understanding of the significance of the comparative key figures in relation to water heat storage.
Editor: Tran Xuan Thang
Tutor: Dipl.-Ing. Franziska Koch, Dipl.-Ing. Stefan Hoppe
Year: 2024

Analyses of potential applications and framework conditions for floating photovoltaic systems in pumped storage power plants
This thesis explores the potential for integrating floating photovoltaic systems (FPV) with pumped storage power plants (PSP). The focus is on analyzing technical, economic, and environmental aspects, particularly using the PSP Niederwartha as a case study. FPV systems can enhance PSP efficiency by generating additional electricity and reducing water evaporation. The study examines three different surface coverage ratios (1 %, 15 %, 30 %) and multiple operational modes. Results indicate that FPV integration is promising from an energy perspective but faces economic challenges due to long payback periods, which might be mitigated by rising energy prices and technological advancements. Legal frameworks and ecological impacts are also considered. Simulations demonstrate the potential for sustainable use of this combination to stabilize the power grid and reduce CO₂ emissions.
Editor: Heidar Mirahmadi
Tutor: Dr.-Ing. Torsten Heyer - TU Dresden, Institut für Wasserbau und Technische Hydromechanik, Professur Wasserbau
Year: 2024

Development of a simulation model for the solar thermal system with district heating feed-in NEST-W 2.0 and comparison with monitoring data
In 2023, the NEST-W 2.0 field installation was commissioned as part of the HYDRA RoS project. This installation consists of solar thermal collectors that transfer heat to the district heating network of the city of Dresden via a plate heat exchanger. The present work deals with the validation of measurement data from this installation and the creation of a realistic simulation model using relevant abstraction methods. The most important operating modes of the installation are examined and implemented in the POLYSUN^® Designer program. These operating modes include feed-in operation, frost protection operation, and stagnation. Subsequently, the quality of the model is verified by comparing selected time periods for the individual operating modes with real measurement data. At the beginning of 2024, the plate heat exchanger in the installation was changed with the goal to minimise the mean logarithmic Temperature Difference. The effect of this reconstruction is first theoretically justified, then verified with measurement data. Furthermore, the two heat exchangers are implemented in the simulation model of the installation and evaluated and compared in this way as well.
Editor: Alex Blandón
Tutor: Dr.-Ing. Karin Rühling
Year: 2024

Development of energy concepts for a laboratory building, taking into account the CO₂ footprint, recyclability and C2C principle
The construction and operation of buildings make a significant contribution to energy consumption and greenhouse gas emissions in Germany. Using the example of the planned construction of the "Centre for Sustainable Materials and Energy (CSME)" laboratory building in the Weinberg Campus technology parc in Halle an der Saale, this study examines various energy concepts for the sustainable supply of heating and cooling.
The aim of comparing the energy concepts is to minimise the carbon footprint.
An energy demand analysis of the new building makes it possible to determine the required heating and cooling load based on the building geometry, the components and the utilisation profiles. This step forms the basis for dimensioning the heating and cooling systems. Energy concepts based on renewable energies are then developed. These concepts are evaluated from an ecological, functional and economic point of view. Particular attention is paid to the Cradle to Cradle (C2C) philosophy, i.e. the recyclability of the systems and the use of renewable energies.
The analysis shows that the energy concept with a reversible heat pump system and compression chillers has the lowest environmental impact and the second-lowest total costs over the entire observation period of 50 years. This variant utilises renewable energies such as environmental energy and solar energy, which account for more than 50% of the final energy requirement. In addition, the reversibility of the heat pump saves material costs. However, the analyses also show that the suitability of the concepts varies depending on the evaluation criteria.
Editor: Mathis Roynard
Tutor: Peer-Uwe Waldbauer - ZWP Ingenieur AG, Jan Richarz - ZWP Ingenieur AG, Dipl.-Ing. Andrea Meinzenbach
Year: 2024

Development and evaluation of heat supply scenarios for an existing neighbourhood heating network
The decarbonisation of heating networks is essential for the transition towards emissionfree heating based on renewable energy sources in germany.
This thesis discusses the decarbonisation of a heating network in Laubegast, a district of Dresden. First, a status analysis of the current state of the heating network was conducted. The heat losses were estimated and the consumption data was analyzed. Following, the renewable energy sources for an emission-free operation of the heating network were identified as geothermal energy, sewage and groundwater. These environmental heat sources can be utilized by using a heat pump. Different solutions to power the heating network based on the aforementioned energy sources were evaluated and compared to each other.
Using the flixOpt optimization framework developed at the GEWV Chair at TU Dresden, the most cost-effective and low-emission supply concepts were determined. The utilization of sewage-heat by installing a heat-pump is, combined with a biomethane boiler and a heat storage, the preferred option for this heating- network.
Editor: Laura Franz
Tutor: Swen-Sören Börner - Sachsen Energie AG, Dr. Franziska Graube-Kühne - Sachsen Energie AG, Dr.-Ing. Karin Rühling
Year: 2024

Design, implementation and measurement of a combined PVT-heat pump system for demonstration and teaching purposes
This thesis presents the design of a combined PVT-heat pump system for student training and demonstration purposes and its implementation steps at the “Zentrum für Energietechnik der Technischen Universität Dresden”. The system consists of four photovoltaicthermal collectors (so called PVT air/brine collectors, Model SOLINK), which form the heat source system for a brine/water heat pump. At the same time, the PVT modules can partially cover the electrical energy consumption of the heat pump. By means of a hot water storage tank and an existing hydraulic module, heat dissipation (space heating and domestic hot water heating) can be realized for different load profiles.
A piping and instrumentation diagram of the system is developed in compliance with the manufacturer's specifications. The existing components are described. Missing components required for the interconnection and safe operation of the system are also designed. Potential tasks are formulated for a future practicum. The number and location of the measuring points required for this are determined.
A designed methodology for the energetic and exergetic yield comparison of the PVT modules with photovoltaic and solar thermal modules of chair-owned systems should give students an insight into the energetic efficiency of the PVT modules. The implementation of the first sections of the PVT heat pump system, such as the connection of the PVT modules to the electrical energy grid, is accompanied and documented. The thesis also makes implementation recommendations for the commissioning of further sections and recommendations for potential extensions.
Editor: Elisabeth Elke Wudenka
Tutor: Dipl.-Ing. Maximilian Beyer, Dr.-Ing. Karin Rühling
Year: 2024

Techno-economic analysis and optimization of battery storage for large-scale PV systems
The switch from conventional to renewable and decentralized energy supply poses new challenges for the energy supply system. As electricity generation from wind and sun cannot be constant and in line with demand, there are increasingly frequent discrepanciesbetween generation and consumption. Grid-connected battery storage systems offer an innovative and potentially cost-effective solution to compensate for these gaps and the associated price fluctuations. This thesis examines whether grid-connected battery storage systems can be operated economically alongside ground-mounted photovoltaic systems if they can be charged from the grid and sold on the day-ahead and intraday auction markets. A model for the two- stage marketing decision was developed for this purpose. Using the Python framework „flixOpt“, a two-stage, stochastic, mixed-integer and linear optimization problem was formulated. In contrast to existing research, this dispatch optimization considers the uncertainty of future intraday auction prices by incorporating their probability distribution instead of working with deterministic modeling.The results show that the economic operation of battery storage systems is only made possible by marketing them on the intraday auction market. Pure energy arbitrage on the day-ahead market, on the other hand, is not sufficient to ensure profitable operation. Combined marketing on both markets leads to a further slight increase in trading income through arbitrage opportunities between the markets, whereby the operation of the storage facility hardly differs from pure marketing on the intraday auction market. In addition, battery storage systems with a C-rate between 0.25 and 0.5 are the most economical for this marketing strategy. The location, whether standalone or next to a photovoltaic system, has no significant influence on the trading income.
Editor: Jan Fischer
Tutor: Dr. Carl-Philipp Anke - Sachsen Energie, Dr.rer.nat. Peter Stange
Year: 2024

2023

SubReg: Substitution of conventional radiator controllers - monitoring and analysis of an individual room control system using the example Merkel-Bau in 2023/2024
This research examines individual room heating and associated error potentials in smart heating systems. The aim of the study is to identify systematic errors and develop early error detection to improve the reliability and efficiency of room temperature control. The investigation includes the categorization of rooms, data collection and processing, and the evaluation of thermal and hydraulic supply. By analyzing usage and analysis periods and implementing intermittent heating operation, significant energy savings were achieved. The results show that precise control of room temperature not only increases thermal comfort but also contributes to reducing energy consumption.
Editor: Martin Fischer
Tutor: Dr.-Ing. André Kremonke, Dipl.-Wi.Ing. Laura Lehmann
Year: 2023

Verification of dimensioning of domestic hot water generators based on heat meter measurement data
In this diploma thesis, the dimensioning of domestic hot water generators of the district heating company Vattenfall Wärme Berlin AG is analysed using primary-side heat meter measurement. The majority of the domestic hot water generators connected to the district heating network in Berlin have heat meters, which means that the data is available at a 15-minute frequency.
The first step is to determine the data basis, which is then used to develop methods for analysing the data. Data processing is carried out using a specially developed Python code, which makes it possible to filter out analysable domestic hot water generators and their heat meter data.
To analyse the heat meter data, operating states that can be evaluated on the primary side are first defined, which vary depending on the domestic hot water generator. Criteria are defined that allow the heat meter data to be allocated. Within these criteria, the average return temperature over the thermal energy is calculated and statistically analysed for each domestic hot water generator. After that the heat map evaluation method is applied, which allows the heat meter data for each domestic hot water generator to be viewed manually. Here, examples of well and poorly functioning domestic heat water generators are analysed in more detail based on the statistical evaluations previously carried out using this method. By calculating the average return temperature over the cumulative volume and the total volume of the domestic hot water generator, these methods enable a comprehensive data analysis of the domestic hot water generator in the context of the district heating network.
Finally, the data analysis is compared with the design of the district heating supply company's domestic hot water generator. The results from those analyses are used to formulate recommendations for action for existing and future district heating systems.
Editor: Dilara Karabacak
Tutor: Marius Bergemann, Luise Mann - Vattenfall Wärme Berlin AG, Dr.-Ing. Karin Rühling
Year: 2023

Energy reassessment of the Gläserne Manufaktur building and development of further optimisation measures
As an industrial building, the Gläserne Manufaktur Dresden (GMD) has a not inconsiderable energy consumption, in which the technical building equipment plays a major role. The technical building equipment systems includes ventilation systems, heating and cooling systems. These systems are analysed and described according to the current state of the art. Energy consumption was last examined and analysed in the GMD energy report in 2007.
Energy consumption has been continuously recorded at GMD for several years, but the results have not been analysed or evaluated in any depth. Based on the recorded energy consumption of the last 5 years, a consumption analysis with diagrams is to be presented and compared with current reference values. In the 2007 energy report, optimisation measures were presented in order to reduce energy consumption. In the meantime, the GMD has been optimised in terms of energy consumption. There was no documentation of the measures actually implemented, so these are to be reviewed for their implementation.
Based on the current status of the building, further proposals for reducing the energy demand are to be presented in this paper. A simplified digital twin of the building envelope is created in order to simulate consumption and demonstrate the savings potential.
Editor: Julius Dietrich
Tutor: Prof. Dr.-Ing. habil. Joachim Seifert, Dr.-Ing. Paul Seidel
Year: 2023

Investigations into an innovative control method for solar thermal power plants
Concentrated solar thermal power plants based on linear Fresnel collectors have lines of absorber tubes welded together that can be several hundred meters long. The outlet temperature should consistently be kept at a target value. Rapid changes in solar radiation pose major challenges for the control system, as the control behavior of the system is very slow due to the long residence time of the heat transfer fluid. Thus, there is a need to predict solar radiation or to record it in real time. It has been observed that the thermal expansion of the line of absorber tubes reacts in real time to the change of solar radiation. As a result, there is an interest in whether the solar radiation on the line can be determined via thermal expansion. However, a mathematically formulated correlation for this is not known.
In this research work, various thermodynamic models are created to formulate a relationship between these values. Next, the behavior of two derived equations was analyzed in simulated test cases. It turned out that one of the equations could follow the profile of the rate of heat flow between the inner wall of the tube and the heat transfer fluid. The maximum observed error of this equation was within the double-digit percentage range. Nevertheless, it could still be accurate enough to be used. According to this, initial investigations in real solar fields should be carried out.
Editor: Jonathan Gläßer
Tutor: Dr. Max Mertens - FRENELL GmbH, Dipl.-Ing. Vera Boß
Year: 2023

Identification of the potential use of existing domestic hot water storages for load management in district heating networks
The conservation of Energy is an increasingly important aspect for the construction and renovation of Property. To allow for an optimal conservation of energy, many different approaches are currently under study, from insulation to Warmwater-Supply.
Within the optimisation of Warmwater-Supply, there already has been a shared project between several academic institutions, including the TU-Dresden, which focused on the implementation of intelligent House-Network-Stations within new and existing structures.
The title of the Project was “Digitalisierung von eneregieeffizienten Quartierslösungen in der Stadtentwicklung mit intelligenten Fernwärme-Hausanschlusstationen – iHAST (Phasen 1-2).
The main topic of the Project was the potential implementation of intelligent Network-Connection-Stations in new and existing properties, to more efficiently manage demand for Warmwater. It detailed several approaches and challenges that come with this implementation.
Following the Project, and topic of this paper, is an investigation into the Data provided by a city, which has implemented several hundred intelligent Connection-Stations. Based on this data it was to be determined, when the demand for Energy was the highest, whether the Data was sufficient to warrant immediate action to reduce sprain on the Water-Suppliers.
During the Paper, a method was developed to identify stations which have a Storage Tank for warm Water, based on the Energy demand and Flow-Volume-Profile of the station. Based on this, Data could be selected to characterize the Subnetworks of the city, each Network being linked to a Water plant.
However, due to the low amount of Data, the high error Rate for some of the Stations and the uncertainty involved with the identification, the result is unsatisfactory. Further investigation with increasing amount of Data is required to validate the findings of this paper, as well as completely determine the actual potential for Energy savings.
Editor: Christoph Zetzsche
Tutor: Dipl.-Ing. Vera Boß, Dipl.-Ing. Vera Alieva
Year: 2023

Further development of the generation portfolio of a district heating grid to integrate waste heat and investigations concerning the optimization of the entire system
The decarbonization of district heating networks is a crucial step in the heating transformation of dendely populated areas. Considering the progress of digitalization and the increasing importance of artificial intelligence, the demand for data center infrastructure is rising as well. In addition to the use of renewable energies, the related potential of reusable waste heat presens an opportunity to avoid greenhouse gas emissions while running heating networks.
This thesis extends the scenarios developed by SachsenEnergie AG and GESA mbH in the transformation plan to decarbonize the district heating network of the municipality of Königswartha (Saxony) . The variants already considered for a low-emission heat supply include the following technologies: solar thermal energy , brine-to-water heat pump, wood chip firing and biomethane boiler. The extension of the variants to include the waste heat utilization of selected data centers in container design serves to develop additional solution proposals . These are optimized for the scenarios 2026, 2035 and 2045 in terms of total costs and greenhouse gas avoidance. The flixOpt optimization framework developed at TU Dresden serves as a simulation environment.
The brine-to-water heat pump is the most important heat generator both in the variants of the transformation plan and in the extension variants developed as part of this study. The integration of waste heat utilization of the data center container results in savings of energy required from other heat generators and enables their nominal power to be reduced .
Editor: Theo Sell
Tutor: Felix Fischer - SachsenEnergie AG, Dr.-Ing. Karin Rühling
Year: 2023

Analyses of thermal (local) comfort when using infrared heating systems
This thesis deals with the thermal comfort of electrical infrared heating systems when used as residential space heating. Due to their high surface temperature, they primarily transfer heat into the room via radiation. Therefore it is important to ensure radiation asymmetry as a local criteria for thermal comfort. Radiation asymmetry depends on the room geometry, the positioning of the IR heating surfaces, the surface temperatures in the room and the position of a person. The analytical calculation of radiation asymmetry can be complex using the view factors describing the radiation exchange. For a simple determination of the radiation asymmetry, a calculation tool was created as part of this work.
By comparing the results of measurements at the Combined Energy Lab of the TU Dresden with those of the calculation tool, the deviation could be reduced by adding insulation. The enclosure in particular, but also the heat transfer coefficient has an influence on the deviations between measurement and tool. Although the results of the measurements show high deviations in the radiation asymmetry, there are only minor absolute deviations in the evaluation of the radiation asymmetry with the Percentage of Dissatisfied.
Editor: Klara Sulamith Bestehorn
Tutor: Dipl.-Ing. Maximilian Beyer, Dipl.-Ing. Lars Schinke
Year: 2023

Implementation of optimizing the use of heat storages in the thermohydraulic simulation of a district heating network
The integration of volatile renewable energy sources and the flexibilisation of combined heat and power plants can be achieved in the district heating supply with the help of large water heat storage tanks. In order to be able to analyse the effects of such scenarios on the district heating network, it is important to investigate them as part of a thermal-hydraulic network simulation. For this purpose, the coupling of a detailed atmospheric water heat storage model into the thermal-hydraulic network simulation with TRNSYS-TUD has already been implemented as part of a co-simulation. Based on this approach, this thesis is dedicated to the implementation of operational optimisation scenarios in TRNSYS-TUD utilizing the optimisation framework flixOpt. In the first part, the given co-simulation environment is analysed and the integration of flixOpt is implemented. The functionality of the interface is demonstrated using a fictitious scenario of model-predictive operation management of the water heat storage tank. This demonstration shows the need for adaptation in the modelling of storage integration in TRNSYS-TUD. Additionally a higher level of detail in the flixOpt energy system model is necessary in order to achieve realistic operational management results. This work offers suggestions for further development requirements and recommendations for subsequent research.
Editor: Konstantin Seifert
Tutor: Dr.rer.nat. Peter Stange, Dipl.-Ing. Bogdan Narusavicius
Year: 2023

Measurement-data based short-term and long-term forecast of heat demand
This thesis deals with the development and implementation of regression models for forecasting the primary-side heat load for a district heating network in Mannheim. The heat load forecast is an important tool for the control and planning of a district heating network. The heat load is dependent on the outside temperature and the user behaviour of the building. It can be forecasted using mathematical regression based on these variables. A multiple linear regression model is used for short and long term forecasting, which is supplemented by a seasonal autoregressive approach for short term forecasting. Models, data preparation routines and functions for assessing forecast quality and visualisation are implemented using the Python environment. This ensures that the models can be exported and enables the program to be used in other district heating networks.
Editor: Anne Luther
Tutor: Dr.rer.nat. Peter Stange, Dipl.-Ing. Vera Alieva
Year: 2023

Optimisation of the cooling system at FEV Dauerlaufprüfzentrum GmbH
As part of endurance tests, engines and drivetrains are tested at FEV Dauerlaufprüfzentrum GmbH. Among other things, a potent and failure-free supply of cooling media is essential for an uninterrupted operation. Especially on hot days, the technical equipment, consisting of 7 air-cooled compression chillers, cannot provide enough cooling capacity to supply all consumers on the secondary side. This can significantly affect operations. Why these problems occur and how the system can also be upgraded for high outdoor temperatures is investigated in this diploma thesis.
Within a literature and market study, a comparison with other cooling technologies is made to determine if the existing system technology is suitable for the application. The system is then examined during operation regarding the supply and exhaust air flows and the processes for refrigeration. For optimization, various concepts are developed and the preferred variant with the necessary plant technology is planned in detail.
Due to the dense installation method and the three-sided conversion with the company buildings, which protects against wind, the supply of cool fresh air is a problem. There are short circuits of the air convections between the hot exhaust air and the air sucked in at the condensers of the chillers. The machines cannot dissipate their waste heat, so that despite the high compressor capacities, the required cooling capacity cannot be applied. The oil circuit overheats and the chillers switch off from system protection.
With the help of open evaporative cooling by nebulizing softened water in front of the condensers in combination with the installation of air deflectors, the existing plant technology can be upgraded with a payback period of only four years. At the same time, lower power consumption is achieved in refrigeration.
Editor: Benjamin Goedecke
Tutor: Dipl.-Ing. Lars Schinke, Prof. Dr.-Ing. habil. Joachim Seifert
Year: 2023

Automated allocation of customer models in the simulation of heating networks
To simulate district heating networks as accurately as possible, consumer profiles should be assigned to the consumers. This is done on the basis of the forecast of the temporal progression of the heat load and the return temperature of the network under consideration. In this work, a district heating network was primarily considered for the assignment of the consumer models. Another network was then used for comparison. By assigning the consumer models, the characteristics of the heat load over a year could be predicted well. However, not all characteristics could be approximated, especially when taking a closer look at smaller time ranges. In addition, the deviation of the predicted heat load from the real data was relatively large for both grids. The rough characteristics of the return temperature could also be mapped by the forecast. Different areas, subdivided according to output, could be predicted with varying degrees of accuracy. For the two networks considered, there was a different quality with regard to some parameters and different areas of the time curves could be predicted differently well. This leads to the conclusion that the combination of the district heating network under consideration and the quality of the available consumer models is decisive for the quality of the forecast. Furthermore, it was observed that a smaller forecast period leads to poorer results for the coefficient of determination R², but to smaller distances between the approximated time series and real data. By forecasting smaller time periods, significantly better results could be achieved than for the sections of the same time periods if the consumer models were assigned to the forecast for the entire year.
Editor: Kai Witza
Tutor: Dipl.-Ing. Tiedo Behrends, Dr.rer.nat. Peter Stange
Year: 2023

Evaluation of different control concepts for grid-oriented control
The electrification of the heating and transport sectors as part of the energy transition is increasing the load on electricity grids, which is why both grid operators and operators of controllable consumption devices with a maximum power consumption of more than 4,2 kilowatts have been legally obliged to participate in grid-oriented control since 01.01.2024. Statutory deadlines apply for the implementation of the control system, which is the responsibility of the metering point operator (Messstellenbetreiber). Runtime tests are used to determine whether these deadlines are realistic or need to be adjusted.
An excerpt of the laws and guidelines that provide the legally binding framework for the operation of the control solutions/concepts is prepared. Current practical control concepts with smart meter gateways are described and evaluated on the basis of defined criteria. Of the control concepts presented, which differ primarily in terms of the communication protocols used and the hardware used in the field, the FNN control box (FNNSteuerbox) concept is the most common. The runtime tests are therefore carried out for this concept. The runtime of the control commands essentially depends on the status of the channel (established or terminated) that connects the external market participant on the data center side with the control device in the field. With the current IT system architecture, the legal deadlines cannot be met even when the channel is established. If the communication of the services in the data center is optimized, the legal deadlines can be met with the channel set up. If the channel is terminated, this is not possible due to the time-consuming connection setup.
The legal deadlines cannot be met in their current form. The adjustment of the deadlines in combination with the optimization of the technical infrastructure represents a realistic compromise for the implementation of network-oriented control.
Editor: Joachim Werner Bernhard Bade
Tutor: Dr.-Ing. Kai Herrmann - robotron Dresden, Prof. Dr.-Ing. Clemens Felsmann, Dr.rer.nat. Peter Stange
Year: 2023

Design and derivation of implementation measures for the upgrading of a test rig for the investigation of heat pumps with flammable refrigerants
Heat pumps are becoming increasingly important in the energy sector. In order to ensure that operation is as climate-neutral as possible, legislation is restricting the use of climatedamaging refrigerants and promoting the use of natural refrigerants. Propane plays an important role here as a natural refrigerant. It is characterised by its good availability and low climate impact. However, its chemical properties, such as its high flammability, are challenging. If a propane heat pump is installed outdoors, the risk is minimised. However, if reproducible tests are to be carried out on such a heat pump, test facilities are indispensable. The Technische Universität Dresden has such a test stand with its “Außenklimaraum" at the Combined Energy Lab. The conditions of the test facility can lead to increased risks from propane-operated heat pumps. An appropriate emergency system must be designed to minimise the risks. To design the system, the concentration behaviour of propane inside the external climate chamber was investigated and a corresponding ventilation system was designed. The installation and the emergency system are subject to DIN EN 387, which was analysed and the corresponding requirements for the emergency system and the external climate chamber were concluded. A software module was developed to control the individual components, which combines the necessary sensors, actuators and normative requirements. As a result, the possibility of installing a propane heat pump inside the “Außenklimaraum” was analysed and a way to implement or upgrade it was discussed.
Editor: Falco Stefan Schmidt
Tutor: Dipl.-Ing. Maximilian Beyer, Dipl.-Ing. Lars Schinke
Year: 2023

Evaluation of thermal comfort for local heating systems based on personal sensor data
The present work deals with the efficient use of energy and the optimization of thermal comfort in office spaces. For this purpose, local heating elements can improve the user’s thermal comfort compared to conventional HVAC systems by creating an individual microclimate. This paper examines an approach to determining thermal comfort depending on human reference variables, which are determined using measurement technology. The aim is to test whether heating elements are autonomously adjustable with this approach, without any user interaction. For this purpose, an in-depth analysis of current literature is carried out, which includes a variety of approaches to investigate predictive control strategies for determining thermal comfort based on body signals. These approaches are based on reference values such as skin temperatures, heart rate, breathing rate, metabolic equivalent, gender, body mass index, clothing insulation, etc. Based on this literature analysis, a corresponding approach is created using a calculation tool in Python, which is to be validated further in this work and in relation to the literature. A suitable test design for experimental investigations is then developed. A small study with subjects to investigate the predictive accuracy of the chosen approach was conducted in the indoor climate room of the Combined Energy Lab of the professorship of Building Technology and Heat Supply at the Technical University of Dresden. Finally, the results are presented and discussed from a comfort perspective as well as the prediction accuracy of the calculation tool studied.
Editor: Sergio Alejandro Espiritu Huaman
Tutor: Dipl.-Ing. Maximilian Beyer, Dipl.-Ing. Lars Schinke
Year: 2023

Development of a data model and validation of measurement procedures in heat pump testing to accelerate the development cycles of new heat pump systems
The increasing digitalisation of the production environment marks a decisive turning point for many companies that are striving to increase their efficiency and competitiveness. Communication standards play a crucial role in this transformation process, as they enable smooth interaction and data exchange between production machines. The central question that arises is whether these established communication standards can also be used successfully outside the production context.
This thesis is dedicated to this question and looks at the potential of using communication
standards in a test facility for heating systems. The focus is particularly on communication in the field of heat pumps. In close cooperation with the company Viessmann SE Climate Solutions, the feasibility and effectiveness of this transfer of standards to a new context is being investigated.
The results of this thesis suggest that standardisation in communication certainly offers opportunities for optimisation. However, it is clear that the decisive step towards standardisation should be taken at an earlier stage of the heat pump development rocess
instead of being implemented in the test area. Early integration of communication standards therefore proves to be essential in order to realise the full potential of this digital transformation and enable synergies between different technological domains.
Editor: Fabius Fürstenau
Tutor: Dr.-Ing. Lars Haupt, Prof. Dr.-Ing. habil. Joachim Seifert, Dr. Marcus Thiele - Viessmann Werke Allendorf
Year: 2023

Creation of an energy concept for a residential neighbourhood
Within the framework of this thesis an energy supply concept was drawn up for a newly
developed residential area. The client formulated an energy-efficient, sustainable and
CO₂-neutral energy supply as a requirement. Based on the existing preliminary development plan, the local conditions were analyzed, and the predicted buildings were typed. For these, the expected energy consumption for space heating, drinking water heating and electrical energy was estimated with an hourly resolution. Three supply variants were created and simulated to supply energy to the residential area. As part of a parameter variation, the influence of changed input variables and assumptions could be examined. Finally, the supply variants were compared and evaluated based on various criteria, such as costs, CO₂ emissions, operator model and legal protection. A decentralized heat and power supply concept turned out to be the preferred option for the residential area, for which recommendations for implementation in the development plan were drawn up.
Editor: Toni Schalling
Tutor: Dipl.-Ing. Jens Kaiser
Year: 2023

Determination of the optimisation potential for spot market purchasing at the Friedrichshafen site of ZF Friedrichshafen AG
This research assesses the load-shifting potential of various facilities at the
Friedrichshafen site of ZF Friedrichshafen AG, aiming to facilitate trading flexibility on the
spot market and optimize spot market procurement. With increasingly volatile energy
supplying systems this serves to maintain grid stability as well as potential cost savings
for the company.
After identifying the seven most significant producers and consumers of energy at the
site, a detailed analysis of their load-shifting potential is conducted. The value of the
potential is determined by the shift duration, which must be at least 15 minutes, the
magnitude of the shiftable load which must be at least 100 kW, and the necessary
premises and investment costs.
Based on the available site-specific energy data and the specified criteria, the potential of
each facility was calculated and subsequently categorized according to ZF’s defined
categories. The evaluation revealed that especially block heating power plants, ventilation
systems, and emergency power generators are well-suited for lead shifting due to their
high shiftable capacity and low investment costs. Loas shifting is also conceivable for
refrigeration and cooling systems, but it would be associated with significantly higher
costs. In contrast, compressed air systems and cooling lubricant systems show little to no
potential due to their limited shift duration.
Using the identified data, the external provider ESFORIN conducted a simulation to
determine the expected profitability. The results confirm that by utilizing all meaningful
load-shifting potentials, savings of up to 440 k€ could be realized, with a significant portion
being contributed by the block heating power plants. The findings of this study
underscore that the Friedrichshafen site has potential for flexibility marketing and lay the
groundwork for initial implementation measures.
Editor: Eva Harriehausen
Tutor: Jörn Forwerk - ZF Friedrichshafen, Dipl.-Ing. Vera Boß
Year: 2023

Development of IoT-concept in an HiL test bench for a bidirectional heat transfer station
This work deals with the development of an IoT concept for a bidirectional heat transfer station in a HiL test bench. Given the increased transition to sustainable energy systems, the integration of decentralized heat sources into district heating networks is of central importance. The bidirectional heat transfer station not only enables the purchase of district heating, but also the feeding in of locally produced heat. This functionality is a crucial step to enhance the flexibility and sustainability of district heating networks and promote the use of renewable energies.
An extensive literature research provides an overview of prototypes and systems that have already been tested and highlights the need for further studies on bidirectional heat transfer stations. The work deals with the integration of different use cases, which is why different system configurations must be enabled. The test stand is implemented in a practical manner using existing laboratory facilities and then equipped with extensive reference measuring points.
Following this, the development of the IoT concept takes place, which enables data transmission from the sensors and actuators to a cloud. Communication occurs via the Modbus and MQTT protocols, with an MQTT broker serving as the central interface. Utilising the N5GEH communication structure, the data is stored in a database and visualised using the Grafana software. The successful implementation of the IoT concept is proven by functional tests.
The work concludes with tests on the transferability of the concept to another heat transfer station at the TU Dresden. Communication paths for data transmission are being developed, and comparisons of measuring points show the adaptability of the concept.
The results of the functional tests show that bidirectional heat transfer can be realised in the test bench using the heat transfer station.
Editor: Erik Wöhner
Tutor: Dr.-Ing. Paul Seidel, Dipl.-Ing. Stefan Hoppe, Dipl.-Ing. Marcel Röschke
Year: 2023

Physical further development of a cloud camera-based measurement method for diffuse radiation
Ground-based measurements of direct normal irradiance (DNI) and diffuse horizontal irradiance (DHI) are of interest for applications in solar energy. However, measurement systems established in the market either have high acquisition costs, require intensive maintenance, or are prone to increased deviations. For these reasons, the measurement of solar radiation using a combined measurement system, consisting of an all-sky camera (ASI) and a pyranometer, henceforth referred to as pyranocam, is currently under investigation at the German Aerospace Center (DLR). The PyranoCam measurement method analyzes the global horizontal irradiance (GHI) measured by the pyranometer in combination with cloud images captured by the ASI and derives DHI and DNI from it. Yet, the measurement method still shows potential for improvement in terms of accuracy and transferability between sites.
In the present diploma thesis, an enhanced physical model of a cloud camera-based measurement method for the quantification of DHI and DNI is introduced. The core of the study is the development of a dynamic diffuse broadband correction factor. This factor is designed to address the errors arising from the spectrally limited sensitivity of the cloud camera sensor. At present, an empirically-based static diffuse broadband correction factor is applied to the pixel intensity values of captured all-sky images to estimate the full broadband spectrum DHI, thereby improving the accuracy of DHI measurement. The novel model calculates the diffuse broadband correction factor dynamically based on the ratio of the red to blue color channels. For this purpose, an all-sky image dataset is fused with spectroradiometer measurements to correlate the measured broadband factor with the color channel ratio. A corresponding regression model is presented, and the results are showcased for two sites: Tabernas in southern Spain and Oldenburg in the northwest of Germany. Within the pyranocam processing pipeline, several steps are involved. Initially, in the base calibration phase, radiometrically adjusted pixel intensities are scaled to correspond to actual values of DHI. Following the initial calibration, the pyranocam methode incorporates a correction phase. In this phase, a correction is applied, either based on physical principles or utilizing machine learning techniques. The comparative analysis of the base calibration reveals that the static method results in a Root Mean Square Deviation (RMSD) of 22.7 W/m², corresponding to a relative RMSD (rRMSD) of approximately 17.4 %. In contrast, the dynamic method achieves an RMSD of 15.6 W/m², corresponding to an rRMSD of 12.1 %, indicating a more accurate performance by 7.1 W/m² (5.3 %) across a dataset of over 869,000 all-sky images. Further examination for physical corrections shows that the static method has an RMSD of 14.2 W/m² and a rRMSD of 10.8 %, while the dynamic method records an RMSD of 11.3 W/m² with an rRMSD of 8.5 %. This demonstrates a slight improvement through the dynamic broadband correction factor. In comparison to the physical correction, the machine learning model enhanced DHI measurement accuracy to a RMSD of 5.4 W/m² with an rRMSD of 4.1 %. However, this shows no significant change when compared to the dynamic method, which achieves an RMSD of 5.3 W/m² with an rRMSD of 4.1 %.
Editor: Paul Matteschk
Tutor: Niklas Blum – Plataforma Solar de Almería (PSA), Michael Meinel – Softwareentwickler DLR, Prof. Dr.-Ing. Clemens Felsmann
Year: 2023

SubReg: Substitution of conventional radiator controllers – Pilot project „Rektorat/Graduiertenakademie“
Within the scope of this work, two university buildings are equipped with a new individual roomtemperature control system. The change is from a mechanical individual room control to electric radiator thermostats in combination with wall thermostats. In preparation, the new components are incorporated into the TU’s own database system and labeled accordingly. Based on this, a topology of the buildings is created, which contains the location of each newly installed component with the corresponding labeling. In order to reduce the work on site to a minimum, the components are prepared externally and integrated into the system. Due to the preparations, less than one working day is required per building for the change to the new individual roomtemperature control system. After the change, a program developed as part of this work is used to determine which components are not integrated into the network. Based on this, appropriate countermeasures are taken. Subsequently, a monitoring system is set up, which continuously generates graphical representations and evaluations of the recorded operating variables.
These are additionally created differentiated by time, which also enables insights into different time periods. In addition, a key figure is developed that provides information on the quality of the data. With the help of the monitoring system, representations are valuated exemplarily. The evaluated data results from an already implemented monitoring system of another university building. At the time of writing, it is not possible to evaluate the data from the retrofitted buildings, as this work was written during the summer months and therefore there is no heating operation. In the conclusion of this work, a system for error detection is developed and partially implemented in the monitoring system. Complete inclusion in the monitoring system is prevented by external error sources. The system for error detection includes algorithms that automatically detect errors in the system and make them recognizable. In combination with a table, possible causes can be deduced. The developed system for error detection is applied exemplarily and found to be functional.
Editor: Robin Böhm
Tutor: Dr.-Ing. André Kremonke, Dipl.-Wi.Ing. Laura Lehmann
Year: 2023

Simulation based generation of typified models of heat consumers
For a future CO2-neutral heat supply, the expansion of district heating networks is essential. Realistic consumer models regarding heat loads and return temperatures are necessary for simulating these networks. The use of measurement data as a basis for the models is challenging due to the lack of information about consumer profiles and the risk of measurement errors.
In this work, various variants of apartment buildings are created in 'TRNSYS-TUD.' Simulations are then conducted to depict the trends of heat load and return temperature of the buildings. Using the principle of multiple linear regression, consumer models are subsequently generated in MATLAB. Predictions about heat load and return temperature are made based on various influencing factors. Models can be created for both the primary-side and secondary-side return temperatures. Subsequently, the goodness of fit of the regression models is evaluated using various metrics. Finally, the created consumer models are stored in the model library 'FreePlan' to be used for network simulations of district heating.
Editor: Max Müller
Tutor: Dr.rer.nat. Peter Stange, Dr.-Ing. Alf Perschk, Dipl.-Ing. Juliane Schmidt
Year: 2023

Thermal analysis of a PV-supported cold storage hall including liquid ice storage to maximize the degree of autarchy
This diploma thesis describes the thermal analysis of an cold store with a ice slurry storage, which self-sufficient operation should also be secured by a pv system. The period of data under consideration extends from August 2022 to July 2023. Based on this data all relevant energy flows and resulting energy demands are calculated. Therefore various approaches are used, such as energy balances and compressor maps. These are evaluated on the basis of their accuracy. For easier evaluation the data is uploaded and organised into a time series database. As a basis for a forecast-based control system, dependencies of the heating and cooling demands of the different storage rooms are identified and a concept for such a control system is presented. Furthermore, the refrigeration machines are evaluated on the basis of efficiency indicators and optimisation potentials are identified and discussed. The demands of the cold store are compared with a simulation and the data provided by the simulation on the performance of the PV system is used to estimate the degree of self-sufficiency that can be achieved with the current system control. The thermal analysis was able to identify the influence of several environmental but also temporal factors and make several suggestions for optimisation measures. The greatest potential was identified in the heat dissipation at the condenser of a refrigeration machine.
Editor: Alexander Bertram Armin Raabe
Tutor: Dipl.-Ing. Carsten Heinrich - ILK Dresden, Dr.-Ing. André Kremonke
Year: 2023

Refurbishment options according to GEG and BEG incl. possible state funding measures using the examples of residential and nonresidential buildings
The energy-efficient refurbishment of the existing buildings in germany is necessary in order to achieve the goals of the amendment to the „Gebäudeenergiegesetz“, namely a supply of at least 65% renewable energies. In order to guarantee this in practice, energy consultations and refurbishments are being promoted. This thesis analyzes practical examples of energy concepts for non-residential and residential buildings. First, the process of energy consulting and energy-related construction supervision was researched and applied. Subsequently, case examples were created and evaluated from an energy-efficient, economic and ecological perspective. The main data sources used were primarily formed by the guidelines of the federal subsidy for efficient buildings, the „Gebäudeenergiegesetz“ and building balancing standards such as DIN V 18599.
The evaluation of the refurbishment schedules shows that the individual consideration of existing buildings and their renovation options is essential for a sustainable and future-proof refurbishment of the building stock and that this is the only way to combine the personal preferences of building owners with energy-efficient measures.
Editor: Alexander Leon Homann
Tutor: Prof. Dr.-Ing. habil. Joachim Seifert, Dipl.-Ing. Vladi Schuralew – RevIng GmbH, Dipl.-Ing. Dennis Scholl – TSBR Ingenieurgesellschaft mbH
Year: 2023

Application of modern simulation methods in the energetic inspection of ventilation and air-conditioning systems
Various tools are used to perform regular energetic inspections of air conditioning systems. Commonly these are static calculation tools to determine the energy efficiency of air handling units. Depending on the results of these calculations, an auditor derives recommendations for action to optimize energy efficiency. These methods do not sufficiently consider dynamic influencing factors such as outdoor conditions or variable heating and cooling loads, which often results in considerable deviations between the calculated and the actual energy demand.
Therefore, the use of dynamic simulation methods will be necessary in the future to optimise the energy inspection.
Due to this need for development, the use of Modelica-based simulation models to support energy inspection is investigated in the present work. For this purpose, a tool chain is conceptualised and implemented, which carries out automated modelling, simulation and result presentation. Based on the usual recommendations for action, the tool chain also checks system adaptations of real air handling units regarding their energy saving potentials. The determined saving potentials are presented comparatively and serve the auditor as a selection aid for the recommendations for action.
Furthermore, the developed tool chain is applied to validated using the example of three air handling units of different types. The results of the tool chain are also compared with those of static methods, whereby the advantages and optimisation potential of the tool chain are worked out.
Editor: Kajetan Simon Benedict Weiß
Tutor: Dr.-Ing. Martin Knorr, Dipl.-Ing. Torsten Schwan - EASD Dresden GmbH
Year: 2023

Creation of extended monitoring concepts for the verification of efficiency indicators and the development of digital twins for heat pumps and solar thermal systems
Against the background of the neccessary decarbonisation of the heating networks, this thesis deals with two heat generating plants that are currently being planned and are intended to feed environmentally friendly heat into the Dresden district heating network. These are an open-pace solar thermal system and a large heat pump system with data center waste heat as an energy source. Concepts for energy monitoring have been created for both systems.
All sensors and actuators necessary for monitoring are identified and listed. The definition of balance areas for determining energetic variables enables the calcu lation of introduced efficiency indicators by reading out the sensor measurement data. These can be used to evaluate the energetic, exergetic and ecological effectiveness of the systems. Characteristic operating states ans approaches for control are specified. The curcuits of both systems are implemented in simulation environments and tested for various conditions. So far, the model of the heat pump systems work only for depicting stationary states. Further development cpould be importing time series and the simulation of dynamic states.
lt turned out that the simulation environment of the solar thermal system is only partially suitable for the specific application.
The results of the simulations are processed and, in conjunction with the created balance areas, enable an initial calculation of the efficiency indicators. After the systems are finished being built, the performance indicators calculated from the simulations can be used as a reference until sufficient measurement data from continuous operation is available.
Editor: Lukas Kayser
Tutor: Dr.-Ing. Karin Rühling, Stefan Hellfritsch – SachsenEnergie AG, Tilo Keil – SachsenEnergie AG
Year: 2023

Application limits of single pipe low temperature networks
Fifth-generation low-temperature networks have emerged as a promising solution for implementing heating systems based on renewable energy sources, providing efficient and sustainable heat supply to neighborhoods. This study aims to present and classify the current state of research and existing knowledge on fifth-generation heat grids, with particular emphasis on the distinction between single-pipe low-temperature networks.
Despite the acknowledged benefits of low-temperature networks, there is a lack of evaluative operational data for single-pipe low-temperature networks. In order to ascertain the application limits of single-pipe low-temperature networks, four different variants of a reference quarter are simulated using Polysun simulation software, both in single-pipe and dual-pipe networks. The simulation results are used to conduct an energetic and and economic comparison between the single-pipe and dual-pipe networks.
The findings demonstrate that the single-pipe network exhibits no disadvantages compared to the dual-pipe network and is not subject to any application limitations that are not also applicable to the dual-pipe network. Thus, both hydraulic network variants are proven to be suitable for fifth-generation low-temperature networks.
Editor: Tim Esche
Tutor: Dipl.-Ing. Cornelius Sternkopf, M.Sc. David Stuckey – Projektleiter, IPJ Wien
Year: 2023

Robust optimization approaches for the dimensioning of generator parks
In this thesis, robust optimisation methods for the dimensioning of power generation plants are investigated. The work consists of a theoretical and a practical part. First, the theoretical basis for optimisation in power engineering is explained. Then, the integration of uncertainties into the optimisation problem is treated in four steps: Identification of uncertainty factors, characterisation of uncertainties, mathematical modelling of the optimisation problem and application of solution algorithms. In the practical part, the optimisation of energy use for the building complex "Sonnenwald" in the Black Forest is carried out. First, data are analysed and the optimisation problem is formulated as a mixed-integer linear model. This is carried out and evaluated with the help of the "flix-Opt" programme for the case of a perfect forecast. Subsequently, the performance of the reference system under uncertain boundary conditions is investigated with a scenario-based analysis, taking into account uncertainties such as outdoor temperature, irradiation and user behaviour. The generated scenarios are used to derive robust investment decisions for the energy system. These robust design variants are compared and reduced to the worst-case design and the two-year combined design. Finally, the impact of the uncertainties on the operational management is re-examined, using the robust investment decisions as a basis. Finally, a comparison of the power systems is made, taking into account the two robust investment decisions and perfect forecast data, in order to determine the additional costs for the robustness of the system.
Editor: Richard Sturz
Tutor: Dr.rer.nat. Peter Stange
Year: 2023

Development of a generation plant park to supply the city of Dresden with climate neutral district heating
A key element in achieving climate neutrality is the transformation of the heating sector.
The district heating supply has a key role to play here. To support the transformation of
district heating generation, an optimization model is presented that can be used to create
a sound basis for discussion of upcoming investment decisions. The optimization model
combines a dispatch optimization with investment decisions to be made at the beginning
of the year. It optimizes the total costs of the system. Using the city of Dresden as an
example, the transformation process of district heating generation until 2045 is mapped
over the base years 2030, 2035, 2040 and 2045. The model is based on the flixOpt
framework developed at the TU Dresden and is validated using real measured values of
Dresden's district heating generation from the year 2021 as well as a comparative
calculation with a commercial dispatch optimization tool. For four scenario calculations
with, among others, different target years for climate neutrality of the district heating
supply (2045, 2045, 2035, without target), the optimal transformation strategy in each
case is presented. In all scenarios, heat pumps play an important role from 2035 on and
heat storage capacity increases at least elevenfold. In particular, cogeneration of heat and
power relies on high storage performance and capacity due to the shortening daily time
windows with high electricity prices. Boilers can act as a transition technology due to their
low investment costs. Hydrogen will only be used in the final step towards climate
neutrality, whereby the energy and power requirements are many times lower compared
to natural gas in 2021. Electrode boilers do not play a role due to the current electricity
price structure (taxes and surcharges). The costs of heat generation in all scenarios are
5 – 19 % below the costs of the reference year 2021 with a high price level. However, with
only slightly higher heat generation costs, the greenhouse gases emitted until 2045 can
be reduced very significantly. Thus, an ambitious target of "climate-neutral district heating
2035" is recommended as a guiding principle, with a rolling reassessment of the
transformation strategy.
Editor: Felix Bumann
Tutor: Dr. Carl-Philipp Anke – SachsenEnergie, Dr.rer.nat. Peter Stange
Year: 2023

Energy efficiency of domestic water installation – Current situation and future option for an example
For the implementation of climate protection measures in the heating sector, it is indispensable to increase the efficiency of the domestic hot water supply. In existing buildings, temperatures at the drinking water heating unit are sometimes set too high. Lowering the temperature while maintaining drinking water hygiene has the potential to save energy, but also represents an important step towards being able to use more renewable thermal energy sources such as solar thermal energy or heat pumps in the future.
This paper deals with the current state of the drinking water installation and the effects on the district heating network parameters. For this purpose, data of the drinking water heating in a number of apartment buildings from the 1970s in Dresden are collected. In addition, the final energy demand, the CO₂ emissions and the thermal losses are evaluated. Recommendations for action are derived from the investigations, which, taking into account the current Drinking Water Ordinance, guarantee considerable opportunities for efficiency improvements. The results show that there is significant potential for savings.
Editor: Hendrik Martin
Tutor: Dr.-Ing. Karin Rühling, Yakup Kaya – Vonovia SE, Georg Hamann – SachsenEnergie AG
Year: 2023

Contribution to the commissioning and first functional and energetic assessment of the NEST-W 2.0
The research project HYDRA RoS NEST-W 2.0 deals with the development and testing
of a novel CPC vacuum tube collector for solar thermal systems. Ritter Energie- und
Umwelttechnik GmbH und Co. KG, and the TU Dresden with several chairs, are involved
in the project. The present work accompanies the successful commissioning, determines
selected energetic characteristic values and analyzes the operating behavior of the system.
The basic task is to run a plausibility check of the collected monitoring data by the use
of appropriate graphical plots. Based on this, the discharge behavior of the collectors
under different strategies is evaluated by specific stagnation tests. A subsequent flushing
and the analysis of the drained water provide information about the effects of the
experiments. In addition, testing of selected operating modes represents an important
part of evaluating the functionality of the system. Calculations for performance and
daily yield control as well as occurring losses provide information regarding the efficiency
of the collector and system.
Editor: Theo Sell
Tutor: Dr.-Ing. Karin Rühling, Thomas Weidemann – Ritter Energie- und Umwelttechnik GmbH & Co. KG, Dr. Rolf Meißner – Ritter XL
Year: 2023

Determination of comparative key figures based on series of measurements of hot water storage tanks
In the research project VKTES, experimental metrics for thermal storage systems were developed to provide information about their actual heat content and efficiency. These metrics are valuable for selecting the appropriate thermal storage system for specific applications, evaluating its performance, and comparing it with other storage systems. This enables engineers and planners to make informed decisions regarding the optimal size, design, and applications of thermal storage systems. Moreover, these metrics play a crucial role in calculating and designing heating and cooling systems, serving as a foundation for energy balances that contribute to optimizing energy consumption and ensuring sustainable and cost-effective operation.
The present study focuses on the charging and discharging experiments of a 400 L domestic hot water storage tank, indirectly charged through two internal heat exchangers. The execution and analysis of these experiments are the primary focus of this work. A central component of this study is the development of an evaluation routine using Excel. An Excel template for evaluation is created, enabling both the graphical representation of measurement data and the calculation of comparative metrics. Additionally, the developed evaluation routine is applied to direct charging, specifically to a heating buffer storage tank. The testing and adaptation of the routine to this specific charging method are also subjects of investigation.
The results of this study contribute to a deeper understanding of the significance of determining metrics concerning water thermal storage systems and offer a practical solution for evaluating and comparing different types of storage systems.
Editor: Zihan Cheng
Tutor: Dipl.-Ing. Stefan Hoppe, Dr.-Ing. Karin Rühling
Year: 2023

Analysis of the effectiveness of a single room control system in a non-residential building
A single room control system is installed in a non-residential building at the Technical University of Dresden. This offers the possibility of a comprehensive analysis of setpoint temperatures, valve positions and room temperatures as well as an enormous potential for energy savings through the implementation of an intermittent heating operation. Within the scope of the work, an effectiveness analysis of the installed single room control system is conducted for the heating period 2022/2023. From October 2022 to mid-April 2023, restrictions in the heat supply, caused by the EnSikuMaV, are active have to be implemented. The restrictions provide room temperatures below comfort temperatures, but are well controlled by the system. An improper measurement of room temperatures by thermostats in rooms without a wall-mounted device requires a setpoint temperature adjustment for rooms without a wall-mounted device. An introduced equation to determine the actual control temperature allows a partial analysis of these rooms. The intermittent operation mode is rolled out for four test rooms in mid-March. An evaluation reveals that the building has increased energy savings potential from night reduction due to poor insulation and building severity, as relatively severe cooling is possible. The heat-up times are in the range of 0 - 3 hours and thus the system has sufficient power reserves for the increased demand requirement during the heat-up phase. At the beginning of April, the intermittent heating mode is implemented for all rooms in the building. Apart from some communication problems of the devices, the implementation is successful. In general, the intermittent heating operation does not cause any decrease in comfort. Instead, weather-variation-adjusted savings for the intermittent heating operation in combination with the implemented federal government policy lead to savings of 21 %, and after the phase-out of the policy, of 17 %, compared to the previous year’s periods without intermittent heating operation. Taking into account potential savings from switching from thermostatic valves to the individual room control system, totals in potential savings are 23 %.
The use of the single-room control system can therefore be regarded as an useful investment from an energy point of view. Problems can be located to a small extent on the software side. The savings potential can be further increased by optimizing the intermittent heating operation. This can be investigated for periods without restrictive policies by the federal government. An investigation at the system level shows that there is also potential in adjusting the current heating curve. The curve is not optimally set for very low and high outdoor temperatures. Theoretical explanations provide an outlook on the implementation of measures for a demand-oriented temperature control with the help of the single room control system.
Editor: Paul Petermann
Tutor: Dipl.-Ing. Markus Arendt, Dipl.-Ing. Juliane Schmidt
Year: 2023

Simplified modeling of a district heating network in operational management optimization
In this paper, the operational management optimization of a district heating network is carried out using different approaches regarding load shifting. These approaches are tested using an example network. The Python-based optimization tool Flix-Opt is used to perform the optimization tasks. In the paper, it is shown that thermal energy can be stored in district heating networks in different ways.
Different approaches are discussed, related to storing heat in buffer tanks, in the water mass within the district heating network pipes and in building envelopes. It is shown that the loads in the district heating network can be shifted by the studied methods. In addition, it is investigated how the local separation of different generators and consumers using a clustering approach affects the operational management optimization.
Editor: Moritz Scheffel
Tutor: Dr.rer.nat. Peter Stange, Dipl.-Ing. Tiedo Behrends, Dipl.-Ing. Juliane Schmidt
Year: 2023

Calculation tool for determining the hygienic comfort parameters in the room incl. creation of a test stand concept
This thesis deals with indoor air quality as a subfield of hygienic comfort. With the aim
of evaluating this, the most important parameters that affect hygienic comfort were
identified and their effects were described. By setting concentration limits for these
comfort parameters, an evaluation of the indoor air quality can be carried out.
Within the scope of this work, a calculation tool in Excel was developed, which calculates
the concentration of pollutants in the room. With the help of this tool, influencing
variables on the pollutant balance were analysed. The volume flow of fresh air and the
number of people were identified as the most important influencing factors.
Furthermore, the background of the energetic balance was discussed and simplified
calculated using the example of DIN EN 16798. This shows that an evaluation of indoor
air quality is important both in terms of comfort as well as the energetic expenditure.
The supply air volume flow can be calculated in a simple and universally applicable way
using a specific parameter. This provides the necessary fresh air volume flow, depending
on the activity level of the people and the desired pollutant difference between supply
air and room air.
With the aim of examinig the air exchange rate and the energy balance on a test stand,
three concepts for the implementation in the Combined Energy Lab at the TU Dresden
were developed and comparatively evaluated.
Editor: Klara Sulamith Bestehorn
Tutor: Prof. Dr.-Ing. habil. Joachim Seifert, Dipl.-Ing. Lars Schinke, Dipl.-Ing. Maximilian Beyer
Year: 2023

Dimensioning of a ventilation system using the BIM planning methodology with a practical comparison of different HVAC applications regarding the requirements of a planning office
In order to measure the current progress of digitization in Germany, the Institute of the German Economy developed the Digitization Index. The index for the year 2022 illustrates, in particular for the "other manufacturing" industry group, which includes the construction industry, that there is still potential for digitization that can be exploited through targeted measures. One possibility for the construction industry is the use of Building Information Modeling (BIM). This creates the opportunity to realize the planning, construction and operation of structures using model-based, digital methods. However, the question arises as to which software combination will be most appropriate to use for planning in 2023 according to the BIM methodology.
Due to this, the present thesis deals with a comparison of three BIM-compliant software
combinations for the ventilation trade using the BIM planning method. For this purpose, the basics of Building Information Modeling and the planning requirements of ventilation systems are explained first. Then, the office building to be investigated and the ventilation concept created for the rooms to be ventilated are described. The latter is further developed by means of a pressure loss and sound calculation and checked for the information content in the resulting component list, measurement list and IFC file. Based on this, the ventilation design is analyzed in two further BIM-compliant software combinations. Due to the faulty import, the analysis includes a redesign of the ventilation concept in the basement of the office building as well as the verification of the pressure loss and sound calculation, component list, measurement list and generated IFC file. Through the subsequent comparison of the considered software solutions, the respective advantages and disadvantages of the analyzed aspects are shown and evaluated on the basis of a developed evaluation standard.
Editor: Marko Tadic
Tutor: Dipl.-Ing. (FH) Bernd Klimes - INNIUS DÖ GmbH, Dipl.-Ing. Jens Kaiser
Year: 2023

2022

Summer space cooling: Implementation of a research methodology based on scalable building and system models for the cooling effect of free heating surfaces in existing buildings
In order to estimate the cooling effect of free heating surfaces, a coupled system and building simulation is necessary. The creation of such a simulation is usually time-consuming and requires expert knowledge. Therefore, a prototype of a web application is to be created in the context of this work, in order to make an estimation of the cooling effect possible also for users without detailed specialized knowledge. The building models are provided in a library. This library will be extended by building models. For the execution of the simulation with free heating surfaces the basic procedure will be worked out to automate the required inputs. With the help of simulations the determined
functions are checked and an estimation of the cooling effect is presented. For the evaluation, ideas for the implementation of the evaluation are shown.
Editor: Stefan Bayer
Tutor: Dipl.-Ing. Andrea Meinzenbach, Dr.-Ing. Alf Perschk
Year: 2022

Development of a supporting tool for the selection of heating systems in existing buildings
In this paper, the replacement of heat generators in existing buildings is considered, with the main focus of the paper being on municipal buildings. To this end, the current political framework conditions, special features of existing municipal buildings and existing decision- making aids are first considered. One focus is on the new draft of the German government with the requirement that heat generators must be operated with a share of 65% renewable energies in the future.
Criteria are established to select technologies to be considered economically for heat generator replacement. This is done on the basis of the summed present values of the energy costs. The investment costs are not considered due to insufficient data. One focus of this work is on heat pumps in monovalent and bivalent operation. Here, the VDI 4650-1 is strongly taken as an orientation.
Furthermore, the results of the methodology are evaluated and the methodology is examined for its uncertainty with respect to the results. The developed methodology is especially suitable to narrow down the choice of heat generator technologies. However, a decision on which technology is best suited for the exchange can only be made with more detailed subsequent considerations.
Editor: Kai Witza
Tutor: Armin Verch - SAENA, Prof. Dr.-Ing. Clemens Felsmann
Year: 2022

Use of a ground-mounted photovoltaic system and a battery storage system to directly supply electricity to a new housing estate in an area network
In this thesis, a concept for the optimal use of energetic yields of a large-scale groundmounted photovoltaic system (PVA) is developed on the basis of a concrete renewable energy project in Saxony. The concept is an area network, which is to serve the direct power supply of a new housing estate. For this purpose, the project conditions and energyeconomical basic conditions are explained first. Then, using the calculation tools "pvlib python" and "LoadProfileGenerator", a yield forecast for electricity yield from the PVA and a load forecast for the electricity demand of the new housing estate are created,
evaluated and compared with each other. It is found that adding a lithium-ion battery storage system to the project could be useful as a neighborhood storage system. This is examined using an optimality calculation in terms of cost effectiveness. It turns out that the proposed extension with a battery storage makes sense, as it improves the energy efficiency of the overall project in addition to the cost efficiency. Based on the results, the recommendation is finally made that the project be expanded to include a battery storage system of the capacity calculated as optimal.
Editor: Justus Jonas Kerlin
Tutor: Dr. rer. nat. Wolfgang Daniels – Sachsenkraft GmbH, Dr.rer.nat. Peter Stange
Year: 2022

Technical design and evaluation of a concept to supply a district heating network with a heat pump using water from the lake as heat source
In the following thesis, a technical concept was developed to provide heat to an existing district heating system using heat from the Groitzscher Lake. In order to do this, the existing heat demand was used as a baseline to create a model of the district heating network which could accurately approximate the future operating parameters of the network following a transformation to reduce network temperatures. Using the model, two heat demands, representing two future demand curves was constructed. The temperature field in the lake was predicted using a 1D-Heat transport simulation tool. Using the temperature distribution data from the lake, the generated curves and considering the legal limitations, a technical concept for a heating plant is developed to supply the network with heat at the given conditions. The heating plant uses a heat pump and a vacuum-ice slurry plant to supply the desired heat. Finally, the effects of all developed models on each other was simulated and the effects of the thermal discharge on lake water was analyzed.
Editor: Ege Cengiz
Tutor: Johann Cavar - ENGIE Deutschland, Prof. Dr.-Ing. Clemens Felsmann
Year: 2022

Economic efficiency of heat recovery systems in ventilation and air-conditioning systems with and without adiabatic exhaust air humidification
Due to the use of conventional compression refrigeration systems, the summer air
conditioning of buildings has a great potential for both energy saving and the reduction
of climate-damaging emissions. To exploit this potential, adiabate cooling systems are
increasingly being used in air conditioning systems as a climate-friendly alternative. From
the perspective of building operators, the question of the economic viability of these
systems also arises. The answer to this question is the subject of this study. The aim is to
quantify parameters that indicate an economical operation of adiabatic cooling system.
The parameters to be examined are the design flow rate, the operating time of the air
conditioning system and the heat recovery system. In order to quantify the influence of
these parameters, they are varied. The subject of this work are two typical non-residential
buildings which, due to their divergent use, represent different plant operating times. The
heat recovery systems considered are plate heat exchangers and circuit-combined
systems. The cost-effectiveness analysis is carried out in accordance with VDI 2067,
whereby the energy demand values are determined on the basis of DIN V 18599-3.
Variants with and without adiabatic cooling systems are compared to the costeffectiveness assessment. As a result of the investigation, it can be manifested that the adiabate cooling system is preferable from an economic point of view only for the hospital with a plant operating time of 8.736 h/a and a design volume flow of 20.000 m³/h. The influence of the heat recovery system used is not significant, since the temperature
exchange rates of different heat recovery systems differ only marginally according to the
current state of the art. Carrying out the profitability analysis according to the method of
amortization period shows that all plant variants are advantageous because they
amortize themselves within the useful life. Due to the indirect CO₂ emission savings of up
to 22 %, the adiabate cooling system is recommended for hospitals regardless of the plant
size. For the university, this applies from a plant size of 20.000 m³/h.
Editor: Paul Straßburger
Tutor: Dipl.-Ing. Ronald Nerger – Brendel Ingenieure, Dipl.-Ing. Felix Valentin
Year: 2022

Energy flow analysis and waste heat utilization in a foundry
This thesis examines the use of waste heat in a foundry. The existing processes and facilities are considered, and the associated energy consumption is analysed. The measured values of the foundry's energy consumption from 2021 serve as a basis. The total energy demand in 2021 was 33,420 MWh and is divided between electrical energy (26,620 MWh/a), natural gas (6,730 MWh/a), and diesel (70 MWh/a). In addition, employees' statements about production steps and processes are used for further calculations. The work aims to present the possibilities of waste heat utilisation and to develop implementation proposals. To illustrate the effects of heat recovery, key figures are collected and evaluated. To utilise the waste heat from the operation of the melting furnaces, the installation of a heat distribution network within the foundry is proposed.
This leads to the reduction of natural gas consumption in several heat sinks. Furthermore,
the recovery of waste heat from the dark radiator hall heaters for heating a fabrication process is recommended. Through the proposed waste heat utilisation, it is possible to reduce natural gas consumption by 1,590 MWh/a, which is equivalent to a reduction of 24 % of gas consumption and 4.8 % of the total energy demand.
Editor: Rubén Günther
Tutor: Dipl.-Ing. Vera Boß, Christoffer Schroth – Schmiedeberger Gießerei GmbH
Year: 2022

Determining demand profiles and behavioural patterns from heat meter datasets
This project thesis pursues the goal of evaluating the measurement data of 20 house
stations from the district heating area of Stadtwerke Böblingen. For this purpose, the
thermal energy of the heat meter is first determined and processed. Subsequently,
relevant parameters and criteria are presented in order to be able to evaluate the data.
Furthermore, the availability and plausibility of the measured data are checked. The
house stations are compared using the parameters and criteria presented, with
conspicuous stations being examined in more detail. A separate chapter examines
whether usage profiles and behavioral patterns can be derived from the measured data,
again focusing on particular stations. Finally, the domestic water heating of the house
station is examined in more detail. In the conclusion, the results are summarized to
provide an overview of the findings. Furthermore, in the outlook, different possibilities for
improving the efficiency of the systems are presented.
Editor: Valentin Grüber
Tutor: Dipl.-Ing. Stefan Hoppe, Dipl.-Ing. Vera Alieva
Year: 2022

Case-based selection of control strategies for consumption optimisation in buildings
In this paper, the question is investigated whether a model-based algorithm, which
operates according to the principle of "Cased Based Reasoning" (CBR), can be used for
consumption optimization in buildings. For this purpose, the energy concept of the
elementary school in Giebelstadt was used as an example for optimization. The building's
heating system, which was constructed in 2019, was modeled in Modelica and validated
with the measured data from the sensors of the real system.
Three different optimization strategies were tested on this model to minimize the
consumption of energy. In the paper, the strategies studied are presented and compared.
They are in control of the plants equipment using a static control variant, a variant using
predictions and the CBR-algorithm. The CBR-algorithm uses typical structures such as a
case database as well as reusing past solutions to perform consumption optimization.
To assess the applicability of the CBR-approach, it and the comparison strategies were
tested on a two-year simulation of the elementary school. This involved simulating the
model of the facility with sensor data from 2020 and 2021 and using the different
strategies to set the control variables of the facility.
Using this simulation as an example, the success of a CBR-algorithm in plant control and
consumption optimization was demonstrated. Here, the algorithm was able to reduce the
total energy consumption by about 1.2% with respect to the predictive variant, and a cost
saving of about 9% was achieved over the two years in comparison with the static control.
However, such a computer-based algorithm must always comply with the system limits in
order to find an application outside of simulation.
Editor: Sven Juhler
Tutor: Dipl.-Ing. René Unger – EA Systems Dresden, Dr.-Ing. Paul Seidel
Year: 2022

Analysis of monitoring and accounting data to determine CO₂ equivalents of the TU Dresden Campus
As part of this work, the sources of the CO₂ emissions from the campus of the TU Dresden were considered. The influence of the climate factor on heat consumption is taken into account. The relevance of this parameter in turn for the assessment of the energy efficiency of buildings, namely the difference between absolute consumption and weather-adjusted consumption. In addition, examples of calculation of the emission factor for different final energy carriers were considered, as well as allocation methods for thermal energy and changing the emission factor for electricity with different supply schemes. An important point of this work is the comparison of already implemented or currently planned energy efficiency measures at other German universities. In the last part, possible measures to reduce emissions were considered, such as replacing energy sources with more environmentally friendly or voluntary emission compensation.
Editor: Heorhii Polskyi
Tutor: Dipl.-Ing. Markus Arendt
Year: 2022

Techno-economic analysis of options for hydrogen production in the context of a global hydrogen market
This work presents relevant production processes for hydrogen and discusses possible operation modes for electrolysis plants. Based on this, a model for calculating hydrogen cost potential curves is developed, which can be applied on the basis of available renewable energy potentials to regions worldwide. The levelized costs of hydrogen and hydrogen potentials of any country can be calculated. To do so, the optimal system design for minimum hydrogen production costs for water electrolysis in combination with renewable energies (photovoltaics and onshore wind energy) is determined. Based on the available renewable energy potentials, five different modeling variants were identified. These are applied comparatively to the countries Morocco and Ukraine for the year 2050 in order to investigate the influence of the spatial resolution of renewable energy potentials and the consideration of hybrid power plants on the hydrogen production costs. For Morocco, the most favorable hydrogen potentials up to 93 Mt_H2 in 2050 result in hydrogen production costs below 2 €/kg_H2. Due to Morocco's particularly good solar potentials, PV-wind hybrid power plants do not have cost advantages and therefore the cheapest hydrogen potentials are produced only with electricity from photovoltaic plants. By using wind energy, hydrogen production costs increase due to the high investments and low wind speeds in Morocco. In Ukraine, on the other hand, solar potentials are smaller. Therefore, the most cost-efficient hydrogen potentials are produced using PV-wind hybrid power. Up to 24 Mt_H2 can be produced using hybrid power plants for costs between 3.00 and 3.50 €/kg_H2. In both countries, the impact of the regional resolution of renewable energy potentials is rather small. A sensitivity analysis shows the largest sensitivities of hydrogen production costs towards renewable energy capital expenditures and the interest rate.
Editor: Jonas Meier
Tutor: Dr.-Ing. Robert Kunze – ESA² GmbH Dresden, Hendrik Scharf, M. Sc. – TU Dresden, Lehrstuhl für Energiewirtschaft, Prof. Dr.-Ing. Clemens Felsmann
Year: 2022

Optimization of the cryogenic test stands in a test laboratory
The FEV Dauerlaufprüfzentrum GmbH tests engines and drivetrains in the context of
endurance tests. Therefore, engines and drivetrains are exposed to different
environmental conditions like hot and cold air temperature or thermal shock of heat
exchange water. This dissertation examines deep cold tests of combustion engines
especially its test stand equipment for conditioning the air, which limits the engine under
test in power because of its heat exchange and air requirement. The target of this analysis
is performing durability tests in deep cold test stands like they are done in standard test
stands with temperatures between 15 and 30 °C.
First the test stand equipment will be described, experimentally tested and the gotten
data evaluated. Then there will be made a calculation tool which can be used to give a
prediction if endurance tests can be realized.
In result, the building envelope of the deep cold test stands has some leaks which must
be eliminated. There also comes a to big volume flow of warm dry-air in the test stand
which is much more than needed as combustion air. The air-cooling unit can only get the
air temperature of the empty test stand to -14 °C. By using data of the cooling down
experiment, there will be the possibility to estimate by the rate of power and thereby the
heat input and consumption air, if endurance runs can be performed. Also, there are
concepts for the optimization the test stand equipment to reach the aim.
Editor: Benjamin Goedecke
Tutor: Prof. Dr.-Ing. habil. Joachim Seifert, Dipl.-Ing. Lars Schinke
Year: 2022

Identification of consumption patterns and fault conditions of customers by machine learning
The amount of installed smart meters is rising– causing a steady increase in data availability. Simultaneously the heating sector is facing the challenges of the energy transition, which can only be overcome if efficiency and monitoring of district heating networks are increased in the meantime. The question if and how machine learning can be used in solving these issues will be explored in this thesis, focusing on the analysis of load patterns and fault detection.
Approaches already described in recent publications are introduced briefly and demonstrated by using two datasets of hourly district heating data. One of these datasets contains buildings where secondary side behaviour is also being monitored. Two possible goals in utilizing this data – estimating hot water usage and identifying the heating system out of smart meter data – are described and the use of machine learning on the available data investigated.
Common concepts of machine learning, barriers in the application as well as their implications in the heating sector can be shown by examples. The introduction of several case studies underlines the discussed topics. Promising methods and typical issues found during the literature review are highlighted and bundled into recommendations for further research.
Editor: Felix Geister
Tutor: Dr.rer.nat. Peter Stange, Dipl.-Ing. Sven Paulick
Year: 2022

Calculation of a branched drinking water distribution network and design of hygienically correct flow conditions in main distribution pipes
The aim of this work is to answer the question of how the selected technical measures and operating situations affect the flow conditions and thus the temperature and hygiene of the drinking water.
First, the relevant requirements for drinking water systems are presented. The various hygienic measures for drinking water are taken up and discussed. In this part, the current technical development for influencing the drinking water temperature is also presented. Subsequently, the flow type of the drinking water pipe is calculated. The heat in the wall is also determined in this part. It results from the heat sources, the ambient temperature of the pipe and the heat flow through the wall. The heat absorption and release of the piped potable water is determined by using the general equation for a heat conduction through a multilayer cylindrical wall. The heat flow through the wall is calculated by using the general equation for a heat passage.
Also, the selected hygienic measures of the flushing effect are derived. The pipelines for cold drinking water can be flushed with an automatic flushing system, a ring system or a cold water circulation system. For hot water, the pipelines can be treated by an extension of the pipeline drinking water circulation, a ring system with flow divider or with electric instantaneous water heaters. Subsequently, the costs of the measures are calculated with the guideline VDI 2067. Furthermore, it is evaluated which measure is optimal for the different variants in the planning and construction process.
Finally, the summary analyzes the possibilities for further research. For the drinking water cold, the cold water circulation system is the most effective. For the drinking water hot, the hygiene measure with the extension of the pipelines drinking water hot costs the least, because in this example project only a few areas need the pipe extension.
Editor: Hyeju Noh
Tutor: Dipl.-Ing. Mathias Behrens - CANZLER GmbH, Dipl.-Ing. (FH) Markus Taubner - CANZLER GmbH, Dr.-Ing. Lars Haupt
Year: 2022

A contribution to modelling the Dresden heating market
In order to limit climate change, the realisation of climate targets is urgently needed. To achieve the urban climate goals in Dresden, strategies for the conversion of the heat supply and the creation of an efficient building stock in Dresden are being developed within the framework of an integrated energy and climate protection concept (IEK), as well as municipal heating planning and the transformation of the district heating supply by the local energy supplier SachsenEnergie AG. Accordingly, a monitoring of the heat demand in Dresden's building sector by mapping the current status in 2021 and the long-term development of the heat demand is fundamentally necessary.
This paper therefore deals with the Excel-based modelling of the heat demand development of the city of Dresden for the years 2021 to 2045. The basis of the model is a building database, which was created bottom-up by comparing and calibrating the heat demand data with the heat consumption data. It assigns an annual heat demand to each building in Dresden, divided into space heating and domestic hot water heating demand. By parameterising influencing variables, the development of heat demand can be calculated in the long term and based on scenarios. Necessary information for the modelling and design of the parameters was compiled in an extensive literature research. The resul ts show that Dresden already has a good average energy-efficient building stock. In the best-case-scenario, the heat demand of the city of Dresden decreases by 64 % from 6.92 TWh to 2.48 TWh and in the trend-scenario by 32.5 % to 4.67 TWh by the year 2045. Efficiency measures such as the energetic refurbishment of the building envelope and the distribution lines represent a large potential for this reduction in heat demand. In addition, a large share of energy can be saved by changing user behaviour. Climate change can only be slowed down to a limited extent by local changes and will lead to a further decrease in heating demand in the event of strong global warming. In order to reduce the heat demand of the city of Dresden, the implementation rate of efficiency measures must be increased through financial incentives and targeted demands, and the population must be sensitised and planning security for the owners must be ensured with the help of municipal heat planning. In Fakultät Maschinenwesen „Friedrich List“ Professur für Gebäudeenergietechnik und Wärmeversorgung order to achieve the climate targets by 2045, in addition to the strong reduction in heat demand in the building sector, the transformation of the heat supply through a change of energy source to the use of CO₂-neutral heat sources is absolutely necessary.
Editor: Anna Ebeling
Tutor: Dr. Anke - SachsenEnergie AG, Dr.rer.nat. Peter Stange
Year: 2022

Combined Operation of an air-water-heat pump: Efficiency analysis and model-based operational analysis in an emulation environment (hardware-in-the-loop)
In the developement of an air-water-heat pump the interaction between the indoor and outdoor units plays a crucial role.
The indoor unit with its hydraulics and control devices affects the efficiency of the overall system. In the case of the heat pump examined, the efficiency is reduced by the heat losses in the indoor unit, by mixtures that arise as a result of the hydraulic decoupling due to measurement uncertainties of the temperature sensors, and auxiliary energy for electrical loads. These have different influences depending on the operating points, but can be roughly estimated with a 5 % reduction in the Seasonal Coefficient of Performance (SCOP). The influences are greatest in the case of high volume flows and high temperature differences to the ambient air.
Long-term test rigs are a good way of testing the robustness of the overall heat pump system. Operation that is as realistic as possible is provided by a building simulation that is connected to the device via hardware-in-the-loop. Due to targeted data evaluation discrepancies, that have not been found by other regular tests, can be eliminated.
Editor: Lea Sprenger
Tutor: Dipl.-Ing. Jens Kaiser, Dr.-Ing. Martin Knorr
Year: 2022

Automated evaluation and allocation of load profiles in the simulation of heating networks
As part of this work, a high-performance program was created which, even with a small data basis of a heating network, carries out an automatic assignment of load profiles to consumers. The program was programmed in Python. The minimum required data for the automatic load profile assignment is the outside temperature, the load profile of the heating network, the annual heat requirement of the customers in the heating network and a load profile database. Various options are available in the program for adapting the automatic load profile assignment to the needs of the user. The user can choose between different reference values, parameters and types of optimization in the graphical user interface. The load duration curve, the load curve for the entire year and the load curve for the heating and non-heating periods of the heating network are available as reference values. Five different parameters are implemented in the program. The optimization of the load profile assignment can be based on random load profile assignment or a newly developed assignment, the optimization based on sets. Compared to random assignment, optimization using sets achieves a satisfactory load profile assignment in less computing time. In any case, the program is preferable to manual load profile assignment. A recommendation for action was derived.
In addition, it was examined what volume of customer data makes the creation of a new profile model preferable to using existing load profiles. This volume of measurement data is reached when the new adaptive model is used to predict the load profile more precisely than with the existing load profiles. The models were created using multiple linear regression. For an accurate forecast measurement data from the heating period, the non-heating period, weekdays and non-weekdays must be available. If measurement data is known for a wide range of outside temperatures, the quality of the forecast improves. A general statement about the required scope of measurement data could not be made.
Editor: Imke Lochner
Tutor: Dr.rer.nat. Peter Stange, Dipl.-Ing. Sven Paulick
Year: 2022

Decarbonization of heat supply of a residential area by means of a small sized low temperature district heating network based on renewable heat sources
In order to decarbonise the heat supply of the garden city Alt-Lößnig in Leipzig, the Leipziger Stadtwerke GmbH plans to replace the current supply of natural gas to the neighbourhood with a small sized low temperature district heating network. The aim of this thesis is to develop a heat supply concept based on renewable heat sources and the use of industrial waste heat. For this purpose, a large-scale solar thermal system and a heat pump that raises the temperature level of a low-temperature waste heat source from the Leipzig-Süd CHP plant are planned on the nearby Leipzig-Süd power plant site. A heat storage system to be dimensioned will temporarily store the sustainably produced heat and thus increase the flexibility of the energy system. Extreme load peaks are covered by a connection to the primary district heating network of the city of Leipzig, which ensures security of supply. In the context of this thesis, a simulation tool is being developed with which the heat flows in the energy system over the course of the year can be represented with hourly precision. Based on technical, ecological, economic and subsidy-specific criteria, different variants regarding the control of the storage loading temperature and the storage volume can be evaluated and compared. Based on the simulation results, a recommendation is made for the control variant and the optimal storage volume. With the proposed solution variant, 90 % of the heating demand of the neighbourhood is covered by the solar thermal system and the heat pump and thus annual CO₂ savings of 1150 t_CO2/a or 68 % are achieved compared to the current state.
Editor: Michel Zimmer
Tutor: Erik Jelinek - Stadtwerke Leipzig GmbH, Dr.-Ing. Karin Rühling
Year: 2022

Conceptual design and development of an energy simulation model for a waste heat supported HVAC system
Herein the creation of an energy simulation model of a waste heat supported climatization system for a fuel cell multiple unit is document ed. The chosen modelling approach is the discretization of the transient thermal processes assuming quasistatic behaviour and conducting a time step integration using the 1D-simulation software Simulink. For the innovative components of the system, including „Thermally Active lnterior", a „Thermal Switch" as well as an absorption cooling system, component models are designed. Their plausibility is assessed by supporting FEM simulations or experiments. As a result the general suitability of the modelling approach could be testified although inhomogeneities in the thermal fields show limitations in researching effects inside the Thermal Switch and the absorption cooling deeply. The component models are integrated into the entire system which additionally includes an air conditioning system as well as several fluid circulations with belonging pipes and valves. Thereby a controlled system is defined. In this present work, so far no corresponding controller was developed. By imposing constant control variables, first interactions between the climatization components and the system behaviour could be examined. In heating operation the whole thermal energy demand can be covered by the fuel cells waste heat. For cooling mode, without a controller, no final statement can be worded so far regarding especially the complex requirements of dehumidification. The modularity of the designed simulation tool enables an evaluation of different interconnection topologies of the climate system. Furthermore, the implementation of a suiting controller and the integration in a whole vehicle dynamics model are projected.
Editor: Björn Kauer
Tutor: Dipl.-Ing. Oliver Garack, Hörmann Vehicle Engineering GmbH, Dipl.-Ing. Andrea Meinzenbach
Year: 2022

Development of a strategy for a GHG-neutral municipal heat supply using the example of the municipality of Leubsdorf
In order to achieve climate protection goals, the heat supply in communities must be planned and implemented with low emissions or as few emissions as possible, both in existing buildings and in new buildings. The municipalities can draw up a municipal heat plan for this.
In this work, the process of municipal heating planning with the goal of greenhouse gas neutrality is to be carried out on the basis of a rural municipality and knowledge about tools and potentials is to be gained. The current status of the municipality should be determined, the potential of renewable energies and waste heat calculated and then combined into measures. By using these measures, heat supply variants are developed. lt should be shown which data is necessary for the status and potential analysis and how weil it is available and usable. A number of programs are also presented and used to help simplify and accelerate planning.
Finally, a comparison is made as to which variants of heat supply are economically viable for smaller locations and to which conditions this economic viability is linked. By including social criteria in the selection of heat supply, local people should be more involved in the concepts.
In the town centers it makes sense to supply the buildings with a low-temperature local heating network. A large number of regenerative energy sources can be used to provide heat. Above all, large-scale solar thermal systems in connection with seasonal heat storage are ideal for supplying people with heat. With this combination, a solar coverage of 82,72 % over a year can be achieved. By using networks, heat production costs of 0,12 EUR/kWh and less are possible. In areas with more sparse development, there is the option of decentralized supply, for example using heat pumps.
In all cases, it is important that the building stock is refurbished and that the energy requirement and the temperatures for heating are reduced.
The electricity required for the heat supply can be generated using existing wind, water and photovoltaic systems, thus guaranteeing that greenhouse gas neutrality is achieved.
Editor: Maximilian Gutwein
Tutor: Dipl.-Ing. André Müller – BCC-Energie GmbH, Dr.-Ing. Felix Panitz
Year: 2022

Feasibility study for the expansion of a local heating network
Due to the expansion of the computer centre of the Potsdam Institute for Climate Impact
Research (PIK), it is being considered to expand the existing local heating network to
include the A 31 building in order to use the additional waste heat. Therefore, this work
examines whether the integration of the building into the local heating network can be
realised without major conversion measures both in the building and in the existing local
heating network. To enable efficient operation of the necessary heat pump, it is
investigated whether the flow temperature in A 31 can be lowered. The data required for
this was determined with the help of a model in TRNSYS-TUD and various simulations as
well as heating load calculations at different outdoor temperatures. The heating load
calculation at the standard outdoor temperature showed undersizing in six rooms.
However, it also showed that it is possible to reduce the flow temperature in most of the
rooms, in varying degrees. Therefore, against the background of minimising the use of
gas, this study recommends that in the course of a possible connection of building A 31
to the existing local heating network, further measures should be taken on the building
envelope or the replacement of individual radiators.
The study concludes that a connection to the local heating network is feasible and worth
striving for.
Editor: Stefan Bayer
Tutor: Dipl.-Ing. Cornelius Sternkopf
Year: 2022

Investigation on alternative concepts for heat transfer substations in the district heating network of the city Dresden
SachsenEnergie AG operates 99 district heating secondary networks of lower temperature
and pressure levels in Dresden, which are indirectly connected to the district heating
primary network via heat exchanger stations. This thesis investigates the direct
connection of secondary networks with the aim of being able to reduce the return
temperature on the primary side due to the omission of heat exchangers in the case of
indirect connection, which reduces line heat losses and thus the required feed-in heat
output of the generators. Furthermore, the analysis of the total hydraulic effort for
indirect and direct connection of the secondary networks is the focus of this thesis. In the
first step, three secondary networks are selected, which are then analysed in a
thermohydraulic heat network simulation for three load cases (summer, transition,
winter), each with indirect and direct connection. The final consideration of the
investment costs of the direct connection in comparison to the indirect connection rounds
off the thesis.
Editor: Benjamin Latta
Tutor: Dipl.-Ing. Dominik Haas - SachsenEnergie AG, Dr.-Ing. Karin Rühling
Year: 2022

Automated detection and diagnosis of malfunction in solar thermal plants
This project work is dedicated to automated fault detection in solar thermal systems. Initially the types of algorithms that are suitable for fault detection in solar thermal systems will be explained. Based on the results of a literature review of existing projects on this topic, the selection of one specific algorithm type will be justified. The procedure for one possible way of implementation will be demonstrated by using selected examples. To do so the freely available programming language Python will be used. The achieved results will be discussed and the potential of an extension of the program code is shown, in case of a continuation of the project.
Editor: Justus Vollmer
Tutor: Dipl.-Ing. Martin Heymann
Year: 2022

Evaluation of the energy perfomance of residential buildings in Saxony
In order to achieve the goals of the federal climate change act, carbon dioxide emssions in the energy, building, industry, agriculture and transport sectors should be reduced. Especially in the building sector, due to the age structure of the residential buildings, there is a potential for climate protection that can be exhausted through trageted and effective measures.
Because of this, the present thesis deals with the evaluation of the energy performance of
residential buildings in Saxony. This is done explicitly for the municipality of Kurort Rathen, which was selected after a through examination of potential municipalities. The data basis was created by contacting selected representatives of the municipality, recording the building via internet research and collecting data on site. Based on this, the final energy consumption, emissions and building renovations were calculated. In doing so, plausible results were archieved with regard to the final energy consumption and according to scenario 2 of the building renovations, a renovation potential for at least 54 residential buildings in the municipality of Kurort Rathen. The expansion of the calculation approach by adjusting the hours of full use led to implausible results. Based on the achieved results an outlook for the other implausible municipalities and measures for reducing carbon dioxide emissions in residential buildings were formulated.
Editor: Marko Tadic
Tutor: Dipl.-Ing. Andrea Meinzenbach, Dipl.-Ing. Cornelius Zunk, Dipl.-Ing. Martin Altenburger
Year: 2022

Investigation on system integration of Solar Plants at several decentralized locations of the Stadtentwässerung Dresden (Dresden municipal sewage company)
This thesis examines the integration potential of solar plants at eight sewage- and
administrative facilities of the municipal wastewater company SEDD to increase
self-consumption proportions and reduce purchases from energy suppliers.
Based on an area analysis, the photovoltaic potential on roofs and open space is
determined and catalogued. Each facility has a minimum of three installation variations
assigned, which have been simulated with POLYSUN SPT yield simulation
software by Vela Solaris. In combination with the specific load profiles, the simulated
annual electrical energy self-consumption is used to analyze the economic
efficiency of the variants and to identify the technological and ecological superior
installation design. The results are transferred into recommendations for further
realization.
Editor: Lukas Kayser
Tutor: Dipl.-Ing. Thomas Schöniger - Stadtentwässerung Dresden GmbH, Martin Schubert - Stadtentwässerung Dresden GmbH, Dr.-Ing. Karin Rühling
Year: 2022

Investigations concerning the system integration of PV plants for an area of the chemical industry
In this scientific work, investigations are carried out into the system integration of photovoltaic systems for the area of the chemical industry Wacker Chemie AG, at the Nünchritz site.
The roof surfaces, facade surfaces and open spaces on the factory premises were subjected to a potential analysis so that several objects suitable for construction could be selected. Two roof areas and one open area were then simulated using the POLYSUN SPT software, a simulation tool for photovoltaic systems from the company Vela Solaris, and a PV system was set up on it. In summary, this resulted in a PV generator output of 662.4 kWp. The program then forecast the yield values of each system for a representative year using stored weather data.
In the further course, regulatory framework conditions were considered, and a profitability calculation was carried out. The calculated payback periods are between almost seven and ten years, so that a positive recommendation for the plant management could be derived from the results of the simulations and calculations.
Editor: Erik Wöhner
Tutor: Dr. Markus Kirchhoff – Wacker Chemie AG, Dr.-Ing. Karin Rühling
Year: 2022

Testing of bifacial glass-glass PV modules in accordance with IEC61215:2021
This thesis presents the new requirements of IEC 61215:2021 for testing bifacial PV modules. This series of standards describes the test procedures and criteria for accelerated lifetime testing of photovoltaic modules, which is an essential part of the quality process.
The test procedures are performed and evaluated on bifacial glass-glass modules manufactured by SOLARWATT as a preliminary step to certification. For this purpose, the new or modified test procedures are analyzed, and necessary adjustments are made on test benches at the SOLARWATT laboratory. The underlying degradation mechanisms of bifacial modules are explained and an overview of the concepts of the different bifacial cell technologies is given.
The parameters affecting the backside power gain are investigated at both the module level and the system level. For this purpose, simulations based on ray tracing and 2D view factor modeling are performed.
The results of the laboratory measurements and simulations will be incorporated into the development of an optimized bifacial module design by SOLARWATT.
Editor: Carl Lukas Voigt
Tutor: Dietmar Wald - Solarwatt GmbH, Dr.-Ing. Felix Panitz, Dr.-Ing. Karin Rühling
Year: 2022

Optimization-based analysis of incentive schemes for self-supplying photovoltaic power in multi-family houses
The expansion of photovoltaics is an important pillar of the energy transition in Germany. In order to achieve the Paris climate goals and to avoid competition for land between agriculture and solar systems, all technical roof area potentials should be used. Roofs of multi-family houses offer great potential in connection with a self-supply of electricity, the so-called tenant electricity (Mieterstrom). In contrast to feed-in only, self-supplying photovoltaic systems allow the generation of decentralized and load-related power. The government’s incentives in the form of reduced electricity price components and the tenant electricity surcharge included in the German Renewable Energy Sources Act (EEG) since 2017 are facing a large amount of administrative effort and have not yet been sufficient to incentivize any significant expansion.
In this thesis, the framework conditions for tenant electricity in Germany are summarized and, based on barriers in the existing system, incentives are developed to accelerate the expansion of self-supplying photovoltaic power on multi-family buildings. The incentive systems developed include individual government measures, variable electricity tariffs, and the integration of electric cars and heat supply into the energy system of the building. The focus is on so far unprofitable, smaller buildings. The incentives are analyzed in one current and three medium-term price scenarios and with the help of a mixed integer linear optimization model with 15 minutes resolution. It can be shown that all developed incentive schemes lead to a more economical operation of tenant electricity projects. The advantages are particularly significant for the integration of variable loads. In the short term, the abolition of administrative hurdles and targeted subsidy programs are promising measures.
Editor: Kristian Prewitz
Tutor: Elias Dörre – Fraunhofer IEE, Dr.rer.nat. Peter Stange
Year: 2022

Considerations for the introduction of an energy management system according to DIN EN ISO 50001 at the Fraunhofer Institute Center Dresden IZD
This diploma thesis contemplates selected aspects of the introduction of an energy
management system according to DIN EN ISO 50001 at the Fraunhofer Institute Center Dresden with a focus on the determination of meaningful energy performance indicators as weil as the development of optimization measures with regard to the improvement of energy-related performance and the further introduction of a standard-compliant energy management system. For this purpose, a methodology for the energetic evaluation that was specially adapted to the area of application was developed and document ed , which is based on the countercurrent principle and meets the requirements of DIN EN ISO 50001.
The Fraunhofer Institute Center Dresden was evaluated for the years 2019 to 2021
according to this met hodology. For this purpose, extensive data acquisition was carried out, which in particular included the evaluation of the stationary measuring devices, the implementation of mobile measurements and the recording of static and dynamic location and influencing factors. The recorded data is evaluated in the form of absolute, relative and statistical energy performance indicators, which are differentiated for comparative considerations according to system boundaries, energy sources and funct ions. They provide a basis for comparison for monitoring and evaluating the development of energy-related performance. Furthermore, the significant energy uses are identified and categorized using an evaluation matrix.
Based on the results of the energetic evaluation, literature references and recommendations from employees, a catalog of optimization measures was developed that contains a selection of the energy management system. The results of the work show that the introduction of an energy management system at the Fraunhofer Institute Center Dresden under the appropriate conditions is possible, sensible and profitable
All relevant basic documents, schemes, analyses, concepts, supporting documents and sources that were created in the course of the thesis are listed in the project folder and will be handed over to the interested parties at the Fraunhofer Institute Center Dresden upon completion of this work.
Editor: Marian Hanke
Tutor: Prof. Dr.-Ing. Clemens Felsmann, Dipl.-Ing. Gerd Obenaus – Fraunhofer Institut für Elektronenstrahl- und Plasmatechnik FEP
Year: 2022

Building evaluation methods
Buildings have an impact on the environment during their production, construction,
operation and demolition. Aiming to build more sustainable and climate-neutral, methods
to evaluate buildings are contemplated. The present thesis describes in its first part
existing certification and verification methods to assess a buildings quality.
Specifically statutory guidelines such as the GEG, the BEG, green building certifications
like LEED and DGNB as well as the EU-taxonomy are examined. Because of a buildings
many requirements the view is limited to the ecological, energetic and daylight quality.
The selected qualities are to be represantative and don’t aim a holistic approach.
Furthermore the evaluation methods are applied on an exemplary building, which is
currently in the planning phase. With the exemplary building, calculation methods
are executed and the results are put in context of the verfication methods. Also the
consistency of the calculation and verification methods is analysed and discussed.
The last part looks at the commisioning phase of the building, which is yet to come.
With the commmisioning of a building the possibilty to verify prognosed values and
optimise the technical facilities occurs. The necessity of an enhanced commisioning
as well as the part of the commisioning in the different verification methods is looked
at.
Editor: Klara Bestehorn
Tutor: Thomas Hoinka – HOINKA GmbH, Prof. Dr.-Ing. Clemens Felsmann
Year: 2022

Implementation and validation of a Python package for the calculation of time-resolved solar yields
The aim of this thesis is to implement and validate a Python package for calculating
time-resolved solar yields. The package provides the tools for estimating solar
thermal and photovoltaic power output with reference to local time (UTC+1).
First, the structure of the developed Python package STLIB and an overview of
the current open source Python libraries for solar engineering are presented. The
weather data for this thesis was provided by the Deutsche Wetterdienst. Weather
data was analyzed and critically evaluated.
The thesis then provides an overview of the theoretical background for estimating
solar position, beam incidence angle, and solar radiation incident on an inclined
plane. Methods for the modeling of solar thermal collectors are introduced in the
thesis and implemented in STLIB. The third-party Python package pvlib was used
for PV modeling. Pvlib is an established Python tool for modeling PV solar systems.
In particular, the PVWatts model for the simulation of photovoltaic modules was
implemented in STLIB.
The validation of STLIB simulation was carried out with the help of the FreeSolCalc
Excel tool, Solites Excel tool, and Polysun simulation software. The validation
results revealed that STLIB can substitute both FreeSolCalc and Solites. However,
comparing solar thermal yields with Polysun showed a relatively high deviation.
The reason for that could be a wrong configuration of Polysun model parameters.
Finally, the STLIB PV simulation demonstrated acceptable results compared with
Polysun PV simulation.
The application of STLIB was demonstrated with a case of integration of STLIB
with the Python optimization tool FlixOpt. A simple example system was built in
the FlixOpt environment, and the simulation results of solar thermal and PV field
were provided. The optimization resulted in the preference of PV over solar thermal
collectors.
Based on the results of this thesis, it can be concluded that STLIB is a suitable
tool for the simulation of solar energy systems. The author, however, recommends
further improvements to STLIB before officially releasing it to the public.
Editor: Bogdan Narusavicius
Tutor: Dr.-Ing. Felix Panitz, Dipl.-Ing. Sven Paulick
Year: 2022

Conceptual design of a multifunctional ventilation unit with heating support for lowest-energy buildings
The presented paper deals with the conceptual design and calculation of technical
building equipment for use in nearly zero emission buildings. Due to the high proportion
of renewable energy required by law to meet demand, the use of conventional
condensing boiler technology is becoming increasingly difficult. Heat pumps are often
named as an alternative because they primarily use energy from renewable sources
to provide heat. However, more powerful devices are usually much more expensive
than the conventional alternatives. Due to steadily increasing energy requirements in
building construction, the amount of heat required is continuously decreasing, which
raises the question of whether a heat pump with a smaller energy output, as typically
used for the provision of domestic hot water, is sufficient to cover the total heat
demand.
First, an insight into the political background regarding the development paths in the
building energy sector will be given. These form the basis for the level of requirements
for newly constructed buildings and buildings to be renovated. This is followed by an
analysis of the requirements of a nearly zero emission building based on the
specifications of the Gebäudeenergiegesetz. Together with a consideration of the
applicable standards, a calculation programme is to be created with the help of which
it should be possible to evaluate not only existing, but also future system concepts.
Based on the findings of the political and normative foundations, a heat pump-based
system concept will then be created and tested with regard to the current requirements.
Finally, recommendations for adapting the system concept for future requirements as
well as additional investigations for a more far-reaching analysis are proposed.
Editor: Kevin Bock
Tutor: Prof. Dr.-Ing. habil. Joachim Seifert, Dipl.-Ing. Lars Schinke, Dipl.-Ing. J. Rammensee – Glen Dimplex
Year: 2022

Combined Operation of an air-water-heat pump: Efficiency analysis and model-based operational analysis in an emulation environment (hardware-in-the-loop)
In the developement of an air-water-heat pump the interaction between the indoor and
outdoor units plays a crucial role.
The indoor unit with its hydraulics and control devices affects the efficiency of the
overall system. In the case of the heat pump examined, the efficiency is reduced by
the heat losses in the indoor unit, by mixtures that arise as a result of the hydraulic
decoupling due to measurement uncertainties of the temperature sensors, and auxiliary
energy for electrical loads. These have different inŕuences depending on the operating
points, but can be roughly estimated with a 5% reduction in the Seasonal Coefficient
of Performance (SCOP). The inŕuences are greatest in the case of high volume ŕows
and high temperature differences to the ambient air.
Long-term test rigs are a good way of testing the robustness of the overall heat pump
system. Operation that is as realistic as possible is provided by a building simulation
that is connected to the device via hardware-in-the-loop. Due to targeted data evaluation
discrepancies, that have not been found by other regular tests, can be eliminated.
Editor: Lea Sprenger
Tutor: Dr.-Ing. S. Kaiser – Bosch Thermotechnik, Dr.-Ing. Martin Knorr
Year: 2022

Energetic and economic assessment of the use of air-to-water heat pumps in existing buildings
The replacement of old heating systems in existing buildings presents the opportunity to switch to heating with renewable energies by using a heat pump.
In this context, the replacement of fossil fuel boilers with air-to-water heat pumps is examined in this paper. The examinations include different renovation variants of existing buildings, which are evaluated according to energetic, economic and CO₂ emission criteria.
For the selection of three buildings, an analysis of the German building stock is carried out with the help of technical literature. Likewise, the results of research into studies and manufacturers' recommendations for the use of heat pumps in existing buildings are used for the planning and design of the renovation measures and the heat pumps. With these findings, the factors influencing the efficiency of a heat pump can be identified.
The simulation of the energy renovations in the modeling of the selected buildings provides the energy characteristics of the heat pump systems in the renovated buildings.
The economic efficiency calculations are carried out with the help of representative investment costs, current energy costs with a fixed development and the calculated energy requirements of the different renovation variants.
It turned out that the use of air-to-water heat pumps proves to be a very economical alternative to conventional boilers, in addition to the low amounts of CO₂ emitted. The high investment costs for energetic renovations are paid off by comparatively low operating costs and lead to large savings when considered over 20 years.
Editor: Mathis Roynard
Tutor: Willi Bromenne – Effizienzpioniere GmbH, Prof. Dr.-Ing. Clemens Felsmann
Year: 2022

Decentralised feed-in of solar thermal energy into an existing district heating network
In this work, the solar thermal potential of the city of Böblingen was investigated. For this purpose, data on the roof areas of the city was analysed. The maximum possible heat yield on the roof areas of installable collector surfaces was estimated chapter 4. If solar collectors are installed on all roofs of the district heating consumers, up to a quarter of the heat demand can be provided by solar thermal. Decentralised feed-in is sensible for facilities with a minimum collector area of 200 m². Facilities with more than 200 m² of collector area cover approx. 5 % of the heat demand.
Four buildings were selected which are particularly suitable for the installation of a solar thermal system. These buildings were examined in more detail. As was determined in chapter 5, the small difference between the consumer and district heating temperature level makes the more costly HANEST not worthwhile for these buildings. For all four buildings, the NEST is the most suitable station type for grid coupling.
In the yield simulations in chapter 6, it was found that the HANEST does not achieve a higher yield than the NEST in every case. The heat production costs calculated in chapter 7 also confirm the advantages of the NEST. The yields of the HANEST cannot compensate for the higher investment costs of the station connecting the facility to the district heating network. The yields of the CPC vacuum tube collectors also do not stand out sufficiently from those of the high-temperature flat-plate collectors to justify the higher costs.
The roof areas of the buildings in Böblingen that are of sufficient size for the installation of a solar thermal system and a district heating connection can cover less than 10 % of the heat demand in Böblingen on average. The buildings considered cover up to 5 % of the heat demand in the summer months. Only in Dagersheim is building 4 able to cover 10 % of the heat demand in the summer months. In order to cover a relevant share of the heat demand of the district heating network with solar thermal energy, significantly more buildings must be included.
Editor: Julia Mara Meierkord
Tutor: Dipl.-Ing. Maren Voß, Dipl.-Ing. Martin Heymann, Dr. Schicktanz - Stadtwerke Böblingen
Year: 2022

Potential of generator usage optimization for the heat supply of a residential complex with CHP and geothermal heat pump
In this thesis, the potential of optimization-based operation management for the heating plant of a 70-apartment residential complex is determined in simulation. The plant comprises a combined heat and power unit, a geothermal heat pump, a condensing boiler and two stratified thermal storage tanks. Firstly, an overview of the structure of building automation systems, common control concepts and optimisation approaches is provided. This is followed by a description of the simulation model of the system and its control.
Two mixed integer linear programming approaches are tested as part of a supervisory model-predictive control. The first approach takes into account the thermal stratification in the storage tank and thus leads to an increased modelling effort. The validation in a reduced test model shows high model uncertainties during discharging despite the high model and computational effort. The second approach describes the storage tank as a single node without knowledge about layer temperatures, so that the model effort is significantly reduced. After a test in the reduced test model, this approach is used to derive an optimization model for the entire system.
Based on two case studies, the theoretical potential of the optimization-based operation management is determined in a simulation over two winter weeks. Considering a gas price of 0.06 €/kWh in the first case, the optimized operation plan comes very close to that of the rule-based control. On the contrary, increasing the gas price to 0,12 €/ kWh leads to a significant change of the operation plan. Compared to the rule-based control, for this scenario operation cost savings of 11.52 % are determined in simulation.
This is followed by a qualitative assessment of the optimization potential with emission factors. In addition, further steps for technical integration of a supervisory model-predictive control for the considered plant are described.
Editor: Leonhard Wenzel
Tutor: Dipl.-Ing. Torsten Schwan – EASD, Dr.rer.nat. Peter Stange
Year: 2022

Evaluation of the effectiveness of a single room control system in a non-residential building
Due to the widespread use of conventional thermostatic radiator valves in existing buildings, heat transfer in rooms has great potential for both energy saving and comfort improvement. In practice, this potential is often exploited by means of electronic individual room control systems. Manufacturers of such systems advocate significant heating energy savings of up to 30 %. The extent to which energy savings can actually be achieved is the aim of this study. This work involves a product- and technology-neutral evaluation of the energy-saving potential of a selected electronic single room control system. The subject of the study is a typical non-residential building with office, teaching and laboratory units of the Technische Universität Dresden in which the selected electronic single room control system is installed and put into operation. In the first weeks after retrofitting, due to the higher average temperature level of the setpoint setting, an additional energy effort is required to heat the rooms compared to the reference state with thermostatic radiator valves. In the course of the practical experiment, a reduction in the temperature level of the setpoint value is observed both within and outside the time of use. This fact and the precise control during the heating operation of the digital radiator valve lead to a heating efficiency saving of 1,3 % in the heating period from 01. 10. 21 to 30. 04. 22. There are two main reasons for the discrepancy between the expected and actual savings. One of these reasons is the comparatively higher temperature level of the setpoint setting at the beginning of the practical experiment. On the other hand, there is no realisation of the intermittent heating operation in the form of a significant reduction of the setpoint value setting outside the time of use. Accordingly, the identified savings do not constitute a reliable evaluation criterion for the electronic single room control system. The general scientific consensus on the large influence of user behaviour on heating energy demand is verified by the practical experiment.
Editor: Paul Straßburger
Tutor: Dipl.-Ing. Markus Arendt, Dr.-Ing. Alf Perschk
Year: 2022

Possibilities of reduction of the district heating temperature on the TU Dresden campus
This paper deals with the topic of temperature reduction in the district heating network of the Technical University of Dresden. Certain technologies, especially those that use regenerative energy sources such as solar thermal energy, geothermal energy or heat pumps, can in principle only reach limited temperatures. In order to be able to use these advanced technologies, the entire system must therefore be designed for low flow temperatures. A reduction in the return temperature, on the other hand, with all other variables remaining unchanged, increases the enthalpy used and reduces the heat losses in the return, whereby both influences in turn contribute to an increase in thermal efficiency. In the case of a flow temperature reduction, either the heating loads are adjusted to the consumers and improvements are made in the control system, or new district heating networks are developed and built, which operate with heating systems that require low flow temperatures. In the case of return temperature reduction, new meshes and heat networks can also be established, which operate in three- or two-wire networks, depending on demand. Furthermore, return connections could also be integrated into an existing heat network. In relation to this, these possibilities are examined in more detail based on the current state of technology. This is followed by different effects of lowering the network temperature, which are examined on the basis of energetic, economic and ecological aspects. Since the work deals with the district heating network on the campus of the TU Dresden, the Merkel-Bau and the Andreas-Pfitzmann-Bau in particular are examined with the web evaluation "Camper-Move" based on their supply and return temperatures. A list of buildings that have installed room-air-technical systems and their effects on the secondary side temperatures is given. Finally, recommendations for action are formulated based on the previous theoretical and practical considerations.
Editor: Dilara Karabacak
Tutor: Dipl.-Ing. Markus Arendt
Year: 2022

Monitoring-based comparison of solar thermal yields of heat pipe collectors with dry and wet integration
This research thesis describes the analysis and evaluation of the monitoring data of
an solar thermal system with cold coupling. The data were recorded in the research
greenhouse of the German Centre for Integrative Biodiversity Research as part of the
Botanical Garden Leipzig (iDiV). The monitoring period covers two years. Two different
integration types between solar collector and heat transfer medium, the dry and the
innovative wet integration, are directly compared. Due to swapped signals in the data
recording during installation, a meaningful comparison is not possible.
Furthermore, from the monitoring data, a raw data set for a reference year is filtered,
in which the plant control hardly changes. This serves as the basis for the creation
of a state machine, which shows the operating states of the entire system and the
solar thermal system in particular, as well as the decisive switching criteria. Based on
this, the discrepancies identified in the comparison between the state machine and the
as-built documentation, such as control parameters that have not been transferred, and
optimization options for the control system are worked out. In addition to the control
parameters defined in the state machine, the reference year also serves as the basis for a
yield prognosis of the entire system using the Polysun software. A comparison with the
practical measurement data shows that the yield on the secondary side is significantly
lower than theoretically expected due to the plant behavior.
Editor: Paula Röver
Tutor: Dipl.-Ing. Stefan Hoppe, Dr.-Ing. Karin Rühling
Year: 2022

Characterization of the operating behaviour of a disctrict heating system using heat meter data with high temporal resolution
In this thesis, a comprehensive investigation of the data of remotely readable heat meters of a real district heating system in Berlin is presented. The data comprises the measurements of approximately 32% of the consumers in a time period of eight months. First, an analysis of the data collection is performed to identify sources of error from the installations, the data communication chain and erroneous measurement signals. From this, suitable data cleansing steps and procedures are derived.
Thereupon, it is shown how the data from the measured house systems can be aggregated to describe the overall network behavior excluding heat losses. The methodology of cluster analysis for automated evaluation of meter data is presented. The aim is to find groups of consumers with similar heat demand behavior. The results of the cluster analysis are combined with other data from the system operator and suitable criteria are selected for the grouping. In addition, an approach for calculating average heat power demands at the design outdoor temperatures of the consumers is applied. Possible interferences of the evaluation from the house system control technology are analyzed as well. In the considered district heating network, the procedure is implemented using the example of the building classes and the heat use (space heating/domestic water heating). Two standard load cases of the network hydraulics result. The period of the coldest measured outdoor temperatures in winter is used to validate the current design point.
The summer case describes a possible design point for the feed-in of decentralized plants. Basic principles for the validation of heat loss models and an indication for physically correct utilization hours are derived. A significant refinement of previous design approaches emerges.
Editor: Luise Mann
Tutor: Jens Unterseher - Vattenfall, M. Sc. (FH) Bilal Kouka - Vattenfall, Dipl.-Ing. Maren Voß
Year: 2022

Integral evaluation of heat pump systems
The decision between an air-to-water heat pump (AWHP) or a brine-to-water heat pump
(BWHP) is based not only on the available capital but also on the reputation of the more
efficient and thus more eco-friendly BWHP. By means of a lifetime analysis, the
environmental performance in terms of greenhouse gas emissions (GHG) and cumulative
non-renewable primary energy demand (KEVNE) is verified on the basis of two reference
systems. The results for the AWHP system are about 6% higher than those for the BWHP
system. This is offset by the high risks associated with the installation and problematic
renaturation of the borehole heat exchanger. Since the heat pump systems are only
comparable to a limited extent due to the very different investment costs, a combination
of AWHP-system with a photovoltaic rooftop system (PV-rooftop system) with the same
total investment costs is established and compared to the BWHP system. It shows a
significantly higher climate protection effectiveness and economic efficiency than the
BWHP system. The higher electricity demand of the AWHP system is greatly reduced by
the self-consumption of the generated electricity, also during winter. The additional grid
supply minimizes the greater need for temporary storage of electricity over longer periods
of time. The alternative participation in a local PV ground-mounted system reinforces
these effects due to the lower specific investment costs and thus higher system
performance. Due to the current regulations on grid transmission, self-consumption of
the electricity produced is not possible. Thus, the plant is significantly less cost-effective
than the rooftop PV system. In order to enable investments that are as climate-friendly as
possible, it would be appropriate to review the mentioned regulations along with the
conditions for subsidizing heat pump systems.
Editor: Felix Bumann
Tutor: Dr.-Ing. Felix Panitz, Dipl.-Ing. Cornelius Zunk
Year: 2022

Energy Evaluation of Tube Bundle-Based Latent Heat Storage Systems Using Numerical Simulations
The present work focuses on the numerical modeling of a shell-and-tube latent heat storage. For this purpose, a three-dimensional parametric simulation model is implemented in COMSOL Multiphysics, which can be used to analyze the storage behavior during a simultaneous charge and discharge operating mode. The purpose of this operating mode is to smooth a cyclically occurring thermal power on the loading side so that a constant discharge power is available. The phase change material RT111HC, which has a phase change temperature of 111 °C, is used; for its thermophysical modeling by means of a solid model, the apparent heat capacity method is applied. After the design of four model variants with equal storage capacities, which differ from each other in the tube bundle parameters (tube diameter, tube spacing, number of tubes), these are compared simulatively under the same process conditions (mass flows as well as inlet temperatures on the loading and unloading side). The parameterization of the tube bundle parameters results in different performance levels of the four storage variants. With increasing performance level, however, a decrease of the performance- or temperature-smoothing effectiveness of the latent heat storage can be noticed. Finally, the most powerful storage variant is subjected to a technical-economic optimization.
Editor: Lennart Heggelmann
Tutor: Dr.-Ing. Ulf Sénéchal - Fraunhofer IFAM Dresden, Dipl.-Ing. Lars Schinke
Year: 2022

About the economic feasibility and primary energy performance of solar assisted heat supply systems of single family houses
Solar thermal collectors or air source heat pump with photovoltaics? This thesis is
about the question, how to heat new single family houses with solar energy in an
economically feasible way. Although the heat supply is the focus of interest, the domestic
electricity demand is taken into account as well being an essential factor for photovoltaic
systems.
Simulations in Polysun form the first part of the study. They have been used to optimize
several variants of the heating system for a high solar fraction. With the energy
bilances of the simulations, energy costs and the primary energy demand can be calculated.
The capital expenditure of the variants is enquired in the second part and leads to
a calculation of economic efficiency using the annuity method. It includes different
depreciation periods for all components, price changes and taxes. A sensitivity analysis
is finally made to find out, how much assumptions about the future can influence the
decision for or against a particular system.
Editor: Simon Grandl
Tutor: Jörg Hohlfeld – FASA AG, Dr.-Ing. Felix Panitz
Year: 2022

Development of a selection aid for room pressure control in cleanrooms
The objective of this paper is the development of an EXCEL tool as a selection aid between
different variants of room pressure control in cleanrooms. To begin with, the basics of
room pressure control are presented regarding various aspects. This is followed by the
definition of the three variants of room pressure control to be considered by the resulting
selection aid. These are variant 1: variable volume flow (VVF) exhaust air control, variant
2: bypass control and variant 3: additional air handling unit for pressure control.
Subsequently, an exemplary investigation of the project-specific suitability of the defined
system variants is carried out based on a real project. General evaluation standards are
then drawn up considering the inspection of the technical and economic comparison
criteria. To obtain a selection recommendation, the resulting evaluations are combined in
an evaluation matrix under the influence of a project-specific weighting. From this, strong
differences between the technical and economic suitability of the variants can be
concluded. The findings from the investigation of the example project are then combined
into a selection aid in the form of an EXCEL tool. Finally, the practical applicability of the
developed selection aid is reviewed. The result is a selection aid for room pressure control
that is easy to use and that provides plausible results regarding the comparability of the
considered system variants.
Editor: Kajetan Weiß
Tutor: Dr.-Ing. Martin Knorr, Dipl.-Ing. (FH) Tom Frömmel – Caverion
Year: 2022

Assistance and documentation of the planning process and the commissioning of the new solar thermal plant at ZET
In this thesis, a part of the planning and modification process of a solar thermal system with „Netzeinspeisestation“ (NEST), which is based on an existing system, is explained. This system is located on the rooftop of the building „Zentrum für Energietechnik der Technischen Universität Dresden“. This new system is planned in cooperation with the company „Ritter Energie und Umwelttechnik GmbH und Co. KG“ and their specially developed evacuated tube collectors. This new system will feed into the primary district heating network of the city of Dresden, just like the existing system. The current system is presented, analyzed and the deficiencies are filtered out. Based on the existing system, the new planned piping and instrumentation (P&I) scheme will be outlined, and all important components will be introduced. Once developed, this simplified concept will facilitate the process of „repowering“ the current system in the future. This scheme shows the process from the planning to the dismantling and the assembly. The concept summarizes the multiple prodcedures involvled as well as the resulting decision-making proccesses.
Editor: Laura Franz
Tutor: Dr.-Ing. Karin Rühling, Mirjam Brielmaier – Ritter XL Solar
Year: 2022

White area mapping for the identification of potential locations of Photovoltaic plants with the help of Geographic Information Systems (GIS)
In this paper, a methodology of potential area analysis of open space photovoltaics is developed and tested, which aims to simplify and accelerate the expansion of this technology. First, the current status of potential area analysis is worked out, whereby differences of some studies on regional and national level are examined. This results in a justification of the need for further potential area analyses. Then, the workflow of a QGIS-supported, partially automated potential area analysis is developed with a focus on company-specific requirements. Based on the gained knowledge from the studies as well as internal company expertise, a catalogue of criteria is created, in which an evaluation system for the criteria is also introduced. Based on this, the potential areas of a region in Central Thuringia will be examined and evaluated. In the course of the implementation in QGIS, some data bases are researched and compared. This is followed by the planning of two exemplary, well-suited potential areas with different financing concepts. To verify the methodology, the energy yields of the photovoltaic systems are simulated. The simulation results are compared with the values of the potential area analysis in QGIS. Finally, the developed methodology is critically discussed with regard to its future applicability for land procurement and alternatives are presented.
Editor: Paula Anabel Clemens
Tutor: Niklas Faust – BOREAS, Dr.-Ing. Felix Panitz
Year: 2022

Analysis and development of a workflow for a direct IFC model coupling to energy simulation programs
In order to achieve the globally formulated climate protection goals, an energy-efficient,
resource-efficient and climate-friendly building stock is necessary. To achieve this, thermal-energetic simulations must be carried out in the early planning phases in order to be able to recognise and avoid errors in the planning.
The multitude of traditional two-dimensional data exchange formats complicates the necessary exchange of information between the partners involved. The already widespread working method of Building Information Modelling (BIM), on the other hand, offers all partners involved in the construction project a three-dimensional image of the building, which should guarantee the complete exchange of information.
In order to be able to carry out the simulations on the basis of this model, the necessary
parameters must be contained in this model and clearly defined conventions are required
for the interface between the applications.
The aim of this work was to analyse the open problem areas in the BIM-based planning
process with a focus on the automated transfer of the geometric model and the associated building physics data. For this purpose, the transfer on the basis of the standardised Industry Foundation Classes (IFC) format was investigated and the necessary steps derived from this for the transfer to the EnergyPlus simulation core were worked out. In both of the programmes examined, impairments were found in the data import with regard to both the geometry data and the building physics. Furthermore, with the Allplan Add-on AX3000 it is not possible to represent the interactions between the individual rooms. The BIM HVAC tool generates serious geometric errors that cannot be corrected manually due to the incomprehensible reduction of all window areas. From the point of view of thermal-energy simulation, neither of the two programmes examined is currently able to transfer the information from the IFC models with sufficient accuracy so that the simulation with EnergyPlus can lead to a realistic result for the buildings.
Editor: Danny Borchert
Tutor: Dr.-Ing. Claudia Liersch – INNIUS GTD), Dipl-Ing. Falk Schumann – INNIUS GTD), Dr.-Ing. Alf Perschk
Year: 2022

Conditions and Application Potentials for Gravity Power Plants in Mining Regions
The thesis deals with the question of how alternative storage concepts based on the
principle of pumped storage can be used in mining regions. It gives an overview of various
storage concepts and their construction and functioning. A closer look is taken at those
based on the principle of gravity power pumped storage. Making use of this a conceptual
design with several scenarios in an opencast mining area in the mining region Lausitz,
estern Germany, is made. Part of the work deals with aspects, which have a significant
influence on the implementation of the concept. This aspects are the electricity market,
mining of brown coal in general and characteristics of the region Lausitz. Possible
uses of and requirements for electricity storage in electricity markets and balancing
electricity markets are shown as the base of the overall economic analysis. The results
of investigation on these markets show that the current payment for electricity and
balancing reserves has increased significantly compared to the last few years. As a
result of this and other regulation changes, the conditions for operators of small energy
storage systems have improved in recent years.
In the concept developed for the Lausitz region, several scenarios are estimated and
compared with each other by means of calculations. These concern weight, material
costs, achievable power and storage capacity. The storage systems used for this are
based on two Gravity Power concepts. On the one hand, the concept of the so-called
Powertower is selected. Varying the sizes, it is used individually or in the combination
of several towers as a cluster in the scenarios. On the other hand, the concept of
Buoyant Energy is selected - a floating reservoir storage that is weighted with additional
loads. The calculations show, for example, that a storage capacity of 16 MWh can be
achieved within an area of about 0,2 ha. Finally, the scenarios are evaluated according
to their usability in and adjacent to opencast mining lakes, especially in the area Nochten,
Lausitz region. Since the technical development of the storage concepts presented is
not yet fully developed, this is the primary starting point.
Editor: Marita Spörl
Tutor: Dr.-Ing. Torsten Heyer, Dipl.-Ing. Niklas Schwiersch (Institut für Wasserbau und Technische Hydromechanik, Professur Wasserbau)
Year: 2022, Poster

Investigations into the effectiveness and costs of energy-saving measures on an administrative building
This script investigates an existing administrative building regarding a renovation of its
heating system. To this end the inventory of the existing heating system was recorded
and its effectiveness has been assessed. A check according the DIN 15378 has been
performed and gives first suggestions of the measures to be taken.
The building in question has 4 floors. The heat supply is realised by using a district heating
station with a connected load of 75 kW. The radiators that are installed do not have
thermostatic valves that can be preset.
On the basis of the inventory that has been taken before a digital model is created using
the software Trimble Nova 16.2 which is used further for a pipe network calculation and
several heat load calculations. The next step defines criteria and suggests measures
specifically for this building which are evaluated using those criteria. A priority list serves
as a summary and ranks the measures according their urgency into three categories.
A cleaning of one of the present heat exchangers needs to be done as soon as possible to
make sure that the whole system is working properly. In the short term it is recommended
to do a hydraulic balancing. Suitable balancing valves and thermostatic valves need to be
retrofitted. The ready room which is located on the ground floor should be regulated
separately. Pumps and the control unit should be renewed. In the long term it is
recommended to insulate the roof and the outer walls.
Editor: Hendrik Pohl
Tutor: Dipl.-Ing. Thomas Hoffmann – Ingenieurbüro Hoffmann, Dr.-Ing. Paul Seidel
Year: 2022

A practical comparison of different HVAC applications used to size a heating system, utilizing the BIM planning methodology
Utilizing model based planning methodologies to enhance efficiency in existing workflows is used more frequently in the field of MEP planning offices. Interdisciplinary operations and lossless data transfer are main aspects of Building Information Modeling (BIM). The selection of appropriate calculation programs in a constantly rising connected environment is complicated due to the variety of MEP development companies. Combined with the number of established architectural modelling software applications, which are the base for the intelligent building model, the quantity of proprietary interchange formats is not practical. This leads to increased popularity of neutral and transparent datamodels utilizing the IFC- or gbXML-scheme. These models are summarized under the concept of "Open-BIM".
To compare the different approaches of applications developed by established companies, the software packages "Solar-Computer" and "mh-software" are evaluated for sizing a heating system. At first a heating load calculation using the DIN EN 12831-1:2017 (DIN/TS 12831-1:2020) standard has to be executed. The base for this is a modelled fictional building instance in Autodesk Revit. An overview of normative boundary conditions and a manual example calculation of one room supports the discussion of systematic problems encountered during the digital BIM-based planning process. The comparison of the transfer between a provided architects model and the specific calculation program, both in proprietary and open data formats, indicates problems in the end to end workflow. This paper focuses on the following criteria: interoperability, correct processing of standardized calculation and dimensioning algorithms as well as a reflection of the usability of the applications.
Editor: Konstantin Seifert
Tutor: Dipl.-Ing. (BA) Robert Richter - Innius DÖ GmbH, Dr.-Ing. Alf Perschk
Year: 2022

2021

Analysis and Evaluation of large Solar Thermal Power Stations using the Software EBSILON
Ever since the United Nations Climate Report of 2007, it can no longer be denied
that the world is heading for a climate disaster if a shift from fossil fuels to
regenerative energy such as solar, wind or hydropower does not finally take place.
The sunbelt of the earth, especially the deserts or desert-like regions, offer an
enormous potential of solar radiation for the generation of electrical energy by
means of solar heat.
This thesis gives an overview of the basics of solar thermal energy as well as its
utilization by means of solar thermal power plants, especially parabolic trough and
solar tower power plants. The different technologies are first of all presented and
compared in detail.
The solar park "Mohammed bin Rashid Al Maktoum" in the United Arab Emirates
and the solar complex NOORo near Ouazarzate in Morocco serve as reference
sites for the subsequent simulation of solar thermal power plants. At these sites,
both parabolic trough and solar tower power plants are to be simulated using the
EbsSolar module of the EBSILON software. Technical reasons unfortunately
hindered the actual carrying out the simulation of a solar tower power plant for
the reference sites, since the additional software required to read in the data
would have to be purchased. To remedy this situation, a solar tower power plant
was nevertheless simulated (…with documented simulation steps) using existing
exemplary data. This thesis documents furthermore the handling of the above
mentioned software, evaluates the results of the simulations and finally makes a
comparison to one of the parabolic trough power plants already existing at the
reference site of Ouazarzate.
Editor: John Omoruyi
Tutor: Prof. Dr.-Ing. Hans Minkenberg – TH Mittelhessen, Friedberg, Dr.-Ing. Thomas Sander
Year: 2021

Conceptual design - Integration of vehicle batteries as stationary battery storages into a building district
Increasing the use of renewable energy means that there is a growing need for more
efficient ways to temporarily store electricity. One particularly sustainable solution is
to reuse batteries from electrically powered vehicles as stationary energy storage units,
giving them a second life. Due to the increasing number of electric vehicles, there will
be large amounts of batteries in circulation in the future, whose capacity is too low
for mobile use in the vehicle, but which can still provide sufficient energy for other
purposes. Since recycling processes are currently still associated with high costs and
little profit in comparison, an option is to extend the useful life of batteries. Factors
such as local availability and quantities of similar batteries on the one hand, and the
determination of the condition of aged batteries on the other, play a role in the useful
reuse of batteries. Batteries from fleet vehicles have proven to be particularly suitable
solutions, as their available residual capacity can be determined with a conventional
capacity test after removal from the vehicle. However, the technical effort and time
required to carry out electrochemical impedance measurements, which can be used to
determine the state of charge and state of health of the battery from repeatable graphs,
are significantly improved. The integration of returning vehicle batteries into a building
district represents a feasible and sustainable alternative to brand-new batteries due to
the wide range of possible applications with manageable additional costs.
Editor: Lucas Tzschoch
Tutor: Dipl.-Ing. T. Goretzki – RWE Battery Solutions, Dr.-Ing. Felix Panitz
Year: 2021

Development of a software-supported experimentation procedure for real experimental set-ups
Experiments are an important component in science and industry. They serve to validate the results of computer simulation and product development. This thesis deals with the development of a software-supported procedure for experiments. The aim is to plan, conduct and evaluate experiments in a structured and time-efficient manner. For this purpose, the methods of statistical experiment design are used and combined with the dimensional analysis. Programmes have been developed that automat the sub-areas of an experimentation project, such as the creation of experimental plans and the calculation of dimensionless characteristic numbers. In addition, regression equations are created and measurement errors are detected automatically. The developed procedure was performed and evaluated in a real experiment. The procedure provides a clear structure. lt is shown how the simultaneous variation of several test parameters increases the knowledge gain and reduces the time required.
Editor: Hauke Beer
Tutor: L. Keilmann - Cloud&Heat Technologies GmbH, Dr.-Ing. Lars Haupt
Year: 2021

Increasing the robustness of data-based load forecasting models against extrapolated influences
Load forecasts are particularly important for energy suppliers in order to process the
generation and distribution of energy to the customer in a needs-based manner.
One method of creating such forecasts is the approach of data-based regression models,
which delivers good results, provided that the range of values of the influencing variables
on which the model is based is not exceeded for the forecast. This thesis discusses
possible solutions to increase the robustness of forecasts outside of the safe value ranges.
Models are set up, the quality of which is finally checked using selected data sets and
extreme values. The result shows successful approaches that contribute to increasing the
robustness.
Editor: Frieder Sparsbrod
Tutor: Dipl.-Math. Anja Matthees, Dr.rer.nat. Peter Stange
Year: 2021

Development of an energetic refurbishment concept for a production and storage hall according to GEG
The aim of this diploma thesis was to develop an energy refurbishment concept for a production and storage hall in accordance with the provisions of the Building Energy Act. The production and storage hall investigated is used by BSH Hausgeräte GmbH at its site at Bad Neustadt. For the elaboration of an energetic refurbishment concept it was investigated how an improvement of the current energetic situation can be achieved by thermal insulation and plant refurbishment measures.
Before suitable refurbishment measures were investigated, the current building and plant stock was documented and evaluated with the aid of the energy consumption certificate. The determined primary energy consumption is 221.34 kWh/m²a and the emissions in CO₂ equivalent are 51.90 kg/m²a. Based on the energy consumption, the building was simulated and a corresponding energy demand certificate was created. By adapting the simulation through appropriate renovation measures, various energy-related renovation concepts could be examined. The energetically best renovation concept uses a wood pellet boiler combined with an air source heat pump for heat generation. This results in a simulated primary energy consumption of 36.74 kWh/m2a and emissions in CO₂ equivalent of 13.67 kg/m²a.
In addition, an energy concept was developed with which the energy consumption can already be reduced during the current use of the building. This concept resulted in a primary energy consumption of 194.05 kWh/m²a and emissions in CO₂ equivalent of 45.41 kg/m²a. Finally, a cost and profitability calculation was carried out using suitable subsidy options. The most economical refurbishment concept uses a natural gas-fired combined heat and power unit in combination with a heat pump for heat generation. This results in a simulated primary energy consumption of 68.56 kWh/m²a and emissions in CO₂ equivalent of 21.60 kg/m²a. In terms of cost-effectiveness, the best refurbishment concept in terms of energy only ranks in the middle of the refurbishment concepts investigated.
Editor: Philip Zechendorf
Tutor: Dipl.-Ing. Andrea Meinzenbach, S. Ebert - BSH Bad Neustadt
Year: 2021

Computational time reduction of generator usage optimization by time series aggregation
With the help of an energy management system, energy generation and consumption
units can be planned and operated. In this thesis, a real energy system of a large German
city is considered for which the use of generation units is to be optimised with regard to
costs. For this purpose, a mathematical optimisation problem is formulated. For large
energy systems and longer periods of time, this results in a large number of variables and
equations, so that the solution takes a lot of computing time. Reducing this computing
time while maintaining the accuracy of the solution is the main focus of this thesis.
Using the approach of time series aggregation, typical time periods are created in order
to reduce the size of the model and thus the computing time. Corresponding procedures
for time series aggregation are presented and applied to the system in order to be able
to compare the aggregated with the original time series. In particular, a dependence of
the accuracy on the number of typical periods is shown.
In a further step, the optimisation problem is adapted to include typical periods. The
optimisation is first carried out for the reference case without time series aggregation
and then based on different period lengths and numbers. A detailed comparison of
the optimisation results follows. With a significant reduction in computing time by
several orders of magnitude, a very good accuracy of the objective function value can be
achieved. For a time-step optimised operating plan, it is shown that the deviation from
aggregated to original time series is partly too high, so that an application to the original
energy system is not possible. Good approximations result for the annual and monthly
use of components. The planning of energy systems, especially a quick comparison of
many variants, can thus be implemented well.
Editor: Tiedo Heie Behrends
Tutor: Dr.rer.nat. Peter Stange, Dr.-Ing. Felix Panitz
Year: 2021

Feasibility study, product concept and prototype of a new type of fastening solution for a light, flexible solar film
The subject of this work is the implementation of a feasibility study of novel mounting solutions of solar foils. The aim should be the development of new installation areas for a special solar foil of the company Heliatek, in order to use at the same time the potential of the solar irradiation better. Since the special foil is already used with the existence of facades and roofs, a dependence on existing buildings is now to be excluded. Methodically, a feasibility study is to be prepared in order to formulate concrete project goals, which will support the project development process. This study will pave the way for an anticipated product launch. In general, the practical elaboration and the product development process shall clarify the question whether a novel mounting solution for the specially developed solar film can be constituted and is feasible. Answers and results are to be provided by the information gained from the development process and practically proven by the construction of a prototype. Likewise, the future product is to be examined for viability and economic viability in terms of the company. Heliatek will provide its laboratory space, machines and a specially created software program for the investigation and practical implementation. Before a detailed presentation of the project idea can take place, basic knowledge about solar technology and solar films must be presented in order to be able to understand decisions for technical decisions in product development. This is followed by the presentation of the concept and the tasks to be implemented. Afterwards the project planning is carried out. Possible clamping systems with different edge reinforcement variants are presented. In the further course it comes to the project execution of the feasibility study, by means of the production of a prototype. Finally, it is recommended an assessment with regard to the technical implementation as well as modification proposals for the company Heliatek. By the won information and compiled results a detailed procedure as well as detailed suggestions for the product introduction can be submitted.
Editor: Dorothee Hannak
Tutor: Dipl.-Ing. Michael Meißner - Heliatek Dresden, Dr.-Ing. Felix Panitz
Year: 2021

Evaluation and control of reversible heat pumps in cooling mode
Due to the progressing climate change, the importance of regenerative heat generators
is steadily increasing. Despite a decarbonization of the economy, weather data indicate
an increase in global temperatures. Thus, an increased demand for air-conditioning
possibilities is to be expected in the future. The reversible application of a heat pump
could provide a simple solution to both problems.
In the present project work, research results of already existing plants with reversible use
are collected. On the basis of these investigations, the findings on individual aspects, such
as the cold transfer, the hydraulic system and the control system, are examined in more
detail. With the help of these sources and current standards, various evaluation criteria
are then worked out. These criteria are then used to optimize a controller programmed
in Python. This is linked to the TRNSYS-TUD simulation program via a Message
Queuing Telemetry Transport (MQTT) interface and controls a heat pump to supply a
single family home. TRNSYS-TUD is used to repeatedly record the cooling capacity
and efficiency for the entire cooling period of the heat pump. After the evaluation, an
optimized control strategy for the heat pump results.
Editor: Robin Schulze
Tutor: Dipl.-Ing. Maximilian Beyer, Dipl.-Ing. Tim van Beek
Year: 2021

Development of a tool to select space cooling systems on the basis of BIM design method
Regarding the climate change along with the increasing of environmental temperature, the dimensioning and rating of cooling systems becomes more and more important. Above all, water-guided surface cooling systems are moving into the focus of technical building equipment, as they convince with their efficiency and a high level of comfort. The planning of these technical constructions follows the digital transformation and is progressively carried out on a three-dimensional level. According to this, the market presence of the BIM design method is increasing in the technical building equipment. It is based on a spatial building model whose data is consistently used by all project participants. This diploma thesis includes the current status of the design method as well as the advantages and disadvantages in comparison to the conventional planning process.
Based on this, an Excel tool is developed which should be included in the pre-planning and concept-planning process of the INNIUS DÖ company. It is used for a semiautomatic rating of surface cooling systems and convectors. A collection of documentations of variant producers forms the cornerstone of the tool, which is transferred into a detailed overview of the relevant cooling system types. Thereby the tool allows an optimized choice of the most suitable apparatus. After the final decision for a product, the cooling systems are convert into a three-dimensional object. In order to accelerate the process, a possible procedure for transferring the tool output data to the building model is designed. Finally, this thesis summarizes the accumulated experience and provides various approaches to extend the tool further.
Editor: Sebastian Zoch
Tutor: Dipl.-Ing. (FH) Bernd Klimes – INNIUS DÖ GmbH, Prof. Dr.-Ing. Clemens Felsmann
Year: 2021

Analysis of a decentralized ventilation system for a retrofit installation in classrooms
The presented paper deals with the analysis of a ventilation system for use in educational institutions. Historically, in most of these buildings, air exchange has only been possible through the windows. However, due to their high occupancy densities, these usually have
insufficient indoor air quality. Concentrated work becomes increasingly difficult as the length of stay increases. With decreasing indoor air quality, however, the general risk of infection also increases, which represents a serious danger, especially in times of the global pandemic caused by Covid-19.
First, an insight into the technical basics of ventilation will be given. In order to obtain a
standard of assessment, the applicable standards will be examined. Subsequently, an analysis of existing buildings and concepts will provide information on sensible variants for retrofitting in educational institutions. The knowledge gained from this should make it possible not only to check existing ventilation concepts based on individual room requirements, but also to simulate new solutions.
Using this evaluation scheme, a pilot system from Glen Dimplex in the Max Hundt primary and secondary school in Kulmbach is to be evaluated and checked for possible improvements.
Editor: Kevin Bock
Tutor: Prof. Dr.-Ing. habil. Joachim Seifert, Dipl.-Ing. Lars Schinke
Year: 2021

About the operation of ice storages
In this scientific work, the latent heat storage type of the ice storage is to be examined more closely.
The technology should first be explained and classified in principle. The different
types and forms of construction are to be presented, also with regard to the underlying physical processes of ice build-up and regeneration.
These theoretical fundamentals will be required again later in the work, as a simple
program for simulating a ice storage and its operations is created.
After the state of the art of the ice storage system has been presented in more detail, a
real example will be used, to deal with how such a storage system behaves in connection with various heat producers, loads and operating modes.
With the help of structural data and drawings, as weil as information about the storage in general, it can be classified into the ice storage variants presented before. In order to provide a better understanding , simplified heat schemes are used and shown in this work. In addition, there is a series of data from a wide variety of measuring instruments, which can be used to make statements about the operation. Furthermore there is an insight into the various operating modes, that are used depending on external influences and in which different parts of the overall system are used. All of this can be better understood on the basis of the operating data.
The evaluation is mainly carried out with the help of diagrams, as special attention is
paid to the illustration of the real operating conditions for better understanding.
After a real ice storage has been examined in more detail, the next step is to simulate an
ice storage of the same type. A program is created with the knowledge gained previously and the experience gained through real operations.
The program should enable a simulation of an ice storage. MATLAB was chosen as the
software environment. Simplifications and assumptions are made, in order to reduce the complexity of the problem, without neglecting the accuracy of the whole. Before that, the processes involved in freezing and regeneration are examined by means of a literature search. The correlations and formulas obtained in this way are then used in the program. In the end, the results from before should be compared with the real ice storage in order to validate the data and to be able to make possible assessments about the assumptions made.
Editor: Maximilian Gutwein
Tutor: Dipl.-Ing. Jens Kaiser
Year: 2021

Investigations of hybrid ceiling systems for heating, cooling and ventilation in the climate room of the TU Dresden
In recent years, the technical possibilities for the targeted control of physical room climate parameters have developed enormously due to the variety of powerful system technology. This progress is necessary because the demands on the indoor climate have increased, especially in the office environment. In addition to the variously used surface heating and cooling systems, concepts for simultaneous fresh air conditioning have already been developed in research. However, there is a lack of targeted scientific studies on user acceptance of the so-called hybrid systems with regard to thermal comfort and indoor air quality.
This paper presents an empirical study that first examines several variants of a hybrid ceiling system under stationary conditions in the climate room of the TU Dresden and then tests one of the preferred variants for its user acceptance in the form of a small test person study.
From the generated results, a comparison is made with the findings from the examination of the pure ceiling heating and cooling systems in order to highlight possible advantages of the combined system. By evaluating the physical measurements as well as the study of test persons, new findings regarding thermal and air-hygienic comfort are thus obtained for the ongoing research of hybrid systems.
Editor: Magdalena Thiel
Tutor: Dipl.-Ing. Lars Schinke, Dipl.-Ing. Maximilian Beyer
Year: 2021

Generation of test scenarios and reference results for the analysis of methods of generator usage optimization
This thesis investigates computation times of operational cost optimizing simulations as well as operating cost of various energy supply system models that provide year-round electrical and thermal energy to their energy system users.
Twelve different energy systems are modeled using various energy supply as well as energy storage components such as: heating plant, combined heat and power (CHP), heat pump, solar collector, photovoltaics, wind turbine, heat storage and electricity storage. All twelve energy system models have a different capacity and are designed to cover one of three different load demand data.
An operational optimization analysis are conducted using a commercial analysis software called TOP-Energy, as well as a code assembled using Python, FlixOptPy. Mixed integer linear programming (MILP) is used for the optimization, and Gurobi is used as a solver for the models. In order to obtain an optimal result, which can be used as a reference for a later research, the entire period is calculated in a closed optimization. Additionally, a tolerance criteria (gap) as well as abortion criteria (maximum computation time) is configured in each simulation for a further fine tuning of simulation.
After systematically comparing results of operational cost optimizing analysis within TOP-Energy and FlixOptPy, it is evident that computation time of a model is significantly increased if gap value is lowered or additional variables are introduced within the energy supply system models. Furthermore, most of energy system models’ calculated optimal operation cost obtained from TOP-Energy and FlixOptPy analysis are very similar to each other with an average deviation of 1 %. A difference in computation time is observed between the end results of TOP-Energy and FlixOptPy. Within conducted analysis, the computation time within TOP-Energy took longer than FlixOptPy. This can be explained by TOP-Energy’s additional variables as well as presentation of results, which take up more time to incorporate within the simulation.
Editor: Se-Hoon Chang
Tutor: Dr.rer.nat. Peter Stange, Dr.-Ing. Felix Panitz
Year: 2021

Conceptual design of a renewable energy supply for the competence center of mobility – Gewerbepark Avantis
This thesis deals with the matter of multi-criteria-evaluation for renewable energy
supplies. The evaluation will exemplarily be applied to the center of competence for
electronic mobility at the industrial estate Avantis. The thesis was written as a part of an
internal project which focusses on the universal evaluation of sustainable technologies.
This is why the core of the thesis is the development of an algorithm for the evaluation of
the sustainability for different supply technologies based on variable parameters
individual to a specific location.
After a short introduction to the underlying economical and ecological situation,
indicators for the evaluation as well as characteristics for these indicators depending on
the technologies are discussed. For the next step the evaluation principle is translated
into logical statements which form the base of the algorithm. In further steps the
algorithm is tested by being applied to a number of scenarios inspecting the influence of
deviation in different parameters to the location. The influence these parameters have is
discussed and verified. As the last step the algorithm is applied to the exemplary location
and a combination of technologies best fitted for the local requirements and conditions
is determined. The thesis is concluded with a prospect on parameters and additional
conditions that need to be taken into account when moving on with the project.
Editor: Niklas Schneider
Tutor: Prof. Dr. Achim Kampker – RWTH Aachen, Prof. Dr.-Ing. Clemens Felsmann
Year: 2021

Simulation of optimization strategies of the gas boiler in an apartment building
The goal of this thesis was to examine the efficiency of the gas boiler and the heating systems of a building from the research project "BaltBest" in more detail. The basic question here was how to optimise the boiler and heating system. In practice, it is difficult to find an optimal strategy for improving the efficiency of the heating system because the parameters interact hydraulically and thermally.
For carrying out the simulations for optimisation strategies, a field test building from the research project was simulated using the simulation software TRNSYS (Transient Systems Simulation). For this purpose, variation studies were carried out in which the following different parameters were varied: Type of gas boiler, modulation limit of the burner, rated output of the gas boiler, heating curve, night setback operation and night and summer shutdown of the gas boiler. The result of the variation studies shows that changing a slope of the heating curve from 1.8 to 1.0 improves the efficiency of the boiler most significantly and at the same time reduces fuel consumption. In the case of the "night shutdown" variation, in addition to improving boiler efficiency and saving fuel, it was also possible to reduce the electricity for the circulation pump. Finally, combined variations were carried out in more detail. The best combination shows an increase in boiler efficiency of up to 5,2 % (88,3 % → 93,5 %), fuel savings of up to 16,9 % (2000 m³/a) and a reduction in electricity for the circulation pump of up to 39 % (172 kWh/a).
Editor: Su Hyun Hwang
Tutor: Dipl.-Ing. (FH) Sebastian Rochau, Dr.-Ing. Alf Perschk, Dipl.-Ing. Jens Kaiser
Year: 2021

Conceptual design of the heat supply with renewable energy sources for a warehouse building
In this thesis, a heat supply concept for a warehouse was developed. In addition to the replacement of the current gas boiler system, the conversion of air heaters into radiant ceiling panels is also planned. For the selection of a heat generation system several possibilities were presented. In addition to the usual concepts the use of an ice storage heat pump system was examined in more detail. With the operating company’s goal to reduce CO₂ emissions by 80 % by 2030, special attention was paid to he ecological footprint of the heat supply system. Furthermore, the examined concepts were investigated in their economic efficiency.
Because the warehouse owner uses wind turbines and thus utilizes green electricity, it is the best option as a power source from an ecological point of view. Replacing the gas boiler with a condensing boiler would result in a reduction of CO₂ emissions of 24,4 %. In comparison, a bivalent-parallel heat pump-ice storage system can achieve a reduction of 89 % of CO₂emissions. The influence of the CO₂ tax and assumptions on the general energy price increase were examined in the form of a sensitivity analysis.
From an economic point of view electrically powered heat supply systems are not worthwhile compared to gas-powered heat supply systems due to the high electricity prices. Furthermore the investment costs of an ice storage system are very high.
Editor: Martin Zacharias
Tutor: Prof. Dr.-Ing. Clemens Felsmann, Dipl.-Ing. Jens Claaßen – HLS-Plan
Year: 2021

Simplified building heat load models for district evaluations
With increasing urbanization and the necessity of climate protection and energy transition, more and more district heating systems are used as energy solutions for urban districts. Due to the large number of buildings included, one of the main focuses of the energy assessment of urban quarters is the simplified prediction of the energy consumption of the individual buildings in the district heating system. Despite simplification, the prediction should be sufficiently accurate. This thesis deals with simplified calculation approaches for determining the heating load profiles and the return temperature of buildings.
The focus of the thesis is on the further development of a calculation approach for
forecasting the return temperature from heating systems. In the selected calculation approach, the heating system of the building is simplified into an equivalent radiator model. The modelling is carried out based on the behavior of radiators. The created calculation model describes the relationship between heating load, overtemperature and mass flow and can be varied according to different assumptions. The validation of the calculation model with coefficients from literature is carried out with the help of measurement data from some district heating transfer stations. The calculation results and their differences with measured data are presented and discussed for each building. To improve the calculation model, the heating load ratios are determined in different ways and the coefficients of the calculation model are optimized using measured data for each heating system. It is verified that the optimizations lead to a better forecast quality. Finally, the possibilities for further development of the calculation approach and its applicability to other heating systems are discussed.
Editor: Chenxi Yang
Tutor: Dipl.-Ing. Juliane Schmidt
Year: 2021

Life cycle analysis of Photovoltaic modules
The conversion of the energy sector to more renewable energies is a challenge of our time. Photovoltaic systems must be expanded to guarantee a stable power supply. It should be noted that the mere manufacturing of the solar modules consumes energy and generates emissions.
A life cycle assessment was carried out in order to obtain an understanding of the magnitude of energy consumption and emissions in the production of a specific photovoltaic module.
This type of analysis is used to evaluate and quantify the consumption of resources and the resulting emissions of a product over its entire life cycle. The stages of life considered were divided into material manufacturing, production, use, transport and disposal. This includes all the supply chains required for component production of a photovoltaic module.
The life cycle assessment was carried out using various data sets. Data was collected during an intensive literature research and evaluated for analysis. In cooperation with Solarwatt GmbH, internal information was made available to validate the literature data. It was found that the two data sets show deviations, but the general order of magnitude for energy consumption and emissions match. In the course of this paper, the topic of disposal was dealt with in more detail. The characteristics of the embedding material of a solar module are directly responsible for the complex disposal processes.
The development of a solar module without embedding material should be investigated in order to simplify the disposal process. The stability and lifespan of this new module design must be observed and checked more closely.
Editor: Annika Richter
Tutor: Peter Schumann – SOLARWATT, Prof. Dr.-Ing. Clemens Felsmann, Dr.-Ing. Karin Rühling
Year: 2021

Operational optimization of biomass conversion plants considering uncertain boundary conditions
This research work adopts an existing optimization framework originally created for fossil
powered energy systems onto the operational optimization of typical biomass conversion
plants. The specific selection of biogas conversion and CHP technology was carried out considering the current energy policy and energy-economic conditions in Germany.
Based on real data two biogas-CHP-plants are modelled which are working under different compensation-regimes for the generated energy and their corresponding boundary conditions and fuel limitations. Relevant operation influencing factors identified from field research are then quantified and put into possible environmental conditions differing from the reference system (2019). Based upon that follows the selection of alternative scenarios and a prognosis of their impact on plant operation. The implementation of the plant models into the Python-based framework FlixOpt makes an operational optimization possible according to maximal profits for plant operators as well as to minimal CO₂-emissions in the balancing group influenced by the plant. Considering a fluctuation of boundary conditions depending on the season slightly different approaches for plant operation could be identified. The optimization under different boundary conditions belonging to alternative scenarios lead to consequences for both profits and CO₂-emissions.
With little adjustments the eligibility of biogas conversion and CHP technology for the optimization in the used framework could be confirmed. Results showed a yet nexploited
potential of biogas conversion technologies for the extensive use in future decentralized energy systems which is endangered by energy policy-making and energy-economic conditions in Germany. The researched technology is capable of covering peak and base loads both electrical and thermal and therefore provides a special CO₂-binding influence regarding certain plant configurations. Additionally the modelled biogas plants showed a
partial consistency in cogeneration efficiency under difficult climatic boundary conditions.
Editor: Davis Kronenberg
Tutor: Dr. rer. nat. Peter Stange, Dr.-Ing. Felix Panitz
Year: 2021

Conceptual design of the ventilation for a cleanroom in microbiology considering the dimensioning of all components
The objective of this paper is the development of a ventilation concept for a clean room using the example of a real laboratory. In addition, the basics for the creation of a tool for the selection of a pressure control variant for a clean room are defined. At first, the cleanroom system is examined regarding its necessary components, the general principle of operation and other important influencing factors. Subsequently, three different variants of room pressure control are analysed and evaluated based on various criteria. This results in an estimation of the suitability of the models for different applications. The choice of system depends strongly on the required cleanliness of the clean room. These findings are applied to the design of the ventilation concept. The pressure control of the real clean room "Sterillabor 1" is therefore carried out by a bypass in the exhaust pipe. The individual components are selected based on the given cleanliness requirements. Consequently, a real existing, efficient ventilation and pressure control system is created.
Editor: Kajetan Weiß
Tutor: Dipl.-Ing. Mirko Tillner – Caverion, Prof. Dr.-Ing. Clemens Felsmann, Dr.-Ing. Martin Knorr
Year: 2021

The energy performance inspection of ventilation systems considering recent legal regulations
This thesis considers the energetic inspection of ventilation and air conditioning units under current legal regulations. The regulations of the German Energy Saving Act (Energieeinsparrecht) according to the Energy Saving Ordinance (EnEV) and the Energy Act for Buildings (GEG) are being analysed in this context for units requiring inspection.
The calculation methods for energy efficiency and energy value of ventilation and air-conditioning units are being displayed according to the DIN SPEC 15240 specifications. The measures of implementation of the energetic inspection are being demonstrated for a unit requiring inspection using the DIN SPEC 15240 specification and the determined value compared to the reference values from the Energy Savings Act. The potential for energetic optimisation specified through the inspection is illustrated in detail.
The cooling supply of the unit works through direct evaporation. Through the inspection of the unit a primary energy requirement of 26.87 kWh/(m³/h)/a can be determined. The energy value of the cooling generation is 3.21. As only the value of the cooling generation conforms with the GEG, a need for action by the unit operator can be identified.
Editor: Lennart Niepraschk
Tutor: Dipl.-Ing. Jörg Isensee – Dresdner Kühlanlagenbau GmbH, Prof. Dr.-Ing. Clemens Felsmann, Dr.-Ing. Martin Knorr
Year: 2021

Model based simulation of urban energy networks
This study deals with the task described in IBPSA Project 1 Task 3.1 to simulate a given urban heating network and to provide further test variants for comparison with other programs.
For this simulation, the program TRNSYS-TUD, which was further developed at the Technical University of Dresden, was used. In this program, the provided radial line network was simulated including the 16 consumers on two main lines. The consumers demand different heat outputs from a central heat source and are to be analyzed for different characteristics.
However, some important specifications, such as the load profiles to be used, have not been precisely defined. This influences the results so much that other programs simulating the exact same network could calculate significantly different values.
The variables to be investigated were, among others, the heat input of the heat source, the losses to the environment or the total water circulated during the simulation. Many of these values follow the expected curves, also due to the strict boundary conditions of the simulation. However, the correlation between the losses and the mass flow in the network was particularly striking. During the variant calculation, it turned out that, contrary to the assumption made at the beginning, an increased mass flow increases the losses of the system and does not minimize them.
At the end of the study, recommendations are made for the future course of Project 1. These include the list of assumptions made and an assessment of the impact on the results, as well as a call to specify these in the problem definition. Suggestions are also given as to what other variations of the network can be investigated. The results of the described basic variant and those of the variant calculations will be made available to IBPSA Project 1. There, the results are compared with those of other simulation programs and contribute to a better understanding of the building simulation.
Editor: Sven Juhler
Tutor: Dipl.-Ing. Juliane Schmidt, Dr.-Ing. Alf Perschk
Year: 2021

Utilization factors in heating networks
The objective of this thesis is to give an extensive description of the concurrency in heating networks, with the main focus on the calculation of the utilization factor. By carrying out four different studies, its dependence on internal heat gains and the chosen balance limits are investigated.
By creating a model, specifically a factory building, and developing an excel tool, the influence of internal heat gains on the heating load of the building and thus the utilization factor of an industrial property can be shown. Especially process heat reduces the heating demand significantly. In consequence, process heat cannot to be neglected whilst designing the heating network and its components of an industrial property.
Based on real measurement data of a heating network and four different scenarios it is shown, that the calculation of the utilization factor can lead to strongly varying results for one and the same network. By determining a network loss function and introducing a factor, which represents the overdimensioning of delivery stations, the calculation approach can be expanded. This allows balancing on the side of the heat generator, aswell as the consumers.
Using an excel tool called FreePlan, the heating network and its load profiles can be simulated. By choosing suitable regression models, the varying influence of different typs of consumers on the calculation of the utilization factor can be deduced. It turns out: The more heterogeneous the network, the more relevant the consideration of the different power fractions of the consumer types.
In a final section, the value of the utilization factor of a network, which consists of artificially generated load profiles, shall be set in advance. To reach the demanded value, a variety of strategies, which are based on either the manipulation of time or the elongating/squashing of values, are being developed. To demonstrate their effects, aswell as derive their application limits, every strategy is being tested by creating a fictitious part of a heating network, which contains ten consumers. After applying each strategy, the results are being evaluated and discussed. It turns out: Setting strict boundary conditions during the manipulation does not necessarily lead to a minor distortion of the original load profile. Depending on the amount of values, that are allowed to be manipulated and the uniformity of the original load profile, a severe deformation can occur.
Editor: Johannes Lenk
Tutor: Dipl.-Ing. Eberhard Dux – PGMM AG, Prof. Dr.-Ing. Clemens Felsmann, Dr. rer. nat. Peter Stange
Year: 2021

Comparative analysis of ice storage applications in office buildings
A new office complex is planned on the outskirts of Hanover. The buildings are to be supplied by an ice storage system that can provide heat and cooling throughout the year, in combination with a heat pump network and a heat exchanger. As a part of this work, investigations were carried out to determine the energetic, economic and ecological advantages regarding the use of an ice storage system. In order to bring the results into a technologically meaningful context, a geothermal heat supply in form of geothermal probe systems was also analysed as a reference for this specific project.
In the first step, an energetic simulation of the project was carried out in order to obtain realistic load profiles regarding the heating and cooling of the rooms. The various construction methods of the office buildings only resulted in minor differences of the annual energy requirement. Using a custom calculation table, the systems behaviour was successfully simulated and the control logic as well as possible operating modes of the ice storage system were adapted to reach an energetic optimum of the system operation. For each possible operating point, the behaviour of all technical components and their interaction with one another was extensively analysed and mathematically described.
The results of the simulation showed that the integration of an ice storage into the system has a moderate potential for energy savings. The ecological advantages of the technology in form of CO₂ emission reductions could also be demonstrated by means of a life cycle analysis. Due to the high investment costs of this technology, however, it was predicted that amortization within its lifecycle of 50 years is not to be expected. In this specific project, the use of a geothermal probe system turned out to be the better solution regarding all points mentioned above.
It was shown that the ice storage has negative effects on the profitability of a photovoltaic
system if it is used to power the system.
Editor: Johannes Reif
Tutor: Dipl.-Ing. Stefan Fiddicke – STRABAG, Prof. Dr.-Ing. Clemens Felsmann
Year: 2021

Space cooling during summer - Consideration of the investment costs for extending heating systems to include cooling operation
In this report, the investment, operating and maintenance costs associated with different heating and cooling systems that are suitable for space cooling during summer by radiators are being examined.
This investigation includes different retrofit variants for extending as well as new installations of heating system to include cooling operation.
In addition to the technical literature, online market analyses and personal interviews with process participants are used to compare manufacturers price lists as well as planning indicative costs in a building-typed system of variants during this process. For this purpose, the German building stock is being analyzed and a selection of eight typical buildings is being used for representative examples, of which cost calculations are being carried out on each. Thereupon, generally applicable methods for the estimation of the investment, operating and maintenance costs for cooling operations are worked out. As a result of the comparisons made, conclusions derived show that heat pumps and sorption chillers can be a cost-effective method of providing a cooling function due to low operating costs.
Editor: Gina Malorny
Tutor: Dipl.-Ing. Sven Schulke - pbr Rohling, Dr.-Ing. André Kremonke, Dipl.-Ing. Markus Arendt
Year: 2021

Numerical calculation of indoor air flow and indoor air quality in a lecture room taking into account an air cleaner
The ongoing COVID-19 pandemic has drawn attention and intense discussion to the transmission of exhaled virus aerosols as a trigger for indoor infections.
Using the air purifier as a complementary measure can provide additional protection for attending a personal event. This thesis examines the effects of the installed supply air system and an air purifier on the slowdown of the spread under different ventilation scenarios. The risk of infection for the people in the room is taken into account based on the aerosol concentration of the virus-contaminated exhaled air of an infected person in the air. It has been found that using both an air purifier and the supply air system can significantly reduce the risk of infection. It should be noted that in the current real operating state of the room, i.e. H. If the supply air system and the air filter are in operation at the same time, each person receives approximately 156.92 m³ / h of fresh air. That is four times what would be required from a hygienic point of view.
In addition, it is investigated whether an unfavorable placement of the air cleaner worsens the situation in the room due to the unfavorable influence on the flow paths, e.g. if an infected person is currently on the purifier drainage path. In this case, the student sitting behind the infected person could inhale a problematic mixture of infected and purified air. Accordingly, it has been suggested to place the air purifier in the center of the room as much as possible.
Editor: Chutan Xue
Tutor: Dr.-Ing. Ralf Gritzki, Dr.-Ing. Markus Rösler
Year: 2021

Analysis and comparison of hourly test reference weather data from Deutscher Wetterdienst
Realistic weather data is an important component of a thermal building simulation. In this student research project, the weather data of the test reference years published in 2011 by the DWD (Deutscher Wetterdienst: Germany's National Meteorological Service) are compared with the locally precise test reference years published by the DWD in 2017. For this purpose, these weather data are compared with measured data from weather stations close to selected locations. Until the new publication in 2017, there were 15 climate regions in Germany and there was one set of weather data with typical weather conditions for each region. In the past, clear differences have been observed, especially between large cities and the immediate surroundings. If necessary, the test reference years could be modified with the help of a tool to represent this urban climate.
For the new publication, the data sets were fundamentally revised. They are now available for every square kilometer in Germany and there are now more than 340,000 new sets of weather data. On the one hand, this is intended to better represent the progressive effects of the climate crisis, but also to simplify the use of the test reference years.
The test reference years were mainly examined with regard to the differences in a dynamic heating and cooling load calculation. It turns out that the choice of the test reference year has less influence on the system dimensions than the comparison with real weather data would suggest. The differences are in the same order of magnitude of other parameters of the planning and should be discussed and agreed upon in the same way. Then there is also potential for savings in the choice of weather data for the construction and operation of the building services.
Editor: Danny Borchert
Tutor: Dipl.-Ing. Falk Schumann – INNIUS GTD, Dr.-Ing. Claudia Liersch – INNIUS GTD, Prof. Dr.-Ing. Clemens Felsmann
Year: 2021

Data-based modelling of return temperatures in buildings
This project thesis addresses the data-based modeling of return temperatures in buildings supplied with district heating. The basis of the modeling is an extensive dependency analysis of measurement data from several residential buildings. This analysis shows that the power of the heating circuit and the drinking water generator is suitable for data-based models. In contrast to this, no general dependencies for the return temperature can be identified. This temperature is significantly influenced by the structure and control of a heating system. To be able to take the internal structure of the heating systems into account, several partial models are defined. Together, these form an overall model. This overall model can calculate the return temperature in buildings. Finally, the quality of the created models is determined and it is shown how the developed model approaches can be integrated into the existing forecast tool FreePlan.
Editor: Simon Kimmig
Tutor: Dr. rer. nat. Peter Stange, Dipl.-Math. Anja Matthees
Year: 2021

Performance evaluation of heating systems in the context of heat generator replacements
The study deals with the performance evaluation of heating systems in connection with the replacement of heat generators. First, the building and system characteristics of the individual properties were documented. Measurement data from the project portfolio of the "BaltBest" research project served as the basis for the evaluation. These were used to quantify the effects of boiler replacement on the efficiency and operating mode of the heating system. Subsequently, proposals for optimization possibilities of the plant operation were elaborated and the expected effects were estimated. It was concluded that the boiler replacement had not been successful. Despite efficiency improvements, a reduction in gas consumption could only be achieved in isolated cases. Most boilers are oversized, which has a negative effect on boiler short cycling. There is great potential for optimization. Possibilities lie in the area of power adjustment and increasing the storage capacity of the boilers in order to reduce the cycle frequency. Hydraulic balancing of the heating systems should be carried out at all properties so that energy wastage is kept as low as possible.
Editor: Paul Teschler
Tutor: Dipl.-Ing. (FH) Sebastian Rochau, Prof. Dr.-Ing. Clemens Felsmann
Year: 2021

Life cycle considerations of plants using renewable energy sources
Renewable energy systems are resource- and climate-friendly during their operating phase, which is why they are taking on a central role in current climate policy. However, the emissions and consumption of primary energy over the entire life cycle cannot be neglected, so that a comprehensive life cycle assessment of these plants is necessary for a fair comparison. This thesis is focused on such a balance including quantification and evaluation of environmentally relevant factors for the technologies photovoltaics, wind energy and natural gas.
Within the framework of the methodology for life cycle analyses defined in DIN EN ISO 14040, the energy generation systems are analysed according to their material consumption, emission of greenhouse gases and primary energy consumption from production to end of life. A user interface with an integrated and expandable database has been implemented for the necessary calculations of cumulative energy consumption and greenhouse potential. As expected, the manufacturing phase of the plants is dominating the result of the holistic LCA, whereas the influence of the transport and maintenance phase is negligible. At the end of life of the plants up to 50 % of the primary energy and emitted greenhouse gas can be recovered by the modulation of recycling processes by substituting primary goods by credit. The technologies are examined in a sensitivity analysis for the influence of significant plant parameters and their connection to the final result. Finally, the technologies are compared with other renewable and fossil energy systems and a concept for the implementation of the life cycle assessment at the corporate level using the EcoDesign approach is developed.
Editor: Sarah Langner
Tutor: Prof. Dr.-Ing. Clemens Felsmann
Year: 2021

Investigation of measures for heat protection during summer for the Biological Institutes of the TU Dresden
In the context of this diploma thesis, the effects of different measures for heat protection for the Biological Institutes of the TU Dresden are investigated.
The new building, completed in 2006, shows a need for action with regard to the thermal situation of non-machine-cooled office rooms.
After specifying the existing thermal building model in the Tas simulation environment, this model is validated with the help of measurement data from temperature monitoring. The simulation results of the measures are analysed and compared on the basis of parameters relating to the minimum requirements for heat protection during summer according to DIN 4108-2 and thermal comfort, for which a composite permissible upper temperature limit was developed according to the requirements from the Technical Rules for Workplaces, DIN EN 15251 and DIN EN ISO 7730. The main criterion is the sum of annual overtemperature degree hours or those occurring during the cooling period.
The final combination of measures contains three control and construction measures. These ensure summer night cooling of certain groups of rooms and at the same time reduce the temperature in the atrium and the rooms by reducing the solar heat input also during the period of use. Furthermore the results show that even with maximum use of measures, individual rooms cannot meet the requirements and consequently need special measures.
The recommended measures increase the proportion of the examined rooms that meet the minimum requirements for summer thermal insulation under the meteorological boundary condition of the test reference year (TRY) 2015_S from a total of 30,9 % to 89 %. At the same time, thermal comfort is increased and the annual cooling energy demand of the building can be reduced by 4.36 %.
Editor: Caroline Julia Rentzsch
Tutor: Dipl.-Ing. Julia Seeger – TU Dresden, Institut für Baukonstruktion, Dipl.-Ing. Markus Arendt
Year: 2021

Potential assessment of a System controller for coupling PV electricity into a district heating supply concept for MFH buildings
The feed-in of electrical surplus causes a higher load on the grid. Increased local use prevents this. Significant potential for the integration of PV electricity for this purpose exists in heat supply. This thesis describes the development and evaluation of a system solution from the cross-sectoral use of PV surpluses and district heating, the latter is often used to supply urban apartment buildings.
According to research on themarket situation, independently controlled heating rods are available for converting PV power into heat. However, a coordinated operation of these heating rods with district heating is not possible so far. The present thesis develops and evaluates different approaches for combining these two heat sources with various hydraulic concepts and system controllers. The highest potentials arise from the use of a forecast-based charging control of a combi-storage tank.
The charging control can be realised with different techniques, either through simple if-then decisions or a model predictive control. This can only use slightly more PV electricity, as the PV heat share is limited due to the time lag between PV surpluses and heat demand. Predictions of future energy flows are necessary for both approaches but these have relatively high errors for individual consumers and PV systems. This thesis demonstrates that more complex forecast approaches (demanding large data sets) do not perform significantly better than simple forecast approaches (that can deal with smaller data sets). Model predictive control requires a higher forecast resolution and is therefore also more error-prone, thus it is not recommended.
The desired relief of the electrical grid can be achieved through local consumption. An economic implementation of the concept is possible with district heating prices above the feed-in tariff for PV electricity, exclusively. Therefore, this concept is currently not economical. Furthermore, the carbon footprint increases through local use.
Editor: Martin Altenburger
Tutor: Prof. Dr.-Ing. habil. Joachim Seifert, Dr.-Ing. Paul Seidel, Dipl.-Ing. Silvio Müller - YADOS
Year: 2021

Space cooling during summer - Evaluation of the suitability of scalable building and plant models to investigate the cooling effect of radiators
Theoretical and practical studies have shown that a significant cooling effect can be achieved using free heating surfaces. As part of this diploma thesis, this cooling effect is to be investigated for various existing residential buildings. For this purpose, a scalable multi-family house building model is created. The scalability relates to the size of the living space and the number of residential units. This offers the advantage of considerable time savings when creating building models. Various variant building models are created with the scalable building model. With this, simulation calculations for summer room cooling with free heating surfaces are carried out with TRNSYS - TUD. The simulation calculations are used to compare and evaluate the perceived temperatures and the cooling energy requirement.
Editor: Toni Frohs
Tutor: Dipl.-Ing. Markus Arendt, Dr.-Ing. Alf Perschk
Year: 2021

Studies about lighting protection at wind turbines
Due to their height, modern wind turbines are particularly vulnerable to lightning strikes. As a result, wind turbines are equipped with a lightning protection system, which directs the electricity into the earth in a defined way in the event of a lightning strike. Rotor blades are the components most badly affected by lightning strikes. In order to obtain insurance coverage for a wind turbine, the functionality of the rotor blades' deflection system must be proven.
The lightning discharge cable of a rotor blade is a metal cable which runs from the lightning catching device in the area of the blade tip to the blade root area. The state of the art is that the functionality of the lightning protection system of the rotor blades is verified with a resistance measurement. For this, a person has to drive along the rotor blade with a battery powered rope ascender and close the circuit at the lightning catching devices in the blade tip area with the help of a long cable. Aside from the dangers that this procedure entails, the results of this lightning protection test are sometimes unrealistic. Even small interruptions in the lightning conductor wire lead to excessively large or infinitely large resistance values. Lightning would simply bridge these line breaks with an arc.
ENERTRAG WindStrom GmbH has developed a procedure in which the lightning discharge cable of the rotor blade is subject to at least 2.000 V alternating current. Small conductor breaks are bridged by an electric arc. By means of a field probe, which is locked on a drone, the developing electrical alternating field can be detected in the blade tip area.
Editor: Max Aschenbrenner
Tutor: Dr.-Ing. Konrad Iffarth - ENERTTRAG WindStrom GmbH, Prof. Dr.-Ing. Clemens Felsmann
Year: 2021

About the combination of Photovoltaic and heat pumps with a special attention on battery storages
The present thesis deals with considerations on combination of photovoltaic systems, heat pumps and battery storage systems. The theoretical basics of all components and their interactions are described and analyzed. Electrical energy generated near buildings from renewable energy components is supported by legislative proposals. Considerations are made in this context of the interactions between the three systems. The significance of
various parameters is examined. For this, simulation tests are performed. The simulation
results are evaluated and lead to the interactions between the parameters and defined target values. Furthermore, the examined variants of the overall system are evaluated
comparatively and a statement is made on the design and dimensioning of the battery
storage system. An economic analysis of a system with the three main components is also
carried out.
Editor: Clemens Kost
Tutor: Prof. Dr.-Ing. Clemens Felsmann
Year: 2021

Room climatic and energetic effect of cooling ceilings in an office building taking into account thermal comfort
This work examines a cooling ceiling in a practical case for its indoor climatic and energetic effect. In addition to physical measurements of the indoor climate, the users of the building were asked about their satisfaction. The indoor climate was evaluated on the basis of thermal comfort and air quality at the workplace. The conducted study of the cooling ceiling included the monitoring of the measurement data. The subsequent evaluation of the data in connection with the users responses is useful for making a statement whether the cooling ceiling worked optimally during the summer cooling period. Consequently, measures can be developed to prevent disruption of the cooling mode and thus increase the efficiency of the cooling ceiling as well as user satisfaction. Regarding the process to design the technical building plan, more information related to the indoor climate can be obtained through the use of increased field investigations. Thus, the building operation can be installed more responsible and sustainable. The communication between building planners and operators of the building can also be improved due to the consideration of the building design. In terms of practical application of the processes described in this work, theoretical knowledge of indoor climate and thermal comfort is indispensable and will thus be characterized in the beginning of this work. In addition, cooling systems that are commonly used on the market were examined for their state of the art.
The result of the monitoring can be summarized as follows: The evaluation of the users responses indicates that the surveyed participants generally assessed the indoor climate as pleasant. However, in some rooms abnormalities of particular room climate parameters were detected, which led to dissatisfaction. To gain a better understanding of the described dissatisfaction, measurement data was examined. The data showed that critical evaluations were the result of a malfunction in the cooling system. By identifying the influencing parameters and disturbance variables, it was demonstrated that the interaction between people and system technology can be improved by two major points: First, it is important to reach a better understanding of the selected room cooling system. Secondly, a detailed instruction of the users is indispensable.
Editor: Magdalena Thiel
Tutor: Dipl.-Ing. Lars Schinke, Dipl.-Ing. Maximilian Beyer
Year: 2021

2020

Empirical validation of calculation methods modelling gas-fired heat generators based on German building stock data
The climate protection plan 2050 describes the requirements for a nearly greenhouse gas neutral Germany up until the year 2050. About one third of the total greenhouse gas emissions are caused by the building sector through heating, which is why the primary energy demand is supposed to decrease by 80 % in 2050 compared to 2008.
This dissertation deals with the heat production in residential buildings. In the context of the BaltBest research project, the increase of the efficiency of heating systems and the related CO₂-emissions are analysed. The aim of the dissertation is to evaluate the suitability of calculation models for gas fired boilers in terms of operational behaviour and to validate them with selected measured data of the research project. Measuring and meta data of more than one hundred apartment buildings which were equipped with suitable measuring technology form the data basis. Furthermore, parameters are to be identified within the scope of a sensitivity analysis and approaches to optimise the computation results are to be developed.
The basis of the calculation models are default values of the standard DIN V 18599-5 as well as mass and energy balance, and principles which were derived from physical basic concepts. To answer the research question, the fundamental losses of heat production (exhaust gas loss, cooling loss, environment loss) as well as the condensation has been calculated with different calculation models and compared with the metrological derived useful heat of the domestic gas consumption. The evaluation of the suitability of the calculation models is based on the relative discrepancy between the metrological and the calculated gas consumption.
The results of the dissertation shows that both the environment loss and the condensation represent relevant parameters which determine the gas consumption significantly. The calculation models predict the monthly gas consumption for gas fired boilers with an accuracy of +3,5 % to -3,5 %. When considering a higher time resolution, deviations between ✝ 10% are generated. Further studies shall verify these results in a detailed analysis.
Editor: Marius Maurer
Tutor: Dipl.-Ing. (FH) Sebastian Rochau, Dipl.-Ing. Jens Kaiser
Year: 2020

Integration of solar heat in the district heating network of Dresden – technical solutions, boundary conditions and limitations and economy
Against the background of a rapid decarbonization of the heat supply in Dresden, three approaches to integrate solar energy into a district heating network were investigated in this thesis. The investigations were carried out on a real secondary network with flow temperatures up to 90 °C and a fictitious open space of 30,000 m².
In the first scenario the projection of a solar thermal system was investigated. The second scenario consists of a photovoltaic system and an air-to-water heat pump system that feeds into the district heating network. In the third scenario, a hybrid photovoltaic-thermal system generates both electrical and thermal energy yields, which serve as a heat source for a brine-water heat pump system.
The dimensioning of the systems was carried out using current solar modules and collectors available on the market. The heat pump systems were developed in cooperation with a manufacturer.
In comparison, the plant according to scenario two has the lowest heat production costs and is therefore the most economical variant. The heat production costs of the plant in scenario three were the highest. A solar thermal system consisting of vacuum tube collectors generates the highest area-specific solar yields. The system in scenario three can ensure efficient operation of the heat pump, cover most of the electricity demand with the solar system and feed electrical energy into the power grid.
It is recommended to plan solar thermal systems on open spaces close to district heating in order to generate an optimal area yield. In addition, the project planning of air-water heat pump systems is recommended. A system according to scenario three is recommended on a smaller scale as a pilot plant.
Editor: Lion Gienger
Tutor: Dr.-Ing. Karin Rühling, Mike Neumann, DREWAG Stadtwerke Dresden GmbH
Year: 2020

Feasibility study about the integration of a heat pump into a district heating network
The integration of a heat pump into the Dagersheim heating network of the Stadtwerke
Böblingen is presented. River water and wastewater are considered as heat sources for the heat pump. The thermal use of the investigated river is possible but is subject to restrictions. The flow rates and the ecological and chemical condition of the river must remain unchanged. River sections where heat extraction would be feasible are only available to a limited extent. A temperature reduction of the entire water body by 1 K is not to be exceeded. The Böblingen municipality recommends installing the heat pump at the sewage treatment plant due to the higher source temperatures and simpler installation.
Three potential locations for the heat pump are being investigated. The heat pump scenarios are featured in a simulation that includes the consumer and heat network behaviour in Dagersheim. The reasons of all locations are in the development of the heat source and the integration into the heating network. The heat production costs increase due to the resulting additional energy and investment costs. The 50 % heat pump coverage required by the Building Energy Act (Gebäudeenergiegesetz, GEG) can be achieved at all locations and is used as a reference value for the design. The seasonal coefficient of performance of 3.5 required by the Renewable Heat Act (Erneuerbare-Wärme-Gesetz, EWärmeG) is not achieved at any location. For the heat pumps with the heat source river water, which are positioned either in the centre of the heating network or near the river, the heat production costs are between 83 and 94 €/MWh. Using wastewater at the sewage treatment plant results in heat production costs of 124 to 137 €/MWh due to the distance to the heat grid.
The use of solar thermal energy offers the potential to achieve lower heat production costs if subsidies are used. Combining the heat pump with a photovoltaic system has positive effects but must be done in a direct spatial link. It is established that the operation of cogeneration units at the sewage treatment plant results in waste heat that has not been used so far. The use of a heat pump for heating sewage sludge should be investigated.
Editor: Marc Kammerer
Tutor: Prof. Dr.-Ing. Clemens Felsmann, Dr. Schicktanz, Dipl.-Ing Nagy –Stadtwerke Böblingen GmbH & Co. KG
Year: 2020

Overall energy concept for 30-storey commercial and service suites block in-cluding an open car park in Kota Kinabalu, Malaysia
This thesis prepares an overall energy concept, which, on the one hand, shall become a practical tool for the Malaysian development team behind the building project to identify current flaws as well as to recommend improvements. On the other hand, it attempts to convey an accurate image of the local building sector including technical building equipment and common practices to better comprehend the overall situation from an external perspective.
The substantive part of the thesis starts with a specification of the framework conditions, such as site location, prevailing climatic conditions and legal requirements. In this context, the only green building code (non-mandatory) is thoroughly evaluated, too. Hereafter, layout and function of all 30 levels are described while dividing the building into sections (commercial, car park, residential). Construction materials are shortly touched on in order to obtain U-values as well as g-value equivalents. A separate chapter concentrates on the primary Malaysian performance indicator for building energy, the Overall Thermal Transfer Value (OTTV), essentially displaying the total heat gain through the building envelope (exclusive of roof and baseplate). Resulting values provide local comparability and support for later analysis to some degree.
Afterwards, the technical building equipment is listed, grouped in electricity, cold and domestic hot water as well as ventilation and cooling. Energy demand approximations are carried out, while taking researched studies and personally measured values into consideration. The subsequent variant matrix shows in-depth energetic, ecological and economical aspects of bigger modifications and installations, e.g. thermal insulation, heat protection glass or a rooftop photovoltaic system. Examined criteria include the total amount of saved (electrical) energy, avoided CO2 emissions, the time it takes to break even from the initial investment (discounted payback period), impact on the aforementioned Overall Thermal Transfer Value and, ultimately, the achievable score for the most common green building certificate in Malaysia. To conclude the overall energy concept, a final recommendation is issued to summarise the previous variants in regard to their possible implementation.
Editor: Kai Ettrich
Tutor: Ngu Ket Yi (B.Sc.) – Bina Puri Holdings Bhd. Executive Director: Datuk Matthew Tee Kai Woon (B.Com., FCPA), Dr.-Ing. Annina Gritzki – TU Dresden
Year: 2020

Exploitation of the energy potential of a big service water pipeline in hydroelectric power station with heat supply option (HEPS-H)
This thesis examines the extension of an existing hydroelectric power station at the location Moskauer Platz (Pelton-Turbine, 720 kW_el) with a heat supply option (HEPS-H). Four alternatives were tested to integrate heat sinks in the established distinct heating grit. The source of heat is the utility water before entering the Pelton turbine (45.000 m³/d) with temperatures between 3 and 20 °C. Despite the challenging boundary conditions during winter season, some producers were found to draw a construction for all-season operation up. No administrative objections because of environmental impacts are expected.
Based on boundary conditions of the district heating, the alternatives integration in a primary district heating grid and in a secondary heating grid, each for a return flow boost of 5 K and for a return flow-flow line feeding were analyzed. It becomes apparent that the heat generation costs are almost the same, for both types of feeding, on the primary and secondary supply. Because of the larger construction size, the return flow-flow line feeding has a greater potential of CO₂ reduction. Most of the costs are allotted to the delivery cost of electricity from the hydroelectric power station, even if costs are saved through self-supply in comparison to a regular grid supply. Thus, the biggest potential of saving costs do have measures reducing this kind of costs, like decreasing the seasonal performance factor of the construction. Right now, there is no direct sponsorship of the operating costs. Therefore, the costs are higher than the marginal costs of the installed gas-fired power plant under the current pricing of CO₂.
In comparison to other renewable alternatives the HEPS-H construction is assessed as good and a sponsorship of operating costs is political discussed right now. Depending on the chosen alternative 700 t_CO2 to 2900 t_CO2 per year could be economized and thus be an important contribution for the achievement of the German climate goals.
Editor: Cornelius Zunk
Tutor: Dr.-Ing. Karin Rühling, Frank Springer – SWE Energie GmbH, Uwe Weiß – Thüringer Fernwasserversorgung
Year: 2020

Technical monitoring in combination with the organization of a building project
This thesis deals with the implementation of technical monitoring for a newly constructed building that houses laboratories using the software tool „Synavision“. First the motivation for implementing a technical monitoring is explained. Next the theoretical basics of technical monitoring as well as the different aspects of its implementation are examined.
The principle of „Aktive Funktionsbeschreibung“, which is the basis for the analyzing tool is
illustrated and the interface and possibilities of the software are explained.
The process of creating the concept for monitoring is explained and the implementation of the controlling programming is showcased for different plants in the project. At the same time specific problems to the project and additional services will be recited.
Next is an analysis of data that was generated while operating the building and a visualization of the software´s analyzing-possibilities. The implementation of the technical monitoring is being evaluated and problems and chances are being illuminated.
Editor: Niklas Schneider
Tutor: Alexander Preuße – decon GmbH , Prof. Dr.-Ing. Clemens Felsmann
Year: 2020

Comparison of heat supply options for a new building
The choice of heat generator, ventilation concept and building envelope for a new building has long-term consequences in energetic, ecological and economic matters. In this respect, the heating demand of a multi-family building was determined on the basis of various requirements, taking into account the thermal building envelope according to EnEV and KfW55 with and without ventilation system, as well as the energy demand for heating drinking water by simulation. As heat generation options a gas condensing boiler in combination with solar thermal energy, an air-to-water heat pump with direct electric peak load coverage, a pellet boiler, a combined heat and power unit with Otto engine and peak load gas boiler as well as district heating were investigated. Furthermore, the influence of the control system on the energy-efficient use of the heat generators was investigated.
The results show that the heat generator option gas condensing boiler with solar thermal system cannot be justified from an ecological point of view under the conditions of the thermal building envelope according to KfW55 and the installation of a ventilation system with heat recovery.
Furthermore, it was found that when operating a pellet boiler and using district heating, a ventilation system with heat recovery does not provide energy savings or emission reduction. The use of solid biomass or district heating from cogeneration achieves a reduction of CO₂ emissions by up to 80 % compared to the reference variant permitted under the new building- energy-law. The option of the gas condensing boiler, which is often recognized as the most economical heat generator, will no longer be competitive in the future, partly because of the CO₂ price. With regard to the control of heat generators, demand-oriented control with hysteresis and suitable spacing of the temperature sensors in the storage tank leads to energy-efficient and low-wear operation.
Editor: Thomas Mehlig
Tutor: Dr.-Ing. Martin Knorr
Year: 2020

Space cooling during summer: Development and testing of an analytical model of the impact of air flow around heating panels and the impact on the surrounding space
The project at hand deals with the topic of space cooling during summer around heating panels. The aim is to develop and test an analytical model for the impact air flow around heating panels and the impact on the surrounding space. This makes it possible to describe the processes within the cold-air lake and to embed the results in the system and building simulation with TRNSYS-TUD.
In order to be able to fulfill the aim of this work, a literature research was carried out, which focused on the phenomenological processes on heating panels and the cold-air lake. These results have been combined in the computer algebra system Mathcad to form a software prototype with two models: the radiator model and the cold-air lake model.
The results of the software prototype show plausible and comprehensible values. In this way, a possibility has been developed to represent the effect of the cold-air lake in contrast to a CFD simulation as an alternative faster and with less effort.
Editor: Lukas Richter
Tutor: Dr.-Ing. André Kremonke, Dipl.-Ing. Markus Arendt
Year: 2020

Development of a forecast model for a model-based evaluation and optimization in manufacturing building
High fluctuation entries as a consequence of the current energy transition pose great challenges for the increasingly decentralized power grid structures. Due to the resulting overall cost increase in the energy market, the manufacturing industry is also increasingly confronted with this problem. Forecast based optimization methods can play a major role in the future in order to avoid own cost-intensive fluctuations in the power grid. The central idea of the thesis is the evaluation of probabilistic or Bayesian methods for load forecasting of a high-resolution time series with a short-term forecasting horizon. Furthermore, a model design is introduced which is comparatively well generalizable due to a low number of influencing variables.
In order to develop the model, several established methods are examined in detail and then evaluated. All presented methods are analyzed with regards to their probabilistic interpretability. lt can be demonstrated that the chosen Bayesian approach using Artificial Neural Networks is generally suitable for load forecasting in an industrial context. Especially the accurate modeling of the standard operation by the Bayesian solution is to be emphasized. A comparison of the different approaches shows that the simple solution consisting of a feedforward power grid structure and a normal distribution as a conditional probability distribution provides the most robust results for the standard operation. The more complex approaches show great potential in the given case, but remain inferior to the simple solution. However, it is to be expected that they exceed it when optimizing the hyperparameters better. lf the input and output values showed a less streng correlation than in this case, the further development of the more complex solutions may be beneficial.
All in all, the Bayesian approach offers a high potential for optimizing internal processes.
Proactively managing the plant's own buffers (batteries, cooling power grid , etc.) by using
probabilistic predictions can thus help minimize power grid fluctuations.
Editor: Kevin Wolf
Tutor: Dr. rer. nat. Lukas Jager – Bosch.IO, Prof. Dr.-Ing. Clemens Felsmann
Year: 2020

Performance and methods of rule-based optimization of generator use
In this thesis, rule-based algorithms are developed for generator scheduling. An energy system is considered, which includes the energy supply by a combined heat and power unit, a boiler and a heat storage tank. The solution by mixed-integer linear optimization serves as an optimal reference solution. Different approaches are pursued in the development of the rule-based algorithms. The regression-based approach controls the generator use via regression equations, which are created on the basis of the reference solution. The fixed logic uses if-then rules to imitate the optimal operating behavior of the reference solution. With the optimized logic, the rules of the regression-based approach and the fixed logic are adopted and selected parameters are optimized with the aim of minimizing the operating costs. In order to evaluate the rule-based algorithms, the solution is compared with the optimal reference solution. The computing time can be reduced significantly with the regression-based approach and the fixed logic. The deviation of the operating costs remains small with all developed algorithms.
Editor: Carlotta Scheder-Bieschin
Tutor: Dr. rer. nat. Peter Stange, Dipl.-Ing. Felix Panitz
Year: 2020

Investigations in the development of a PCM storage system for the storage of waste heat from industrial processes
Within the scope of this work, detailed investigations in the field of latent heat storage are carried out to provide the basis for the development of a storage system. The development tasks include metrological investigations to improve the thermal conductivity of phase change materials by addition of additives. Furthermore, they include the conceptual design of a laboratory test storage unit to investigate different encapsulation variants.
As a basis for the metrological investigation of the improvement of the thermal conductivity, promising options from the literature are compiled. Subsequently, samples are prepared from one phase change material and one additive each. The effective thermal conductivity of the sample is measured with a special apparatus which is based on the guarded hot plate method. Expanded natural graphite and fibers of an aluminum alloy have proven to be suitable.
For the design of the storage unit, existing design variants are researched and evaluated regarding their suitability. A preferred variant is selected and dimensioned accordingly. The chosen variant is a storage tank based on a shell-and-tube heat exchanger design. It consists of a cylindrical stainless steel tank, which carries a flow display pipe in the center to allow visual control. The capsules can be fixed either in a special fixture or by creation of a bed. The storage tank is suitable for the investigation of different encapsulation techniques and is flexibly scalable.
Editor: Henrike Puschmann
Tutor: Torsten Seidel - Fraunhofer IFAM Dresden, Dipl.-Ing. Lars Schinke
Year: 2020

Comparative evaluation of domestic hot water systems
In the context of the present diploma thesis, classical (instantaneous water heating, storage and storage charging systems) and innovative systems (systems with low return temperatures, heat recovery) for domestic hot water are subject of a comparative evaluation. By means of various economic and ecological assessment criteria (e. g. heating power, investment and maintenance costs, space requirements, integration of renewable energies, hygiene) the necessary basis for comparison is created for different systems and system configurations and subsequently an evaluation is carried out. The obtained results are supplemented by IT-supported calculations (using Hottgenroth Energieberater software) according to DIN V 18599 and an evaluation of current literature. The combination of these approaches leads to the following results:

The systemic approaches for a single-family house and a multi-family house are completely different and the best solution for one single family house can look completely different compared to another single-family house due to varying conditions.
Depending on the initial situation, even a minor change in the system configuration can generate a significant improvement (e. g. replacement of the boiler)
There are many possibilities for improvements in the heating of drinking water: These are mainly aimed at primary energy savings.

The possible measures and the associated potential for improvement are based on the existing conditions (supply location, premises, existing system configuration, etc.). Decisions in practice for or against concrete measures are then to be examined individually depending on the case of need. Only the case of need in the context of the existing environmental parameters provides the necessary weighting of the presented evaluation results and the resulting knowledge about which measures are actually useful.
Editor: Yannick Dederichs
Tutor: Prof. Dr.-Ing. Clemens Felsmann
Year: 2020

Development and validation of a method to identify the flexibility potential of major electricity customers
The share of electricity generated through renewable energy sources is rising in
Germany. This results in a higher share of volatile infeed from sources such as wind
turbines and photovoltaic plants. To address the fluctuations between power generation
and consumption a flexibilisation of both is required.
The objective of this thesis is to develop and validate a standardised method to identify
the technical flexibility potential of major electricity customers. The obtained results
are intended to assess and compare a variety of different customers. Thus, the resources
needed for detailed investigation can be used to target a specific range of
customers.
This thesis describes a characterisation of different operating modes of electrical consumers
and their ability to be operated flexibly. Therefore, corresponding parameters
and a basis for the calculation of the technical flexibility potential are defined.
As a guideline for the investigation, the partially interactive tool FlexID was created
with Microsoft Excel. It includes templates to create profiles for the customer’s flexible
units. All results are displayed and graphically evaluated on a separate worksheet.
The validation was carried out using the drinking water supply of Dresden. The identified
flexible units are pumps for reservoirs as well as pumps and air blower units used
to backwash the filters. Due to the low electric power of the analysed units the flexible
operation is currently not economically feasible. Nevertheless, changes in the regulatory
framework might lead to profits in the future. However, the method was validated
and FlexID was successfully tested to the full extent of functions. Therefore, it can be
used to assess more powerful units.
The critical review showed: Identifying the technical flexibility potential can lead to a
misinterpretation of the feasible potential. Thus, the detailed investigation of a customer
is recommended to demonstrate the usability of the determined results. Extending
FlexID to flexible power generation, will take further flexibility options into
consideration.
Editor: Richard Weiß
Tutor: Dipl.-Ing. Holger Hänchen – DREWAG NETZ GmbH, Dipl.-Ing. Juliane Schmidt
Year: 2020

Comparison of different approaches for the computation of the cost optimal year-round use of energy generators and heat storages
This thesis investigates different methods to the time-efficient solution of year-round optimization problems for the management of an integrated energy system. Mixed integer linear models (MILP) are used for the optimization. The tests are carried out using a real example, which is supplied by three combined heat and power (CHP) plants, two heating plants and a thermal energy storage. All energy producers are operated with either coal or natural gas as fuel. Three scenarios of thermal energy storage are discussed in this work, each of them has different heat capacity. In addition, the time steps and the relative solution accuracy of the optimization are also different. The closed year-round optimization is used to generate reference results. Four other self-implemented optimization methods as well as a solution with the commercial software TOP-Energy are compared to the reference method. In two of these methods the overall problem of one year is decomposed into various sub-problems to shorten the calculation time. This includes segmented calculations with fixed boundary conditions and with overlapping time ranges. In addition, a rolling optimization with different prediction horizons is also performed. Furthermore, a self-developed, rule-based, iterative approach is compared with other results of the optimization. After systematically comparing all methods, it can be concluded that the computing time for year-round optimization can be significantly reduced by using the segmented calculation. Under certain circumstances, however, the tested methods lead to a decline in the quality of the optimization result.
Editor: Jinyu Zhou
Tutor: Dr. rer. nat. Peter Stange, Dipl.-Ing. Felix Panitz
Year: 2020

Space cooling during summer - Development of a concept for calculat-ing the cooling load in TRNSYS-TUD
The cooling load calculation of a room due to summer temperatures is part of the building and installation simulation. The simulation program TRNSYS-TUD is used at the professorship of energy technology and heat supply of the TU Dresden in regards to buildings. A cooling load calculation mode is currently being implemented for TRNSYS TUD. VDI 2078 provides special calculation rules and validation options for cooling during the summer period. VDI 2078 includes a so-called design period for determining the maximum loads. The design period is characterized by maximum thermal loads and enables the cooling load to be calculated under reproducible boundary conditions. In the context of this work, an implementation for TRNSYS-TUD is described. Furthermore, the VDI provides test examples for the validation of a cooling load simulation program. Same selected test examples will be recalculated and compared with the VDI. The values, which will be used for comparison, are the results of other simulation programs. Ultimately, the validation requirements are compiled and evaluated with regard to the validation
options.
Editor: Toni Frohs
Tutor: Dr.-Ing. André Kremonke, Dr.-Ing. Alf Perschk, Dipl.-Ing. Markus Arendt
Year: 2020

Passive geothermal cooling - potentials and limitations depending on energy source (bore hole field), weather conditions and use
In times of change from conventional heat generation to regenerative solutions, the use of near-surface geothermal energy for heating and cooling makes an important contribution. The goals set by the Federal Government in the 2030 Agenda for sustainable development promote this expansion.
This diploma thesis provides an overview of the design of a geothermal probe field for passive cooling for the training center of the Sportgemeinschaft Dynamo Dresden e.V.. The design starts with the floor plan of the building over the use and the resulting cooling energy requirement to the design of the geothermal probe field with Earth Energy Designer. Then the amounts of energy provided by the geothermal field are varied by changing the building boundary conditions and the consequences for the soil are analyzed. The examined variants include a change in the use of sun protection, a change in the way the system is operated, and the influence of extreme weather conditions. The resulting consequences for the probe field are evaluated and a recommendation for actions to maintain the passive cooling within the legal limits is given. The author strives to gain knowledge about the possibilities and limits of a geothermal field for heating and cooling.
Editor: Andreas Blümel
Tutor: Dr.-Ing. Martin Knorr
Year: 2020

Preparation of measurement data and regression analysis of heat demand and return temperature profiles
Utility companies, energy traders as well as power plant operators use load forecast to predict load needed to meet the equilibrium of demand and supply. Within the energy sector, the accuracy of forecasting is a great significance, and it is influenced by many factors, such as, consumer’s consumption pattern, demographics, weather forecast, etc. In order to perform an accurate load forecast, an extensive amount of data are needed to predict case scenarios.
The aim of this study is to determine which of the provided model data can be transferred to the FreePlan, a load forecasting tool for heat demand and return temperature, to expand its model database.
In the methodical construction, the provided data, which contains diverse measurements (e.g. temperature, global solar radiation, day and date, etc.), is analyzed and processed. Based on the processed data, characteristic profile sheets for model data are created. Subsequently, regression analysis are carried out in such a way that they are evaluated based on their regression model evaluation metrics (e.g. 𝑅2, 𝑀𝐴𝐸, 𝑅𝑀𝑆𝐸). The regression coefficients of the chosen data model, which meet the standard of FreePlan, are adopted as a model in FreePlan.
The results of the regression analysis show that six out of 31 records are acceptable for the use of data expansion in FreePlan. The low number of accepted data can be explained by the length of the measuring period and type of building, where the model data are sourced from.
Editor: Se-Hoon Chang
Tutor: Dr. rer. nat. Peter Stange, Dipl.-Math. Anja Matthees
Year: 2020

Analysis of the energy supply infrastructure in agricultural areas regarding the operation of a field robot charging station
In this thesis, the energy supply for a field robot charging station in rural areas is analysed using the example of the Free State of Saxony.
At first, field robots in general, their range of tasks and the current state of development are presented. Then the platform CERES, which serves as the basis for the considerations, is presented and the energy demand of this robot as well as its required battery capacity are calculated.
This is followed by the selection and presentation of the farms, where the local provision of energy at the farms by means of photovoltaics, biogas, etc. is examined as an example and an analysis of possible network connections to medium and low voltage networks is carried out. For this purpose, three concepts are worked out on the basis of which a detailed investigation is carried out. The results are compared and evaluated.
Finally, the results are summarised and future developments and their influence on the technology and the research question are examined.
Editor: Alexander Rommelmann
Tutor: Dipl.-Ing. Catrin Weyers (Fraunhofer Institut für Verkehrs- und Infrastruktursysteme Dresden)
Year: 2020

Considerations about the flexible heating network operation with cellular balances
The thesis deals with the flexible operation of district heating networks using cellular structures. A transfer of the cellular approach for electrical energy networks to district heating networks takes place. Important terms in the context of a flexible, cellular operation of district heating networks were defined and summarised in a glossary. First it is explained how flexible network operation with partially cellular approaches has already been implemented or investigated in practice and research and which experiences can be drawn from this.
Based on this and the expected developments in district heating, a matrix of variants with flexibility options to be investigated was created. The application to existing networks is in the focus.
The flexibility options will be implemented within the framework of three simulation studies. In simulation study S1, a semi-central local supply temperature adjustment is realized by using a heat pump or a mixing loop. In simulation study S2, the heat retention of decentrally fed-in energy in a cell by heat storage is investigated.In simulation study S3 the demand-based supply temperature control at the central heat generator is implemented. The simulative implementation is carried out on an example network using the simulation software TRNSYS-TUD.
The simulations undertaken are initial analyses of cellular flexible network operation and show further investigation potential.
Editor: Luisa Lindner
Tutor: Dipl.-Ing. Sven Paulick, Dipl.-Ing. Vera Volmer
Year: 2020

Energetic building simulation of the „Family Center Amman-Marka“
This diploma thesis Energetic building simulation of the “Family Center Amman-Marka” examines a building which is planned to be renovated and expanded. It is a development project funded by the German government to be used as educational facility for refugee women. A building simulation is used to evaluate the building design. All the following factors are considered (both individually and in combination with each other): thermal insulation, shading due to rooftop photovoltaic system and/or mashrabiya (window with latticework) as well as night ventilation during summer.
The special climatic conditions and local structural standards were taken as a basis for all calculations. Furthermore, no air-condition should be installed according to the contractor, therefore cooling and ventilation must be achieved through natural ventilation. In order to complete this task, the traditional Iranian architectural element of the windtower is added to the building (simulation).
In the proof of concept, it will show that insulation and night ventilation via the windtowers are key factors to erect a building in Amman (Jordan) without technical air-condition. Certain characteristic values concerning indoor climate and energy are thoroughly studied.
The thesis will provide sufficient proof that this building design is perfectly adapted to fit the climatic conditions and will ensure a pleasant indoor atmosphere. This project can be seen as a model for energy-efficient construction in this region.
Editor: Jakob Reiter
Tutor: Dr.-Ing. Alf Perschk, Dr.-Ing. André Kremonke, Dipl.-Ing. Olaf Reiter – Reiter Architekten GmbH
Year: 2020

Efficiency audit of a CHP-System with and without an absorption cooling plant in a hospital based on VDI 2067
The use of financial resources is essential for exploiting the potential of modern medicine. However, as a result of the increasing privatization and partial privatization of the healthcare system, there is steadily growing cost pressure for hospitals. Therefore is it necessary for hospital operators to verificate established structures and procedures for their cost-effectiveness.
The present study paper addresses this problem on the part of the energy supply. The subject of the study is the „Elblandklinikum Meissen“.
The development of two variants for the optimization of the heating and cooling generation bases on the consumption cost accounting from 2018 for the media electricity and district heating as well as the technical data of the system components of the refrigeration supply structure.

Use of a combined heat and power plant without an absorption chiller, i. e. Refrigeration from compression chiller (variant 1)
Use of a CHP with absorption chiller (variant 2)

the dimensioning of all analgesic components of the respective variant bases on an estimation of the thermal base load of the Elblandklinikum Meissen. The subsequent economic viability analysis based on the VDI 2067 is carried out taking into account capital, operating and consumption-related costs. The proceeds are also taken into account.
The study paper shows that the use of combined heat and power plant can make a significant contribution to reducing the financial expenditure for energy supply. The main reason for this is the self-consumption of the electricity produced.
Editor: Paul Straßburger
Tutor: Dipl. Ing. Roland Nerger - Brendel Ingenieure, Prof. Dr.-Ing. Clemens Felsmann
Year: 2020

Application of industrial heat pumps based on waste heat
More than a third of the final energy input for heat generation in Germany is required for industrial production processes. The waste heat generated in these processes has a great efficiency and saving potential. By using a heat pump system, the waste heat temperature can be raised and used again in operating processes or for heating purposes. This report analyses internal heat sources within production networks of a specific industrial company and examines the potential to applicate a heat pump system in it. Because heat supply is often be ensured by only fossil fuels, the use of heat pumps could lower the usage of fossil fuels and therefore result in reduced emission of CO₂. Various calculations were carried out on specific heat pump types in the report by using an optimization tool in Excel. Based on load profiles and energy cost evaluations the economic efficiency and environmental sustainibility of different application scenarios for waste heat utilization were estimated. It also examines the extent to which an adjustment of the company's temperature grid on heat pump operation leads to an increased efficiency. The results of the calculations show that savings of up to 130.000 € per year compared to the existing heat generation technology are possible. At the same time a reduction of CO₂ release of about 1.000 tons per year could be achieved.
Editor: Melanie Petzel
Tutor: Felix Kosack – Bosch EBS, Dipl.-Ing. Stefan Hoppe
Year: 2020

Superposition, smoothing and analysis of PV performance time series
The goal of this paper is the comparison of the performance of photovoltaic systems of SOLARWATT costumers to a theoretical performance. With the help of solar radiation, air temperature, module area, installation angle and alignment angle the theoretical power is calculated. The analysis uses R as its programming tool. The associated software RStudio is freely available.The evaluation and examination of different customer energy systems are part of this analysis. The photovoltaic systems differentiate in module type, location, installation angle and alignment angle. The Deutscher Wetterdienst (German weather service) offers free of charge radiation data for Germany. This data is necessary in this thesis for further evaluation. One can generate time series after using different methods to interpolate, linearize and smooth the data. The author examines and analyses one photovoltaic system specifically in this paper. This includes the time series of the measured energy and the calculated energy of the photovoltaic system as well as the deviation of the two.
Editor: Annika Richter
Tutor: Norbert Betzl – Teamleiter Produktmanagement Solarmodule
Year: 2020

Cluster analysis in heating networks with regard to flexible supply temperatures
To flexibilize supply temperatures in existing heating networks can be beneficial for
energy saving and integration of low-emission heat sources. Therefore, methods for
finding network areas with low customer supply temperature requirements must be
determined. A group of costumers, that are located in a specific area of the heating
network and have similar supply temperature requirements, form a supply temperature
variable cell.
This work examines the possibilities cluster analysis can provide to identify those cells.
The network topology should be taken into account with the spatially and temporally
discrete cell formation.
Firstly, there will be given an overview about the methodology and former applications
of cluster analysis in the energy sector. Approaches to estimate the needed supply
temperature of a costumer are shown and it is analized which cluster algorithms are
suitable for cell formation.
In the clustering process graph modells of the heating network are used to generate the
data basis for the algorithms. The Single Linkage algorithm, the density based DBSCAN
and OPTICS as well as Affinity Propagation and Spectral Clustering are considered particularly.
Using Python, the cluster algorithms are demonstrated on an urban, unmeshed
heating network example to evaluate their applicability.
Editor: Luise Mann
Tutor: Dipl.-Ing. Sven Paulick, Dipl.-Ing. Vera Volmer
Year: 2020

Sample catalogue for different building types including HVAC systems for energy performance comparison
The building sector offers significant thermal energy saving potential and the resulting carbon dioxide reduction. Its implementation is possible by providing higher heat protection levels and adapting the system technology to the current technical standards in the new construction area and in already existing buildings. This thesis examines the development of the German building stock and the influence of the building envelope, building size and system technology on the energy requirements in the heating situation. Taking into account thermal physiological aspects, user behavior and building standards of different construction years a possible calculation and simulation model is presented. After adapting the model to different conditions, the determined values are compared with one another and the energy requirement is shown taking into account various influencing factors.
Editor: Madelaine Göksin
Tutor: Prof. Dr.-Ing. habil. Joachim Seifert, Dr.-Ing. Alf Perschk
Year: 2020

Methods for evaluating the impact of technologies on climate change
The current global warming is proving to be anthropogenically caused. The emission of greenhouse gases, combined with the forecast uncertainties described, is the cause of past and future global warming. This leads to a number of direct consequences for the earth system, such as glacier retreat, sealevel rise and changes in the mean global precipitation distribution, which have already been observed in the recent past and are predicted to a far greater extent for the future. Indirectly, this has negative consequences for ecosystems, people and society, such as the extinction of species, negative consequences for food security, shortages of (drinking-)water and the threat to global security posed by conflicts over dwindling resources.
To limit these, the rapid reduction of greenhouse gas emissions has proven to be the most e˙ective security measure. This reduction puts technologies - in this case technologies for the provision of heat and electrical energy - at the centre of attention, since they are responsible for a large part of the greenhouse gases emitted in Germany. Life cycle analysis, based on the life cycle assessment method in DIN EN ISO 14040, is used to record the greenhouse gases emitted by a technology during its life cycle as comprehensively as possible. This work involves a comprehensive search for available data that should be as close as possible to the requirements of life cycle assessment. The German government and selected studies formulate the necessary greenhouse gas path for Germany in line with the goals of the Paris Climate Convention.
On the basis of these, transformation paths for society and the energy system are drawn up, from which the greenhouse gas paths for specific sectors emerge.
At the same time, leading studies have shown that the binding targets of the Paris Climate Convention can only be achieved with the help of ambitious eÿciency improvements in all sectors and thus also ambitious energy demand reductions.
This results in sector-specific greenhouse gas paths and energy demand paths up to 2050, from which average greenhouse gas emissions per supplied energy are calculated, depending on the year of construction and the duration of life.
In the final part of the work, the assessment is then made by comparing the emission factors of the life cycle analysis of technologies with these average emission factors. This will be carried out using selected technologies as examples.
The results show that the technologies of the future will have to meet extremely ambitious requirements in terms of greenhouse gas emissions per unit of energy supplied. In addition, it is shown that the current technology mix deviates significantly from these requirements.
Editor: Claudio Gardtke
Tutor: Prof. Dr.-Ing. Clemens Felsmann
Year: 2020

Optimization and controlling of a battery storage with fast charging infrastructure for curative and preventive grid management
In the course of the energy revolution, as well as for the avoidance of harmful nitrogen oxides in urban regions there is a steady substitution of conventional cars by electric vehicles. In order to shift the transport sector as quickly as possible to alternative engines in addition to their subsidisation, there is the nationwide expansion of charging infrastructure in Germany.
In Dresden, the expansion of conventional and fast-charging infrastructure primarily take place at mobility points. In order to promote the expansion of fast-charging infrastructure the temporary support of conventional fast-charging infrastructure will be done by a storage application. In a pilot project three fast-charging stations will be supported by a battery storage.
The task of this work is to find the economic efficiency and the required storage parameters for different scenarios of this storage application.
For this purpose, empirical fast-charging data is validated, weighted and used to generate distribution functions. The determined charging parameters are used to generate individual charging curves. Within the framework of a Monte Carlo simulation loading parameters are generated for an analysis period of one month and are used to generate charging curves. The charging curves of individual charging points are cumulated and represent the time-dependent charging curve of the charging infrastructure.
Once a meaningful charge curve has been selected, it serves as a Boundary condition of the optimization model. The optimization model compares two Battery storages of different cell chemistry and a flywheel storage. The individual storage applications are evaluated with regard to their degradation effects, lifetime and investment costs. The optimization model selects the optimal storage for the implemented load vector. The LiFePO4-battery is the preferred storage due to its low investment costs and the ability to guarantee high charge rates.
With the optimization model the monthly total costs of the storage with charging infrastructure were calculated. It was found that the storage application cannot recoup for any of the considered scenarios.
Editor: Julius Jacob
Tutor: Paul-Martin Körner – DREWAG-NETZ GmbH, Dr. rer. nat. Peter Stange
Year: 2020

Potential of distributed provision of heat from waste water in Berlin and documentation in the form of heat map
A Fundamental transformation of the heat supply with a significant increase in the share of renewable energy sources is necessary to reach the Berlin climate targets. A reasonable part of the furture energy mix can be heat recovery from domestic and commercial wastewater, which can be used by heat pumps due to its year-round high temperature level. With the aim of raising public awareness and increasing the implementation of waste water heat utilization, suitable locations are identified and documented in a potential map in this thesis.
A comprehensive literature research and discussions with employees of Berliner Wasserbetriebe (BWB) identify relevant boundary conditions and evaluate their relevance for the potential analysis. The waste water volume flow turns out to be the most important influencing factor. Because of this, the distribution of all sewage volume flows in the urban area is analyzed using extensive models for the different sewage systems. A heat extraction potential is deviated from the determined flow data for each location.
The results are presented in the BWB's Geographic Information Systems (GIS). These show a considerable heat extraction potnetial, which in some locations is a maximum of up to 23 MW. A total of 586 km of wastewater infrastructure is shown to have potential. In a rough estimate, a city-wide total potential of apprx. 275 MW is determined.
Further research needs include improving the model quality and implementing an automated model update. Furthermore, the data should be overlapped with renovation data in order to utilize synergy potential in the construction process. For an increased implementation, the publication of the potential map on suitable platforms is recommended, whereby an important aspect is the coupling of the generated data sets with data on heat consumers and producers in Berlin.
Editor: Heinrich Gürtler
Tutor: Dipl.-Ing. Michel Gunkel – Berliner Wasserbetriebe, Prof. Dr.-Ing. Clemens Felsmann
Year: 2020

BIM methods for the design of technical building services by the example of „Autodesk Revit“
With Building Information Modeling (BIM) construction industry is facing a new challenge. Buliding Information Modeling is a method for creating, changing and managing a digital building model. This building model is a central database of all current information in order to achieve better planning on a secure basis. Planning a building with BIM requires software solutions that enable constant data exchange and collaboration between all those involved. The technical building services are becoming more relevant considering the energy transition in the building sector for economic and ecological building. Due to the complex systems in technical building services a high requirement for data exchange in the BIM software is needed .
This paper examines whether the Autodesk Revit® software solutions combined with liNear Bulidings® and SOLAR-COMPUTER® meet the requirements for BIM. To check the data exchange and the possibility of collaboration in the BIM-oriented planning process a heating load calculation is done on a building model.
The calculation shows that the requirements cannot be fully met. The Problem is the constant data exchange. A more constant flow of information can be achieved with a definition of standards based on the understanding of data exchange. This leads to an additional effort at the early phase of the project, which can be partially compensated by using the BIM method.
lt turns out that the tested BIM software for the area of technical building services is not yet fully developed. Nevertheless, especially Autodesk ® approaches many goals of BIM with its software Revit®.
The BIM method changes processes and planning software but also the job of a technical building services engineer. Their technical expertise is still required, but more for plausibility checking the results than for the calculations themselves. Rather, knowledge of the information technology processes will become more important in the future.
Editor: Maximilian Lambertz
Tutor: Dipl.-Ing. Jens Kaiser, Dr.-Ing. Alf Perschk
Year: 2020

Automatic model adaptation for the generation of heat load forecasts
The forecast of heat requirement is an important basis for optimizing the use in energy
systems. As a result of climate change, global energy demand is increasingly covered by
renewable energy sources. Since the energy yield from these sources fluctuates strongly,
an accurate forecast is essential. In this way, the need for energy is reliably met in times
of high demand.
Automatic model adaptation makes it possible to continue using forecast models, even
after influencing the characteristic course of load profiles. This eliminates the need for
time-consuming measurements to adapt the models to new user characteristics. This
paper examines the forecast quality during a continuous model adaptation and evaluates
it in a suitable form. A model adaptation is understood as a constant updating of the
historical measurement database and continuous recalculation of the model parameters.
In addition, the forecast is corrected by a gradual adjustment. The adjustment adapts
the absolute amount of the forecast heat demand to the underlying measurement
database. In addition, typical start-up times or transition periods are elaborated after
which these models provide reliable forecasts.
In this thesis four different models are introduced and examined. A standard load profile
model, a regression model, an ARIMA model and a combination of the regression and
ARIMA model. The implementation is carried out by creating three test scenarios, which
are named alphabetically. Scenario a describes a measurement start without an existing
historical measurement database. Scenario b simulates a change of user, which influences
the characteristic course of the load profiles in terms of time and quantity. Scenario c
deals with a reduction in demand due to modernization.
The paper demonstrates that the continuous updating of the historical measurement
database improves the quality of the forecast. Furthermore, maintaining former, uncoordinated measurement databases can prevent outliers in the forecast. The gradual
adjustment for corrections, if the heat demand changes significantly in the absolute
amount, achieves an improvement in the forecast quality in scenario c for a reduction in
demand of 65 %. This is noticeable immediately after the need reduction occurs. The
combined Regression-ARIMA model has given the best results in all three test scenarios
and is therefore the most suitable.
Editor: Fabian Burkhardt
Tutor: Dr. rer. nat. Peter Stange, Dipl.-Math. Anja Matthees
Year: 2020

Development and validation of an energy management system to control a refrigeration plant in the context of Smart-Grid
As a part of the project “Solar Split” the Institute of Air Conditioning and Refrigeration Dresden develops a control concept for space cooling for a mono-split air conditioning unit with an integrated ice storage and a PV system. The objective of this work is the development, implementation and testing of an energy management system for the control of the combined cooling system considering the available PV energy supply, the thermal building load and the user requirements. In the course of a market research, a commercial energy management device for the coordinated use of PV energy in cooperation with the control system is selected. An interface solution is developed and implemented for the communication between the control system and the energy management device. The design of the control system is carried out under consideration of various optimisation criteria, of which the provision of a defined thermal comfort and the maximisation of the self-consumption of the generated PV electricity are prioritised for the implementation. Various operating states with fixed control variables are defined, which can be specified for the cooling system. The control algorithm is set up in such a way that a rule-based calculation and selection of the operating states is carried out taking into account the current room air temperature, the state of charge (SOC), the available PV power and the previous operating state. Furthermore, two self-learning forecast algorithms are developed and implemented. One is used to calculate a target SOC and the other to forecast a cooling load profile for the following day. Then, the control algorithm as well as the forecast algorithm for calculating the target SOC are implemented in an existing control software, executed on a controller and tested on a test stand together with the energy management device and the interface solution. The implementation of the algorithm for load forecasting, on the other hand, takes place as a separate software module, which is tested on more powerful hardware.
The control algorithm was able to keep the room air temperature within the specified temperature limits for most of the time and thus provide the required thermal comfort. The occurrence of strong load changes of the outdoor unit during switching between direct cooling and charge mode has been avoided by re-adjusting the algorithm. The electrical energy demand of the mono-split unit was largely covered by PV energy. In the tests performed, the system solution achieved solar coverage rates between 87 and 100 %. It was possible to achieve an increase in solar coverage rates of 19 % on average compared to a system without ice storage. The self-consumption rate was 41 % on average.
Editor: Daniel Kröger
Tutor: Dipl.-Ing. Wolfgang Hernschier – ILK Dresden, Dipl.-Ing. Carsten Heinrich – ILK Dresden, Dr.-Ing. André Kremonke
Year: 2020

Operation of a pressurized thermal storage with multiple charging and discharging layers in a LowEx supply concept
The heat supply of a school and sports centre was revised during a modernization of the building which included the construction of a pressurized thermal storage. This storage is intended for the use on a daily basis in a complex energy system with several producers for the load management in the heat supply. In order to monitor the temperatures of the thermal storage, distributed temperature sensing (DTS) is used as an innovative measurement technique based on glass fibre to measure the temperature at the storage wall with high resolution in place and time.
For this diploma thesis, DTS measurement data have been processed and suitable cable sections have been determined which are horizontal layers and a vertical measurement section of the glass fibre cable. With the help of existing programming code which has been modified to the specific geometry of the storage configuration, it was possible to develop a front-end which depicts all the measurement data by illustrations and animation films. Thereby, the operation of the pressurized thermal storage could be characterized under consideration of the specifics of the construction.
A particular structure and number of diffusors separates the tank volume into three different storage areas which are distinguishable by different temperature levels and separated by small transition areas. Moreover, the DTS technology enables to determine charge levels of the storage areas and the verification of peripheral effects and shear stratifications. Here the DTS technology is in accordance with the PT100 sensors which enables the operational analysis of the thermal storage interacting with producers and consumers in this complex energy system. Particularly, it was discovered that the control technology of the heat producers should be improved in order to obtain an operation of the thermal storage with better stratification.
Editor: Hoang Le
Tutor: Dipl.-Ing. Luise Umbreit, Dr.-Ing. Karin Rühling
Year: 2020

Technical and economical analysis of ice-detection systems at wind turbines
This paper is meant to compare different ice detection systems for wind turbines and deliver a guidance on retrofit projects in the wind farms of „ Das grüne Emissionshaus GmbH". So the biggest relevance is seen for them but also as a guideline for other operating companies.
Therefore icing and its different forms of appearance are explained. This icing and the resulting problems lead to the necessity of a proper ice detection. Hereon the advantages and disadvantages of the various concepts of ice detection are discussed. An analysis of climate data and SCADA data shows the relevant wind farms for the retrofit of a blade based ice detection. An economical discussion containing payback period rule leads to the guidance.
The most critical form of icing on wind turbines is roter blade icing because the additio nal ice load causes imbalance which results in mechanical damages of the turbine. Also ice throw is a danger for the surroundings. Therefore turbines must be stopped when icing occurs which results in gain losses. Blade based ice detection systems can lower gain loss by 40 - 70 % thanks to an automated restart when icing is no longer detected. Concluding, the economical assessment suggests retrofit in the wind farms Ahlerstedt and Hohenlochen whereis in Königsfeld and Kambacher Eck it needs to be reconsidered if the economicals gains and additional benefits, like saving turbines from damages by additional iceload, are worth the investment.
Editor: Thomas Schmidt
Tutor: Herr Rudolph – Das grüne Emissionshaus GmbH, Prof. Dr.-Ing. Clemens Felsmann
Year: 2020

Exemplary considerations about the self-sufficiency of buildings
In the present graduate thesis a self-sufficient water supply for a concrete residential building is designed. The selection of the system components is based on a technically and practically feasible implementation. A small wind turbine with a nominal output of 2.5 kW drives a water pump to pump well water to a water reservoir 10 m above.
The design of the water reservoir with a size of 8 m³ is based on consumption characteristics and wind energy available at the site. Due to the difference in height and the provision of water, the supply security for a six-person household is guaranteed at all times.
A subsequent subsystem based on an 85 Ah battery provides sufficient electrical energy for a pressure boosting system for the domestic water network and a circulating pump for the hot drinking water. The use of a larger battery will enable the system to be expanded in the future to provide an independent power supply.
Surplus energy can contribute to the heating of drinking water and be fed into the public power grid. The thermal energy to be fed into the drinking water is covered by wind energy to an average of 20 %.
A final economic calculation about the efficiency of the system leads to 2.4 times the water price charged by a public utility company, so that a self-sufficient water supply only makes sense in areas not connected to the public water supply network.
Amortization of the system is only possible through own consumption of the surplus energy in the form of household electricity.
Editor: Thomas Schmidt
Tutor: Prof. Dr.-Ing. Clemens Felsmann
Year: 2020

Simplified modelling of a heating network in FreeOpt
In the present project a mixed integer optimization model is created for the operation of a district heating network at minimal costs. Due to clustering, the district heating network will be divided into several areas. These clusters can transfer thermal energy to other clusters. Consequently the heat producers can also be operated optimally across the clusters. The focus is the linear modelling of the individual components and the dependencies resulting of the clustering. The constraints and the objective function will be formulated so that the operational costs can be minimized. The aim is to investigate the influence that the network clustering has on the operational management.
Editor: Carlotta Scheder-Bieschin
Tutor: Dr. rer. nat. Peter Stange
Year: 2020

Analysis and Optimization of heat supply in an existing district heating network
In 2018 a public utility company produced 127 MWh of heat, which they distributed through their central district heating grid. 79 % out of those originated from the residual waste cogeneration plant. Therefore, it is inherent to the entire grid.
The, with the displacement mix method determined, primary energy factor of -0,321 as well as the, with the Carnot-method calculated, CO₂-emissions-factor of 40,79 t CO₂/GWh are below the, in 2014 during the official assessment, determined values for the combined
heating grid. Because of the high share of heat from the RMHKW, a change in the evaluation method for PEF wouldn’t cause a rising PEF.
Formulating the technical and economical restrictions as requirements, represented by
linear relationships, provides the necessary tools for the optimization of the generation.
The various options of heat generation can be classified as pure renewable- and as sectorcoupling options. While the options that use sewage water-heat-pump (Option 1), solar thermal energy (Option 2) or ligneous biomass for heat production belong to the prior, the option using a Power-to-Heat (Option 4) plant can be affiliated to the latter.
As a result of the economical assessment of the generation options it becomes evident,
that the only options to reach net heat production costs in the target, range are using
ligneous biomass or a power-to-heat-plant. It is shown that the integration of renewable
heat generators, providing base load energy, leads, for this particular district heating
system, to an increase of the calculated primary energy factor, as long as the displacement method is applied. A decrease can only be achieved, if the heat generators, which themselves only produce heat, don’t displace heat generated by a cogeneration plant. But none of these increases influence the to be published primary energy factor of the public utility company.
Editor: Johannes Dornberger
Tutor: Prof. Dr.-Ing. Clemens Felsmann
Year: 2020

Integration of an Ice Storage into a Mono-Split-AC-System for Increase of PV-Self-Consumption – Determination of optimum operating parameters
As part of the “SolarSplit” project, the Institute of Air Handling and Refrigeration Dresden is investigating the implementation of an ice storage unit in a solar-driven mono-split system for residential air conditioning. The main goals are to increase the share of private consumption of photovoltaic energy and to allow decoupling of cooling from actual cooling demand (load shift). In the context of this thesis, the test facility “SolarSplit2” is cobuilt in order to perform field tests under real conditions. This test facility consists of an indoor unit, an outdoor unit and an ice storage unit, which are connected by a secondary brine circuit. The objective of this thesis is to determine optimum operating parameters for charging and discharging the ice storage unit, concerning speed range of the brine pump and value for power control of the indoor and outdoor unit. For this purpose, both operation modes are measured by varying the above mentioned parameters to draw conclusions on plant efficiency. During storage discharge the melting behaviour is examined and the thermal resistance between brine and ice is modelled under idealised conditions. The charging process is investigated in combination with the plate heat exchanger, which ensures the heat transition between brine circuit and refrigerant circuit. In consideration of all results general statements about optimum operating parameters can be formulated.
Editor: Michel Zimmer
Tutor: Dipl.-Ing. Carsten Heinrich – ILK Dresden, Dr.-Ing. André Kremonke
Year: 2020

Model-based analysis of the potential of thermal use and storage of self-generated electricity in a residential building
In this paper, a simulation model in the MATLAB/Simulink environment is presented. The simulation model depicts a single-family house with a photovoltaic system, a thermal
buffer tank, a heating and hot water heat pump, and a thermal energy management system. The thermal energy management optimizes the system in terms of energy efficiency and economy by intelligently linking and controlling the components photovoltaic system, thermal buffer storage and heat pump.
The simulation model is based on an existing model, which is first described in detail in the paper and then optimised and extended. The simulation model depicts a real building, for which extensive measurement data were recorded by Stiebel Eltron within the framework of the WPuQ research project.
Based on these measurement data, a validation of the simulation model is carried out. In the simulation environment, an energetic and energy-economical variant investigation of the drinking water and buffer storage tanks with regard to volume is then carried out. The result of the validation is that the thermal relationships of the single-family house used for comparison are represented sufficiently accurately by the simulation model.
The analysis of the variants shows that there is a need for optimisation of the buffer storage tank volume. The use of a smaller storage tank is more reasonable from an energy and economic perspective. In the case of the drinking water tank, the optimisation potential is comparatively low. The storage tank used differs only slightly from the variants
investigated.
Editor: Jakob Petrek
Tutor: Lion Franzen - Stiebel Eltron, Prof. Dr.-Ing. Clemens Felsmann
Year: 2020

Integration of an Ice Storage into a Mono-Split-AC-System for Increase of PV-Self-Consumption – Comparison of charging process of different configurations and evaluation of field test
In ILK Dresden’s project Solar Split, an ice storage system for mono-split air conditioners is being developed. Using photovoltaic energy and the thermal storage, living space ought to be cooled. The aim of this paper is the experimental investigation and energetic evaluation of the developed heat exchangers and systems. Therefore, the charging process was experimentally and theoretically investigated for a direct evaporation system and the brine-based system. For the comparison of all three evaporator designs and the brine-based system, the thermal resistances were calculated. These were compared as well as the experimental results.
The wire-and-tube evaporator showed improvements in the efficiency compared to the previous prototypes. At 50 % of the outdoor unit’s capacity an energy efficiency ratio (EER) of 3.5 was achieved. A problem of this evaporator is corrosion. With the brine-based system further improvements in the efficiency of the charging process were achieved. A higher EER and a lower thermal resistance were proven. A downside is the longer charging time. For the evaluation of the whole system using photovoltaic, the ice storage and a compression refrigeration system, a field test with the brine system and automatic control was carried out. With a temporal shift between PV power generation and cooling demand, the solar coverage ratio can be increased by using an ice storage. The efficiency is slightly lower compared to the direct cooling mode. For a significant economical statement further continuous measurements under summer conditions would be necessary.
Editor: Maren Voß
Tutor: Dipl.-Ing. Carsten Heinrich – ILK Dresden, Prof. Dr.-Ing. Clemens Felsmann
Year: 2020

2019

Considerations about methods for a deep renovation of the building stock
In the course of the progressing climate change and its adverse effects on the global ecosystem, realizing the reduction of greenhouse gas emissions in all German sectors has
become a priority. Besides the biggest users of energy, the in- dustrial and transport sector, German households were responsible for 26% of the total final energy consumption and therefore exhibit a great potential of energy savings.
The paper examines a selection of energy-saving measures of structural and technological nature of the German building stock and its effectiveness in the reduction of energy consumption and the ensurance of thermal comfort. It focuses on whether the desired conditions of a primary energy demand below 50 kWh/m²a and the summerly heat protection can be met.
To achieve results that can be considered representative of the entirety of house- holds an initial research on average building parameters has been conducted. Ac- cording to those results, building models are created which are implemented in the respective simulations that are realized by a validated calculation program.
The assessment of the results shows that the more housing units a residential building has, the easier it is to meet the energetical requirements. It must be taken into account that merely structural energy-saving measures do not provide a sufficient thermal protection to reach the set goals. In addition to those measures, the replacement of the existing heat supply system and the establishment of a controlled ventilation system coupled with a heat recovery unit must take place.
Based on this documentation it is found that there exists a massive unused poten- tial regarding the improvement of home insulation and the efficiency increase of most recent supply systems in existing buildings. Albeit an energetic rehabilitation can be of varying effectiveness due to different structural frameworks and de- mands of the inhabitants, it proofs to be a worthwhile investment in many cases.
Editor: Johannes Reif
Tutor: Dr.-Ing. Annina Gritzki, Dipl.-Ing. Jens Naumann - GWT
Year: 2019

Studies about the application of heat pumps in existing buildings
The majority of buildings in Germany are supplied with heat by conventional boilers. Low fuel and acquisition costs favor the choice of this type as heat supply system. Common installed radiators are often designed with oversize. Therefore heating requirements can be achieved with low flow temperatures. Due to the technical design of heat pumps, they cannot meet energy requirements for heat supply in every system. The implementation of heating pumps into an existing system requires a hydraulic adjustment of the installed components.
Higher interest for the application of heating pumps is caused in lower emissions of greenhouse gases, which emit in the process of combustion of fossil fuels.
This paper investigates electric heat pumps, which can be run with different heat sources. Simulations are used to check the applicability of electric heating pumps for existing individual heating systems. The selected variants have to supplement by additional technical components to ensure a continuous and unobstructed operation of the heating system. In addition to the first option, replace the boiler system by heat pumps, further simulations were run to check the variant of an additional heat pump in combination with an existing boiler system. The existing system was modeled and used as a comparison value to classify the simulation results.
The evaluation of the results shows that it is possible to secure the heat supply by using a heat pump for the selected building types (single-family / multi-family house) under specified conditions.
The consumption related costs in a single-family house can theoretically be reduced by an implementation of a monovalent brine-water heat pump. Multi-family houses have an equal cost level related to the initial state by using an additional air-water heat pump. All variants have a significantly lower primary energy requirement to run the heating system. The utilization of electricity leads to a reduction of CO₂-emissions. An addition of a photovoltaic system lowers a further reduction in primary energy.
Editor: Hannes Jänicke
Tutor: Prof. Dr.-Ing. Clemens Felsmann
Year: 2019

Evaluation and analysis of measures increasing the efficiency of gas boilers
As part of a research project the „Allianz für einen klimaneutralen Wohngebäudestand“ is currently testing the effectiveness of different technical measures to increase energy efficiency in rental housing. A total of eight energy saving measures were implemented and tested. The buildings involved were equipped with numerous measurement sensors to record data. The measures are presented and characterized within this thesis.
The intended goal of this thesis is to evaluate the effectiveness of the technical measures. The collected data has been inspected and verified if they can be used for analysis. A lot of properties were excluded from this analysis because they were lacking both in data density and quality. This thesis will give a brief overview of the data density and data quality which was accumulated in a recent thesis. Useful data sets were weather-adjusted and compared with data of previous years. In addition, the annual utilization rates were determined. Unexpectedly, the majority of the properties registered an increase in consumption. However, through optimization of the hydraulic systems which was realized in the beginning of 2018 positive changes have been found and proven. Following the analysis, the effectiveness of different operating parameters and their effect on heat generation efficiency were identified and valued. Lastly, a recommendation on how to continue the implementation of the technical measures for other properties is provided.
Editor: Steffen Begerock
Tutor: Dipl.-Ing. (FH) Sebastian Rochau
Year: 2019

Research on Basics for the Temperature Reduction in the District Heating Network of the Meißener Stadtwerke GmbH
Regarding the reduction of heat losses, the efficient operation of heat generators with cogeneration and the saving of pump work while operating existing district heating networks, the return temperature and the lowering of the temperature level in the district heating network are always in focus. Since the resulting return temperature in the house connection station represents the interface to the customer systems, the network operators demand for low return temperatures as well as the endeavors of the customers to maintain the existing systems and low investment costs for new systems, are in conflict.
In this work, the basics of temperature reduction with a focus on return temperatures are
presented, using the application example from Meißner Stadtwerke GmbH. This includes a network analysis, the systematization of the customers systems, a description of the influencing variables on the return temperature as well as an investigation of the potential for a future temperature level reduction, considering the network hydraulics. Possibilities for lowering the return temperature are shown and evaluated. The return connection of consumers is examined as a preferred solution in more detail and its potentials for implementation, temperature reduction and energy savings are determined for the existing district heating network. Since a long – term lowering of the return temperatures and the expansion of return connections are associated with investments in the heating systems on the customers side, research is carried out to find support and discuss incentives from municipal utilities to support this process.
Editor: Laurenz Schitthelm
Tutor: Ute Zingel - Fachbereichsleiterin Netzmanagement – Meißener Stadtwerke GmbH, Dr.-Ing. Thomas Sander
Year: 2019

Monitoring of a LowEx-district heating system with distributed feed-in
Investigation of a low-temperature district heating network in Berlin, which consists of multiple consumers and a heat transfer station. One of the consumers is supported by a thermal solar generation plant. The overproduction of this solar thermal plant can be fed back into the low-temperature district heating network.
In the study, the provided monitoring data were checked for plausibility.
The monitoring data were evaluated and an operational analysis of the consumer with the thermal solar generation and its feeder pump was carried out.
The operating behavior of the heat transfer station for the low-temperature district heating network was also examined and options for operational optimization identified.
Both the heat transfer station and the consumer with the thermal solar generation plant were initially considered individually over a certain period of time.
The data from the two plants were then viewed for the same time period in order to determine the interaction between both plants.
Editor: Christian Beigl
Tutor: Dipl.-Ing. Martin Heymann
Year: 2019

Considerations about the Energy and load management for Renewable Energy sources
Main goal while analyzing an industrial factory is detecting the problems as well as the potentials of energy and load management. Industrial parks usually consume large amounts of power and energy, resulting in emissions and costs both. Initially the particular requirements and demands of an exemplary production site in Germany are specified and summarized. Installed technical generators, consumers and the networks in between are evaluated resulting in a reduction of costs and a lower discharge of carbon dioxide. This is achieved by prioritizing the usage of waste heat and lowering temperatures in cooling systems. The following substitution of the original gas heating with electricity-based heat pumps and a power-to-heat-module provides further savings. Additional a large renewable power plant is estimated and joined with the system. The fluctuating power production can be stored in suitable energy storages, such as a hot water storage tank (50 m³) and a lithium battery (1,5 MWh). The dimension of the tank is adjusted to balancing an average day; the battery is measured to shave the peak load delivered by the system operator.
The adjusted industrial system is implemented in an optimization and simulation software called Top Energy. Following, a theoretical optimum is calculated for the year 2018.
Since actual facilities are usually unable to control their generators and storages through mathematical optima, simple parameters and priorities are preferable. For determining those, 20 different variations with different inputs are tested and their results compared. Nearly optimal is a combination of a prioritized heat generation, a privileged waste heat usage and charging the storages depending on the current wind speed. If the threshold value of 3,5 m/s is surpassed, all storages are to be charged.
The management system is tested with alternative versions of the original industrial system. The stability is confirmed, as long as the storages, the wind farm or the waste heat potential is not significantly smaller. This project is an example for the simultaneous implementation of sustainability and economic advantages.
Gained insight regarding the general approach is summarized and the adaptability to similar problems or systems assessed.
Editor: Hannah Hundt
Tutor: Jan Schulze, M.Eng.(FH) - Bosch BT-IE/SPB2-ES-DE, Prof. Dr.-Ing. Clemens Felsmann
Year: 2019

Energy concept for reduction of greenhouse gas emissions of road maintenance buildings
The reduction of greenhouse gas emissions according to the German government’s Climate Protection Plan 2050 also affects the motorway and road maintenance departments that are part of the road infrastructure. The objectives of this thesis are an
analysis of the energy needs of the departments and the identification of potentials for
energy saving and increased use of renewable energies. For this purpose, five reference
departments were examined. The data basis formed both inventory documents and
questionnaires as well as on-site inspections. The buildings were analysed with regard
to their building physics, technical facilities and use. The focus was set on the heat
supply, although the approach of a holistic view of the energy and material flows was
pursued. An essential part of the inventory was the evaluation of the consumption
data.
The building structure of the departments can essentially be divided into an administrative area, the workshops and the vehicle parking halls, although the number and distribution of the buildings differ. The energetic condition varies between the departments depending on the age of the buildings and the renovation history. Besides
typical fossil fuels, there is also experience with regenerative energy sources for the
heat supply.
On the basis of the inventory, energy demand calculations of the heated buildings
were carried out according to DIN V 18599 and compared with the consumption
data. It turned out that the energy requirements of the department buildings can
only be represented to a limited extent with standardised assumptions of the standard
and that the available database did not generally permit any detailed adjustment.
The next step was to formulate individual measures for the energetic optimisation of the
building fabric, technical building equipment and use. A simplified profitability analysis
was obtained by comparing the energy cost savings with a rough cost estimate of the
necessary investment. Energy standards considering the legal requirements allowed an
evaluation of the departments. Aspects of implementation and financial feasibility were
also discussed.
Editor: Christoph Hübner
Tutor: Dipl.-Ing. Tobias Wolf – Intep - Integrale Planung GmbH, Prof. Dr.-Ing. Clemens Felsmann
Year: 2019

Energetic evaluation of a solid oxide fuel cell (SOFC) using the “Hardware in the Loop”-method
Content of this thesis is the energetic evaluation of a solid oxide fuel cell (SOFC) using an emulation test rig 4.0, which is based on the hardware-in-the-loop methodology. In contrast to stationary or simulation-based evaluation methods, this method takes the influences of device and control specifics on the overall efficiency into account. In detail,after a comprehensive introduction to the state of the art of SOFC technology, a simulation of possible hybrid system concepts for the energy supply of a single-family house was carried out and a selection from energetic, ecological and economic aspects was made. The selected concept, consisting of the SOFC and an air-to-water heat pump, was transferred to the emulation test rig. The test rig was adapted to the new test setup with regard to measurement sensors and actuators plus settings in the control system were made. By connectingthe numerical building and plant simulation TRNSYS TUD with the physical plant technology,the SOFC could be operated dynamically. The measured values were used to determine the degree of utilization.
Editor: Tim van Beek
Tutor: Dipl.-Ing. Lars Schinke, Dipl.-Ing. Maximilian Beyer
Year: 2019

Evaluation of innovative technologies with regard to CO₂ neutrality in the building sector
The Federal Government's energy and climate policy plans envisage an ambitious reduction in GHG emissions. By 2030, 66-67 % of emissions in the building sector will be saved compared to the reference year 1990 and by 2050 80-95% of the emissions. Particular attention is paid to the oil and gas heated housing stock. Around three quarters of all apartments are heated by fossil fuels. In addition, the inventory of heat generators is characterized by insufficient efficiency.
The impact of using innovative technologies on GHG emission savings should be analyzed. For this purpose, the plant-specific savings potential was first determined using emission standard values standardized to the useful heatoutput. It showed that efficient savings an be achieved with efficient systems. Above all, the use of ambient heat to increase efficiency holds great potential.
In addition to the plant-specific GHG savings, the GHG savings were also considered in different type buildings with different restoration depths. This shows that, in addition to the plant-side refurbishment, the renovation of the building envelope also entails a significant reduction in GHG emissions. After analyzing the factors influencing the market opportunities of the respective technologies, the savings of the type buildings were extrapolated to the total stock. The extrapolation shows that, in order to achieve the GHG reduction targets for 2030 and 2050, an interplay of ambitious increases in plant efficiency, rehabilitation of structural heat protection and emission reduction on the energy carrier side is necessary.
Appropriate valuation methods can increase the market opportunities of innovative technologies. In particular, decarbonised fuels should be considered in the environmental assessment. Likewise, innovative plant concepts should be quickly included in current assessment standards. An appropriate consideration of the system suitability of powergenerating and electricity-using installations in the ecological assessment shall be made.
Editor: Florian Emmrich
Tutor: Dr.-Ing. Bernadetta Winiewska – ITG Dresden, Prof. Dr.-Ing. Clemens Felsmann
Year: 2019

Experimental characterization and model-based evaluation of an electrically charged latent heat storage
In order to promote the establishment of renewable energies and at the same time ensure a reliable energy supply, storage technologies are needed to compensate for fluctuations. Through Power-to-Heat, thermal energy storage systems offer the advantage of sector coupling and contribute to the electrification of the heat sector. Latent heat storage systems benefit from the melting enthalpy that is absorbed or released during the phase change of the storage material.
This paper presents the experimental studies of a latent heat storage of DLR which is charged electrically and discharged thermically. For this purpose, experiments with measurements of the electrical energy of the heating rods, the volume flow of the heat transfer fluid and local temperatures are carried out on a latent heat storage unit in plate design. The storage is filled with nitrate salt as a storage material using the solid-liquid phase change at 222 °C. Heat transfer structures of aluminum compensate the salt’s low thermal conductivity by increasing the heat transfer surface. Thus, depending on different charging strategies, such as variations of the heating rod constellation, and discharging strategies, such as variations of the heat transfer fluid temperature, detailed information about the storage behavior could be gathered. Active control of the heating rod temperature has made it possible to reduce the duration of the charging almost by half. In context of the possible accuracy, the comparison with results of a simulation model showed good agreement.
Editor: Nele Merve David
Tutor: Maike Johnson; Wolf-Dieter Steinmann – DLR, Prof. Dr.-Ing. Clemens Felsmann
Year: 2019

Development and evaluation of an energy supply concept for a manufacturing company focussing on energy efficiency
An energy concept has to be developed for a new production hall. Firstly, the current state is taken into consideration and secondly the new building is examined. After that, boundary conditions are listed. For this, laws and the specifications of the purchaser are noted.
The next step is an energetic analysis, here the variants are registered for the first time. These include a heat pump and the waste heat of a combined heat and power plant. Subsequently, the heating load is calculated for both buildings. Additionally, an existent solar thermal system is simulated.
With all results the evaluation according to EnEV can be realised. The program provides the design requirements which have to be fulfilled. In the next step the producers are dimensioned for the two variations. Finally, an economic efficiency calculation is carried out. It will be showing the best cost-benefit-factor.
Editor: Nicole Zimmermann
Tutor: Dipl.-Ing. (FH) Lutz Drechsler – Drechsler + Liebich Werkzeugbau Heidenau, Prof. Dr.-Ing. Clemens Felsmann
Year: 2019

Automated Classification and assessment of operational states of HVAC systems
Behind the operation of heating, ventilation and air conditioning (HVAC) systems hides due to operational faults often great savings potential. Fault detection and diagnostics in the field of air handling play an important role. An algorithm for automated fault detection and classification of operating states is developed following the approach of U. Habib [1] and M. Bär [2]. This algorithm uses the hourly average of the operating data and classifies the operating hours into different clusters by using hierarchical clustering. The clusters correspond to different operating conditions or faults. This algorithm is applied to three HVAC systems with similar structure in a shopping center. The 4 expected operating conditions were identified, and a few operational faults were coordinated, namely the time and location at which the errors occur. In addition, the robustness of the algorithm with incomplete sensor equipment and the influence of the normalization procedure on one system of the three were examined. The algorithm works very robustly in the absence of unimportant sensors or with different normalization methods.
Editor: Mingjun Wei
Tutor: Dr. Andreas Wilde – Fraunhofer IIS-EAS, Prof. Dr.-Ing. Clemens Felsmann
Year: 2019

Ecologic and economic consideration of the GEG draft version
The new Building Energy Law is intended to approach the climate goals in the building sector. This thesis provides a detailed analysis of the heat supply in buildings with the requirements of the Building Energy Law. It will also demonstrate whether the bill represents an improvement of the old standard, the Energy Saving Ordinance. By utilizing the energy planner program of the Construction Cost Information Center of German Architects' Chambers, the heat requirement of three different heat-insulation-standards in combination with conventional heating systems is calculated with the help of a model building.
This thesis addresses which plant combinations are permitted under the draft law and which is the best option. It further illustrates that some heating systems meet the maximum primary energy requirements of the Building Energy Law draft exclusively by installing additional energy saving measures and a photovoltaic system. According to the draft law, the possibility of a direct crediting of self-generated photovoltaic electricity to the primary energy demand makes it feasible to install otherwise not permissible heating systems. The requirement for the use of renewable energies is very easy to meet. From an economic point of view, higher thermal insulation and additional energy-saving methods are not worthwhile. The energy costs thus saved do not outweigh the higher investment costs. Compared to the Energy Saving Ordinance of 2014 with changes from 2016, there is no significant improvement visible.
Editor: Larissa Warnke
Tutor: Dipl.-Ing. Marcel Ebert – Leipziger Institut für Energie, Prof. Dr.-Ing. Clemens Felsmann
Year: 2019

Analysis of an HANEST pilot (including the dedicated solar thermal plant) project planning, commissioning, and engineering
In the years 2012 to 2018 a combined supply and feed-in substation in a low-temperature district heating network in Berlin Adlershof was planned and implemented. Today, a HANEST-system feeds solar heat into the low-temperature grid and draws in district heating to supply a house with hot water. A solar thermal system provides heat for the local consumers and surpluses are fed into the heating network. The HANEST-station in Berlin is up until now the only one of its kind, which is operating in a real district heating network.
In order to enable the implementation of further HANEST-systems in the future, the planning, construction and commissioning were reconstructed, and the mistakes made were analyzed.
The communication between participants is a key factor for problem causes and solutions. The success of the planning phase is determined by the quality of the information sources and the experience of the professional planner. External influences such as the house construction and material deliveries determine the construction process and installers experienced in the field of district heating and solar thermal energy, enable an error-free installation. Commissioning a complex system requires structure, communication and detailed logging, to better identify and resolve problems.
The use of a HANEST-system, instead of the simultaneous use of a supply substation and a feed-in substation, only makes sense under certain conditions - among others the installed collector-field size, the load of the local consumers, the temperature levels of the district heating network and of the local heat utilization (see SOLSTAND), so the additional investment and the increased technical effort pay off. The given conditions in Berlin did not require a HANEST-system.
The station has been in automatic mode since June 27, 2018, supplying the residents with heat and feeding solar surpluses into the grid. There is potential for optimization in order to better secure the HANEST function and the customer supply.
Editor: Anna Lisa Raab
Tutor: Andreas Reinholz - BTB Blockheizkraftwerks- Träger- und Betreibergesellschaft mbH Berlin, Dipl.-Ing. Martin Heymann
Year: 2019

Analysis of the use of energy performance indicators in order to prove an energy performance improvement at Robert Bosch GmbH in Reutlingen
The aim of this research is to determine how the demonstration of the continual improvement of the energy performance as a standard requirement of the ISO 50001 can be implemented at the Robert Bosch GmbH site in Reutlingen.
In this context, it was analyzed which specifications the main standard and accompanying standards compose. It has been shown that a single superordinate indicator cannot be squared with the standard at the examined location with an enormous power consumption and a complex supply technology. Therefore, a concept was developed that involves the combination and aggregation of different energy performance indicators. In addition, the suitability of energy performance indicators known from energy efficiency benchmarks for an implementation was examined. Subsequently, the correlation between power consumption and influencing variables as well as process parameters was analyzed for the as main consumer identified area of epitaxy in semiconductor manufacturing. Using these findings, several appropriate energy performance indicators could be developed along a methodology that can be applied to other areas. The final recommendation for a specific indicator takes into account various aspects such as manageability and accuracy.
Editor: David Neugebauer
Tutor: M. Sc. Mario Kauderer – Robert Bosch GmbH, Prof. Dr.-Ing. Clemens Felsmann
Year: 2019

Use of variable time step sizes in the optimization of unit commitment
This thesis investigates an approach to reduce the computing time for a mixed integer linear optimization (MILP) of a crosssector energy system. The components and their specific data of the energy network are given, a combined heat and power plant (CHP), a boiler (GK), a heat storage (WS) and a Photovoltaic system (PV). The linear equation and inequality conditions are mapped in the operational optimization. The optimization problem is solved with the powerful solution algorithm CPLEX within the Matlab-Mathworks einviroment. To reduce the computational time as much as possible, first of all the given Matlab code is optimized and then adapted and extended. For the further computation time reduction, variable time steps are used for rolling calculations. The step sizes are not only equidistant but also non-equidistant defined. In the equidistant case, the time step width equals one hour and the prediction horizon is set in 24h, 48h and 72h. In the non-equidistant case, the same prediction horizons with variable time step sizes are set. For each prediction horizon, two to three combinations of time steps are examined. The optimization time and results of different optimization models of three optimization scenarios are compared, the closed optimization is considered as the reference. The results of the work show that the shortening of the computing time of a rolling optimization can be achieved by using variable time steps, but it leads to a slight decrease in the quality of the optimization result. The influences of the variable time steps on the optimization result depend on the season, prediction horizon, optimization period and many other factors, therefore the relative deviations from the reference model are different.
Editor: Jinyu Zhou
Tutor: Dr. rer. nat. Peter Stange
Year: 2019

Studies on the energy self-sufficient supply of a self service department store using local renewable energy sources
In the present diploma thesis, two concepts are developed on the basis of the estimation of expected future energy consumption of Globus self service department stores, which are to cover the forecasted demand with locally available regenerative energy sources and with the aid of storage facilities balance sheet or physically.
In this context, load profiles of an existing department store (Globus Rüsselsheim) were evaluated qualitatively and quantitatively as well as by type of energy source.
Subsequently, an adaption to the future location in Neunkirchen (Saar) was carried out under the influence of several factors. As a result of this analysis, the energy requirements of the future site to be covered were determined.
The next step was to investigate which energy sources are available at the site and to what extent. On the available areas the conceivable installable potential was determined in each case.
Following a theoretical assessment of the feasibility, a pre-selection of the technologies to be considered during the concept development was made.
From the results of these two considerations with regard to consumption and potential energy supply, several concepts were then developed, with regard to both balance-sheet and load-oriented self-sufficiency.
The results obtained were evaluated with regard to the degree of self-sufficiency, proportion of own consumption and space requirements, and on this basis a balance-sheet and a load-fair concept were selected. Both concepts were finally subjected to an economic consideration with regard to possible feasibility.
The results show that an implementation of the two selected concepts is currently not economically viable. However, operating with alternative energy sources which nevertheless meet the electricity demand at lower self-sufficiency levels can already be economically viable today.
Finally, the impact of developing technology and energy costs on the economic efficiency of the concepts was investigated. With the predicted development paths, both concepts under consideration can be implemented economically in the longer term.
Editor: Leona Freiberger
Tutor: Dipl. Ing. Guido Koch – Globus SB-Warenhaus Holding GmbH & Co. KG, Prof. Dr.-Ing. Clemens Felsmann
Year: 2019

Application of Machine Learning methods on building monitoring data
Due to environmental, political and technological development, monitoring data acquisition within the building energy sector is becoming increasingly extensive. In this regard new data driven methods are gaining importance specifically for system analysis and optimization of such systems and the associated technical components. This thesis aims to investigate the relevance and applicability of Machine Learning (ML) in solving application specific challenges, using the monitoring data of a modern energy system of a building, as a case study. A ML based toolchain was developed consisting of three general research objectives, namely learning of sensor associations for system understanding, data validation and concrete system analysis. Individual ML pipelines, applying the general pipeline architecture, were developed utilizing Association Learning (AL), classification and regression base ML algorithms. Thorough evaluations of each showed that AL had limited applicability, whilst the classification and regression-based pipelines performed well, offering successful solutions to the associated objectives of data validation and system analysis. Concretely the Random Forest showed the best results, being able to learn underlying system dynamics, with potential in reducing manual effort in the process of system analysis. The results show that ML is applicable to building monitoring data, providing promising methods in terms of automatization and data-driven solutions to interdisciplinary challenges, whilst giving insight into general ML pipeline design.
Editor: Ole Zießler
Tutor: Dipl.-Ing. Torsten Schwan – EASD Dresden GMBH, Dipl.-Ing. Jens Kaiser
Year: 2019

Automatic pattern identification and modelling of domestic hot water demand profiles
The intention of this thesis is the creation of an automatic pattern recognition and forecasting model of data-based domestic hot water profiles. The foundation of this tool are extensive measurements of domestic hot water (temperature and volume flow rate) of 73 objects. The data was a result of the research project EE+HYG@TWI. First, an analysis and examination of the influence of temperature and volume flow rate on the required heat demand of the domestic water heating take place. After that, an automatic pattern recognition, based on artificial neural networks, is performed. The residual loads of all building are categorised in clusters. The information of the different patterns offer the opportunity to assign new buildings, based on their specifications (type of building, number of apartments/people, etc.), to a fitting cluster. Based on the data of the respective cluster it is possible to forecast data-based domestic hot water profiles.
Editor: Jonas Haupt
Tutor: Dr. rer. nat. Peter Stange, Dipl.-Math. Anja Matthees
Year: 2019

Comparison of proband data concerning dry skin with results of a human model
In order to validate a human model by comparing it with test person data regarding the evaporation rate under different room climate conditions, measured data and the associated boundary conditions of experiments carried out by the Bundesanstalt für Arbeitsschutz und Arbeitsmedizin in Dortmund in 2017 and 2018 were analysed. As a result, 8 scenarios with temperatures of 20°C and 24°C and relative humidity of 20 % and 40 % each with displacement ventilation and mixing ventilation could be selected, whereby only mixing ventilation is considered in the scope of this work. Furthermore, the comparison of test person data with the calculation results of a human model (based on Streblow, R: Thermal Sensation and Comfort Model for Inhomogeneous Indoor Environment, Dissertation RWTH Aachen, 2010) was carried out using the selected scenarios. The changes of the evaporation rates with variation of the boundary conditions were considered in order to be able to evaluate tendencies of the model. It was found that in 60 % of the cases, the tendencies of the model coincide with those of the subject data, but the data often were in other dimensions. The comparison of absolute values of the evaporation rate from literature, subject data and human model shows that the model data are significantly lower, which confirms the results of the previous examination of the tendencies. In order to improve the model, heat transfer coefficients could be optimized and thus different ventilation forms could be represented. A further possibility would be, the more exact view of the isolation of clothes and the formation of air pockets caused by changes of the posture. Particularly regarding the degree of detail, the model shows possibilities for improvement. The head is regarded as one body segment so far and could be divided into several calculation points. This would make it possible to make much more precise comparisons with subject data. Respiration also does not find enough consideration in the current model and could be presented in more detail.
Editor: Noah Mertens
Tutor: Dr.-Ing. Markus Rösler
Year: 2019

Creation of an excel-based calculation tool for the calculation of a ventilation concept and for the design of ventilation systems with all required components according to DIN 1946-6 : 2019 with consideration of further standards
The subject of this thesis is the documentation and creation of a planning-based calculation tool based on the new residential ventilation standard DIN 1946-6: 2019 for the calculation of a comprehensive ventilation concept. The key aspects that are important here for creating a ventilation concept and designing a ventilation system for a residential building are:

the Calculation and design of free- and fan-assisted exhaust ventilation systems
(DIN 1946-6:2019)
the Interaction of the ventilation systems with exhaust ventilation systems according to DIN 18017-3:2019
Fan-assisted ventilation for heating load calculation (DIN SPEC 12831:2018)
Ventilation systems and fireplaces (DIN 1946-6: 2019 Bbl. 3 and 4)
the use of combined ventilation systems (DIN 1946-6: 2019)
the special features of the basement ventilation (DIN 1946-6:2019 Annex F) and
the radon load in addition to the basement ventilation (DIN SPEC 18117-1: 2019).

The work is divided into four parts. First of all, a literature search is carried out on the standards listed here and the algorithms, special situations and terms of home ventilation are described. A comparison between the old DIN 1946-6:2009 and the new version of DIN 1946-6:2019 was also listed below. Subsequently, the most important steps for the conception of the calculation tool are presented, among other things the problem of the tool, the necessary input / output variables and flow diagrams for the illustration of all program components, processes and interfaces to further standards. The focus of the third part of the thesis is on the finished calculation tool. Here the structure is presented and the operation explained by screenshots. Through a series of manually and automatically calculated ventilation concepts from other authors, the validity of the calculation algorithm can be demonstrated. At the end of the thesis the result will be discussed, possible weaknesses will be revealed and hints given to the norms.
Editor: Hristo Markov
Tutor: Prof. Dr.-Ing. Thomas Hartmann – ITG Dresden, Dipl.-Ing. Christine Knaus – ITG Dresden, Prof. Dr.-Ing. Clemens Felsmann
Year: 2019

Analysis of the effects of uncertain boundary conditions in the optimization of generator use
The thesis investigates the robustness approach for mixed integer linear programming used for power producers. In this connection the uncertainties of the deterministic variables shall be integrated in the programming for making it immune against fluctuations in the input variables. The focus is on the various approaches for the consideration of the uncertainties. The results are pointing out how the fluctuations affect the outcome of the optimization and their importance in the future. For including the uncertainties the robust counterpart is used. With the help of this tool you can choose the procentual fluctuations and the direction of the fluctuations yourself which leads to a fast adaption to the problem.
Editor: Claudius Schenuit
Tutor: Dr. rer. nat. Peter Stange
Year: 2019

Development, simulation and design of the frame structure of a wave power plant
Wave energy is becoming increasingly important for renewable power generation, as it
offers decisive advantages in comparison with established technologies such as photovol taics or wind power. The company SINN Power (Gauting,Germany) is developing a wave energy converter (WEC) for decentralized power generation in coastal areas. The WEC consists of a floating network of individual modules,that are connected by a frame struc ture. The upward and downward movement of the waves is transmitted via the floating bodies of the individual modules to a lifting rod and from there to the generators, which then produce electricity.
SINN Power's developments are first tested on individual WEC-modules, that are mounted on a harbour wall on the island of Crete. The first floatingwave power plant will be erected in 2020. This thesis deals with the necessary development of a new frame structure for the floating WEC.
Based on previous scientific investigations carried out by SINN Power, the existing deficiencies of the frame structure and the main bearing of the lifting rod were identified and improved. In addition,a new buoyancy concept for the floatingWEC was developed. Parts of the frame structure now generate additional buoyancy, resulting in a 50 % increase in performance with 54 % lower loads at the same time.
The thesis includes the iterative concept design and the constructional detailing of the frame structure and the main bearing.The core of the construction are three newly developed cast components. In addition,the assemblies are dimensioned based on a multi body simulation model of the WEC. Thus,they are designed for the increased loads in the floating power plant. The result is an economical, high-performance frame structure, that forms the keystone for competitive power generation from ocean waves.
Editor: Annabel Michel
Tutor: M.Sc. Dominik Schwaiger – SINN Power GmbH | Wave Technology, Prof. Dr.-Ing. Clemens Felsmann
Year: 2019

Inventory and Optimization of a municipal small-scale district heating system
In the context of this paper an extensive inventory of the district heating system of the eastern Saxon town Wilthen was conducted. One essential part hereof was the creation of a georeferenced network map that contains all relevant components, such as heating system sections and consumers. Within the scope of the inventory thermal bridges have been identified that lead to an increase of heat losses. Those could be reduced near-term by specific remediation measures.
Based on the heating network map a thermohydraulic network model was generated and simulated with the network computing software "TRNSYS-TUD"'. Using own measurement data as well as the provided operations diary the model was validated. Here the increased heat losses due to partially degraded insulation and thermal bridges became apparent.
Using the created network model different changes to the network's operational management have been studied. The minor savings that resulted herefrom suggest that the operational management is already in a beneficial state thanks to different small-scale improvements that have been implemented in the past.
Furthermore five different scenarios that include investments have been simulated. Both by reducing temperatures and by optimizing the structure of the heating network high potential energetic savings can be achieved. The results have been compared to each other in an economic efficiency calculation considering public aid programmes.
Editor: Andreas Fuchs
Tutor: Dipl.-Ing. Felix Panitz
Year: 2019

Building services in historic buildings
The following thesis analyses to which state preservation order and energy efficiency are compatible. Therefor legal requirements and funding opportunities are presented. From analysing four exemplary restructuring projects results, that energetic refurbishment is, despite the limitations due to conservative interests, categorically useful. With insulation and installation of an efficient heating system, the primary energy demand can be reduced over 50 %. To fulfil the legal efficiency requirements though, the integration of renewable energy is decisive.
For one specific old farming house five heat generating systems (which use wood, solar and ambient heat) have been simulated in Polysun and assessed. All alternatives are reaching a very good primary energy demand from 30-50 kWh/(m²a) (energy efficiency class A). Because of its ecological and economic advantages, it is suggested to realise the installation of a wooden boiler with solar thermal system. This can reduce the carbon ejection about 70 % and the energy costs about 45 % compared to the current system. If all suggested restructuring measures are realised, the building would reach the KfW-Efficiency-House standard 70.
With the results of this thesis, guidelines for reconstruction measures at building monuments have been formulated and visualized in decision trees.
Editor: Christiane Zietz
Tutor: Prof. Dr.-Ing. Clemens Felsmann
Year: 2019

Space cooling during summer – Evaluation of the possibilities for cold supply
As a consequence of the current climate policy discussion and against the background
of climate change, new and efficient ways have to be found, to meet people’s comfort
requirements.
This paper-work is based on the technical concept of room cooling by means of free
heating surfaces, which are applyed with cold water.
The aim is to present and subsequently evaluate various plant types for providing
the required cold water in an office building. The refrigeration provision is examined
by means of a compression refrigeration machine, absoprtion refrigeration machine,
adsorption refrigeration machine and gas engine heat pump. The focus is on the
elaboration of plant-specific characteristics, on the investigation of the possibility of
net serve operation, on the use of new refrigerants and on the possibility of combined
heating, cooling and power. Subsequently, the different systems are examined with
regard to the external influencing parameters and evaluated economically as well as
ecologically.
Editor: Markus Knispel
Tutor: Dr.-Ing. André Kremonke, Dipl.-Ing. Markus Arendt
Year: 2019

Modeling, simulation and production cost analysis of solar district networks
One of the challenge of our time is to develop a more sustainable environment, with a gradual reduction of fossils supply and an increasing use of renewable energy systems. Regarding space heating and heating of domestic hot water, many advantages occur with the application of district heating networks, for the possibility to use many different sources of heat.
The purpose of this work is to present the planning of the integration of a solar thermal plant connected to the heating network and to compare the procedure with the use of a software.
The dimensioning of a solar thermal plant is structured on many levels, that have to be carried forward at the same time, in order to obtain good performances and to observe the precautions determined for the solar plant and the district heating network.
With the use of a tool, the workload can be strongly reduced, by running a simulation in few seconds and having the possibility to change not only the structure of the system, inserting and removing elements, but also their size and properties.
The conclusions obtained show that the software Sceno-Calc Fernwärme 2.0 is able to calculate the solar heat that can be possibly produced with the boundary conditions characteristic of the network; it takes into account the main elements required by a solar thermal system, such as collectors, storage tank, heat exchangers and pipe lines, and, by varying their parameters, shows the possible different situations and configurations that can be chosen.
Editor: Giorgia Tomassini
Tutor: Prof. Dr.-Ing. Clemens Felsmann
Year: 2019

Evaluation and energy performance optimization of a multi-compressor chilled water system
This study concerns oneself with an alternative cooling process of the cooling care at the Neumarkt in Dresden. Therefore data of the cooling station Kulturpalast and the cooling combine was used and evaluated. The basis of the results are the measurements from the year 2018. The data were analysed referring to the current mode of operation, the resulting Problems and the necessary boundary conditions. All kinds of alternative cooling processes have been individual rated and following compared to each other. Resulting it is very difficult to find an alternative way, which is practical in an energetic and economic point of view. The utlilization of waste heat with a heat pump to supply warmth to the district heating system will be the favourite option. In this case maybe it is possible to make the operation of a heat pumps economic practial in the future. Also the heat pump as a renewable source of heat can contribute a little part of the energy revolution.
Editor: Rubén Günther
Tutor: Swen-Sören Börner – DREWAG, Dipl.-Ing. J. Löffler – DREWAG, Prof. Dr.-Ing. Clemens Felsmann
Year: 2019

Energy saving and decarbonisation strategies for multi-family houses
With regard to the objectives of the Federal Government for the year 2050, this
thesis examines the energy saving and decarbonisation strategies for existing
multi-family houses. Taking ecological and economic factors into account,
redevelopment measures are presented and evaluated.
Two sample objects, located in Dresden, serve as examples and are examined
more closely. But first the constructional and technical condition of these two
objects has to be propounded. This happens with the help of the software ZUB
Helena.
The subsequently part deals with constructional redevelopment measures in
general and with the fundamental options for the reduction of transmission heat
loss. Besides, also special requirements concerning residential buildings are
thematized.
Thereupon, fundamental technical measures and regenerative energy systems for
the reduction of CO2 emissions are introduced all well as popular possibilities for
the heating of rooms and drinking water. Furthermore, with respect to the
changing climate conditions, the option to cool the building is also broached. A
categorization of various energy sources according to ecological aspects is made.
Considering the sample objects, there is eventually a simulation of individual
constructional and technical redevelopment measures with the help of ZUB Helena.
For the moment, the measures are examined individually and afterwards evaluated
from the ecological and economical point of view. Then suitable measures are
combined and with the aid of the two objects simulated. And these are again
examined from the economical and ecological viewpoint.
After a discussion about promotional programs of the Federal Government a
guideline for the creation of individual redevelopment plans are suggested in this
thesis. In the meantime fundamental results of the simulation are considered.
It is shown that it is possible to realize a tremendous decarbonization of exciting
multi- family houses until the year 2050 under economical conditions. Basis for
that is the long-term definition of individual or several reorganization measures. If
there are measures anyway, it will be a good opportunity to optimize energetic
aspects of a building.
Editor: Markus Bauch
Tutor: Prof. Dr.-Ing. Clemens Felsmann
Year: 2019

Data collection and analysis of the operating states at the CHP-plant Reick
The effective use of the heat generated by cogeneration of the central heating power plants of DREWAG via the central district heating network is implemented via the heat storage facilities in the Dresden-Reick power plant. The effects of the energy transition are reflected not only in fluctuating electricity generation but also in district heating supply in the form of increasing variable pressure and temperature conditions in the district heating network. In this thesis, the operating states of HWK Reick are evaluated on the basis of historical data and assessed with regard to the permissible operating ranges and critical system states. Furthermore, for a future intelligent control algorithm models for the heat storage operation are created in order to calculate operating points depending on the differential pressure of the central district heating network so that critical operating conditions are avoided and the control speed is increased. The results of this evaluation show that the control technology has to be further developed with regard to future requiremen ts, since the expansion of HKW-Reick with a CHP will fully exploit the previously hardly used load flexibility of the heat accumulators.
Editor: Martin Herlt
Tutor: Klaus Höhnel - DREWAG, Dr.-Ing. Thomas Sander
Year: 2019

Considerations about the energy performance evaluation of heat pumps
The optimisation of heating systems offers the possibility of increasing efficiency. Particulary with heat pumps, the use of electricity as drive energy makes the highest possible efficiency desirable in order to reduce the demand of primary energy. The present diploma thesis therefore deals with the evaluation and interpretation of the operation of a complex heat pump system with several heat pumps in combination with heat generators which are using fossil fuels to cover the heat and cooling energy demand. A special feature of the system under consideration is the use of ice storage tanks and solar collectors as a double heat source, which has only been available on the market for about ten years. This diploma thesis can be divided into three main areas.
In the first part, the current study situation on systems with the same use of heat source is explained in advance and the efficiency values to be expected are defined on the basis of this. With the help of VDI 4650, the balance limits for the evaluation of heat pump operation are defined and the novelty of the use of ice storage tanks in heating systems is explained. Furthermore, the special features of the building, the planning concept and the methodology used to evaluate the collected data are explained.
The second part consists of the description of the integration of the heat pumps into the heating system and the actual evaluation of the operating behaviour.
Following the evaluation of the normal operation, further influences on the efficiency of the heat generation as well as the achievement of the planning intentions are examined. Finally, the developing evaluation aids for the heat pump operation are presented, which enable continuous monitoring of the efficiency of the individual heat pumps. On the basis of this, possibilities for the optimisation of the heat pump system are suggested in the outlook.
Editor: Philipp Röll
Tutor: Dipl.-Ing. Jens Kaiser
Year: 2019

A study about the retrofitting of heat pumps in existing buildings
The retrofitting of a heat pump to a conventional, fossil fueled heating system in existing
buildings is often inefficient because of its demand to a high temperatured supply flow for the heating circuit. On the one hand, the integration of a heat pump leads to a reduction of greenhouse gas emissions but on the other hand high investment costs, high maintenance costs for both systems and also the high electricity costs in Germany are making it difficult to find a profitable way of integration. To validate these statements this study systematically analyzes influence factors for retrofitting heat pumps. Besides the investigation of different types of hydraulic integrations, various operation modes and performances of heat pumps, as well as a decrease of the circuit temperature have been probed. Because of the easy exploit of the heatsource air, the simple assembly and the reasonably low investment costs, the simulations just used air-water-heat pumps. The results are showing, that retrofitted heat pumps for base load supply can reduce energy expenses in apartment buildings when there is an oil fueled heating boiler. In single-family houses, high maintenance and procurement costs are exceeding the decreased energy costs. Only the connection of an oil fueled heating boiler and a heat pump with a high percentage of the total heat demand can reduce the expenses. The integration of a heat pump to a gas fueled heating boiler shows no positive financial outcome. Every single variation of the integration reduces green house gas emission and the reduction amounts up to 50 percent.
Editor: Johann Höflitz
Tutor: Prof. Dr.-Ing. Clemens Felsmann
Year: 2019

Development of a control algorithm for hybrid energy generation systems consisting of heat pump and photovoltaic system in residential buildings
Against the background of the climate policy goals of the German government to increase the share of renewable energies and to reduce both CO₂ emissions and primary energy requirements in the building sector, this paper examines a hybrid energy generation system (HEGS) consisting of a heat pump, electric heater, PV generator and an electric and a thermal storage device. Within this examination the main concern is the coordinated control of the different individual components. For this purpose, a conventional controller with a smart grid interface and communication possibility between the single components and an optimized controller with an additional 24-hour prediction will be developed.
The application to an apartment building with four residential units has shown that HEGS can be an important component in achieving climate policy goals. The conventional controller already achieves a self-consumption rate of 0.95 and a degree of self-sufficiency of 0.31, so that the network load is low. By adding a 24-hour prediction to the controller, grid demand, total consumption, operating costs and CO₂ emissions are reduced within a range of 1 to 1.5 % compared to a conventional controller. A reduction of 1.5 percentage points in self consumption indicates that the prediction function can be further optimised.
Editor: Jonas Franken
Tutor: Dipl.-Ing. Maximilian Beyer, Dr.-Ing. Martin Knorr, Herr Forster - Fa. NordWestPlan
Year: 2019

Modeling and Simulation of ventilation systems in existing buildings
In this thesis presented the development of four dynamic simulation models of centralized and decentralized ventilation systems in Modelica. The ventilation systems are configured with the existing residential building under assumptions and standards. With these models, quantitative comparison of dynamic hydraulic behavior and energy performance of different ventilation variants can be achieved. By relatively small design volumetric flow the use of the main fan can reduce electrical energy consumption compared to only with decentralized fans. Besides controller models based on demand controlling were developed. By parameterizing the controllers, it is verified that the main fan is more "sensitive" than the decentralized fans. A sensitivity analysis of the fans via changing set volume flows, pressure losses and control parameters are carried out. By implementing a co-simulation with EnergyPlus, the selected variants are
compared with the decentralized fan system in the building model with defined user behavior and external conditions.
Editor: Fanglin Chen
Tutor: Prof. Dr.-Ing. Clemens Felsmann, Nicolas Carbonare – Fraunhofer ISE, Freiburg
Year: 2019

Space cooling during summer - Development of a building and system model with TRNSYS
The thesis at hand aims at identifying the cooling potentials generated by radiators
within the framework of the research project „KUEHA“ [2]. To proof the suitability of the
system, thermal comfort is used as an indicator. Therefore, the fundamentals of thermal
comfort are explained, followed by a short description of the used program „TRNSYSTUD“.
Additionally, the required assumptions and scope conditions are defined. As a
model serves the extension of the Merkelbau, based on the campus of the Technische
Universität Dresden, which was already used for technical experiments. In this sector of
the building different kinds of heating and cooling systems are installed. The results
of those different constructions are compared to each other, which helps to evaluate
the adequacy of the model. According to that the radiators provide a significant
contribution to the reduction of the operative room temperature and are furthermore
able to compensate a higher room temperature due to a stronger insulation. However,
the comfort cooling systems provide slightly better results concerning the thermal
comfort. Additionally, the advantages of a combined utilisation of different kinds of
cooling systems are demonstrated.
Editor: Felix Taubert
Tutor: Dr.-Ing. André Kremonke, Dr.-Ing. Alf Perschk, Dipl.-Ing. Markus Arendt
Year: 2019

Heat pump application for the building stock
Considering climate change, objectives to reduce climate-damaging greenhouse gases are gaining priority. The German building stock is contributing a lot to those emissions.
Therefore, in this thesis was evaluated how heat pumps, which play an important role in the scenarios for energy transition plans proclaimed by the German government, can be used in existing buildings and whether this is economical.
In addition to a broadly defined analysis of the German building stock regarding the
expectable boundary conditions, two sample buildings have been comprehensively analysed by calculating different variations of modernization and, on this basis, simulations of various types of heat pump systems. Other technologies like solar thermal energy and photovoltaic were also incorporated.
As it turned out, huge amounts of greenhouse gases can be avoided by using heat pumps. Unfortunately, it also became apparent that the combination of heat pumps and existing buildings is rarely economic.
The cause is not to be found in a lower efficiency of heat pumps in existing buildings
compared to those used in new buildings but in the achievable savings which are too low to compensate the high investment costs.
Editor: Daniel Kellermann
Tutor: Prof. Dr.-Ing. Clemens Felsmann
Year: 2019

Modelling and Calculation of Heat Transfer at Structured Heat Exchanger Surface Areas
The aim of this work was a detailed research and evaluation of the currently available numerical models for the determination of the heat transfer and the flow pressure loss in structured heat exchanger surfaces. For this purpose, studies were used on apparatus with pipes and plates. All studies results confirm the known higher heat transfer and flow pressure loss in structured heat exchanger surfaces. The realizable k-ε turbulence model demonstrated good flow simulation behavior for single structured tubes and for plates with chervron design and led to a good estimation of the experimental results. The same was true for the RSM model for simulating single structured tubes. The SST model and the standard k-ε model are not recommended for simulations of single structured tubes. By contrast, the standard k-ε model, despite a simplified view of a two-dimensional axisymmetric flow, led for the parallel structured tube to a good estimation of the experimental results. It was shown in the studies that the changes in the structural parameters and the structural geometry have a different effect on the heat transfer and pressure loss increase compared to the smooth surface over the Reynolds number. The choice of suitable structuring thus depends on the application.
Editor: Alexander Bouguila
Tutor: Dipl.-Ing. Torben Möller - G.A.M. HEAT GmbH, Dr.-Ing. Markus Rösler
Year: 2019

Simulation based development of a decarbonization concept for Volkswagen’s vehicle production using the site in Zwickau as an example
This work is dedicated to the elaboration of a concept that enables CO2-neutral producion of vehicles at the Volkswagen site in Zwickau considering scope-1 and 2-emissions which are a consequence of its energy supply and process related energy conversion. Demand side load profiles were modelled by means of multiple linear regression in Matlab. The model of the energy providers that include among others a CHP plant was created using TRNSYS. The models were then linked and used for the simulation of the effect of measures aiming towards CO₂-reduction and their impact on each other. After the evaluation of those measures regarding their reduction potential and CO₂-abatement costs they were combined in a decarbonization concept that involves an adapted mode of operation of the CHP plant, the transition to CO₂-neutral firing and the combined use of a heat pump and cooler in one device.
Editor: Till Meinel
Tutor: Marlisa Janke-Laumer – Volkswagen AG (K-PPSU/E), Prof. Dr.-Ing. Clemens Felsmann
Year: 2019

Evaluation of cooling technologies for office and administration buildings
Editor: Christoph Hübner
Tutor: Prof. Dr.-Ing. Clemens Felsmann
Year: 2019

Energy performance analysis of an administration building
In the context of this thesis, the spacecooling by means of free heating surfaces is placed at the centre of the considerations. The aim is to evaluate and optimize the system with the help of simulation tools based on variant calculations. The models of the building and the thermal equipments were created in TRNSYS-TUD and POLYSUN. The TRNSYS-TUD model represents the building in detail, while the POLYSUN model represents the tehrmal equipments better. With the help of these models different variants for spacecooling were compared with the uncooled variant. Cooling via free heating surfaces leads to a significant reduction in room temperatures (approx. 5 K) and thus to a significant improvement in thermal comfort. The temperature reduction potential increases with increasing room temperatures. A summarizing evaluation under the consideration of ecological, energetic and economic aspects takes place on the basis of a long-term observation horizon. The investment costs of the variant with only radiator-cooling are significantly higher compared to the variant without cooling, but only half as high as the costs of cooling via chilled ceiling. lf the total energy costs are considered, there is not much difference between the uncooled case and the cooled case, because the electricity costs are substituted by the langer operation of the CHP.
Editor: He Xu
Tutor: Dr.-Ing. André Kremonke, Dr.-Ing. Alf Perschk, Dipl.-Ing. V. Braune - Ohra Energie GmbH
Year: 2019

Operational optimization in district heating networks
The expansion of renewable energy sources continues to increase. The reason for this is the shortage of finite fossil resources and the increased climate change caused by these fossil fuels. Due to the lack of space in cities, renewable energy sources are often located in a decentralized location, so they have to be connected to networks. In this work, the impact of decentralized energy sources feeding their heat into the district heating network is examined for centrally located producers. Different scenarios for two district heating networks are considered. The scenarios differ in their central producers, the decentralized feeders and a heat storage with different limitations and operating modes. The year is divided into type-weeks for the different scenarios. These weeks reflect the fluctuating thermal performance of the network for both summer, winter and transitional times. For one scenario, a segmented year-round optimization is performed and the problem of segmentation is explained.
The goal is to determine the best possible operation mode of the central producers and the heat storage with the help of the Application FreeOpt 3.0.
The results show that the decentralized feeders have small influence on the central producers during the wintertime. In the summer and transitional periods, the operating hours of central producers are largely reduced. The restriction of the heat storage has shown that the solar thermal yield can not be fully utilized due to stagnation.
By restricting the storage operation mode, the central producers must be driven more frequently and in some cases thermal energy remains unused in the heat storage.
The most cost-effective scenarios are those with the largest amount of decentralized heat feed-in with a flexible, unlimited heat storage.
Due to the high investment costs of heat storages, which were not taken into account in this optimization, it is questionable whether such large heat storages are economical.
Editor: Fabian Burkhardt
Tutor: Dr. rer. nat. Peter Stange
Year: 2019

Development and evaluation of an sensormodule to measure tempratures of it-hardwarecomponents
This project thesis addresses the development and evaluation of a sensor module for temperature measuring on IT hardware components. If they have to be cooled by a heatsink, there is just very little space for temperature sensors and common measuring system can not be used.
First of all, the thesis starts with an introduction in temperature measuring and different sensor types. A component part analysis leads to the spacial boundary conditions for the sensors. A thermal analysis is performed to asses the influence of different sensors on the heat transport from the IT hardware component to a cooling fluid. Furthermore the measurement uncertainty is calculated. Based on these analyses different sensors are compared and the two best types are chosen. In order to reduce measurement uncertainties they are calibrated. For the evalution of the sensor module measurements on the components of a graphic card are performed and the measurement results are evaluated. The thesis concludes with improvement suggestions and further examinations concerning the thermal behavior of IT hardware components and sensors.
Editor: Simon Kimmig
Tutor: Dipl.-Ing. Karl Wolffgang, Dipl.-Ing. Stephan Wiemann, Dipl.-Ing. Lukas Friedenstab - Cloud&Heat Technologies GmbH Dresden
Year: 2019

Potential Evaluation for the Usage of Decentralized Solar Thermal Heat for a Neighborhood
Europe currently puts much effort into the guarantee of a low-emission energy supply. Hence the integration of regenerative energy sources into the heat supply plays an important role for a successful energy turnaround. The focus of this thesis is the decentralized feed-in of heat provided by solar thermal systems into district heating networks. For this purpose, I will evaluate the “Solarpotential-Dachkataster“ (a cadaster for the solar potential of the roof areas) in the city of Dresden that aims to identify and list all areas on roofs that can be used as solar collector areas. The evaluation reveals some deficits in the accuracy of the listed potential collector areas, but is used in modified form as data basis in this work.
I will investigate a secondary network section in Dresden with 131 customers using the prognosis tool FreePlan and the simulation tool FreeSolCalc. Following questions will be answered: (1) To what extent can solar yields be achieved? (2) To what extent can they be used locally? (3) Is the distribution via the district heating network possible, and (4) what thermal storage facilities should be provided? For this purpose, 2 scenarios are developed how the potential collector area can be assigned to buildings with several domestic substations. I present the concepts for district heating substations for decentralized feed-in developed in the SOLSTAND research project. I will evaluate the considered district heating consumers regarding the annual solar yield maximization and therefore apply a conception draft from SOLSTAND. The maximum annual yield can usually be achieved with a NEST or HANEST with storage tank, whereby the result of
both the district heating and customer storage dimensions shows large size so they are difficult to realize in reality. First assumptions can be worded as to how the selection of a station utilisation concept can be further simplified.
Editor: Elisabeth Wudenka
Tutor: Dipl.-Ing. Martin Heymann, Dipl.-Ing. Toni Rosemann
Year: 2019

Development of a system concept for the Integration of biogas CHP-Systems in energy management systems
This diploma thesis examines possibilities for integrating a flexible CHP system fueled by biogas into a higher-level energy management system. First of all, a comprehensive literature research on possibilities of flexibilization as well as the description of these is carried out. Based on this, the components of a CHP system including a biogas plant in Matlab Simulink are modeled. Using real thermal load data from a previous thesis, apredictive control algorithm is developed for heat utilization optimized and maximally flexible operation of this system. To implement this, an MSR concept is derived. Then the flexibility potential of an exemplary scenario is analyzed. In the summer, there is agreat potential for load shifting over several days. Autumn is identified as a critical period for the stability of a biogas heat-driven CHP system due to the sudden and sustainedincrease in required thermal power. In this period, flexibility is limited. In winter, taking into account the storage state variables, a flexible arrangement of operating blocks within the day is possible.
Editor: Sebastian Eichhorn
Tutor: Dr. -Ing. Paul Seidel, Dipl.-Ing. Jens Werner, PD Dr.-Ing. habil. Joachim Seifert, Maximilian Geisberger - Geisberger Gesellschaft für Energieoptimierung
Year: 2019

Use of Renewable Energy Sources in historical buildings
Historical buildings are often excluded from the duties of energy-related policies by a paragraph, since the appearance and building substance are to be preserved. If building owners still decide to proceed with their energy-saving measures, it is important that they do so with close collaboration with the office responsible for the preservation of historical buildings.
At first, the essentials of the legislative texts and options for funding related to renewable energy and historical buildings were summarized.
Different options for energetic renovation were described and judged by their usability in historical buildings. Some of those options were presented with good practice examples.
Finally, the usability of different energy-saving technologies in historical buildings were compared regarding energetic, ecological and economical effects and a priority list was created.
Editor: Martin Zacharias
Tutor: Prof. Dr.-Ing. Clemens Felsmann
Year: 2019

System concept for a decentralized ventilation unit with high heat recovery efficiency
The paper first provides an overview of the currently available decentralised ventilation units and the technologies used in these units. In particular, the technologies for heat recovery are explained in detail. The legal and normative framework conditions are used to define the requirements that a decentralised ventilation unit must meet. Particular focus is placed on the energy requirements of the ErP Directive and the air quality requirements according to DIN EN 16798-1...3. With the aim of meeting the set requirements, two decentralised ventilation units with different heat recovery
components are designed for both summer and winter use. One of the units uses a heat pump for heat recovery, the other a plate heat exchanger. In winter, both units can meet the requirements, in summer only the unit with heat pump can do this without restriction. Both devices must be analysed on a HIL test bench in order to check the theoretical design.
Editor: Jakob Petrek
Tutor: PD Dr.-Ing. habil. Joachim Seifert, Dr.-Ing. Markus Rösler
Year: 2019

Requirements of building automation for the ICT structure
In this thesis essential "intelligent" functionalities are categorized by research and according to the existing standard DIN EN 15232-1 in order to later derive the requirements for the information-communication-technical-structure for the conception of a building automation system. On the way, important connections and concepts are explained. The term smart home, smart building and networked building automation are in the foreground. Subsequently, the energy efficiency and energy savings for the type buildings single-family house, multi-family house and office building are estimated by functionalities using a calculation tool based on the model of DIN EN 15232-1 (weighted procedure). Finally, the question should be clarified whether the networked building automation for the type buildings considered, and especially for a smart home system of a family house, taking into account the investment costs, is profitable. This also results in recommendations for new construction and retrofitting.
Editor: Hristo Markov
Tutor: Dr.-Ing. Martin Knorr
Year: 2019

Evaluation and Analysis of technical measures to improve the energy efficiency of multi-family houses
As part of a research project of the EBZ Business School Bochum, which deals with the potential savings in the area of building heating, building data was collected over several heating periods. Eight different energy saving measures were tested. This thesis provides an overview of the properties involved. The measures are presented and characterized. In addition, the structure and handling of the database, in which the data is stored, will also be described.
The effectiveness of the measures will be evaluated in the course of this work. For this purpose, the collected data were inspected and checked for their usability. For many properties, a critical data set was found, which is why they were analyzed more closely. The procedure and the method of the sighting will be explained in more detail. This resulted in an overview of the data quality of the gas and heat meters of all participating properties. Useful data sets were weather-adjusted and compared with historical consumption data. In addition, the annual utilization rates were determined and the attempt was made for a profitability analysis. No pattern could be identified, thus confirming the effectiveness of the measures. On the contrary, even greater consumption was determined. However, positive changes were found after optimization of the hydraulic systems. At the end, comments on the experiment and possible sources of error are named and discussed.
Editor: Martin Lehmann
Tutor: Prof. Dr.-Ing. Clemens Felsmann
Year: 2019

Analysis of measured data from existent photovoltaic systems at Technische Universität Dresden
In this thesis the effect of different influencing factors on system performance of photovoltaic system is investigated. For this purpose, the measured data from existent PV systems at TU Dresden are evaluated regarding the yield and system performance.
The required reference yield was simulated with good accuracy based on local weather data. Therefor models of the plants are set up in the software Polysun.
Orientation and inclination of the modules have the greatest influence on the yield. In addition, close objects that cause shading result in a negative effect. If enough row spacing is considered, the negative effect of self-shading is neglectably low. In the case of façade systems, yield and system performance are significantly worse than with inclined modules. Two of eleven analyzed plants showed a declining performance over the years.
Editor: Eric Schulz
Tutor: Dr.-Ing. Annina Gritzki, Dipl.-Ing. Dennis Thorwarth – TU Dresden, Institut für Baukonstruktion
Year: 2019

Energy and economy related analyses of heat pump applications in air heating systems
Due to regulatory requirements, the proportion of low-energy houses in the EU will continue to increase. As a result, the market for the use of air-guided heating systems is also growing.
The aim of this diploma thesis is to analyse different circuit variants of heat pumps in air heating systems as well as the integration of regenerative energies in such systems. In addition to an energetic consideration, the economic efficiency of the various measures is also considered. For this purpose, the state of the art was researched and a market analysis was carried out. Building and system simulations were used to calculate the energy consumption of the heating system of a reference building. The effect of active cooling in summer was also investigated. Subsequently, the results were compared with each other and an analysis of the economic efficiency for a period of 20 years was carried out.
The use of exhaust air as a heat source for the heat pump is the most economical and energy-efficient option. The integration of regenerative energies is energetically advantageous in many cases, e.g. with a solar thermal system for DHW heating or with a geothermal heat exchanger for air preheating. However, an economically viable integration of renewable energies can only be achieved with the aid of a photovoltaic system.
Editor: Paul Seeber
Tutor: Dipl.-Ing. Stefan Hoppe
Year: 2019

Thermal modelling of a Lithium-Ion battery storage for residential buildings
In the work, the thermal behavior of a lithium-ion battery storage is investigated. The battery storage is designed for residential applications and is being developed by a company that is cooperating to create this work.
The thermal behavior is investigated by means of a simulation program for a detailed analysis of the steady state and a specially developed, simplified model for the calculation of temporal temperature profiles. The structure, the mode of operation and the thermodynamic equations for the calculation of this model are described and the plausibility tested. From the investigations of the thermal behavior of two constructions under consideration of different boundary conditions as well as further constructive variations recommendations for future constructions are derived.
The prototype tests are described, and the measured temperatures used to validate the simulations. The assumptions made and the suitability of the model developed for mapping the real temperature profiles are checked. The possibilities for applying the model and the calculated results in the further development process of the battery storage are presented.
Editor: Johannes Eckel
Tutor: M. Hemery - Viessmann Werke GmbH & Co, Prof. Dr.-Ing. Clemens Felsmann
Year: 2019

Development, evaluation, and optimization of the energy concept of a daycare center
The first step to the developement of the energy concept of the day-care centre in
Teltow would be an analysis of the current situation on site. External conditions, e. g. by contractors or by law, have to be listed and carefully taken into consideration. A wide variation of heat generators is examined to obtain a brief overview of all possibilities. Among these, there will be a close-up of an air-water heat pump, a brine-water heat pump and, finally, of a new gas condensing boiler. Energetic, ecologic and economic aspects have to be thoroughly inspected, this will partially be done in a self-coded environment. As a final result, a recommendation for the further course of action can be given.
Editor: Jakob Reiter, Kai Ettrich
Tutor: em. Prof. Dr. rer. nat. habil. Steffen Wagner - TU BA Freiberg, Prof. Dr.-Ing. Clemens Felsmann
Year: 2019

Evaluation of cooling technologies for office and administration buildings
For office and administration buildings, which are mainly used in the daytime and where people are supposed to work willingly, cooling concepts are in increasing demand. Besides to the requirements for the cold production, there are also challenges for the cold transfer into the offices. On the one hand, air currents can dissipate thermal energy, but can also cause noise emissions or drafts, which decrease the thermal comfort. On the other hand, systems, which also use radiation solve this problem, but often do not dehumidify the air and therefore cause problems with condensation. In addition, offices must supplied with fresh air in order to comply with hygiene standards. An evaluation of cold transfer systems helps in making a decision. However, comparability is only possible if the criteria are universally and independently. Firstly, the thesis deals with the influencing variables and research results for the cooling requirements. In the next step, the evaluation criteria are defined and the regarded systems are described. As a result, the thesis contain a rating scheme for the system selection and also a examination of a sample building.
Editor: Christoph Hübner
Tutor: Prof. Dr.-Ing. Clemens Felsmann
Year: 2019

Optimization of an existing bypass valve using numeric flow simulation by means of „Mentor FloEFD“ in „PTC Creo”
Home stations are a good way to supply residential units in multi-family homes with domestic hot water. But at low flow temperatures, such as when using heat pumps, the required domestic hot water temperatures cannot always be maintained or only with a reduction in efficiency. To compensate for this, instantaneous water heaters can be used for electrical reheating. This leads in return to very high pressure losses at large hot water taps quantities, such as those that occur in comfort showers.
This work deals with the optimization of an existing bypass valve, which is used to reduce the pressure loss at large hot water tap volumes. The aim is to find a new geometry that would produce less pressure loss and would not require a gasket. It should therefore be a performance and cost optimization. In order to achieve this, various valve geometries were examined with the simulation software "Mentor FloEFD" integrated in "PTC Creo" and evaluated according to their pressure drop. Subsequently, prototypes of the best geometries were fabricated, and measurements of these prototypes made. The pressure loss could be significantly reduced and at the same time the necessary parameters for the function of the entire system could be kept. Based on these results, the managers of the company Stiebel-Eltron decided to take the new valve into series production.
Editor: Klaas Albers
Tutor: Alexander Janzen - STIEBEL ELTRON GmbH & Co. KG, Prof. Dr.-Ing. Clemens Felsmann
Year: 2019

Digitization of building energy technology - requirements, technical status and development paths for control components of energy systems in buildings
With regard to digitization in the energy sector, essential development paths for building energy technology will be discussed. Before that, essential technical characteristics and requirements for the technical devices and the transmission standards for building automation are discussed. In addition, intelligent field devices and radio technologies are considered, which are currently used. The discussion about the potentials and obstacles is mainly about the increasing networking through IoT. The potentials have been increased energy efficiency, increased comfort and new concepts. The main barriers are data security, the lack of competence in dealing with big data and machine learning. The introduction of standards for the greatest possible interoperability also plays a role.
Editor: Florian Emmrich
Tutor: Dr.-Ing. Martin Knorr. PD Dr.-Ing. habil. Joachim Seifert
Year: 2019

Elaboration of a maintenance schedule for a multi-motor-plant
The German electricity market requires very flexible power generation. The regional energy provider of Dresden, the DREWAG, realizes this need by using big combined heat and power plants for the central production of both. The objective of this study is to determine technical principles as well as requirements of the position Dresden-Reick for building a new combined heat and power plant. Refering to the maintenance procedure as well as the maintenance plan predetermined by the manufacturer an operation schedule of the new combined heat and power plant was designed. The aim of this schedule is a very flexible and efficient power generation, when susceptibility of disturbance is low.
Editor: Martin Herlt
Tutor: Klaus Höhnel - DREWAG. Dipl.-Ing. Jan Löser
Year: 2019

Integration of solar energy and heat pumps district heating during summertime
To determine the advantages and disadvantages of substituting a gas fueled plant with a regenerative plant for district heating DNV GL Energy Advisory GmbH commissioned the formulation of this thesis. In the term paper different models of solar collectors and heat pumps are presented. Their yield is calculated. With the load curve of an exemplary district heating system the number of solar collectors and heat pumps to cover the smallest demand in summer is determined. Three systems with differently sized heat storage tanks are developed. The regenerative systems do not bring any savings of primary energy of emissions if they displace heat produced in a combined heat and power plant. If a boiler is replaced the savings of not regenerative primary energy and emissions of the solar collectors amount to approximately 3 percent of the boiler’s primary energy consumption. The savings of not renewable primary energy of the heat pumps compared to the boiler can be up to 13 %. Most of the heat pumps discharge more emissions that the boiler. Only half of the considered systems without storage are profitable. None of the solar plants are economic if a heat storage tank is added to the system. The size of the heat storage tank does not have a significant impact on the economic efficiency of the heat pumps.
Editor: Julia Meierkord
Tutor: Dr.-Ing. Robert Huhn – DNV GL GmbH, Dr.-Ing. Karin Rühling
Year: 2019

Investigations on long term behavior of different PV-plants at the same location
This thesis deals with investigations on the long term behaviour of the three different photovoltaic plants, which are under operation at the Zentrum für Energietechnik (Center for Energy Engineering) since June 2010.
The focus of the analysis is on the noticeable consequences on the plant’s behaviour caused by different incident and shading conditions. The evaluation is made from three perspectives and shall allow a statement regarding degradation and flaws in the plant. The analysis of the real area-specific yields of the strings was performed by measurement-based yields, which are gathered by the Professorships own database system DATA. In addition to the evaluation of seasonal and long term specific yields the data of incident and temperature sensors, which record the module temperatures of the facade located plant, were interpreted. To create a yield simulation the entire plant was mapped in the program Polysun Designer by Vela Solaris. Therefore, the plant and string-specific shading situations, which are caused by adjoining buildings, trees and other photovoltaic modules, were considered. A characteristic curve measurement was run with the help of the curve measuring instrument by h.a.l.m. elektronik GmbH to gather electrical parameters of the strings. Thereby the obtained parameters were compared with the data given by the manufacturer of the modules. The characteristic curves were analysed recording conspicuous behaviour.
Finally, recommendations for further operation of the plant were drafted.
Editor: Caroline Julia Rentzsch
Tutor: Dr.-Ing. Karin Rühling
Year: 2019

Quarter energy management system (QEMS) – Sizing the heat supply systems of quarters
In the light of global climate change, the supply of electricity and heat to buildings is increasingly drawing attention to it. The clustering of many individual buildings to quarters offers promising opportunities to turn conventional, fossil energy infrastructure into renewable, local and profitable energy supply. Integrated energy systems presumedly are the key to those changes. The optimization of plant operation additionally holds out the prospect of increased efficiency and profitability. However, the scope of energy utilities opens up a huge solution space for planning energy systems. The impact of a control system on the dimensioning is uncertain as well.
This thesis describes the design of a Quarter Energy Management System (QEMS) as a simulation and optimization environment to handle these questions. The QEMS optimizes energy systems with the help of a genetic algorithm. To do so, the QEMS accesses mathematical models of the behaviour of various energy components and automatically generates the model of any desired quarter energy system. To rate the performance of a given dimensioning, the QEMS performs dynamic simulations of the corresponding energy system. During the simulation it optimizes the operations by usage of a model predictive contraol (MPC) regime. Hereby, the QEMS optimizes not only the selection of technology and it's dimensioning, but also the operational strategy of the energy system.
Consideration of the operational strtegy promises effects on the final dimensioning. The thesis attempts to validate this presumption by identifying and varying suitable parameters of the MPC.
Optimization runs on an artificial example quarter show that an impact ot the operational strategy on the dimensioning is perceptible. Within the scope of this thesis it is too early to conclude an universal statement. For that purpose, detailed following studies are needed.
Editor: Lukas Hoffmann
Tutor: Lukas Ruck – IAV GmbH, Dr. rer. nat. Peter Stange
Year: 2019

Energy related optimization of compressed air supply at GSK Dresden
The task of the project work was to study the creation of the compressed air at GSK Dresden. The informations from the build-in measuring points and counters were recorded, prepared and evalueded.
In consequence of this studies the pressure level can not be reduced. The quantity of the compressed air is absolutely oversized. That is why the compressors often drive in a no load or in a partial load mode. Actually, the compressors power up and shut down in a very frequently modus. These can be observed especially at the night and in the weekend hours. Because of these bad designs there were a lot of expensive maintenance work in the past.
With these results it was searched for a new compressor which has the following characteristics. The pressure level must be 9,5 bar and the quantity at most 450 m_N³/h.
For the selected compressor from Boge was prepared an implementation recommendation.
Editor: Theresa Ettingshausen
Tutor: André Petters – GSK GmbH & Co. KG, Prof. Dr.-Ing. Clemens Felsmann
Year: 2019

Comparative energy performance evaluation of gas heat pump applications
A gas heat pump is one of the new and emerging technologies that combine renewable and fossil energy sources and use them efficiently for heating. A market analysis was carried out to know the sales situation of gas heat pumps in the heating market. For the energy assessment of gas heat pumps, the relevant standards and guidelines were described and the performances for assessing the efficiency of a gas heat pump were derived. In order to test the energy-saving potential of gas heat pumps, the use of gas heat pumps in residential and commercial properties was considered by using the EnEV Solar-Computer software and compared with conventional system variants. With the help of the sensitivity analysis, significant factors influencing the optimized operation would be worked out. A gas heat pump is not a small investment, so there was a cost study for gas heat pumps. Despite the high efficiency of gas heat pumps, there is no economic advantage compared to other heating technologies.
Editor: Jiaqi Yuan
Tutor: Prof. Dr.-Ing. Clemens Felsmann
Year: 2019

Space cooling during summer – Possibilities of using photobioreactors
Photobioreactors (PBR) as façade panels can contribute to the ecologic building energy supply. As one of the first technologies they make façade and window surfaces accessible as energy sources.
The present paper researches the application of photobioreactor technology within the energetic supply and demand structures of the administrative building of the Ohra Energie GmbH, which is a regional energy supply company in western Thuringia. Different use concepts for heat and biomass yields in the interaction with the building’s existing heating and cooling facilities have been examined.
Biogas that is produced from the PBR’s biomass yields can easily be used for example for heat and electric power generation in combined heat and power plants and fuel cells or to fuel combustion engine-powered motorcars.
The usability of heat yields that are mostly produced in summer and represent the largest part of the cumulative energy yield is a considerable challenge. As the most self-evident scenario their use for cold production has been researched. In the present situation heat is generated by a block heat and power plant though, whose cost-effectiveness cannot be achieved by the PBR facility.
Overall integration of a PBR facility into the researched, existing energetic structures of Ohra Energie’s administrative building is not feasible yet.
However, for potential successive projects with newly designed heat and cold generation facilities PBR can be an attractive alternative to conventional heat sources. Regarding design, plant management as well as integration into energy supply systems PBR technology has still great potential for optimization.
Editor: Andreas Kaden
Tutor: Dr.-Ing. André Kremonke, Dipl.-Ing. Markus Arendt
Year: 2019

Studies on the thermal and electrical performance of a solar hybrid photovoltaic
thermal (PW) collector in the facade
The combination of photovoltaic (PV) and solar thermal (ST) technology in a hybrid Photovoltaic-Thermal (PVT)-module increases the electrical efficiency η_el of the PV-cells by active cooling while using the removed heat for low-temperature applications. The required space is minimized. An uncovered, uninsulated, façade-integrated PVT-flat plate collector with rear ventilation, developed by the Institut für Baukonstruktion (IBK) of Technical University Dresden is analysed. It consists of a glass-glass thin film PV module and an aluminium plate for heat removal. A model of the collector is developed, using the software Delphin 5.9. Through variation of different energetic parameters, the optimised construction and operation conditions of the collector are defined. Important parameters are the flow rate and inlet temperature of the fluid and the diameter and distance of the fluid channels. The influence of the rear ventilation is marginal, an insulation of the collector is not required. The parameters of the collector’s characteristic curve are determined according to DIN EN ISO 9806. The optical efficiency η₀ is 0,486 and comparatively low. The annual electrical and thermal yields of the system embedded collector are determined using the software Polysun. Thermal yields of 303,4 kWh_th/(m_Koll²a) at an outlet temperature of 9 °C and electrical yields of 87,85 kWh_el/(m_Koll²a) are predicted for collector operation at the outdoor test stand of IBK. Compared to uncooled PV-cells, the electrical yield of the PVT-collector is 4,55 % higher. By Integration of PVT-collectors in the borehole heat exchanger cycle of a ground source heat pump, the collectors’ low temperature heat can be used for the regeneration of the borehole.
Editor: Charlotte Vivian Ahrens
Tutor: Dipl.-Ing. Christian Popp, Dr.-Ing. Karin Rühling
Year: 2018

Energy-related analysis, evaluation and optimization of building-related energy systems and subsystems applied on the “Schul- und Sportzentrum Lohr am Main”
The sustainable and energy-efficient energy supply is increasingly becoming a central theme in today’s society, especially in the building energy sector. In this context, the importance of integrating intelligent energy management systems and complex data monitoring systems is increasing. Such systems help plant designers and operators to make energy production and energy consumption of a building or complex of buildings energy efficient and to optimize it continuously during operation. This approach has been used i.a. applied with the help of the TU Dresden to a practical reference object. As part of an energetic general refurbishment, extensive measures were taken (building and plant technology) for a sustainable energy supply for the school and sports complex in Lohr am Main. The aim of the present work is to analyze the technical components and refurbishment measures carried out in the heat-generating subsystem, to establish the actual and real situation of the plant operation in the form of an energetic starting point and, consequently, to derive possible improvement approaches for operational optimization. The analyzed subsystem includes several heat pumps, one CHP unit, two gas condensing boilers, as well two solar absorber fields and one heat storage system. These diploma thesis offers on the one hand a theoretical manual (based on a research of common standards) to carry out an energetic operational analysis and operational optimization and on the other hand their practical application on the practical reference object. The results of the analyzes as well as the calculated energy parameters and efficiencies of the individual systems as well as of the total system of heat generation are represented by suitable visualizations. As a result, the subsystem offers a good energy efficiency, but in some places certainly has room for improvement. The respectively discovered optimization approaches are summarized in a catalog of measures and could be applied in future in consultation with the planners and operators.
Editor: Stefan Rüdiger
Tutor: Dipl.-Ing. Jens Kaiser
Year: 2019

2018

Development of eMobility concept for a community taken into account energy policies and technical feasibility
In order to reduce the negative environmental impacts of transport and at the same time meet the increasing demand for mobility, sustainable mobility concepts for passenger transport must be developed. They should combine measures to reduce specific emissions and to avoid, shift and optimize traffic.
The aim of this thesis is to develop mobility concepts involving electromobility that are adapted to different conditions of urban planning, transport and demographics. For this purpose, the relevance of electromobility for energy policy is validated against the background of the triangle of energy policy goals. Technical feasibility is an important requirement for the implementation of electromobility. Therefore, an investigation of the performance of electric vehicles and charging infrastructure is carried out.
As a next step, mobility concepts for urban, rural and urban-rural areas are developed that involve measures with the greatest potential to reduce transport-related energy consumption and emissions. A specific mobility concept for the Leingarten community is devised and evaluated energetically by simulating the environmental impacts.
Editor: Juliane Schanze
Tutor: Tomislav Boras – ZEAG Energie AG, Prof. Dr.-Ing. Clemens Felsmann
Year: 2018

Investigation on integration of solar thermal plants in an existing district heating network
In this thesis a decentralised solar feed-in into an existing DH network build in 1993 was simulated. The network has an installed thermal load in total of 3,4 MW by 19 consumers. An analysis of preprocessed measurements showed an average inlet temperature of 80 °C and return temperature of 61 °C. Differential pressure at the zentral heat generator was 1 bar on average.
A potential assessment turned out negative for ground-mounted systems in the network areal, but showed up a rooftop surface of 15.000 m² in total which fits for installation of solar collectors. The performed simulation study compared eight systems, differentiated by location of feed-in, collector area, collector tilt and orientation, station concept and storage usage. The systems split up in four categories: ST - feed-in with A_K,brutto = 250…320 m², SP - feed-in with 50 m³ tank and A_K,brutto = 1.000…2.000 m², SPN - feed-in with target temperature increase and A_K,brutto = 1.000…2.000 mm², ST-TWE - local solar thermal support of drinking water heating at 17 consumer locations without feed-in and A_K,brutto,sum = 354 m².
Simulation results show category ST systems achieving a solar faction of around 2 % with only 10 days were the solar thermal plant runs into stagnation. The category ST-TWE system reaches an equivalent solar fraction of 3,6 %. Results for category SP/-N systems show 78 to 186 days of stagnation which is a clear sign of an oversized gross collector area compared to DH network and tank size. But the results proof the energetic feasibility of a solar fraction above 5 % in networks of this size. The simulation of a target temperature increase for solar feed-in within category SPN systems results in a small decrease in specific annual solar yields compared to category SP systems but without the entire tank installation.
A first cost estimate of the heat producing costs of each system and comparison to the current heat price of the network of 68,56 €/MWh was done. It turns out only some category ST systems can get below the heat price. But with multiple funding programmes and scaling effects for bigger plants the other systems will at least match the heat price. Overall the smaller south-west orientated solar thermal plants turn out to be most cost-efficient.
Editor: Kaspar Konrad
Tutor: Dipl.-Ing. Sven Paulick, Dipl.-Ing. Christoph Schroth, Dipl.-Ing. Matthias Mehnert – WVR GmbH, Dr.-Ing. Helmut Adwiraah – Averdung Ingenieurgesellschaft mbH
Year: 2018

Phenomenological Modeling of a latent heat storage and model based design of a demand oriented control of a heating system
In the project Heat2Go of the Fraunhofer IVI, a latent heat storage heater is being developed, to heat electric city buses in winter emission-free and without any restriction of the range. As a part of this project, a heat storage heater simulation model is developed in MATLAB-Simulink. Based on that, a needs-based control is designed. The model consists of the submodels interior, heating circuit and phase change material (PCM)-heat storage. For the PCM-storage, which is electrically charged and hydraulically discharged, a charge state analysis is performed. The interior model is validated, regarding to its heat transfer coefficient and its capacities, based on measured data. Continuing the heat demand of the bus is examined on the interior model. As an example, the control is tested on a real driving cycle for different ambient temperatures. Also, a coupling of the created thermal model, with an electric model of a bus takes place. With that, an usage optimization of the PCM-storage, using recuperation energy, can be tested and its effects on the cyclical life of the traction battery are considered.
Editor: Daniel Scholz
Tutor: Dipl.-Ing. Stefan Kuitunen – Fraunhofer-Institut für Verkehrs- und Infrastruktursysteme IVI, Prof. Dr.-Ing. Clemens Felsmann
Year: 2018

Measurement of the temperature distribution of a large atmospheric heat storage tank - preparation and evaluation of the data
An atmospheric heat storage tank was equipped with the new measurement Distributed Temperature Sensing (DTS). The heat storage tank is also equipped with the standard sensoring, which is need for the daily operation mode. This document gives an overview of the preparation of the DTS-data. With them the vertical temperature distribution, especially the layer between hot and cold water, is evaluated. A horizontal part of the meassurement gives also the oppertunity to investigate the temperature distribution under the lower diffusor. To prepared and evaluate the DTS-Data the data of the standard measurement are preparade and interpolated on time of the DTS-data. After that the DTS-data gets an allocation in the tank. Therefore, special points of the measurement system are identified. After the preparation there is a visualisation of the data in an animated way. With this animation some special situations in operation mode are chosen and descripted.
Editor: Jana Reichelt
Tutor: Dipl.-Ing. Andreas Herwig
Year: 2018

Elaboration of an internal energy communication concept for site 40 with regard to ISO 50001 requirements
For a successful energy system transformation in Europe and maximum energy efficiency increases, the employees of a company must be involved. Without this link, the full potential of reducing energy consumption will not be exploited. Against this background, an energy communication concept for the Mercedes-Benz plant in Berlin will be developed within the framework of this diploma thesis. The goals are to meet the communication requirements of DIN EN ISO 50001, to develop meaningful energy indicators and to strengthen energy awareness in the production area.
Through quantitative and qualitative employee interviews with various groups of people, the requirements for energy communication in the production halls, which are regarded as the most energy-intensive areas in the plant, were developed. To ensure effective reporting in the production area, new energy indicators will be developed to increase energy awareness. In addition, possible measures taken by employees to save energy and improve the performance indicators are presented. The final research topic is the development of an internal energy communication concept for the production area.
The surveys of employees in production revealed a need to improve energy communication. More up-to-date information on energy consumption with short-term reporting intervals and comprehensible key energy figures are desired. The energy reporting system was expanded to include monthly hall reports and a weekly report for a pilot cost center. In this context, three new energy efficiency indicators were developed, which enable the electricity consumption per cost center to be allocated according to the cause and can serve as a control instrument. This provides employees with a faster means of reducing consumption. Finally, an energy communication concept has been developed for the production area that meets the requirements of ISO 50001 of 2011 and the revised draft standard of 2017.
Editor: Fabian von Bienenstamm
Tutor: Andreas Klotz – Daimler AG, Prof. Dr.-Ing. Clemens Felsmann
Year: 2018

Heat pumps and CHP - a reasonable combination?
Power systems connecting heat pipes and technologies of cogeneration (CHP) are currently rarely used. This paper examines possible ways of application and the resulting technical demands. In this case the focus is set on compression heat pumps and motor-driven block-type thermal power stations.
First, different concepts of this connection are presented. In the second part an exemplary plant is simulated under aid of the program Polysun. Aspects of plant design as well as thermal and electrical storage are analysed. Another part of the examination is the performance of heat pipe and power station during operation and the implementation of control and automation systems.
As the results of the examination show, a combination of heat pipe and CHP can be used in a wide range of applications. The main area of operation could be objects with a combined demand for heat, power and refrigeration. Implementation seems realistic for residential areas, office buildings and public institutions. However, there are high demands on design and management of the energy system. High investment costs have to be compensated with savings during operation.
Editor: Jonay Brandel
Tutor: Prof. Dr.-Ing. Clemens Felsmann
Year: 2018

Design of a benchmark method for the evaluation of technical components within a overall energy system with high share of renewable volatile feed in using the example of the BMWi funding programme WINDNODE
This paper covers the design of a benchmarking methodology for the pilot project WindNODE, which seeks to demonstrate the operation of an energy system with high levels of volatile electricity generation as part of SINTEG (“Smart Energy showcases – Digital agenda for the energy transition”), a programme funded by the German Federal Ministry for Economic Affairs and Energy. A benchmarking study will be used to validate the scientific and technical results of the project by means of a qualitative comparison with matching projects all over Europe and will also determine possible further utilisations for these results. Since the traditional benchmarking method as described by Robert C. Camp is only intended for market-based businesses, and even modifications, such as Patricia Keehley’s and Neil Abercrombie’s version for the public and non-profit sectors, cannot facilitate the application to a very thematically complex pilot project, the purpose of this paper is to adapt the stages of the original benchmarking process for WindNODE’s thematic and organisational characteristics as well as the temporal
restraints that come with a governmentally funded project.
The adaptation and designing process for this new benchmarking methodology consists of developing appropriate qualitative metrics that will enable the study to consider both the system approach that is present throughout all WindNODE’s project activities (system metrics) as well as a standardised assessment of individual concepts or practices (concept metrics). To allow for a qualitative comparison, the metrics are specified as a set of scales, each with several achievable statuses, that are derived from
a frame work describing different degrees of success in reaching the German energy transition goals. The performance gap can be determined by assigning ordinal values to these statuses and subsequently calculating the difference between the status value of the benchmarking object and the status value of the benchmarking partner. Depending on the type of the performance gap (positive, negative or parity), varying courses of action are required. Additionally, the methodology provides criteria for the selection of benchmarking partners, following both a concept-based approach as well as a systembased one, to ensure a coverage of all issues relevant to the WindNODE benchmarking study that is as exhaustive as possible. Finally, the method offers a detailed action plan for the execution of all necessary sub-studies. It is then tested for functionality in a pilot study with the benchmarking partner Smart Grid Gotland.
The test study shows that the benchmarking methodology can be applied in the desired way and will be applicable for the WindNODE benchmarking. To avoid possible misunderstandings regarding the qualitative and simplifying character of the comparison, or its prevailing purpose (validating the results of the project, indicating problems and opportunities), caution is advised when communicating the results of the benchmarking study. For similar benchmarking projects, consideration of further controlling and quality management tools is recommended due to the significant time and effort involved in carrying out the study; or at least an equally as thorough adaptation to the parameters of the respective benchmarking object as described in this paper in regards to WindNODE.
Editor: Wiebke Kraeft
Tutor: M. Graebig, WINDNODE / 50 Hertz, Prof. Dr.-Ing. Clemens Felsmann
Year: 2018

Technical and economical comparison of solar-assisted block heating systems
Falling heat demands as a result of increasing demands at building insulation lead to decreasing heat density at quarters. Furthermore environmental goals require a reduction of greenhouse-gas-emissions at heating supply.
In this context does the present paper look for possibilities to support the heat supply of quarters by solar energy through the use of LowEx heating networks (Low temperature heating networks). Two quarters with different heat densities are evaluated. One quarter is characterized by urban apartment buildings and the other by rural detached houses. For both of the quarters are designed two supply concepts. One concept with solar energy, delivered through photovoltaics in combination with compression heat pumps, and one concept with solar thermal energy is designed.
The concepts are compared on the Basis of simulations with the Polysun Designer software. Technical, energetic, ecological and economic aspects of the supply solutions are discussed.
Editor: Peter Scheer
Tutor: Dr. Tilman Werner, Dipl.-Ing. Katja Weinhold (DREWAG Stadtwerke Dresden GmbH), Prof. Dr.-Ing. Clemens Felsmann, Dr.-Ing. Karin Rühling
Year: 2018

Comparative evaluation of heat pump application in buildings
In this paper, the future role of heat pumps will be investigated. First, an overview of the climate goals to be achieved is given, after which the target scenarios (based on these goals) are compared with the trend scenarios, which represent a more real development. As a result of this comparison, the desired and the real achievable heat pump shares in the overall heat supply should be identified and the deviations occurring should be discussed.
In the next part of the thesis, the different heat pump types and technologies will be presented. It is concentrated on the electrically operated heat pumps. Here we want to show for which species a leading role in the future is predicted and which varieties will remain in niche potential. During the evaluation, the focus is on the building sector.
The last part of the thesis defines concrete application scenarios for heat pumps. Based on suitable reference cases, the heat pump types that are relevant for the future are compared with each other and with conventional fossil heat generators. The aim is to find out to what extent the heat pumps can contribute to minimizing the climate impacts (primary energy and greenhouse gas reduction) of the building sector in specific application cases.
Editor: Boglárka Johanna Braunitzer
Tutor: Prof. Dr.-Ing. Clemens Felsmann
Year: 2018

Numerical analysis and comparison of cross-corrugated tubes with conventional tubes in shell and tube heat exchangers
In the present work the heat transfer and pressure loss in the inner and outer flow of crossed spiral tubes was determined by numerical simulation. It could be proven that the structuring of the wall surface led to a substantial improvement of the heat transfer compared to smooth tubes. At the same time, an increased pressure loss was determined due to the higher pipe friction coefficients. For the simulations, the SST turbulence model was used, with which the tendencies of the experimental results from the literature could be proven.
Editor: Alexander Bouguila
Tutor: Dipl.-Ing. Torben Möller – G.A.M. HEAT GmbH, Prof. Dr.-Ing. Clemens Felsmann
Year: 2018

Comparative evaluation of methods to be used to estimate seasonal energy performance of heat pumps
Seasonal Coefficients of Performance of heat pumps define the efficiency of the provision of useful heat via auxiliary energy over a specific period of time. The Seasonal Coefficients of Performance determined by prognostic methods often deviate from the results during real operation. Predictable efficiency values, profitability and environmental compatibility is essential for investors and funding programmes. Consequently, this project thesis investigates the methods of the three norms VDI 4650, DIN EN 14825 and DIN V 18599. These methods are applied to a model created by the simulation software POLYSUN. Performance data is acquired through the variation of boundary conditions during a sensitivity analysis and subsequently discussed.
Editor: Marc Kammerer
Tutor: Prof. Dr.-Ing. Clemens Felsmann
Year: 2018

Energy-economic analysis of CHP marketing strategies
This paper treats the means of promotion for combined heat and power plants (CHP) in Germany according to the CHP and Renewable Energy Laws (Kraft-Wärme-Kopplungsgesetz KWKG and Erneuerbare-Energien-Gesetz EEG). At first the promotional measures of the respective laws will be displayed, to secondly evaluate and compare the past grants with regard to their efficiency and goals reached. Thirdly the influence of the promotions on construction and operating mode of a block type thermal power station for a single-family household will be examined.
As a result, the high rates according to EEG allow for a more economic operation of biomass plants compared to oil and gas fuelled stations as well as biomass plants promoted by KWKG.
Editor: Hannes Friedrich Knischewski
Tutor: Prof. Dr.-Ing. Clemens Felsmann
Year: 2018

Development and testing of a wireless-based system for data transmission within buildings
The energy transition aims to eciently cover the energy requirements of buildings and neighbourhoods with a maximum share of renewable energies. In this context, virtual power plants, which integrate decentralized producers and consumers into pools, are an important tool. The TEK-EKG project responds to this need by developing a short-term analysis system. This should enable an accurate and well-founded recording of the energy supply characteristics of a property. In regards to this task, the conception of a robust communication system for the radio-based transmission of data in buildings was of central importance and the goal of this work. In a literature research, the state of the art was described, then the technical requirements of this system were recorded and defined. Subsequently, a market research was carried out, which led to the selection of the radio modules "LoPy" of the company "Pycom". Within the scope of field tests, these were programmed to simulate typical data traffic in buildings and generate measurement data. A sandstone building and typical concrete building were chosen as test environments. In an Excel evaluation, the arrival rate was calculated based on the above-mentioned results. The results were summarized, compared and analyzed.
Editor: Karam Chehade
Tutor: PD Dr.-Ing. habil. Joachim Seifert, Dipl.-Ing. Paul Seidel
Year: 2018

Considerations about the energy performance evaluation of heat pumps
Heat pumps offer a large saving potential of primary energy, both for heating and cooling of buildings, by their high possible efficiency values and the usage of environmental heat. Nevertheless, the efficiency values in real operation repeatedly deviate from those of the design and endanger the economic efficiency of the plants as well as their energetic meaning. In this paper, the measured values of a real heat pump system, which uses geothermal energy as a heat source, are set in relation to the expected, calculated efficiency values. For this purpose, the calculation of the coefficient of performance using VDI 4650 is explained and current, real efficiency values are presented using a meta-study which analyses the development of efficiency and also sources of error. Subsequently, an evaluation of the temperature development of the geothermal probe field since commissioning and its influence on the surrounding soil follows on the basis of a specific object. Finally, measured and expected values are compared and suggestions for a better prediction of the efficiency parameters are developed. In this context, the difficulties in optimising real projects, for which no monitoring was originally planned, are discussed.
Editor: Philipp Röll
Tutor: Prof. Dr.-Ing. Clemens Felsmann
Year: 2018

Considerations about heating and cooling load calculations based on building simulation
Within the scope of this work, a programmatic implementation for the simulation of room temperature, heating and cooling loads was realized in C++ based on certain standardized calculation algorithms from standard ISO 52016/52017. Plausibility studies and validation runs were carried out to evaluate the prediction quality, reliability and robustness of the implementation. Furthermore primary testing was executed to evaluate the performance. The development status is fully documented and discussed for further research.
Editor: Richard Franke
Tutor: Prof. Dr.-Ing. Clemens Felsmann, Dr.-Ing. Alf Perschk
Year: 2018

Experimental Investigation on a Thermosyphon based on several Ferronanofluids
In this research, an experimental study was conducted with the existing experimental system of the short thermosyphon of the ILK GmbH Dresden. The presented study aims to investigate the heat transfer performance of the short thermosyphon using a newly manufactured ferrofluid with / without magnetic field. Deionized water is employed as the reference working fluid.
Compared with using deionized water, a reduction in thermal resistance of the short thermosyphon was obtainedat low inlet temperature of the evaporator when using 5 vol.% ferrofluid as working fluid and an increase in thermal resistance of the short thermosyphon was achieved at medium to high inlet temperature of the evaporator when using 5 vol.% ferrofluid as working fluid. The changes in thermal resistance of the short thermosyphon with the 5 vol.% ferrofluid were weakened by the applied magnetic field
Editor: Shen Liu
Tutor: PD Dr.-Ing. habil. M. H. Buschmann - ILK GmbH Dresden, Dr.-Ing. Karin Rühling
Year: 2018

Considerations about cooling loads and thermal summer protection in buildings
Within the framework of the graduation thesis, the basics of the minimum requirements for summer heat insulation in accordance with DIN 4108-2 and the cooling load calculation according to VDI 2078 are determined as a priority. And the consistency of the boundary conditions is checked. In addition, proof of summer heat protection and calculation of cooling load for the example buildings (residential and non-residential buildings) are performed by simulation software and the calculated data are compared with each other to analyze the influence factors. Finally, structural and technical measures for reducing the cooling loads are compared with each other according to the cost and their environmental impacts, from which a priority list for those measures is derived.
Editor: Yulong Shang
Tutor: Dipl.-Ing. Markus Arendt
Year: 2018

Considerations about the energy efficient cooling of buildings
The present work deals with the energy-efficient cooling of buildings. Because of rising temperatures and increasing comfort requirements the energy required for the cooling of buildings will further increase. In order to keep the burden for the power grid low, two approaches are examined. The first approach concerns alternative technologies to the electrically operated compression refrigeration systems. Established options are the thermally-n advantage of these systems is that they can be driven via solar thermal systems. The second approach is a grid-supportive operation of electrically driven compression chillers. The use of thermal storages as a flexibility option can shift the power purchase in more favorable times. The Grid Support Coefficient, as an indicator to rate the power purchase with regards to economical and ecological parameters, is presented. Finally the cooling supply system’s power purchase which is optimized in terms of two evaluation parameters is rated using the Grid Support Coefficient. It can be seen that the installation of flexibility options has a positive impact on the Grid Support Coefficient but is not yet financially worthwhile when looking at refrigeration only.
Editor: Leona Freiberger
Tutor: Dipl.-Ing. Juliane Schmidt, Prof. Dr.-Ing. Clemens Felsmann
Year: 2018

Creation and practical validation of a control concept for a heat pump system solution for parallel heating and cooling
The following work describes the development of a control concept of a heat pump system for parallel heating and cooling in co-operation with the heat pump manufacturer Glen Dimplex Thermal Solutions (GDTS).
On the basis of the predefined control algorithms, a new control concept is developed, which enables the operation oft the considered heat pump system for parallel heating and cooling.
With the operation of a pilot plant, the functionality of the developed control concept could be proven and optimized.
In addition to that, the hydraulic-concept oft he considered heat pump system is checked. Necessary safety devices according to DIN EN 12828 are described. A first calculation of the hydraulic concept and necessary components is made. By using existing components of the manufacturer GDTS, the heat pump system can be designed with variable heating and cooling performances. Finally, the energetic use of the considered heat pump system is shown. For that, the supply of an example scenario with two different systems is considered. The primary energy demand and the greenhouse gas emissions that arise during the operation of the two systems are determined and compared.
Editor: Jakob Beetz
Tutor:apl. Prof. Dr.-Ing. habil. Th. Hackensellner – Glen Dimplex Deutschland GmbH, PD Dr.-Ing. habil. Joachim Seifert
Year: 2018

Analysis of Features and Advantages of modern planning programs for technical building equipment regarding an upcoming software change at the company LUXHaus
Since the department “building technology” at the firm Luxhaus was using an outdated planning program a software changeover became necessary. Based on five requirements the choice could be limited to three possible programs. Finally, the currently used Plancal nova in its newest version was chosen because its costs are little, and it mostly meets the requirements.
In the new program a reviewed planning procedure should be used. This newly developed procedure includes drawing in 3D, calculation of technological systems, and generating quantity lists. The new method requires 20 % more time for each building but offers advantages like 3D visualization, provable standard conforming dimensioning and a precise quantity survey, which is supposed to save expenses.
The user of the new program should be able to apply Building Information Modelling (BIM). BIM allows the collaboration of all disciplines, which are involved in the planning, construction, and operation of a building, in one virtual model. This model contains building information and is being updated after every single modification. Since the other departments work with different software, the use of BIM at Luxhaus with Plancal nova is only possible to a limited extent.
It became clear that engineers of building or energy technology should have extended skills of using planning software for technical building equipment. Therefore, the extension of an existing course at TU Dresden is reasonable, so that the students meet those requirements.
For this purpose, a course assignment for using a planning program is possible.
Editor: Niklas Wank
Tutor: Patrik Gangl (B.Eng.) – LUXHaus GmbH & Co KG, Prof. Dr.-Ing. Clemens Felsmann
Year: 2018

Integration of an Ice Storage into a Mono-Split-AC-System for Increase of PV-Self-Consumption in Solar-Driven Air Conditioning Systems in Residential Buildings – Development and Investigation of a Forecast Control System
Due to the relationship between solar radiation and the need for cooling, there is a great potential in the use of photovoltaic energy for residential air conditioning. This potential can be significantly better exploited by integrating an energy storage unit into a solar-driven air conditioning system. As part of this thesis, the implementation of a control algorithm for an integration variant of an ice storage in a mono-split air conditioner is being investigated at the Institute of Air Handling and Refrigeration Dresden. The objective is to increase the self-consumption of the generated power and to store cold for times without photovoltaic yield. For this purpose, a preselection of potential hardware is made and evaluated. The control variables at the test bench must be identified and controlled by the selected controller. After deciding on a platform, the previously simulated logic is translated into a python program. With a view to the overall objective of developing a marketable solution, some PT100 probes are replaced by digital sensors. To include forecast data for cooling demand and pv yield in the control algorithm, these data is queried by a web server. After the commissioning of the control system and the first series of measurements with variable heat load and variable pv power, the developed solution forms the basis for further investigations. Based on this work , the predictive management strategy can be investigated in further long-term tests.
Editor: Tobias Franzky
Tutor: Dipl.-Ing. Carsten Heinrich – ILK Dresden, Prof. Dr.-Ing. Clemens Felsmann
Year: 2018

Development and Validation of Plate Heat Exchanger Models in District Heating Applications
This paper deals with the modelling of plate heat exchangers in case of dynamic changes in operating conditions.
Due to the increased use of renewable energies, dynamic changes in operating conditions in the energy networks occur more frequently. Therefore, the models of components of these systems must also be able to depict the dynamic operating behaviour. With the mathematical and physical fundamentals and the analysis of different model approaches, two different models could be implemented: the epsilon model and the cell method model. Four different plate heat exchangers were measured for an initial validation. After a detailed analysis of the simulation results, it could be shown that the models deviate a bit from the real measured data and have certain validity limits. Finally, a plate heat transfer could be mapped under dynamic operating conditions. This was particularly evident in the validation of the epsilon model using the measurement data of a plate heat exchanger in a HANEST.
Editor: Mathias Hauskeller
Tutor: Dipl.-Ing. Sven Paulick
Year: 2018

Establishment of a thermal response test as basis for long-term investigation of a borehole field assisted by distributed temperature sensing
The seminar paper on hand is concerned with the Thermal Response Test (TRT) as
possibility for an analysis and oberservation of soil. The focus is on a depth-dependent
evaluation.
At first the examined plant in the ZET of the TU Dresden as well as evaluation methods
of a TRT are presented. After a literature research of similar TRTs the findings are adapted to the plant as effectively as possible.
The realised experiment is evaluated in terms of soil properties and outside influences.
Furthermore a thermodynamic approach as well as an attempt of a simulation are implemented to allow a depth-dependent evaluation despite the exceptions of the plant.
Finally suggestions for further researches at this plant are made which shall be integrated into an internship for students.
Editor: Tiedo Hele Behrends
Tutor: Dipl.-Ing. Stefan Hoppe, Dipl.-Ing. Jan Löser
Year: 2018

Integration of hot / cold water storages at Technische Universität Dresden
In this thesis the usage of large cold water storages will be evaluated for two location at the Campus of TU Dresden. The first location is the Andreas-Pfitzmann-Bau. The cooling demand is characterized by the low temperatures that are needed for the cooling of the building and that the demand is constant until 10 C, above this temperature the needed power rises proportional to the outdoor temperature. The second location is the Lehmann-Rechenzentrum, which has a constant cooling demand that is not influenced by the the temperature outside. Additionally the temperature level is higher.
The simulation of different system concepts is made by a self created excel-tool. Two different concepts for control of the storage use are implemented. The first way is to use a prognose of the outdoor temperature to control the use of storage in the summertime. The second way is not to use this prognose. The storage capacity is variated to find the most cost-effectiv solution.
Editor: Alexander Hentschel
Tutor:Dr.-Ing. Annina Gritzki
Year: 2018

Investigation on thermal load management for a waste water treatment location in case of increasing renewable performance
This thesis investigates the integration of solar thermal plants and waste heat utilisation
of cogeneration units at the waste water treatment location of the Stadtentwässerung Dresden. For three potential areas, different solar thermal plants were designed. After their output capacities were calculated by means of the simulation software Polysun Designer and the measurement data of the cogeneration units were analysed, operation concepts could be developed. These base on the feed-in into the close-by district heating system. Since the solar thermal systems and the cogeneration plant were dealt with at the same time, it was only evident in the end that the generated heat would exceed the capacity of the district heating network in summer. A profitability analysis according to VDI 2067 has nevertheless shown that the installation of a solar thermal plant and usage of the available waste heat are recommended.
Editor: Maren Voß
Tutor: Dr.-Ing. Karin Rühling, Dipl-Ing. Thomas Schöniger – Stadtentwässerung Dresden GmbH, Dipl.-Ing. Bernd Klimes – INNIUS DÖ GmbH, Dresden
Year: 2018

Modeling, simulation and life-cost analysis of Fifth generation district heating and cooling (5GDHC) networks
Fifth generation district heating and cooling (5GDHC) networks are characterized by supply temperatures in the ambient range of 15-25 °C, which not only reduces heat loss but also allows for integrating various kinds of low-temperature waste heat sources. The ability of these networks to absorb waste heat that is normally unrecoverable makes them an attractive solution for the future energy supply of urban areas. To enhance the adoption of these networks, this research pursues the development of a software tool to analyze the feasibility of 5GDHC systems in both new and existing districts.
The research attempts to answer the question, \which buildings should be connected to a low-temperature hydraulic network given both the incremental bene ts and costs relative to the scenario of decentralized (dedicated) heating and cooling of each building?" Therefore, all possible network layouts of the buildings are considered where the heating and cooling demands of each building are met by the 5GHDC network. Simulation results quantify the performance of the 5GDHC network based on various output metrics, including primary energy usage, CO₂ emissions, and network implementation cost. The buildings in these networks constitute as thermal energy prosumers since the buildings can at times act as consumers, and at other times as producers, depending on whether a building is in a heating or cooling mode. For the heating and cooling load characterization of the buildings, reducedorder models are used while renewable energy and waste heat sources are included in the network.
The focus of the thesis lies on the development of a hydraulic model for exible use in the
urban energy modeling and the optimization of the 5GDHC network topology for a given
urban district.
Editor: Justus von Rhein
Tutor: Prof. G. Henze – University of Colorado, Boulder USA , Prof. Dr.-Ing. Clemens Felsmann
Year: 2018

Investigation of a ventilation concept with partially central fans
The main purpose of this thesis is to investigate the energetic and economic assessment of two air ventilation concepts for a new building, the Technical Criminal Department (TCD) in Dresden. The TDC follows the valuation system for sustainable buildings and its conditions. Based on these conditions, two air ventilation types were selected, a conventional single duct air conditioning system and an innovative system with a central air conditioning unit and decentral fans. By calculating the necessary air volume flow and the pressure loss in the constructed duct system, suitable units and fans were selected. Afterwards both systems were evaluated, by determining the energy demand and costs during the typical utilisation period of an air ventilation system. Thus the potential of the new system for both energetic and economic savings shall be displayed
Editor: Hoang Thanh Long
Tutor:Dipl. –Ing. Michael Deuble (Planungsgruppe M+M AG, NL Dresden), PD Dr.-Ing. habil. Joachim Seifert
Year: 2018

Use of an air-to-water heat pump in a historical building
In the context of this thesis, the example of the complete renovation of a listed mixed-use building will be used to investigate the possibility of using a heat pump under given conditions and estimate the improvement in the building energy efficiency and the reduction of CO₂emissions compared to a conventional heat generator. For this purpose, the building will be introduced, and the building heating load is calculated used as basis for the later designing of the heating system. After describing the common heat pump types on the market, the prevailing local conditions will be examined, by means of which suitable heat pumps will be selected. Four concepts are used for the software-based primary energy analysis according to DIN V 18599, of which three are suitable for practical use.
In conclusion, for the treated building with an electric air-to-water heat pump compared to a conventional heat generator, primary energy savings of 34 % and CO₂ savings of 19 % can be achieved. This concept, compared to these using a condensing gas boiler without and with an additional gas absorption heat pump, causes 13 % and 22 % higher costs, respectively, with a view to future rising energy prices for electricity and natural gas.
Editor: Christian Beise
Tutor:Dr.-Ing. Annina Gritzki, Dipl.- Ing. U. Linkmann – IKG-Ingenieurbüro
Year: 2018

Investigation on the influence of different system designs and control methods on the PV internal consumption and grid purchases for solar-electric air-conditioning systems based on mono-split-systems with integrated ice storage
This work is about the solar-cooling-simulation by using the coupling of a mono-split refrigeration system and an ice storage. The energy performance of this complex cooling system is researched by Dymola (Modelica). The model mainly simulates the influence on the energy performance of the cooling system, for example, the control method, implementation variants for ice storage integration, size of ice storage and location. A PID-controller is used in the model. Optionally, a weather forecast can be integrated by using fuzzy control. The results show that relatively more complex implementation methods and control methods significantly reduce the user's dependence on the power grid. In addition, the combination of ice storage and refrigeration system is more efficient in hotter areas than in colder areas.
Editor: Ming Sheng
Tutor: Dr.-Ing. André Kremonke, Dipl.-Ing. Carsten Heinrich –ILK Dresden
Year: 2018

Heat recovery in ventilation systems installed in existing buildings
To reduce power consumption and greenhouse gas emissions from ventilation units, the European Union released a regulation. This regulation makes requirements for heat recovery and ventilation power. This paper shows what impact these requirements have for existing buildings and presents technical possibilities for central ventilation stations. Different flow rates for supply and exhaust air were integrated in the calculations and the degree of efficiency for heat exchanger connected in series considered. Supported by user requests and flow rate calculation from “Württembergische Landesbibliothek” possibilities for renovation were investigated and based on technical, economic and structural practicability compared. Finally variants to declare the conformity for the regulation are presented. Due to the structural conditions of the library only a central heat recovery system can be integrated.
Editor: Lukas Rothmann
Tutor: Dipl.- Ing. Sebastian Günther – Günther Ingenieure GmbH Dresden, Prof. Dr.-Ing. Clemens Felsmann
Year: 2018

Investigation on electric load management for a waste water treatment location in case of increasing renewable performance
The present study investigates the potential of increasing the degree of energetic self-sufficiency through photovoltaic systems for the area of the municipal sewerage of the city Dresden which is located in the district Kaditz. Based on a research on the technologies of electrical energy storage, a comparison has been made between the currently most important battery technologies. By creating detailed concepts of photovoltaik systems for two roof surfaces and one open space with the simulation tool Polysun Constructor from Vela Solaris, yield forecasts were generated. These have been compared with the generation and supply profile of the municipal sewerage. Variants of the operational management were designed taking into account a battery storage system. Recommended price quotations were obtained for the plant concepts and afterwards an economic efficiency study was carried out in accordance with the norm VDI 2067 with and without storage. Finally, recommendations for further action of the operator of the municipal sewerage are described.
Editor: Merlin Mitzel
Tutor: Dr.-Ing. Karin Rühling, Dipl-Ing. Thomas Schöniger – Stadtentwässerung Dresden GmbH, Dipl.-Ing. Uwe Burmeister – INNIUS DÖ GmbH, Dresden
Year: 2018

Development, implementation and test of a state machine for the HANEST functional model
The decentralized integration of solar heat plants on existing district heating systems could be a contribution to lower emissions of the heat supply of cities and municipalities. A statemachine based automation of the experimental plant HANEST at the TU Dresden shall help to get exact, fast and uncomplicated earning prediction. It’s also possible to analyse and compare the behave of the plant while proceed different typical test days. The unification of the data preparation and of the following graphic building makes the evaluation standardized and more easy to read. To get a efficient and a low-vibration operation behaviour the regulatory parameters of the valves and pumps have been adjusted. With a low-vibration system it’s also easier to define the state change criterias. The comparison of the automated and hand done messurement shows quit the same results. The state changes occurred without problems. The HANEST test plant could give important insights for practical realized plants with similar architecture.
Editor: Johann Höflitz
Tutor: Dipl.-Ing. Toni Rosemann
Year: 2018

Application of batteries for operating reserves – Development of an EXCEL-simulation tool
The German energy transition comes with a radical change of the national energy market. New technologies are applied to provide operating reserves. Those are needed to keep the power grid stabilized and to ensure security of supply while the fluctuating power generation is rising. Batteries are excellent suited to do this – they provide fast and precise compensation for shortterm fluctuations in the power grid. Today batteries can only do FCR, in the future they should be used for aFRR and mFRR as well. While FCR is provided for short periods aFRR and mFRR must be available for at least four hours. Compared to the use in the FCR the battery power must be much lower by using the same battery capacity. For the provider of the operating reserve this is not economically viable. This document discusses the opportunities for batteries to be used in the aFRR or mFRR especially considering the usage of targeted transactions to keep the state of charge within certain limits. Intended to point out limits in the choice of the battery parameters an EXCEL tool was developed to simulate a battery suppling aFRR,
based on the guideline of the TransmissionCode and historical aFRR call-off data.
Editor: Martin Merkel
Tutor: Arndt Neubauer – Tennet; Ronny Strobel – Tennet, Prof. Dr.-Ing. Clemens Felsmann
Year: 2018

Multiobjective and lifecycle optimized design of energy systems
In the course of the climate targets defined by the Federal Government complex incentive programs evolved, which aim at raising the standards in different sectors. One of these sectors is the energetic modernisation of buildings. One possibility to increase the efficiency of an existing building is the addition or new installation of the already available heating unit's components with a combined heat and power unit. The basic conditions relevant to this case are going to be discussed in the paper at hand and applied in a simulation model. The simulation optimises multi-objectively both relevant factors for the lifecycle of the heat and power unit and monetary factors. The subsequent analysis with the aid of the developed algorithm enables the user to conduct a potential analysis of the modernisation measure and as a consequence contributes to the realisation of the climate targets.
Editor: Felix Taubert
Tutor: Dr. rer. nat. Peter Stange
Year: 2018

Energy-related analysis and evaluation of buildings and building-related energy systems based on performance indicators applied on the “Schul- und Sportzentrum Lohr am Main”
The aim of the diploma thesis was to assess and evaluate the energy performance of the
buildings and technical installations of the „Schul- und Sportzentrum Lohr am Main“ with the help of performance indicators. Performance indicators should be defined based on the analysis of building certification approaches, relevant standards and guidelines. Subsequently, the building and plant engineering systems and subsystem at the „Schul- und Sportzentrum Lohr am Main“ were to be identified. The energy balance should be based on the available measurement data and the results should be evaluated on the basis of available benchmarks.
However, not all defined performance indicators could be formed with the available
measurement data. One reason for this was that the previous measurement period was too short. The diploma thesis is recommended for all those who are concerned with the energetic balancing and evaluation of buildings.
Editor: Tom Heinze
Tutor: Dipl.-Ing. Jens Kaiser, Prof. Dr.-Ing. Clemens Felsmann
Year: 2018

Modeling of an integrated portfolio management system accounting for generation, consumption and flexibility of grid-bounded operation
„In order to operate the future energy system safely, the need for flexibility increases. One way to provide more flexibility is to make the demand side more flexible. As part of this work, a portfolio-oriented energy management system will be developed in the MATLAB modeling environment. The management system has the task of minimizing the variable costs of energy consumption for the media heat, cold and electricity depending on existing generation plants of the site. Furthermore, within the management system it is possible to determine the added value of demand-side flexibility by participating in the spot or balancing power market. In this work, the quantification of the added value of marketing flexibility in the minute control power market and spot market for the year 2017 using a grocery store was examined. Taking into account the current constraints of the German market and the necessary investments, the marketing of demand-side flexibility did not provide any economic added value. This indicates that there are currently enough providers of flexibility in the market to meet the demand.”
Editor: Lucas Schröder
Tutor: M. Sc. Christian Wengert – BLS Energieplan, Dr.-Ing. Dipl.-Wirtsch.-Ing Juan José Victoria Villeda – BLS Energieplan, Prof. Dr.-Ing. Clemens Felsmann
Year: 2018

Use of data center waste heat recovery atTU Dresden
This paper analyses the current use of waste heat of the supercomputers (HPC) of the Lehman Centre - Computer Centre (LZR) in the Hermann Krone Building (KRO). First of all, the state of the art in the field of data centre cooling is presented and the various types of cooling are discussed. In connection with this, the various possibilities for using the carried-away heat and also waste heat are generally considered. Following the presentation of the current state of development at the LZR, HPC heat production, the use of waste heat in LZR and KRO and the heat dissipated to the environment are analysed on the basis of existing heat data. Load profile analyses and temperature comparisons of heat supply and demand are prepared and evaluated. It has turned out that about 50 % of HPC waste heat is currently being used. In the rough economic evaluation, the economic sense of waste heat utilization is proved. Finally, the possibility of using the unused amount of LZR waste heat in other buildings is assessed.
Editor: Boglárka Johanna Braunitzer
Tutor:Dr.-Ing. Annina Gritzki
Year: 2018

Further development of a flow test stand
In the field of energy engineering, fluid flows are measured to be used in calculations and evaluations. To determine and reduce the uncertainty introduced by the measurement, flow- meters get calibrated. This project report describes the planning, construction and evaluation of a test rig for flowmeter calibration. The results of the process steps literature research, con- ception, planning, implementation and testing are described in detail.
Furtermore an evaluation of the test rig in terms of measuring uncertainty is given. It shows that the assembled test rig is not able to calibrate flowmeters yet, because of high measuring uncertainties. These un- certainties can be improved by the integration of components and by performing more tests. Anyway, the target of constructing and evaluatong the test rig was met.
Editor: Johannes Bärschneider
Tutor: Dipl.-Ing. Karl Wolffgang, Dipl.-Ing. Paul Seidel
Year: 2018

Model based test of methods for the unit commitment in district heating networks
In the following thesis a model based test platform, for the purpose of validation and assessment of unit commitment algorithms, based on a district heating network, was developed. Basis for this was the development of a Modelica-based simulation model (SimulationX/Green City). This was done using real, technical conditions and parameters and is characterised by the heat generators, thermal storage, control units and the heating system (consumer) as well as their interaction and properties during operation. Through the flexible integration of Day-Ahead unit commitments, thermal load and temperature predictions a dynamic simulation of the system as a whole can be facilitated. The dynamics of the simulation takes into account complex technical and physical characteristics and parameters and thus enables a realistic depiction of operational procedures. The simulation model was tested based on plausibility and sensitivity, using real unit commitment algorithms. Through this the application possibilities, for the validation and assessment of said algorithms, could be depicted.
Editor: Ole Ziessler
Tutor:Dipl.-Ing. T. Schwan –EASD, Prof. Dr.-Ing. Clemens Felsmann
Year: 2018

Generation of Excel-based design tools for the approximate calculation of volume air flows in buildings and for the resultant indoor air quality
The subject of this thesis is the creation of two excel-based planning tools for the approximate determination of outside air flow rates through free ventilation in buildings and the subsequent assessment of the resulting indoor air quality in school buildings. The work is roughly divided into two parts.
First, the "Tool 1" is treated, which is intended for the determination of the outside air volume flows. First, a literature search is carried out on the free ventilation and infiltration of buildings, on the basis of which the algorithm for the tool is to be developed. Then all the important input and output variables are summarized, the tool interface presented, and the calculation results compared with the literature. A metrological comparison is not yet possible because the interpretation of the experimental results at the time of completion of this work was not yet available.
The focus of the second part is on the BNB tool, which is based on Tool 1 and should also calculate the CO₂ concentration over time in an office or school building using variable boundary conditions and evaluate the indoor air quality according to the BNB criteria profile [1]. For this purpose, a literature search is also carried out, a program schedule is drawn up and the user interface is explained. The results are then metrologically checked with your multi-week test series for the determination of outside air volume flows, CO₂ concentrations and indoor climate conditions for various concepts at the ILK Dresden. This is done by varying essential boundary conditions (e.g.: room occupancy, CO₂ output rate of the participants, outside air flow rates).
Editor: Hristo Markov
Tutor: Prof. Dr.-Ing. Thomas Hartmann - ITG Dresden, Dipl.-Ing. Christine Knaus - ITG Dresden, PD Dr.-Ing. habil. Joachim Seifert
Year: 2018

Economic Comparison for Heating and Domestic Hot Water Systems 2017-2035
A large part of final energy consumption in Germany is related to the generation of heat in the building sector. This makes heating systems an important carrier of the energy transition, which was decided in the climate protection plan of the Federal Government. Not only ecological factors are important for consideration. The cost-effectiveness of a heating system also plays a significant role, especially for the operator.
In this work, heating systems were examined for their profitability. First, it was compared for the reference year 2017 to capture the current situation. Thereafter, the impact of energy prices on the economics of a plant was studied to quantify their impact and to forecast future economics.
Under the proviso that ecological requirements also increase for future plants, the emission of CO₂ emissions and of primary energy consumption, with changing energy carrier parameters, was also examined. Assumptions and forecasts were made that could reflect a realistic development.
The compared heating systems were compared according to their current situation and possible development to make recommendations based on the assumptions made.
Editor: Florian Emmrich
Tutor: Prof. Dr.-Ing. Bert Oschatz - ITG Dresden, Dipl.-Ing. Jens Rosenkranz - ITG Dresden, PD Dr.-Ing. habil. Joachim Seifert
Year: 2018

Design of CHP-plants taking into account flexible und uncertain operation conditions
This thesis has been written to examine how uncertain design and operation conditions affect the economical effectiveness of a combined heat and power plant (CHP-plant). For the operator of an energy facility it is essential to know, if he gains an economical advantage and how big it is. The forecast is aggravated by the fact that it is impossible to predict the exact load and operation conditions years ahead. This is caused by unsteady external conditions, such as ambient temperatures and weather, and by altering technical and economic conditions, which require a certain flexibility.
The result is, that the sensitivity of CHP-plants concerning these topics depends on the direction, in which possible uncertainties are occurring. Overbuilt plants should be avoided by all means. It is more secure to pick a slightly inferior power capacity, even if it is not the optimal solution according to the design conditions. The full economic potential may not be achieved, but adverse scenarios, in which an inferior utilization ratio would be attained, could be avoided.
Editor: Jacob Kriehmig
Tutor: Prof. Dr.-Ing. Clemens Felsmann
Year: 2018

Development of a robust and mobile flow measurement system based on ultrasound
There are several ways to measure the flow through a pipe. Research was carried out to highlight the most common ways to do so, in order to nd the right solution for the design and development of a measurement system.
A single-board computer was incorporated to act alongside the actual flow meter, as the
centerpiece of the system. This paper aims to design a program which allows the computer to analyze the flow meter measurement data and store it in an appropriate le format that can be practical for the end user. The whole assembly of components was built into a solid hard-top case with several connection possibilities to ensure mobility and protection against environmental impacts. For testing and validation of the designed measurment system, different comparisons with different flow meters have been carried out. Documentation of the assembly and the generation of instructions are shown at the end of this paper.
Editor: Lukas Hubert
Tutor: Dipl.-Ing. Karl Wolffgang, Dipl.-Ing. Paul Seidel
Year: 2018

Analytical and experimental investigation of plate heat exchangers in cooling systems with ice slurry as a secondary refrigerant
The use of ice slurry can increase the energy efficiency of cold supply systems and reduce the amount of refrigerants that are harmful to the environment. In this work commercially available plate heat exchangers were examined for their suitability for ice slurry flow. For this purpose, a test rig was designed, built and integrated in an existing experimental test field. Substantial knowledge for this as well as for the selection of the test plate heat exchangers could be derived from a literature data analysis. Therefore, the focus of this work was on the investigation of the influence of different plate profiles. The design and installation of a flow calorimeter allowed a continuous determination of the ice content during the investigations. All of the selected plate heat exchangers allowed the perfusion of ice slurry. Nevertheless, an influence of the plate profile could be demonstrated. Finally, the results of the experimental investigations were compared with the substantial knowledge of previous work as well as the theories of the VDI-Wärmeatlas. Based on this work, further investigations can be carried out.
Editor: Johannes Schwarz
Tutor:Dipl.-Ing. Christoph Steffan – ILK Dresden gGmbH, Prof. Dr.-Ing. Clemens Felsmann
Year: 2018

Building simulation
In the beginning the basic principles of thermal building and plant simulation and other combinable kids of simulation are presented. This is followed by an overview on the legal aspects of energetic building design and the requirements of building certificates and state subsidies. To become familiar with the large amount of input parameters of simulation software the individual aspects of data entry will be addressed. An analysis of the planning phases of the German HOAI is followed by the discussion of preferably universal and not project-specific usages of simulation software and their allocation in the planning process. The temporal availability of input parameters is pointed out. An overview about how the input parameters are linked to the usages of simulation software is developed. The usages for which alternate static calculation methods are available are compared to those. Afterwards the ones for which no alternatives are accessible are introduced. The utilization of simulation software for quality assurance and operation optimization will be treated separately and in combination with the “Performance Gap” between predicted and measured energy performance of buildings, because these topics are particularly relevant for each other. An attempt is being made to quantify the economic aspects of thermal building simulation. Also, the future trends of simulation and the planning process itself are addressed. With Building Information Modelling a worldwide transformation of building design is currently taking place, which will have a strong impact on the application of simulation software. Finally, the potential for development of simulation in context of Machine Learning and Artificial Intelligence is presented. In addition to the theoretical elaboration of these issues, real projects have been simulated during the work at Firma SOWATEC GmbH. Extracts from these are to be found in the paper for visualization purposes.
Editor: Patrick Eger
Tutor: Dipl.-Ing. Jens Kaiser, Prof. Dr.-Ing. Clemens Felsmann
Year: 2018

Considerations about grid support of electric heat pumps
Higher shares of variable renewable energy in future power systems lead to a more fluctuating power production. If driven flexibly, electrical heat pumps can add to balance power production and power demand. In this paper, impacts of an increased number of heat pump units on the future energy system are investigated. Based on hourly thermal load profiles, electrical demands of installed heat pumps until the year 2030 are identified and compared to a model of electrical power production.
It is shown that higher numbers of heat pumps in individual dwellings can lead to reduced primary energy input and CO₂ emissions. Furthermore higher shares of renewable energies can be incorporated. At the same time increasing numbers of heat pumps result in higher residual loads. Primary energy input and CO₂ emissions of heat pumps can be further reduced by flexible operation. Moreover increasing the flexiblity of electrically driven heat pumps lead to the incorporation of higher shares of renewable energies.
Editor: Moritz Clausnitzer
Tutor: Prof. Dr.-Ing. Clemens Felsmann
Year: 2018

Economic, ecologic and technical evaluation of the heating and air-conditioning systems in an office building
This paper evaluates the optimation potentials of technical facility equipment in office buildings to increase energy and cost efficiency. The concept for analysing building technical systems is described in theory. The concept is applied to a concrete use case, analysing optimation potentials in the office building of GSA-CAD GmbH & Co. KG. The existing equipment is documented in CAD drawings in Autodesk Revit. The energy certificate is developed on the usage-based settlement of heat and electrical energy. Based on this, an assessment of the technical building equipment is performed. Hereinafter available technologies to complete or replace the existing systems to increase energy and cost efficiency are examined. The result of the investigation is illustrated in a calculation of the pay-off period based on annual savings and acquisition costs.
Editor: Christian Keil
Tutor: Dipl.-Ing. Andrea Meinzenbach, Axel Wulke – GSA-CAD GmbH & Co. KG, Udo Clement – GSA-CAD GmbH & Co. KG
Year: 2018

Modelling and simulation of a large hot water storage tank with COMSOL Multiphysics
The thesis „Modelling and simulation of a large hot water storage tank with COMSOL Multiphysics®“ had the aim to examine a 500.000 m³ pit thermal heat storage. The central focus was to show the realistic operation with a long term simulation. Identifying possible and necessary simplifications and considering the overall conditions a simulation model was created. A five year simulation provided detailled information about heat losses of the storage and ground warming. The results demonstrate that still after five years the storage heat losses don´t reach stationary conditions. Ground warming effects have an expension of about 30 m. The major part of the heat losses was identified at the floating cover and on the ground surface directly next to the storage. These parts of the storage reveal potential for optimization. A considerable heat input to a ground water layer which is located 10 m underneath the storage couldn´t be identified. As an theoretical input to the Green Heat³ project this thesis can be used for further investigations.
Editor: Alessandro Hülser
Tutor: Dipl.-Math. Anja Matthees, Dr. rer. nat. Peter Stange
Year: 2018

Considerations about the application of CHP in hybrid energy systems
This diploma thesis demonstrates the possibilities of additional CHP capacity by analyzing an existing multivalent heat generation system used in a hospital, with an installed capacity of 6.500 kWth and 420 kWel. The analysis evaluates this existing system based on past production and consumption data, examines existing errors, and identifies unused thermal and electrical capacities for enhanced CHP performance. These results then form the basis of energy considerations for different aggregates,
which are compared and evaluated for different characteristics, such as self-consumption of electricity. In addition to these parameters, the current legal framework conditions are established so that the conditions and subsidy rate provided by the German Combined Heating and Power Act (Kraft-Wärme-Kopplungs-Gesetzes) can be taken into account in the profitability analysis. Based on this information, the cost-effectiveness of different CHP aggregates are investigated and a comparison made with the development of capital values and payback periods in a business sense. Based on the
energy consumption and cost-effectiveness of the results, EM-238/363 was selected as the optimum CHP value for the heating system in question. This aggregate was then integrated into the hydraulics of the existing system and the corresponding components tested and sized accordingly. The overall construction measures were then evaluated in a rough cost estimate amounting to €290 thousand, which was used by the hospital to set up a financing plan as well as to verify the assumed investment costs in the profitability analysis.
All the necessary short-term optimizations of existing problems and the economical use of peak load windows are then explained which can be realized independently of implementing a new CHP aggregate. Finally, the medium- and long-term possibilities for forward-looking integrated heat and power generation systems are presented.
Editor: Michael Wördemann
Tutor:Dipl.-Ing. (FH) B. Klimes – INNIUS DÖ, Dresden, Prof. Dr.-Ing. Clemens Felsmann
Year: 2018

Fluid mechanic analyses of debris bed filters
Packing bed filters are used to purify air in various fields of industry. Within the current project which is named as “NPP DOEL1 & 2”, zeolite pieces are used to separate radioactive products after nuclear reactor accidents.
Hence it is necessary to study about how to use filtering materials efficiently. As the air will need full contact with filtering pieces, it is of great importance that the air can get through the zeolite pieces at a uniform speed.
In the project “NPP DOEL 1 & 2“, this thesis studies and optimizes the way air gets through the filter so that the air is uniformly distributed. Especially, the design of the filter is studied utilizing fluid dynamics simulation. To do this, a testbed has been established correspondingly. In addition, the simulated results are compared with experimental results correspondingly in detail.
To estimate whether the air gets through the filter uniformly, a coefficient of variation is used, i.e., the smaller the coefficient of variation, the smaller the variation of the air speed in that area. The aim of this thesis is to keep the coefficient of variation of the speed field under 5%.
A CFD model is established using the software Pheonics from the cmpany Cham, in which several variations have been optimized to uniform the air speed when it gets through the filter. In addition, the simulated results have been verified, as the coefficient of variation in the simulation is kept under 2.36% in the best conditions, while it is kept under 5% in the testbed experiments, too.
Editor: Ge Liu
Tutor:Dr. Eckehard Fiedler – Caverion Deutschland GmbH, Dr.-Ing. Claudia Kandzia, Dr.-Ing. Markus Rösler
Year: 2018

Conceptual design of clean rooms / white rooms
The aim of the present project work in the practical course was to compile all necessary guidelines and equipment for the planning of clean room facilities. The relevant standards and guidelines were examined and described. All current technical systems for the operation of clean room systems have been compiled in their function and the resulting benefits. A decisive parameter is the purity class and the air change rate which is defined by the standards DIN ISO 14644 and VDI 2083. Also, based on the necessary purity, the choice of the final filter can be determined. Here, the service life is observed after the filter deteriorates its efficiency with increasing particle deposition. The comparison of clean room area and the necessary filter area indicates the percentage filter occupancy. This is crucial for economic efficiency and should be adapted to the necessary conditions. The amortization of the plant begins with the production in the clean room. The “in Operation” is the last of three operating or standby phases of a clean room system and follows the “as Build” and “at rest”, which can be considered as construction phases and describe the contamination risks in the clean room.
Editor: David Hess
Tutor:Mr. Frank Pietsch – M+W Central Europe GmbH, Dresden , Prof. Dr.-Ing. Clemens Felsmann
Year: 2018

Further development of a heat pipe flat plate collector with consideration to the production process
A solar thermal flat-plate collector prototype with heatpipes is designed, produced and rated within this diploma thesis. Heatpipes are used to reduce the stagnation temperature. To be able to design the collector a collector model is developed, which takes the characteristics of heatpipes in account. The aim due to the zero loss collector efficiency is 75 %. The stagnation temperature should be less than 120 °C.
The heatpipes are especially produced for the collector prototype. Therefore, a possible forming is searched for. This aims to identify forming close to production.
To remove the heat absorbed and transported by heatpipes a manifold is used. This manifold is investigated in terms of production. A tool for producing the manifold in a hydraulic press is developed and tested.
After the documented completion of the prototype, the zero loss collector efficiency, the collector efficiency characteristic and the stagnation temperature are determined at “Institut für Solarenergieforschung Hameln”. It is to be emphasized that the target of zero loss collector efficiency is reached by determining it at 76,2 %. The same collector prototype shows a stagnation temperature of 125 °C.
Editor: Sebastian Braun
Tutor: Dr.-Ing. Karin Rühling, Dr.-Ing. Steffen Jack – KBB Kollektorbau GmbH Berlin
Year: 2018

Modelling of an aggregator of heterogeneous flexibilities in the low voltage grid
As part of the energy transition, the share of photovoltaic systems and wind energy installations increases in power generation. Because of their strong dependence on the weather, the volatility of power generation rises. Suitable actions must be taken to ensure grid stability. One of these actions is the use of flexibilities. Therefore, either high-performance plants can be used separately or several low-performance plants can be pooled by aggregators.
The objective of the present study is to build a model for an aggregator. The model describes how to pool flexibilities and how to disaggregate the pools power to the separated flexibilities.
The included flexibilities are all connected to the low-voltage grid and have different characteristics that should be observed during the modelling. Furthermore, the model differentiates spot market trading and german control power market trading. To evaluate the model, it is implemented in a program code and followed by a simulation.
Editor: Saskia Hübner
Tutor:M. R. Neubauer – Kiwigrid GmbH, Prof. Dr.-Ing. Clemens Felsmann, Dipl.-Ing. Jens Werner – TU Dresden
Year: 2018

Considerations about building services of a Smart Building using the example of an office Building
The presented thesis deals with the technical planning of a new build office and administration building including broadcast studios. Furthermore the term of a Smart Building is examined. At the beginning the architectural characteristics of the building as well as the functional concept is explained. Afterwards a detailed assessment of the technical building services is made to gather information about the planning process. As an orientation for the following aspects an own definition of the term Smart Building is shown. To get an idea of different energy supply systems three reference buildings are explained. After that three alternative concepts are presented which will be compared among themselves and finally with the current planned one.
The aim is to decrease the energy demand. To add functions of room automation with focus on usability the principles of a building automation system is described. Subsequently a comparison of the automation functions and those of the DIN standard 15232 is made to show the practicability of the norm. Finally it will be proved whether the building is a so called Smart Building or rather other results relating to this term are found.
Editor: Robert Matthias Scharf
Tutor:Dipl.-Ing. Uwe Hopf – Kofler Energies Energieeffizienz GmbH, Prof. Dr.-Ing. Clemens Felsmann
Year: 2018

Use of resources in building energy systems operation – Modeling the prediction of energy consumption and wastage of installed HVAC systems
The aim of the project was to create a model based on DIN V 18599 for predicting the energy consumption of buildings. For this purpose, an energetic assessment of a test building in the software "Solar-Computer" and the Excel tool "EnerCalc" was adapted as closely as possible to reality by varying parameters. It was compared with measured energy consumption. Subsequently, forecasting models and possibilities were examined. In the course of the project, wear and tear of the TGA was also considered. The general problems and relevant physical principles of action were investigated, as well as the representability of ageing mechanisms in models according to DIN V 18599. Furthermore, a description of the model-based support of the HVAC operator in building operation under the aspect of ageing and a economic feasibility study of the ageing models took place.
Editor: Noah Mertens
Tutor: Prof. Dr.-Ing. Clemens Felsmann
Year: 2018

Development and characterization of direct hot water cooling for graphics cards
This diploma thesis addresses the development and characterization of a direct hot water cooling for graphic cards. For that, a new graphic card cooling unit is thermally and hydraulically designed for the use in water-cooled data centers with waste heat utilization. First of all, the thesis starts with an introduction to different cooling technologies for data centers. Further, an overview of concepts for the water-cooling of graphic cards as well as the different possibilities for waste heat utilization is given. The special requirements for the graphic card cooling provides the basis for its dimensioning. These are the boundary conditions given by the graphic card and the possible integration of the cooling within the cooling circuit of water-cooled data centers. A 3D printing process is used to create the prototype. Therefore it is tested, how far water-, pressure- and temperature consistent structures can be produced with this printing procedure. Some basic considerations on the heat transfer from the electrical components to the cooling water serve as the groundwork for the thermal dimensioning. In the following, the detailed design of the finned heatsink is carried out, defining its optimal geometric diameters. Within the thesis, a concept of the fluid flow through the graphic card cooling is developed as well as a 3D model. Looking at the characterization, a measurement concept is developed in order to evaluate the performance and efficiency of the graphic card cooling. This contributes to the development and construction of a test rig, which is used for measurements of a charged graphic card. Thereby, not only the characterization of the cooling but also the definition of the graphic cards’ performance is possible. The thesis concludes with optimization proposals concerning the graphic card cooling, production process and the test setup.
Editor: Lukas Friedenstab
Tutor: Dipl.-Ing. Lars Schinke, Dr. Jens Struckmeier – Cloud&Heat
Year: 2018

Planning of Wind Power Stations in Saxony
There are various aspects to consider at planning wind power stations. The location of the wind power stations is not only dependent of the prevalent wind conditions, but also of the surrounding nature and landscape and the designation of areas for the use of wind energy by the regional planning. Laws and regulations increase the planning effort, but ensure the sufficient protection of people and nature. This paper deals with the criteria, which matter for choosing the location and the type of the wind power station. Moreover the legal conditions and the reports concerning the impacts on the environment, which are necessary for an approval of a wind power station, will be clarified, as well as the sequence of the planning and the approval procedure. Lastly the role of the social acceptance and the politics at the expansion of wind energy will be discussed.
Editor: Carlotta Scheder
Tutor: Dr.-Ing. Thomas Sander
Year: 2018

Energy system analysis – renewable energies in Kuwait
Modelling, analysis and evaluation of the integration of renewables into the power grid and optimization of the power plant structure
The state of Kuwait is, as a result of increasing local resource consumption and challenges due to climate protection, seeking to diversify its energy production. In this context the question arises to what extend the integration of renewables in the energy system is recommendable, and which composition of renewable and conventional technologies the future energy system should consist of.
The aim of this thesis is an evaluation of the optimal power plant portfolio with a high share of renewable energies and its potential impact on the entire Kuwaiti energy system. This thesis ascertains that an integration of renewable technologies into the energy systems can be considered useful. The integration of photovoltaic and wind energy was considered useful in all scenarios. The expansion of CSP plants and battery storage systems is heavily dependent on selected requirements for the renewable power plant fleet, as well as developments in terms of fuel and CO₂ costs.
Editor: Florian Dallhammer
TBearbeitenutor:Dr.-Ing. Niklas Hartmann – Fraunhofer ISE, Freiburg, Prof. Dr.-Ing. Clemens Felsmann
Year: 2018

2017

Study of the stratification behaviour of a hot water storage tank by using distributed temperature sensing
This thesis gives an insight into the study of the stratification behaviour of a hot water storage tank with a distributed temperature sensing (DTS) measurement system. It belongs to the Chair of Building Energy Systems and Heat Supply of the Dresden University of Technology and hereby, not any experiments have been carried out for a long period. Thus, this thesis was initialized in order to perform new experiments with the hot storage water tank.
Distributed temperature sensing measurement systems are still new and the measurement principle is not alike other conventional temperature measurement systems as resistance temperature sensors or thermocouples. Hereby, it is possible to use the propagation of laser pulses through fibre cables in order to determine the temperature by the rescattered signal.
During this thesis, all technical equipment became fully operative and all temperature sensors were calibrated on one particular temperature measurement system as reference. Moreover, the fibre cable used for DTS measurements and structured as storage grid was realigned and the position assignment between measurement grid points and fibre cable was edited.
Main aspect of this thesis are discharging experiments which discharge a full loaded storage tank by different volume flows. For the experiments, discharging volume flows of 1.5 m³/h and 6 m³/h were chosen in consideration of the storage tank gross volume of 6.3 m³. During all experiments, same experiment conditions have to be considered to guarantee comparability.
For the analysis of the measurement data, discharging experiments with different volume flows have to be compared at states of same amount of delivered water volume. For this purpose, the chronological development of temperatures was analysized for each storage tank layer by discharge curves.
As a result, it could be observed that high volume flows excite more mixing processes during discharging experiments in comparison to low volume flows. At low volume flows, water entering through the diffuser streams to the bottom of the storage tank and only minor mixing processes were excited that have little influence on the initial stratification. However, even the highest considered volume flows cause only moderate mixing processes so that the initial stratification of the storage tank was preserved. These results and for this thesis developed analysing tools could be applied for further research and study theses to conduct more experiments and to implement further studies with this hot water storage tank.
Editor: Hoàng Lê
Tutor: Dipl.-Ing. Andreas Herwig
Year: 2017

Use of liquid ice in Power-to-cold applications - theoretical and empirical analysis of selected additives for secondary coolant temperature adaptations
Within this thesis, among other things, a definition of the term Power-to-Cold was introduced and a system comparison of suitable cold storage systems was developed. The focus of the further theoretical considerations were water ice mixtures as a storage medium. In order to be able to expand the range of use of ice slurry, a freezing point-depressing additive must be added to it. For this purpose, additives which are suitable for the production process by direct evaporation were identified within the work and investigated theoretically and experimentally. The selection of the additives, which should be examined, was based on the comparison of important thermophysical properties of those aqueous solutions such as the specific heat capacity, the thermal conductivity or the dynamic viscosity. Within the experiments, it was possible to achieve the desired ice slurry temperature. Finally, recommendations were made on constructive adjustments to the test rig and future necessary examinations.
Editor: Sandra Giese
Tutor: Dr.-Ing. Mathias Safarik – ILK Dresden, Dipl.-Ing. Christoph Steffan – ILK Dresden Prof. Dr.-Ing. Clemens Felsmann
Year: 2017

Analysis of electrical load profiles regarding photovoltaic power generation at Technische Universität Dresden
This thesis examines to what extent attainable solar power yields of fictional expansion scenarios with photovoltaic systems on the campus of the Technische Universität Dresden can be used for self-consumption within the low and medium-voltage distribution grid of the campus. In addition, this paper examines where the installation of battery energy storage systems is useful, to increase the proportion of self-consumed solar power.
First of all, a brief overview of the current state of science and technology of photovoltaic systems and battery energy storage systems is given. Subsequently, the load profiles of the different voltage levels of the campus grid are analyzed. Then, two expansion scenarios with photovoltaic systems are presented, which were chosen for the solar yield simulations. This is followed by a comparison of the simulation results of the respective scenario with the different load profiles as well as the calculation of specific key figures for the consumption of self-generated solar power. Based on the key figures, considerations of places to install battery energy storage systems are made. For this purpose, a rough overview of the dimensioning and capital costs of battery energy storage systems is given.
The results show that almost the whole amount of solar power can be used for self-consumption in both expansion scenarios. Only in two medium-voltage rings of the campus a significant solar yield surplus can be achieved with a maximum degree of expansion with photovoltaic systems. By integrating large battery energy storage systems within these medium-voltage rings, the solar power surplus could be almost completely stored and used for self-consumption. However, the high investment costs of such battery storage would lead to significant additional costs for the entire project.
Editor: Daniel Kröger
Tutor:Dr.-Ing. Annina Gritzki, Dipl.-Ing. D. Thorwarth
Year: 2017

Boundary conditions for evaluation of thermal comfort
In the adaptive comfort model, behavioural, physiological and psychological adaptive processes are stated as reasons for the discrepancies between predicted mean vote and
observed comfort votes. The “soft factors”, which are not thermically determinable, can indirectly influence the adaptation processes. However, because of insufficient studies, little is known about the influence of the “soft factors” on the thermal comfort.
In this student research project, a literature research on existing thermal comfort criteria and the several study results about the “soft factors” is done. This student research project also presents an experimental design, which is specially meant for the research in the student’s room of ILK Dresden. This experimental design was in the student’s room of ILK carried out. And the gained results are assessed. Finally, some suggestions are made to solve the identified obstacles for a long-term study in the future.
Editor: Liu Shen
Tutor: Dr.-Ing. Markus Rösler, Dipl.-Ing. Alexander Buchheim, Dr.-Ing. S. Blei, Dipl.-Ing. (FH) H. Rosenbaum – Institut für Luft- und Kältetechnik GmbH Dresden
Year: 2017

Options to extent the chilled water distribution net at Technische Universität Dresden
This seminar paper aims the analysis of the refrigeration supply at the Campus of TU Dresden. Also it analysis the possibilities to realise respectively to expand already existing chilled water distribution nets. Therefor information about the 7 allready existing refrigeration supply-areas were collected (kind of refregeration machines, installed chiller capacity, etc.) To get the energetic parameters, data like consumption of cooling energy, operating energy for the chillers and distribution net-temperatures were collected by using different building management systems (Desigo Insight, Siemens Navigator, Siemens Visonik). With the assistance of that data it was possible to provide information about cold loads, end energy consumption (current, district heating), seasonal energy efficiency ratio and the CO₂-emission of the refigeration supply at the Campus.
The results of this paper allow, to gather wide-ranging findings about the present chilling-plant operation and the potential for optimization of the refrigeration-supply-systems at the Campus of TU Dresden. Furthermore the results present a basis to conceptualise the future structure of the refrigeration supply at TU Dresden.
Editor: Peter Scheer
Tutor:Dr.-Ing. Annina Gritzki
Year: 2017

Energy related and economic aspects of heat pump systems
This paper deals with the basic structure of a heat pump and its operation. It also gives an overview of the types and uses heat sources in environment. In addition, depending on the different heat source, capacity and other characteristics, the global market for heat pumps will be analyzed. Enclosed are the German market and American market as examples analyzed in detail. After rough calculations of two scenarios in 2020, the relationship between development of electric heat pumps and electricity consumption as well the share of regenerative energies in electric energy supply is estimated. Finally, the optimal control and regulation of the heat pumps for flexible use are put together to compensate the above mentioned effects of electricity consumption as well as the share of renewable energies in power ectricity consumption as well the share renewable energies in power generation.
Editor: Yulong Shang
Tutor: Dr.-Ing. Martin Knorr
Year: 2017

Energy-economic evaluation of heat pump applications in low temperature district heating systems
This paper deals, on the one hand, with the reduction of system temperatures in existing district heating systems and, on the other hand, with the use of decentralized heat pumps in low temperature district heating systems. In the course of this paper the energetic, economic and ecological effects of such concepts are examined with focus on the use of district heating as a source of heat for decentralized heat pumps. First of all, general information on low temperature heat networks is given and a couple of district heating systems with decentralized heat pumps are presented. Subsequently, some of these concepts are simulated with the software Polysun. The result of the simulation shows that the use of heat pumps in low temperature district heating systems can have a positive effect for the consumer in terms of both economy and ecology.
Editor: Yannick Dederichs
Tutor: Prof. Dr.-Ing. Clemens Felsmann
Year: 2017

Building energy performance analysis by multi-agent-simulations
Within this diploma thesis, agent based simulation toolchain to generate building load profiles based on occupant behaviour developed. The integration of the generated electrical load profiles into the Modelica-based building energy simulation software “SimulationX”, was realised in a sequential form as well as in a co-simulation setup with a FMU (functional mock-up unit). The agent-based model and simulation was implemented with Netlogo. The model describes the occupant behaviour in an apartment building and focuses on electrical appliances. The input parameters in the toolchain witch can be configured for different setups are based on statistical and stochastic correlations. The resulting load curves of the toolchain are classified and compared against conventional methods of building energy simulations as well as with anonymized measured values. The tool chain enables a more accurate and variable design of electrical load profiles, for the building simulation, when compared to conventional methodologies.
Editor: Tom Eckhardt
Tutor: Prof. Dr.-Ing. Clemens Felsmann, Dipl.-Ing. Torsten Schwan - EASD Dresden GmbH
Year: 2017

Considerations about the practical application of heat transformators
This thesis explains the technology of heat transformer. There are new possibilities and challenges in the upgrading and using of heat loss and due to relatively new policies regarding climate change it needs to be researched how a technology like this can benefit technical progress in general. The technology could make a significant difference in the struggle to lower CO₂-emissions and push technical progress. This evaluation shall discuss how the heat transformer can be utilized. After describing the historical evolution and the technical basics, operating limitations are presented. Furthermore, used materials and possible areas of use are debated and looked into. Conclusions are drawn regarding the economical and environmental implications of heat transformers. Additionally the ability of this technology to sustain itself on the international competitive market is evaluated and the latest developments and inventions presented. It turned out, that especially for industrial applications the heat transformer supplies a variety of economic and meaningful use.
Editor: Markus Bauch
Tutor: Prof. Dr.-Ing. Clemens Felsmann
Year: 2017

Analysis and improvement of thermal storage models for linear mixed-integer programming
The optimization of the operational planning and the storage systems's charging and
discharging control strategy is central to the design of thermal energy storage (TES) systems. So far, commonly applied mathematical models of thermal energy storage systems do not represent with sucient precision the thermal strati cation in a TES system. In this paper, the focus lies on the analysis of the influence that existing storage models exert on the heat generators' control strategy in a default optimization environment, followed by the further development of a model for an energy storage tank with thermal stratification. Compared to the default storage models, the refined TES model exhibits a significant improvement in thermal stratification and shows, due to realistic reproduction, a major modification of the heat generators' control strategy. The insights gained from the development of the stratified thermal energy storage tank model can be used to improve the computer-aided simulation and optimization of TES systems.
Editor: Steffen Schröder
Tutor: Dr. rer. nat. Peter Stange, Dr.-Ing. Bernd Hafner – Viessmann
Year: 2017

Evaluation of the energy concept of the Botanic Garden at TU Dresden
For the Botanical Garden at TU Dresden, a comprehensive modification, modernization and ex-pansion measure is planned. This diploma thesis examines the media and energy supply of the location regarding an energy-efficient, sustainable and economic realignment.
For this purpose, research into the energetic optimisation of greenhouses will be carried out and innovative example projects of similar facilities and research projects will be presented. An op-eration and consumption analysis of the existing buildings and greenhouses of the Botanical Garden Dresden serves as well as existing planning documents and user requirements as the basis for the creation of an energetic concept of the new construction and rebuilding measures. Thus, a concept based on energy considerations is developed and simulated with the green-house design software HORTEX. Based on the predicted energy demand values for the Botanical Garden, project studies on energy supply concepts are set up and compared regarding their technical feasibility as well as their economic and primary energy benefits.
The use of a gas condensing boiler with a combined heat and power plant with 15 kWel installed capacity as base load proves to be the most economically viable supply solution. From a primary energy perspective, the purchase of Dresden district heating and a complete electric power sup-ply from the electricity grid are to be preferred. As an innovative version, a supply combination of a base load combined heat and power plant as well as the renewable energy sources near-surface geothermal energy, photovoltaic system and solar thermal heat supply is conceivable.
Editor: Laura Fritsche
Tutor: Prof. Dr.-Ing. Clemens Felsmann
Year: 2017

Investigations on system integration of solar thermal plants at a waste water treatment location
This thesis investigates the potential of solar thermal power plants at the waste water treatment location of the Stadtentwässerung Dresden. The first step was to analyse roof areas and open spaces in order to install solar thermal collectors. Relevant informations of the areas were listed into a database. With this informations factsheets of the open spaces and roof ares within the location were made.
Roof areas of three buildings were chosen and several solar thermal installations were designed. Subsequently these plants were calculated with the simulation tool Polysun 10.0 by Vely Solaris. The annual heat production was compared to the heat demand of the waste water treatment location.
After investigations in the economic feasibility and integration in the local heating network the best designs were identified.
Editor: Tobias Franzky
Tutor: Dr.-Ing. Karin Rühling, Dipl-Ing. Thomas Schöniger – Stadtentwässerung Dresden GmbH, Dipl.-Ing. (FH) Bernd Klimes – INNIUS DÖ GmbH, Dresden
Year: 2017

Solar Cooling – Technical options and feasibility study for selected locations of the Daimler AG
This paper is showing the technical options for solar cooling sites, while doing a feasibility study for buildings of the Daimler AG. Solar cooling is the technique to use the energy of solar irradiation to provide cooling. In this paper industrial uses are prioritised. The basics of solar cooling are gathered within the current market situation. To utilise solar cooling correctly, a location study for the buildings of the Daimler AG is necessary. The analysed buildings are in Jawor, Kecskémet, Rastatt and East London. The analysis of the buildings, which are mainly being built currently or their cooling systems are getting upgraded, includes the cooling needs for different type of buildings. With all this information, several solar cooling variations, based on literature or other sites, are evaluated.
Afterwards all the variations are calculated for the different buildings, including economics, energetics and technical feasibility.
The results are getting compared to standard cooling systems using electricity from the power grid. This showcases the possible savings of CO2-Emissions, using a solar cooling site. Also, problems and risks of building the solar cooling sites are evaluated. Within the comparison of all significant economic and energetic parameters, advices for building or not building a solar cooling site are added to the mix. Those advices show, whether it is wise to usesolar cooling at the buildings of interest.
Editor: Lukas Keul
Tutor: Prof. Dr.-Ing. Clemens Felsmann, Dipl.-Ing. Marius Eydner – Daimler AG
Year: 2017

Evaluation of integrated power utilization processes with Power2Gas and CHP
As a result of the increasing expansion of regenerative production capacities and the resulting fluctuating feeder line, their integration into the existing power supply becomes increasingly difficult. Respectively of the advance of the German energy transition, the electricity storage requirements continue to increase for excess electrical energy. A combination of power-to-gas and combined heat and power can be used to store large quantities of electrical energy over a long period of time. The energy management assessment of this process chain is the goal of this work. The entire process chain is described in detail and its material and energy flows are balanced. Furthermore, the state of the art and the market availability of the individual components of the Power-to-Gas-to-Power-Process chain are researched. In addition, the questions are clarified as to which electrical energy quantities are available for the process chain in the future, and which suitable application cases exist for a possible, perspective application of the process-chain in the German energy transition. The assessment of the use cases is based on the estimation of power generation costs, system losses and efficiency levels. Finally, alternative usage concepts (such as current storage) are compared with the process chain under consideration.
Editor: Lukas Zitzmann
Tutor: Prof. Dr.-Ing. Clemens Felsmann
Year: 2017

Power generation with paving slabs
This paper discusses the possibility of using human steps to generate electrical power. The aim is a case-study in form of a demonstration plant of special energy harvesting tiles on the campus of the TU Dresden. The most suitable technology and the most appropriate location to lay energy harvesting tiles will be chosen and the possible energy return is calculated.
Pavegen’s V3 product was chosen as the technology for the system, because it is the easiest way to ensure road safety for the installation. To find an eligible place the number of daily and yearly pedestrians is determined to estimate the quantity of provided electricity. The most suitable locations are the entrance and exit of the university library and the entrance hall of the canteen building “Alte Mensa“.
A presentation of an installation concepts for both locations is given at the end of this paper, whereby the concept for the Alte Mensa was developed as a part of the study paper. A comparison between both demonstration plants shows that the proposed plant in the canteen achieves a higher annual electricity gain as the installation concept for the library, but the energy gain for both systems is too low for an amortization. At present, more energy is needed to produce the tiles than can be provided by the plant during their lifetime. There are possibilities to use this demonstration plant efficiently to raise public awareness of new ways of generating electricity and of the energy consumption of everyday appliances.
Editor: Hanna Krüger
Tutor:Dr.-Ing. Annina Gritzki, Dr.-Ing. André Kremonke
Year: 2017

Development of a new rotating heat exchanger for ventilation applications
In this work a compact central ventilation unit was developed and analyzed. To this end, a new experimental set-up was developed. The ventilation unit has some special features. On the one hand, the two air volume flows -internal air flow and exhaust air flow-are conveyed through only one drive. In addition, a rotating heat exchanger with radially rotating heat pipes is used for the heat recovery. The drive that is responsible for the rotation of the heat exchanger also carries out the air volume flow. Initially, the performance of the system plays a subordinate role. The focus of this project was rather to investigate the extent to which this concept is suitable for the construction of a simple, compact ventilation device and to identify problems that need to be solved before using/ developing/ marketing such a system. In this project, we successfully built a functioning device which reaches a heat recovery rate of 38 %. Problems were mainly caused by leaks inside the device, which influence the measurement results. Further adjustments and optimization must be carried out. The following problems remain to be solved: reduction of internal leakage, increase of heat recovery rate and optimization of volume flow.
Editor: Philip Schneider
Tutor: Prof. Dr.-Ing. Clemens Felsmann, Dr.-Ing. Karsten Hackeschmidt – ILK Dresden
Year: 2017

Comparative performance evaluation of heat pump applications in buildings
This work focuses on the planning and evaluation of heat pump systems. Initially two fossil fuel based supply concepts are compared to a common heat pump system using by the means of a sample project. Therefore, the economical and primary energy characteristics of each system are determined with the using of conventional planning methods and opposed in a decision matrix. The results suggested that heat pump systems are cheaper while simultaneously requiring the lowest primary energy.
Furthermore, the software ‘SimulationX ‘ is used to provide a model of the heat pump system and to calculate its characteristics for the time period of one reference year. In comparison to the conventional planning data only minor deviations emerged.
Within DIN EN 15450 different types of standardized hydraulic circuits in heat pump systems are specified. Since the type of circuit affects the energetic characteristics, another part of this work examines the differences of economic efficiency due to switch types. Three standard and two further variations of hydraulic switches are evaluated with the aid of a sensitivity analysis in ‘SimulationX ‘.
In conclusion, it appears that the cooperation of conventional planning and simulation software gains the best results for the evaluation and planning of heat pump systems. After a basic conventional calculation, the simulation software can be used as a helpful and time-saving tool for optimizing the characteristics of a system within the detailed planning stage.
Editor: Felix Schlamm
Tutor: Prof. Dr.-Ing. Clemens Felsmann, Dipl.-Ing. U. Bauer – IPROconsult GmbH
Year: 2017

Mechanical energy storages for offshore wind parks
With the energy revolution, energy supply is increasingly converted to renewable energies, especially wind and solar energy. This is accompanied by the problem of fluctuating energy feed into the grid. In this student research invistigates the potential of mechanical energy storage systems to equalize the energy input of offshore wind energy and to reduce the load on transport and transmission networks. After deriving the need for energy storage capacity in the vicinity of the offshore wind turbines and investigating the environmental conditions at the sites of North Sea and Baltic Sea, various mechanical energy storage concepts were examined. For these concepts, economic aspects such investment and operating costs, financial support programmes, tax treatment and other surcharges were considered. This was followed by a comparison of energy storage concepts for the previously defined comparison criteria and a final outlook showing the potential of mechanical energy storage systems, wich, however, are limited by political circumstances.
Editor: Laurin Benedict Leuker
Tutor: Prof. Dr.-Ing. Clemens Felsmann
Year: 2017

Numerical simulations of the impact of wind profiles on the output of a small wind turbine in the vicinity of buildings
The renewable energy is quite economic competitiveness and development potential. Wind energy is one sort of the most popular clean energy. With the progressing of wind facilities, it provides a substantial reduction in production costs. The performance of a wind turbine is mainly dependent on the wind speed and the flow conditions, which is strongly influenced by the wind profile and the surroundings. This is particularly evident in the case of the building near small wind turbines, as the flow is changed by the building or by the surrounding obstacles.
In this thesis, the performance of wind turbine is investigated. A steady working condition of a wind turbine under different classes of wind speed has been simulated by using an open source CFD (Computational Fluid Dynamics) toolbox OpenFOAM. With the assumptions of mechanical and electrical losses of the generator, the power output of the wind turbine has been evaluated. These calculated values are compared with available manufacturer data. Based on the simulation results, an estimate of annual full last hour is made.
As following the flow profiles are modified so that the wind velocity distribution is close to the reality. Three building-near layouts have to be implemented. So that the obstacles impact on performance can be evaluated by the comparison with ideal inflow.
Editor: Yongqing Xia
Tutor: Dr.-Ing. Markus Rösler
Year: 2017

Analysis of the computational performance of different approaches in the predictive optimization of an energy system
This thesis investigates several approaches for the optimization of mixed-integer linear
programs which are solved as part of the model predictive control of an energy
system. The author analyzes heuristic and deterministic algorithms and presents their
implementation in MATLAB. As a deterministic approach, dynamic programming
is used. The heuristic approaches under examination are a genetic algorithm and an
ant colony optimization. In comparison to commercial Branch & Cut algorithms, the
alternative methods give worse solutions and need longer calculation times. The reasons
for this behaviour are analyzed and improvements as well as alternative modes of
application are presented.
Editor: Ronny Gelleschus
Tutor: Dr. rer. nat. Peter Stange
Year: 2017

Examination an optimization of the operation mode of the cooling supply of non-residential buildings for grid-supportive operation on the example of the Zellescher Weg (BZW) building
These thesis give an examination of the cooling system of the Bürogebäude Zellescher Weg (BZW) at the University TU Dresden. Part of the thesis is a survey about the users of the BZW, a study of the individually components of the cooling system, an evaluation of the recorded data, a regression for estimating the cooling power and some proposals for
improvements of the system.
At the first topic the thesis gets down to the topic of thermal comfort. Afterwards the process of making the survey is shown and the results of the survey are presented. In the second chapter the main components of the systems are examined and explained. Furthermore, some of the recorded data is used to show the working cycles of the different components.
The next topic is about an energy accounting with the recorded data. All calculations are
explained and the results are presented in a sankey diagram. Eventually a regression model for the cooling power of a whole summer season is made. The discussion of the regression indicates that the regression can only be used as an average value of the needed cooling power. Finally other ways of using the thermal storage for improvements are presented. In the end improvements of the system will need a few investments.
Editor: Felix Hennig
Tutor: Dipl.-Ing. Juliane Schmidt, Dr. rer. nat. Peter Stange
Year: 2017

Consideration of energy concepts for residential buildings taking into account the building energy law and rebound effects
This diploma thesis deals with climate neutral supply concepts for residential buildings. At first the building energy law, which is to replace the current energy laws, will be discussed. A guide with the changes by the previous energy laws is given. Also the rebound effect is discussed. This is grouped into three categories and a range of values is given for the reduced energy efficiency increases resulting from the rebound effect. Then a typical multi-decked residential building of Bonava is defined with regard to cubature, physical parameters and supply load profiles. In the next step, five supply concepts are drawn up and compared. The two selected supply concepts are then designed. This is followed by an energetic and economic evaluation of the concepts. Finally, the rebound effect of these variants is estimated based on the previously conducted literature research.
Editor: Florian Bauch
Tutor: Dipl.-Ing. Lars Schinke, Dipl.-Ing. Marcel Moersch – Firma BONAVA
Year: 2017

Evaluation of existing software tools for the energy analysis and optimization of districts and settlements
Despite the huge technological progress in the building industry in recent years, the building sector is still responsible for a major share of the final energy consumption and greenhouse gas emissions. In order to further improve energy efficiency in building sector, to build sustainable cities and to reach the ambitious climate protection targets of the federal government, the optimization of individual buildings will not be sufficient. It is time to broaden the scope from the building scale towards the neighbourhood and district scales.
In this thesis, the concepts of energy planning at district level are explained, the necessary processing steps and planning phases for the energetic urban planning are summarized and the appropriate methods are discussed. Six computer-aided tools and programs developed in the framework of the energy research program in Germany in recent years are presented and compared. At the end of this work an energetic analysis of the campus of TU Dresden at district level will be performed with the help of a previously presented software tool. With this example the application of the software tool will be evaluated and further development requirements are derived.
Editor: Siyuan Fan
Tutor: Dr.-Ing. André Kremonke
Year: 2017

Fluid mechanic and energetic optimization of indoor air flow in the city hall of Chemnitz
The present paper investigates the indoor airflow in the city hall of Chemnitz. The goal of the investigation is the fluid mechanic optimization of the indoor air flow and the implementation of a variable volume flow operation of the air conditioning plant. The first step is an analysis of the stock to describe and evaluate the current situation. Subsequent an investigation of the effort for ventilation and air conditioning reveals a great potential to increase the energy efficiency of the air conditioning plant, by using a variable volume flow operation. This type of operation, without a decrease of thermal comfort in the occupied zone of the hall, wasn`t possible until today. Within the optimization an adjustment of the air outlets is developed to realize the gradually control of the volume flow. Furthermore, the size of the air outlets is adjusted and with the help of the relationships of free jets, the air velocity in the occupied zone is estimated. Through the optimization an improvement of the thermal comfort is only available in one out of the three areas of the hall. Finally ensues an evaluation of the achieved results and a prospect of the future operation of the air conditioning plant.
Editor: Laurenz Schitthelm
Tutor: Dr.-Ing. Markus Rösler, Dipl.-Ing. (FH) Robert Kittel – Klemm Ingenieure Dresden
Year: 2017

Modification of the calculation model of cell-to-module losses for photovoltaic modules with shingled solar cells
Photovoltaic modules with shingled solar cells offer the opportunity to decrease power and efficiency losses due to the module integration by using a direct cell interconnection and a more efficient use of the module surface. This work uses and extends the existing model of the cell-to-module ratio to predict the power and efficiency of such a module and to compare it with a conventional photovoltaic module. The structure and assembly of both module technologies are presented as well as the general calculation of the cell-to-module ratio. Several assumptions are considered before calculating the individual geometrical, optical and electrical gains and losses in detail for modules with shingled solar cells. Two newly considered electrical losses are introduced and calculated for both module technologies. The results of the cell-to-module analysis are being compared and put into perspective by estimating the cost-effectiveness of each technology. A mini-module with shingled solar cells has been built to validate the results and to show not only the feasibility but also the risks and disadvantages of shingle modules in their construction process.
Editor: Johann Rüdiger
Tutor: Dr.-Ing. Karin Rühling, Prof. Dr.-Ing. Clemens Felsmann, Max Mittag – Fraunhofer ISE
Year: 2017

Investigations on system integration of PV-plants at a waste water treatment location
This thesis investigates the potential of photovoltaic plants for improving the degree of electrical self-supply of the waste water treatment location of the Stadtentwässerung Dresden in Dresden-Kaditz.
At first the general photovoltaic potential of the open space within the location was analyzed. The results are combined in a catalogue. PV-installations were designed for two buildings and one open space with the simulation tool POLYSUN Constructor by Vela Solaris. The annual electricity output was predicted and the plant operation was planned with the aim of not feeding in the public electricity grid. After an analysis of the economic efficiency the best technical and ecological designs were identified. Finally, the results were conducted into recommendations for the operator of the location.
Editor: Theresa Struckmann
Tutor: Dr.-Ing. Karin Rühling, Dipl.-Ing. Thomas Schöniger – Stadtentwässerung Dresden GmbH, Dipl.-Ing. Uwe Burmeister – INNIUS DÖ GmbH, Dresden
Year: 2017

Creation of a design tool for chp-plants in residential buildings based on monitoring data of a field test
The aim of the thesis was to define, on the Basis of the field test for a Regional Virtual power plant (RVK), suitable investment of the circuits of combined heat and power (CHP) systems in residential buildings for participation in a RVK and the knowledge gained in a design tool. To do this, the field test of a RVK with 17 properties for a period of six months in respect of the failure was the phenomena in the data transmission, the energy effectiveness of the system circuits, and the specific operation of the cogeneration plants in the RVK point evaluated. In a further step, standards, guidelines, manufacturer analyzed data and literature sources and findings for the dimensioning of cogeneration plants as part of the RVK are derived. A parameter analysis on the Basis of a Matlab-created simulation environment, brought further theoretical insights for the system dimensioning. In the result of the work of dual fuel-powered cogeneration plants are particularly suitable for use in a RVK, since they are characterized by a good controllability. In Microsoft Excel implemented design tool includes not only the dimensioning of such complex circuits and their CHP units, additional producer, and the buffer memory but in addition a simulation environment, which offers the user the possibility of individual observations of different plant circuits.
Editor: Nils Reeh
Tutor: PD Dr.-Ing. habil. Joachim Seifert, Dipl.-Ing. Paul Seidel
Year: 2017

Options to support an energy-efficient chilled water generation at Technische Universität Dresden
The following thesis analyses the cooling system of the computer science building (APB) at TU Dresden and evaluates different variations in order to increase its efficiency in an energetic, ecologic and economic way.
About a third of the endpoint energy of the APB is used for cooling. At the moment it is supplied by an absorption cooling machine which uses the energy of a district heating in combination with free cooling during the cold months and a compression cooling machine for peak load operation.
With the help of criteria, which have been assessed beforehand, three alternative cooling technologies have been evaluated, which include the cooling with high-efficient compression cooling machines with turbo compressor, adsorption cooling machines and heat pumps with feeding the surplus heat into the district or local heating grid.
At the End the realisation of the turbo compression cooling machine in combination with a photovoltaic system has been recommended. It convinces by the reduction of primary energy, CO₂-ejection and energy supply costs and an excellent partial load operation.
Editor: Christiane Zietz
Tutor:Dr.-Ing. Annina Gritzki
Year: 2017

Technical and economical performance evaluation of heat pumps to improve energy efficiency of CHP plants
The present thesis deals with heat recovery from a cooling system in the CHP plant “Nossener Brücke” using a large heat pump. The aim of the project is the utilization of waste heat from power production for district heating in Dresden.
At first the theoretical background is determined and the selection of refrigerants for the heat pump is examined. Furthermore, a discourse about fields of application and a market review about large heat pumps in the selected temperature range are depicted. After the determination of thermodynamic boundary conditions some integration possibilities are examined. For the planning, a model in EBSILON Professional was developed and a variation of parameters was carried out. Moreover, possible installation places are analyzed and the connection with the necessary medias like hot water and electricity is discussed. Further, the capital budgeting and an energetic evaluation of the projected use case of the heat pump are analyzed. In addition to that a suggestion for the specific realization of the project is provided. Finally, an outlook of other use cases in the CHP plant is offered and other topics are pointed out, which are also interesting for further examination.
After the comparison of the use case and installation sites, an optimized configuration was found. Considering the boundary conditions, the realization appears to be economically and ecologically profitable.
Editor: Marwin Kretschmer
Tutor: Dr.-Ing. Thomas Sander, Herr Hellfritsch – DREWAG
Year: 2017

Cooling load calculation according to VDI 2078 for estimating flexibility options
The aim of the seminar paper was to examine the effects of flexibility options on the cooling load. The basis was the search to existing climatic systems and cold storage as well as the calculation of cooling load according to VDI 2078. The extent to which the VDI 2078 is suitable for the purpose of the investigation was evaluated qualitatively. As a result of the results, sample simulations were carried out. These were carried out with the software implementation of the maufacturer „mh-Software“ with ist program „mh-BIM“. The conclusion of the investigation was that some flexibility options can not be taken into account by VDI 2078. This includes, among other things, the cold storage and a targeted room comprehensive load management. Nevertheless, the effects of flexibility options can be investigated by varying of the regulation, operating and control mode of individual components. The seminar paper is recommendable for those who want to carry out cooling load influencing with the VDI 2078, since the potentials and limits are shown.
Editor: Tom Heinze
Tutor: Prof. Dr.-Ing. Clemens Felsmann
Year: 2017

Integration of the new operating mode cycling feed-in in the state machine of a solar thermal feed-in substation
This student research study develops an alternative feed-in operation mode to upgrade the current system for a solar thermal feeding station located at the Center for Energy Technology at the Technische Universität Dresden. The main target of the developed operation mode is to raise the feed-in heat amount to the local district heating system at days with low solar radiation. At the beginning a patent research was done to present current technologies from well-known german solar plant companies.
For the online decision between the regular continuous feed-in and the new developed
operation mode different radiation sensors were analyzed to integrate one into the controlling system. The new feed-in operation mode was developed first based on the measurements of the existing continuous feed-in and later optimized based on tests at the real plant. Finally a simple calculation was made to estimate the benefit of the new feed-in operation mode to the heat amount fed into the district heating network.
Editor: Rolf Terzan
Tutor: Dipl.-Ing. Toni Rosemann
Year: 2017

Determination of heat losses through the bottom plate of a large hot water storage tank
The aim of this thesis is to determine a method to calculate the heat losses throughout the base plate of a large heat storage system. To date, there is already a considerable amount of these hot water storage systems in use but the exact thermodynamic behaviour is still not very well understood. Therefore, TU Dresden has started a research project called SPICE with the goal to investigate this subject by equipping several large heat storage systems with measurement technique. Because of the complexity of the temperature field at the bottom of the heat storage tank, a calculation is nontrivial.
One attempt is made in the guideline FW313 provided by the AGFW.
The approach of this thesis is to develop a model of an existing system, and to simulate the thermodynamical process by using the open-source toolbox OpenFOAM. This toolbox includes a solver for heat transfer and heat conduction problems. In the first chapter the model is created, and basic assumptions for the geometry and the thermophysical properties are made. Afterwards, the mesh of the model and its size were designed appropriately and the numerics were adjusted and tested. Like that, it is ensured that future variations are minimized. In chapter three, data obtained by the SPICE-project was used to improve the model. Therefore, some changes regarding the geometry and the thermophysical properties were made. Furthermore, the heat flow throughout
the base plate was finally estimated, and compared with another value calculated using the existing guideline FW313. The fourth chapter discusses the results, methods of improvement, as well as changes and adjustments still to be made.
The results of this thesis suggest that a simulation can be an appropriate way of estimating the heat losses throughout the base plate of large heat storage systems, even if there are still some inaccuracies. But with the use of further data to improve and validate its design, it is likely that meaningful results can be achieved, which could be used in an early stage of the planning process for such heat storage systems.
Editor: Markus Mazanec
Tutor: Dipl.-Ing. Andreas Herwig
Year: 2017

Development of a 3D volume model for porous cellular structures
Open-cell cellular metal foam structures comes from nature and have been used in many branches of industry for several years. The present work aims to develop a 3D volume model for open-cell cellular structures with the example of metal foam. First, the physical, technical, thermal, mechanical and acoustic properties of some typical representatives of the metal foam are systematically documented through a literature research. Various manufacturing processes of the metal foams are discussed and compared with each other. 17 open-cell metal foam samples were collected for analysis, from which seven metal foam samples were examined using stereomicroscope, scanning electron microscope and X-ray computed tomography to determine the geometrical structure. With the acquired knowledge, three methods for developing 3D volume models for open-pore metal foam were invented and compared with each other. The Kugelmodell and the Stegmodell have high reproducibility but can not reflect the reality fully. The models from 3D scan have almost identical structures with the metal foam samples and could be used for further simulations. The limitations of this modeling method are the computing and memory capacity of the computer being used. The Stegmodell is tested on an analyzed metal foam sample and shows satisfactory results regarding to pore morphology.
Editor: Shengqing Xiao
Tutor: Dipl.-Ing. Jan Löser
Year: 2017

Overall Efficiency of cold production through absorption chillers in consideration of the related CHP system
The Dresden University of Technology participates in the project „EnEff Wärme: Feldtest
Absorptionskälteanlagen für KWKK-Systeme“, which is aimed at testing and evaluating the operation of absorption chillers that are integrated in existing heat supply systems. The present thesis works on the effects of absorption refrigeration on district heating networks as well as heat generators. To quantify the effects, network and generator models are developed in MATLAB® and several simulations are performed. Measurement data from the project is involved in the calculations.
This thesis is divided into three main chapters in which the effect of the additional consumer absorption chiller on heat losses, hydraulic losses and operation characteristics of the heat generators is analyzed seperately.
It turns out that increasing the flow temperatur has the biggest impact on additional heat
losses, as they can increase by up to 13 %. The higher return temperature as well as the
chiller’s transmission line have a rather negligible effect.
The electrical energy consumed by the network pump can increase by up to 21 %. The
position of the absorption chilller within the network is essential for the results. A general conclusion is thus hardly possible.
The models of the heat generators that are being developed in this thesis are not yet technically mature enough for a detailled analysis of the results. For this reason, the focus is placed on possible improvements of the heat generator models.
Editor: Vera Volmer
Tutor: Dr.-Ing. Karin Rühling, Dipl.-Ing. Felix Panitz
Year: 2017

Modelling a Collector Field of a Solar Thermal Field System with a Decentralized Feed-in Substation
A simulation model of a solar thermal plant has been developed in this study. A vacuum tube collector with heatpipes and the pipes connecting the collectorﬁelds is examinated.
After a brief introduction to the topic and discussion of the dynamic collector equation according to DIN EN ISO 9806, a model for the collector and the pipelines was created using the simulation tool Dymola.
Behause of the extensive measurement technology of the examined plant on the roof of the Center for Energy Technology of the TU Dresden, it was possible to determine heat transfer coeﬃcients which could be used as parameters in the simulation.
Finally, the model was validated by performing simulations with the speciﬁc parameters. The simulation models found in this study are able to simulate the system status “Standby“ and “frost protection“.
Editor: Robert Bosse
Tutor: Dipl.-Ing. Martin Heymann, Dipl.-Ing. Toni Rosemann
Year: 2017

Analysis, evaluation and optimization of heat consumption domestic hot water systems in buildings served by public energy supplier
The revision of the heating costs regulation resulted in an unusually broad dispersion within the heating bills for municipal property in Freital. This spread affected heat consumption and heating costs associated with drinkable water heating. As a result, an analysis, evaluation and optimization of the heat consumption of selected domeestic hot water systems was carried out.
For a better understanding of the heat cost accounting, the individual calculation steps and the legal requirements used in the process have been comprehensibly worked up. Subsequently, the present billing data of the properties were analyzed with regard to different areas of investigation. The results were used to select some buildings for a more detailed investigation and subsequent test measurements. The obtained measurement data formed the basis for the solution-oriented processing of the deviations shown. The causes and suggestions for improvement proposed are
intended to serve the operators of the drinking water installations as an aid to reduce the energy costs and the costs of drinking water heating.
Editor: Julia Schreiber
Tutor: Prof. Dr.-Ing. Clemens Felsmann, Dipl.-Ing. Rössel – Technische Werke Freital, Prof. Dr.-Ing. Reichel – HTW Dresden
Year: 2017

Examination of the operating mode of a compressor chiller in connection with a chilled water storage using the example of the Zellescher Weg (BZW) building
The main idea of the thesis is to study how a compressor chiller in connection with a
chilled water storage in building BZW works, and to find the possibility to optimize the
performance of this system.
A data measuring system is utilized to learn how the refrigerating system works. First
of all, a measurement plan is designed, based on the information of requests of users
and the system, the technique and the operation record of the instruments, and the
experience of users on the system. According to the measurement plan, a
measurement system, i.e. A TX-25 sensor operated with an external temperature
sensor, is installed on the refrigerating system.
As the data is acquired, a special tool used in Excel is designed to analyse it, by which
the condition of the instruments could be presented in a formula based on the
downloaded related data.
Enlarging the chilled storage and connecting the system to other refrigerators in TU
Dresden campus are considered as potential ways to optimize the operation of the
system. The possibility of enlarging ice bank and an improvement of its operation is
discussed in the thesis. In addition, the possibility of waste-head utilization is also
discussed.
Editor: Ge Liu
Tutor: Dr.-Ing. André Kremonke
Year: 2017

Setup and test of a measurement acquisition system for monitoring tasks
In this paper a measurement acquisition system which is still under development is tested in monitoring tasks. The measurement acquisition system allows the acquisition of flow, return flow temperature, the middle surface temperature on the radiator, the flow and return flow temperature on the pipe, the room temperature and the relative humidity. The measurement acquisition system is installed in two sections in the Andreas-Pfitzmann-Building. Thus the usefulness and meaningfulness of the system are evaluated and the operating behaviors of the selected sections are evaluated. As the results of the paper the shortening of the radio range and the fragility and stability of the radio module are the greatest problems. After the analysis of measurement data it can be ascertained that, the difference between flow and return flow temperature is too small and the flow temperature fluctuates. Probably the cables laid in the floor are insufficiently insulated and the temperature control valves are instable because of the high differential pressure in the pipe.
Editor: Lei Chen
Tutor: Dr.-Ing. André Kremonke

Decarbonized energy supply for a Saxony community in 2050
Because of the possibility to generate electrical and heat energy from renewable energies everywhere, a rural community can implement a decarbonized and economic energy supply till 2050. In this thesis, a reference scenario for the community ofObergurig is developed for the year 2050 in consideration of demographic developments and climate policy objectives. It is based on the current situation of the energy supply and the electricity and heat demand ofresidential buildings, industries, trade and services, municipal properties and transport systems. Resulting from the reference scenario, three energy supply variants are analyzed energetically and economically. The decentralized energy supply variant achieves the highest cost-effectiveness by using the entire photovoltaic potential and a central energy storage. The electricity grid is loaded by the high current feed in the summer months and the energy demand during the winter months. Furthermore, a central heat supply with a local heating network can be economically, too. Without changing the charging behavior of the electric vehicle users, electric mobility increases the self-consumption of photovoltaic electricity on the one hand, but represents an additional grid load on the other hand. This type of regional energy supply effects the grid stability, security of supply and the resulting interactions and have to be considered further.
Editor: Adrienne Gehre
Tutor: Prof. Dr.-Ing. Clemens Felsmann, Dipl.-Ing. Uwe Kluge - Sächsische Energieagentur, SAENA GmbH

Evaluation of feed-in measures of EEG-plants
The feed-in of the “EEG-Plants” is legally regulated through the §14 EEG. Through this renewable energy plants are expected to reduce or even switch off energy feed-in to prevent overloading of the energy grids. Feed-in curtailment has substantially increased in the past years. This is evident when looking at the year 2015, in which the Federal Network Agency reported a threefold increase in curtailment resulting in a loss of 4 722 GWh and linked compensation claims of 478 Million EUR. The following study will evaluate, in the specific example of the grid area of “Schleswig Holstein”, the link between weather conditions and curtailment and methodology implemented. From this information many conclusions can be made about how individual power plants were producing energy during feed-in reduction periods. The goal of this study was to clearly show why and when specific curtailment measures were implemented. With help of the studies formulated data bank, actions and measures can be analyzed and through this saving potential can be identified. High costs arise, for the end user, through the implementation of the feed-in management. These costs could be reduced through investing into the expansion and development of the transmission grid. In conclusion different types of energy storage will be introduced which, in future, could become significant in increasing the share of renewable energies in the electricity grid as feed-in reduction can be better managed and controlled.
Editor: Kolja Rubel
Tutor: Prof. Dr.-Ing. Clemens Felsmann, M.Sc. Volker Berkhout – Fraunhofer IWES

Performance and grid support analysis of a low-exergy chilled water system using long-term monitoring data
In this thesis long-term monitoring data of a laboratory buildingis analyzed in order to identify potential to raise the energy efficiency of its low exergy cooling system, which can be achieved by demand side management. Another goal is to analyze how the consumption profiles can be adapted in order to obtain a grid supportive behavior of the cooling system.
For this purpose, the impact of various modifications of the buildings controlsystem and the influence of external parameters on energy efficiency are evaluated. A Greedy algorithm and simple models of the energy systems components are used to calculate load profiles optimized for energy efficiency and grid supportive behavior. The results show that the cooling systems energy efficiency can be increased by 27%, if the components are operated during periods with low ambient temperature and close to the determined optimal operation points.
To evaluate wheter there is potential for a more grid supportive behavior, the buildings “relative grid support coefficient” (GSC_rel) is calculated and compared to the GSC_rel of optimized load profiles for “grid supportive” and “energy efficient” behavior of the components. Compared to the grid-neutral behavior in the analyzed period, the most “grid-supportive” behavior can be achieved by optimizing the control system for thefraction of wind and photovoltaic in the electricity mix. Because this scenario goes along with a significant decrease of energy efficiency, there is a target conflict between efficiency and grid Supportive behavior incase of the laboratory building. Nevertheless, the optimization for the Day-ahead-price at the European Energy Exchange proves to be a compromise allowing to partly achieve both goals, as it results in an increased energy efficiency.
Editor: Andreas Kast
Tutor: Prof. Dr.-Ing. Clemens Felsmann, M. Eng. Benjamin Köhler – Fraunhofer ISE

Development of a temperature-controlled window-element for test rigs
This thesis is dedicated to the development of window units with a glass surface which allowsa consistent and precise temperature control. The conception of the window unit was established as part of the Climate Chamber Project of the Chair of Building Energy Systems and Heat Supply at the Institute of Power Engineering of the TU Dresden. Glass surfaces play a major role in investigations of building energy systems since they allow the monitoring of enclosed rooms and since the percentage of glass in relation to other building materials in modern domestic, commercial and industrial buildings increases constistently. One of the primary requirements concerning the conception of the prototype was its portability to other test rigs. The evaluation of adequate temperature control technologies within a decision matrix resulted in the preference of thermo-electricity. Thermo-electricity facilitates a modular construction and thus enables a scalable performance of the window unit. The development of the prototype involves the construction, the thermo-dynamic and electronic design, the planning of the drive and control technology and its implementation. Throughout a series of tests the prototype was measured with step, ramp and jump signals within a temperature range of 20 °C to 28 °C. The measurements confirmed the applicability of the thermo-electric technology for the temperature control of the prototype. Based on these results further application areas apart from building energy systems, e. g. automotive heatinsulation, are discussed.
Editor: Jannik Schug
Tutor: Prof. Dr.-Ing. Clemens Felsmann

Simulation models of cooling energy supply systems based on measurement data
Taking into concideration, that the cooling demand is increasing worldwide, the emission of heat is of great importance. It a ects the e ectiveness of the cooling system and requires an adapted, ecient regulation. In this work, dry coolers of various locations with coolingsystems based on absorption are examined and compared. In the following, suitable calculation approaches are created in order to construct simpli ed simulation models with these and with the aid of measured data. These models estimate the cooling outlet temperature of the dry coolers. The physical model is subsequently expanded in order to calculate the electrical energy demand of the dry coolers with the help of the given set-temperature. Finally, the models are evaluated and aproaches for optimization are presented.
Editor: Theresa Kramer
Tutor: Dr.-Ing. Karin Rühling, Dipl.-Ing. Felix Panitz

Analysis of the electrical energy consumption on the campus of the TU Dresden
The increase of electrical power consumption on the campus of Dresden University of Technology in combination with a continuous rise of the price of electricity in recent years caused a significant expenditure for the university. Besides this, CO₂ emissions generated during the supply of electrical energy has a considerable impact on the climate and the environment as well as on the future energy supply. In the present thesis, the electrical power consumption of the Merkel-Bau, which is a building on the university campus, will be analysed. In doing so, usage-dependent and consumer group-dependent demand parameters had to be defined. The aim is to classify the electrical power consumption of all buildings on the campus for a further evaluation of the future development of electrical power consumption on the campus of Dresden University of Technology. Moreover, the analysis will help to detect possible energy-saving potentials and to provide suggestions for an appropriate retrofitting of electrical energy meters in order to balance the electrical power consumption completely. The achieved results serve as a basis for further analysis and measures for a sustainable use of electrical energy.
Editor: Corinna Strube
Tutor: Dr.-Ing. André Kremonke, Prof. Dr.-Ing. Clemens Felsmann

Simulation models of an absorption chiller based on measurement data
This student research project researches, implements and analyses different modelling methods for absorption chillers. These models are entirely based on measurement data. The adapted characteristic equation method and various multivariate polynomial regression models are evaluated in detail. Two types of machines located at five different locations in Germany are analysed: Hummeln and Bienen. It is then tested, if a combined model is precise enough to describe a single machine. Lastly, the gained data and developed models are used to give an overview over the characteristical system parameters for each absorption chiller.
Editor: Lisa Müller
Tutor: Dr.-Ing. Karin Rühling, Dipl.-Ing. Felix Panitz

Validation of weather forecast modeling regarding to predictive control in building- and plant systems
Nowadays, it is possible to use predictive control with weather forecast in building- and plant systems. The goal of this paper is to check the weather forecast accuracy for the predictive control. The weather forecasts in this paper come from two different sources. They will be compared with the local measured weather data for city of Dresden and the accuracy of the weather forecasts will be analyzed. For that purpose, firstly the sources of the weather forecast und measured data are explained and an overview about weather forecast and local influences is described. Then the weather forecast errors are examined in detail and the forecast qualities of both forecast sources are assessed. A possible method is presented to improve the forecast accuracy with local measured data. In the following, the relations between the weather and energy demands or yields of chosen buildings and plants are researched. Then the influence on energy demands or yields, which is caused by the inaccuracy of the weather forecast, will be analyzed. The paper ends with the evaluation of using weather forecast for the predictive control.
Editor: Yaxi Ou
Tutor: Dipl.-Ing. Sven Paulick, Dr. rer. nat. Peter Stange, Prof. Dr.-Ing. Clemens Felsmann

Options for reducing supply water temperature of geothermal heating plants within the SWM DH-system
To fulfill the vision of supplying the district heating (DH) system in Munich entirely out of renewable energy sources the Stadtwerke München GmbH (SWM) focuses on the use of geothermal energy. An increasing profitability of geothermal energy can be reached through lowering the highest supply temperature of the DH-grid. This thesis describes options for reducing the supply water temperature in the SWM DH-system. Apart from a precise prognosis of the load and knowledge about the network hydraulic, it is important to study the behavior of the consumer installation. Since the SWM has only few information about their characteristics, a study was conducted to analyze the behavior of the DH distribution station. Due to hydraulic limitations of the DH-grid, an unlimited lowering of the supply temperature is not possible, as the DH-grid already reaches its limit during winter. Therefore, three concepts of increasing the supply water temperature of geothermal heating plants and their economic benefit are analysed.
Editor: Johannes Schrader
Tutor: Prof. Dr.-Ing. Clemens Felsmann, Dr. Nadine Wasserrab - Stadtwerke München

Analysis of thermal comfort under stationary conditions for surface heating systems
The aim of this research project is the steady assessment of the thermal comfort of surface heating systems. For this, experiments with 10 experimentees were conducted in the climate room of the TU Dresden. At the beginning, the current knowledge of the thermophysiological evaluation was discussed. The following section provides an overview of the possibilities, problems and technical execution of surface heating systems. Afterwards, the methodology of the subjects' examinations and the experimental area are discussed. In the penultimate section, the measuring technique used is briefly explained. The work is completed by the consideration of the results obtained and the comparison with the standard.
Editor: Christian Pappermann
Tutor: Dipl.-Ing. Maximilian Beyer, Dipl.-Ing. Lars Schinke, PD Dr.-Ing. habil. Joachim Seifert

Concept for a district heating based heat supply of a single family house development
This paper examines the profitability of a possible local district heating grid for a small settlement in Bärnsdorf. This includes research on the heating load of the buildings and scaling of the heating grid for different layouts.
The simulation takes a variety of different heat suppliers into account. The focus here is on sustainability and renewable energy sources. Furthermore, the decentralized inclusion of solar heat and photovoltaics is regarded.
The second part compares the economic aspects of three different district heating designs to decentralized oil heaters, therefore investment cost and heat generation cost are considered.
Editor: Luisa Lindner
Tutor: Dr.-Ing. Karin Rühling, Dipl.-Ing. Felix Panitz

Comparative analysis of energy and economic aspects of heat pumps
To reduce the production of Greenhouse gases while generating heat in homes, it is appropriate to use a compression heat pump. The heat pump has, operated with renewable electrical energy, only little emissions and is characterized by its high efficiency. To ensure that high efficiency, the heat pump’s integration in the heating system must be perfectly adjusted.
Thus, there are several standards, directives and guidelines which enable the optimal involvement of the heat pump in the hydraulic circuit. To give the user a clear overview of the planning references, a comparison was made. Thereby five systems which are introduced in three guidelines were contrasted and their advantages and disadvantages were highlighted.
All five systems consist of a heat pump, combined with a panel heating and a storage for drinking hot water. Additionally, buffer storages, connected in parallel or in series, are employed. In two systems, the heat pump is being supported by either a solar thermal system or a pellet boiler.
The operation of all circuits under the same reference conditions was reconstructed in a simulation program. This simulation determined that the heat pump, connected in series with a buffer storage, works the most efficient. However, the combination of a heat pump and a solar thermal system has the highest system efficiency.
Editor: Niklas Wank
Tutor: Prof. Dr.-Ing. Clemens Felsmann

Integration of decentralized heat generators in an existing district heating network with respect to the network hydraulic
The politically induced change in energy supply aims to reduce fossil fuels. As a result, the supply structures of the secondary network considered in this diploma thesis will change in the coming years. Therefore research and analyses about decentralised heat supply are essential.
Based on measurement data, simulation models of the secondary network were created using the software tool SINETZ. The network hydraulics were computed and analysed.
Building on these results, the possibility of network compression was investigated. Considering the heat exchangers between the primary and secondary networks, the circulations pumps, as well as the network hydraulics, the feasibility of supplying additional loads with a total thermal power of 3.2 MW_th was verified.
Subsequently, investigations on the decentralisation of the system were carried out, whereby three variants were identified. The first option is a division of the secondary network into eight subnets, which are supplied with heat independently. In order to maintain the network structures, the construction of an energy cluster (combination of several combined heat and power plants, a power-to-heat system and a heat storage unit) at the location of the heat transfer station was investigated as the second modification. The third variant provides a combination of a power-reduced energy cluster at the location of the heat transfer station and the supply via the primary network.
Finally, the most promising decentralization option could be determined by means of an evaluative comparison.
Editor: Robert Kerstan
Tutor: Dr.-Ing. Karin Rühling, Dr.-Ing. Mathias Rieger – VPC GmbH, Vetschau/Spreewald

Determination of energetic parameters of micro-cogeneration systems and brine-water heat pumps with a hardware in the loop test stand
This paper examines the determination of the energetic values of micro-cogeneration systems and brine-water heat pumps in a hardware in the loop test stand. For this purpose, the paper discusses existing standards and guidelines for evaluation procedures regarding microcogeneration systems and heat pumps. Thereafter a new dynamic assessment procedure is presented, which uses a hardware-in-the-loop test stand. The test stand is checked and commissioned, subsequently emulation tests are carried out and evaluated. In addition, a brine module for the integration of a brine-water heat pump will be added to the test stand. This brine module is dimensioned and constructed in this work. Finally, the first experiments with the heat pump are carried out to test the extension of the test stand.
Editor: Florian Bauch
Tutor: Dr.-Ing. Martin Knorr, Dipl.-Ing. Maximilian Beyer, Dipl.-Ing. Lars Schinke

Energetic balancing of a DEC air-conditioning system extended by a magnetocaloric cooling unit
Starting with an extensive literature research about DEC air-conditioning and magnetocaloric cooling, a calculation tool for computing of all points of state and energy flows in a DEC air-conditioning system extended by a magnetocaloric cooling unit is developed within this work.
For well-chosen operating conditions with assumptions about outdoor and indoor air conditions as well as heat and moisture loads an energetic balancing is carried out using the Excel-tool. Besides the DEC process a balance limit including the magnetocaloric cooling unit (MCU) is used as well. The overall driving power consumption of the DEC air-conditioning system can be reduced in parts up to more than 50 % by the integration of a MCU. This is pointed out by the energetic balancing. The energy flows in the DEC air-conditioning system extended by a magnetocaloric cooling unit are presented in a Sankey-flowsheet.
With the calculation results and a separate sensitivity analysis design criteria for developing a demonstration unit of a DEC air-conditioning system extended by a magnetocaloric cooling unit are derived. Because of the necessary cooling power of the MCU of 400 W and the required temperature difference of 22 K it appears that an implementation of such a system is challenging but it seems to be reachable regarding the state of the art in magnetocaloric cooling.
Editor: Paul Adam
Tutor: Dipl.-Ing. Lars Schinke, PD Dr.-Ing. habil. Joachim Seifert

Technical realization of heat pump systems
The aim of this present work is to provide an overview of various heat pump system
concepts and to evaluate these energetically using different simulation tools as well as to compare them qualitatively with each other. Three standard hydraulic circuits are selected according to DIN EN 15450 and by the Leitfaden Hydraulik (guide to hydraulics) of the German Heat Pump Association. Their hydraulic integration and operation have a big influence on the energy performance indicators.
For the determination of the so-called energy characteristics, which are explained, possibilities of the necessary measuring devices are illustrated.
In addition, the previously selected heat pump systems are simulated using the Polysun
software in order to illuminate their image and conclude a comparison between the different planning tools.
Editor: Maximilian Schicker
Tutor: Prof. Dr.-Ing. Clemens Felsmann

Development of a conceptual design and marketing tool for small wind power stations
This thesis has been written to convey the basic knowledge needed to use small wind power stations. Therefor technical, geographical, economical and legal concerns are relevant and need to be considered.
As a result, prospective customers of a small wind turbine should obtain an overview of influential factors and how to handle them. Thus, an electronic design tool will be developed, which includes all mentioned emphases. This consists of a list of common small wind turbines and their essential parameters and a calculation table, which provides expected yields and costs in an easy way. Therefor only few input quantities have to be supplied, for example wind speed and energy demand.
Because of this simplified procedure, it is possible to quickly gain a non-binding overview, what should be expected of a small wind power station in a particular location. However, this does not replace a detailed dimensioning, but it can be used as a helpful guideline.
Editor: Jacob Kriehmig
Tutor: Dr.-Ing. Markus Rösler; Prof. Dr.-Ing. Clemens Felsmann; Dietmar Pöter – aedes engineering GmbH

Conceptional reflections regarding the energy and water supply of a mountain cabin
In summer as well as in winter the Dresdner Hütte placed in Austria (a mountain cabin) is an attraction for lots of tourists because of its special position and magnitude. For that reason the demand of better convenience raises every year. Nevertheless the Dresdner Hütte is still a so called “Schutzhütte”. Preserving this status is very important. That is why the demand is not followed blindly. It is the aim to eradicate flaws, raise comfort, decrease costs and reduce environmental influences through intelligent and energy saving methods. In according to that this paper shows a way how to modernise the heating and air ventilation system. The description of the heating concept is divided into two parts. On the one hand a supply through conventional solutions on the other hand through regenerative energy resources. For the air ventilation system a concept with a centralised air ventilation device and a concept with peripheral devices is described. To show the requirements of a modernisation the special position of the cabin, the climatic circumstances as well as the technical situation is analysed. Furthermore the current energy supply system of the Dresdner Hütte is compared with equal cabins. Therewith it is to be shown whether there are other supply opportunities and whether an improvement is necessary. Correspondingly the demand of heat and supply air is calculated and the different concepts are designed. To present a recommendation an internal comparison for the heating supply solution and the air ventilation concept is shown and as an all-inclusive concept submitted.
Editors: Alexander Kosel, Marwin Kretschmer, Thomas Mehlig, Robert Scharf
Tutor: Herr Dr. Konrad – Deutscher Alpenverein, Prof. Dr.-Ing. Clemens Felsmann

Preparing calculations for water turbines with Lattice-Boltzmann-Methods
Lattice Boltzmann methods have in principle an advantage over other numerical computation methods when the geometry changes during the process to be investigated. In this work an overview of the lattice Boltzmann method (LBM) will be present. Two fluid simulation models will be implemented with lattice Boltzmann method, a steady water flow in turbine housing and a flow channel with rotating blade. The fundamental principles and configuration of the simulation will be explained in detail. This result from simulation gives a velocity and pressure distribution for both simulations, which can be used as preparations for the calculation of water turbines. According to the result from the simulation the pressure in empty turbine housing drops and the velocity difference well mixed; an obvious pressure difference is added through the rotating blade in the square channel. An outlook from the evaluation of the results is given, that the calculation of water turbines with LBM and the demonstration of how it works will soon be available.
Editor: Yongqing Xia
Tutor: Dr.-Ing. Markus Rösler

Wast Heat Recovery
The worldwide during industrial processes produced heat that is not used within the production process (waste heat) represents an untapped efficiency potential. The utilization of this potential can make a crucial contribution to achieve the ambitious aims of the Paris Agreement.
The following paper will give an estimate of the worldwide available waste heat potential. Furthermore, the distribution of this potential regarding different potential uses will be analyzed.
The investment cost for two different possible uses will be considered and assessed with respect to the industrial requirements for an investment.The technology selection is often accompanied by uncertainties. Therefore, a selection method for the main component of a waste heat utilization system, the heat exchanger, is developed.
Editor: Oliver Lind
Tutor: Dr.-Ing. Thomas Sander, Dipl.-Phys. Thomas Schille – Siemens AG, Power and Gas Division (Strategy), Görlitz

Ice slurry production by direct evaporation and absorption of water vapour in low vacuum
A growing interest in comfort and increasing technical progress lead to a worldwide rising demand for refrigeration. Absorption technology offers the potential for providing cold conduction using heat as driving energy. Environmental aspects, efficiency and fluctuating load profiles as a result of an expansion of regenerative energy sources increase the demand for technological concepts that meet the listed requirements. For this purpose, an experimental field for the investigation of liquid ice generation by using direct evaporation and thermal compression in the coarse vacuum was developed. A lithium bromid / water absorption refrigeration system is used as a thermal compressor. In the experimental field, water serves simultaneously as a refrigerant, refrigerant carrier and storage medium without additional heat transfer losses. The generated liquid ice is a two-phase mixture. During the thawing the sensitive and latent heat can be used. The theoretical concepts as well as the interpretation and conception of both subprocesses and their joining are finally reviewed and critically assessed during the commissioning of the test facility. The thesis is to serve as a basis for further research in the experimental field.
Editor: Kristin Wiegand
Tutor: Dipl.-Ing. Christoph Steffan - ILK Dresden, Prof. Dr.-Ing. Clemens Felsmann

Empirical analysis of an evaporative cooling device, deduction of optimization recommendations and discussion about a future application
In the present work, the prototype of a new evaporative cooling device was investigated by the Fraunhofer IVI as a part of the project autartec®. Extensive velocity measurements were required for the flow analysis. The performance characterization required temperature and humidity measurements under different climatic conditions. Further optimization potentials were shown and concrete recommendations for changes were made. The evaluation of hygienic risks using a laboratory analysis revealed low microbiological stresses. Finally, a discussion followed about the usefulness of evaporative cooling devices in vehicles. It turned out, that the devices did not meet the respective requirements optimally. However, in the cooling of buildings, the autartec® evaporative cooler will be able to make a valuable contribution in the future, if appropriate optimizations are implemented.
Editor: Tim Böttner
Tutor:Dipl.-Ing. Christian Städel – Fraunhofer-Institut für Verkehrs- und Infrastruktursysteme IVI, Prof. Dr.-Ing. Clemens Felsmann

Dynamic simulation of air conditioning systems for buildings
This student research project is about simulation of HVAC-systems using the simulation
software TRNSYS-TUD, especially the module Type 94. Measurements of the HVAC-unit
of the climate room - part of the Combined Energy Lab were performed at different conditions.
Afterwards this scenario was simulated in TRNSYS-TUD. Whereas steady state cases can be well reproduced using some workarounds, it is not possible to reproduce dynamic condititions at a good level with Type 94. Therefore thermal losses and heat capacity effects are missing in Type 94s calculation. Furthermore this paper shows alternate simulation software for hvac-systems and analyses them. Finally further development strategies for simulating hvac-units with TRNSYS-TUD were discussed.
Editor: Christian Doerffel
Tutor: Dr.-Ing. Alf Perschk, Dr.-Ing. Markus Rösler, PD Dr.-Ing. habil. Joachim Seifert

2016

Strategies to inspire an energy-saving user behavior
As the largest university in Saxony, the energy demand of the TU Dresden is equivalent to a small town. To protect the climate and save resources, employees and students must contribute their effort to decrease energy consumption. Therefore, an extensive literature research was conducted to show psychological and technical factors that determine strategies to inspire energy-saving user behavior. This paper not only presents studies on how behavior change is achieved in organizations, it also outlines the TU Dresden’s status quo on this topic and specifics in its management. After analyzing the saving potentials for different types of room use that are typical for a university, a study was conducted to explore the employees’ user and mobility behavior. The results show a mostly sustainable use of energy and awareness of energy-saving strategies. Great saving potential lies in the employees’ motivation to act. From those results, a catalogue of measurements and recommendation for action are developed, which centerpiece forms the information platform “Energy”.
Editor: Lorin Neumann
Tutor:Dr.-Ing. Annina Gritzki, Dr.-Ing. André Kremonke

Analysis of the commissioning and testing process of building facilities of a laboratory building, taking into account the revised standards
Planning and object supervision of complex systems used by technical building service installed in laboratory buildings are gaining in importance because of increasing technical advancement. In order to improve the procedures, an analysis of the commissioning process, a clarifying and de ning of the term conformity assessment of a plant as well as a theoretical and practical review on the creation process of the matrix for a re protection control system was performed.
Meeting legal regulations and standards, recommendations for action and assistances in terms of step sequences, checklists and blank templates for planning and object supervision were developed. Afterwards, the guidelines and its practical applicability were checked and optimized in a sample building project.
Those recommendations, checklists and templates facilitate the future procedures in a building project for the user.
The evaluation of a commissioning process, the conformity assessment of a plant and the matrix for a re protection control system, showed a potential for improvement in varying temporal placements in project execution. Therefore it should be acted on those suggestions as soon as possible within a project. Furthermore responsibilities should be determined and administrative cooperation should be encouraged.
Editor: Judith Jung
Tutor: Dipl.-Ing. Lars Schinke, Dipl.-Ing. U. Pahl – PG M+M AG

Optimization tool for integrating renewable energies into building energy systems
The study work describes the development of a tool that provides the perfect system selection and dimensioning for the energetic supply of a family house. A main connection to the power grid and a photovoltaic system with optional solar power storage are compared for the electrical power supply. In order to cover the thermal energy requirements, an air heat-pump and a solar heating system are placed in each case with buffer heat storage, facing each other. The optimization is thus carried out from self-sufficient supply, right up to the pure network cover.
A self-chosen period can be calculated for economic consideration. This is followed by a renewal of the investment technology, whilst taking the price of the development in consideration. Furthermore, there is also a consideration of the development of energy costs during the optimization period, which can be changed by the user in given scenarios.
The aim of the work is to provide the basis for a calculation-tool for builders or energy consultants, which they can rely on. With the help of this tool builders and energy consultants get a guideline, which regenerative plant engineering is the most profitable for the individual case.
Editor: Daniel Scholz
Tutor:Dipl.-Ing. Richard Kratzing; Dipl.-Ing. Christian Städel – Fraunhofer-Institut für Verkehrs- und Infrastruktursysteme IVI, Prof. Dr.-Ing. Clemens Felsmann

Air-Water heat pumps and geothermal air preconditioning
The present paper deliver insight into water-air heat pumps technologie with geothermal air preconditioning. Therefor stragety and benchmark methodes were developed to research the performance enhancement and efficiency improvement by the use of geothermal air preconditioning. Technical application of present geothermal air preconditioning were analyzed and used for stragety method validation. Afterward the stragety and benchmark methodes were employed to three selected buildings. Though energy, commercial and ecological issues were implicated in the benchmark. The benchmark shows the actual potential of this technologie and references to further development.
Editor: Theo Gottwald
Tutor: Prof. Dr.-Ing. Clemens Felsmann

Time variable ecological balance of electricity
Panitz et al. (2015) developed an approach to assess the time variable ecological balance of electricity due to the augmenting and volatile share of renewables in the production mix. Both types of evaluation – mix and marginal electricity – neglected the allocation of primary energy input in CHP power plants as well as were based on a rarely detailed merit order. This study uses an electricity market model named ELTRAMOD to determine an hourly, optimized operation of the power plants which thereby can be used in the variable ecological balance approach. In total 21 CHP-types are considered to be heat led and therefore a nationwide heat load curve for Germany is modeled with the help of synthetic load profiles. Considering as well the possibility to cover heat demand with a gas-fueled boiler or using power-to-heat derives a model-based hourly optimum which can be used to calculate electricity production in CHP power plants by applying statistical CHP coefficients. The results coincide well with actual data on a yearly and monthly basis and were used to estimate primary energy factors by applying as well the exergetic allocation method. The outcome shows a growing effect of allocation considering the changes in the German energy system from 2013 to 2030 along with the need for a detailed merit order to be used.
Editor: Sebastian Eberhardt
Tutor: Dr.-Ing. Karin Rühling, Dipl.-Ing. Felix Panitz, Prof. Dr. rer. pol. Dominik Möst, M.Sc. Christoph Zöphel

The energy saving capabilities of innovative solutions for artificial lighting at the Technical University of Dresden
The purpose of this work is to study possible methods for lighting-related energy-saving in different areas. The various energy-saving methods are discussed in terms of content, considering the requirement of good lighting and the relevant legal standards. So that the knowledge of these energy saving methods can be implemented in practice, the energy demand and lighting conditions of an office building - MER-BAU in the campus of TU Dresden – would be considered. The study is carried out through a questionnaire from user behavior and an inspection of the building. According to the VDI 3807 sheet 4, it shows a low level of installed capacity, low hours of operation and a low specific energy consumption. This is however the partial of the large net floor area of the building, in which the rarely used area are not considered. According to DIN 15232, the lighting systems is associated with the efficiency class "D". Reducing the annual energy requirements and improving the quality of light in the MER-BAU can be achieved by replacing the inefficient lamps or luminaries with LED systems and conventional Ballast with electronic Ballast. Compare to the annual energy demand prior to the implementation of energy saving measures, energy can be saved ca. 52%, and The light quality of the building can be improved as well.
Editor: Anchalee Prapatsornpittaya
Tutor:Dr.-Ing. Annina Gritzki, Dr.-Ing. André Kremonke

Investigating the occupants behavior and acceptance regarding the cooling of an office building located on the campus of TU Dresden
Due to rising temperatures during summer, the demand of cooling-capacities for office buildings increases. Especially in existing buildings new technologies need to be developed, which can be installed and operated with small employment of capital. Using free heating surfaces like radiators for cooling may be a viable option, since radiator installations are common in most buildings in Central Europe. To investigate the effects of this cooling-technology the heating system of a building of the TU Dresden was extended, so that cool water could be pumped through the existing heating circuit.
Relevant parameters of the indoor air, the occupant behavior and the satisfaction of occupants with thermal comfort where measured in a period with and without activated cooling. The results of this study show, that a cold air pool developed inside the rooms. This cold air will rise due to thermal buoyancy around occupants, which leads to a cooling effect. The satisfaction of occupants with thermal comfort rises in general, but especially for high room temperatures an improvement was measured. Since this technology works on low operation points, environmental energy can be used to supply the demanded thermal energy.
Editor: Fabian Franke
Tutor: Dipl.-Ing. Alexander Buchheim, Dr.-Ing. André Kremonke

Energy performance and cost efficiency optimization of an automated painting plant for plastic parts
As part of an energy efficiency project in the private sector, I investigated the potential for energy saving in an automatized paint shop for plastic parts and their periphery in order to produce a catalogue of measures to increase the energy related output. The factory is part of a complex production system of an automobile manufacturer. Using the existing energy and media meters to conduct a structured analysis of the processes of production, plant and equipment, as well as supply systems I have compiled an energy monitoring. Subsequently, applying methods such as a load course analysis and plant inspection, I extrapolated the energy-saving potential from a technical, process oriented and economical perspective. Keeping the high requirements regarding both, quantity and quality, in mind, I then implemented technical and organizational measures, which I prioritized according to factors such as process intervention, time-to-value and realization effort. My results amount to an energy-saving potential of almost 1,8 GWh/a, of which I recommend measures adding up to 600 MWh/a in the implementation package.
Editor: Stephan Pursche
Tutor: M. Sc. Alexander Schlegel, OSB AG Leipzig , Prof. Dr.-Ing. Clemens Felsmann, PD Dr.-Ing. habil. Joachim Seifert

Numerical investigations of the pressure loss and heat transfer of heat exchanger plates with Ansys-CFX
The Hybrid heat exchanger uses plate elements to transfer heat between two process streams. As a special feature, the plate heat exchanger simulates a shell-and-tube heat exchanger flow. In this way the Tubular plate structure shapes a tube-like flow channel that the second medium flows around. The present paper investigates the fluid flow between the plates numerically by using the commercial software ANSYS-CFX. The pressure loss, the heat transfer, as well as the general flow behavior were taken into account. These variables were simulated for individual plate elements, plate blocks and various shaping depths for laminar and turbulent flows. As a result, correlations for dimensionless numbers were developed. These semi-empirical equations facilitate an estimation of the heat transfer and pressure loss in the future, without requiring a time-consuming CFD-simulation.
Editor: Alexander Bauer
Tutor: Prof. Dr.-Ing. Clemens Felsmann, Dipl.-Ing. (FH) Torben Möller - G.A.M. Heat GmbH

Cooling loads and cooling supply options of commercial buildings
The refrigeration load of non-residential buildings is the result of different influencing factors. Not only the solar heat input but also the internal processes are relevant factors. Additional gains of heat are therefore the staff, the lighting and the equipment. The goal of this work is to calculate the cooling loads according to VDI 2078 by using the example of the Andreas-Pfitzmann-Bau (APB) and to analyze thereby which changes could lead to an optimized cooling supply. A simulation of the APB was designed with the aid of the program mh-software and to calculate the cooling loads. These calculated results were compared to the measured data. There were considerable differences between the calculated and the actual cooling loads. Another part of this work are a detailed description of designing the simulation as well as the exact steps for calculating the cooling loads. The simulation was also the basis for the sensitivity analysis which analyzed the dependencies of the factors. The conclusion shows how many influencing factors lead to an increase of the refrigeration load in the near future. At the same time, there are also many technical developments to raise the efficiency of cooling devices and to reduce the gains of heat.
Editor: Johannes Schwarz
Tutor:Dr.-Ing. Annina Gritzki, Dr.-Ing. André Kremonke

Analysis of grid-supportive operation strategies for the cooling supply of non-residential buildings on the example of retail trade
The thesis deals with the developement of different grid-supportive operation strategies for the cooling supply of non-residential buildings on the example of food retail trade.
The focus lies on the interaction between recent cooling technologies in food retail trade and possibilities to optimize those technologies regarding the use of operating reserve. The developement of the cooling supply strategies is based on the actual scientific literature and different economic and technical boundary conditions. In total three different grid-supportive cooling supply strategies are developed and evaluated. Out of those three concepts one favoured strategy is worked out, which is optimized for the cooling supply in food retail cooling and the use of operating reserve.
Based on the favoured strategy the potential for the usage of operation reserve in the whole food retail sector is estimated.
Editor: Christian Schwind
Tutor: Dipl.-Ing. Juliane Schmidt

Preparation of a valuation method for grid-supportive operation strategies for the heating and cooling supply of non-residential buildings
Developments in the expansion of renewable energies with volatile power output, like wind and solar power, push the electricity grid to its limits. Next to investments in grid expansion and energy storages, grid-supportive operation of loads can be implemented as Demand Response (DR). Electrical powered Heating, Ventilation and Air Conditioning (HVAC) and refrigeration systems inhere a large potential for load management. Especially in the commercial sector potentials for DR have not yet gained much attention. The large variety of buildings, HVAC and refrigeration systems, usage types, load shapes and inhomogeneous ownership structure does not allow for any sure formulas.
This thesis develops a valuation method to assess the potential of grid-supportive behaviour of energy systems in buildings of the commercial sector in Germany. A linear optimization model was developed to estimated cost savings by applying a Real Time Pricing (RTP) DR approach. The model includes a simulation of temperatures in an office building with one-hour time resolution during one year. Demand response approaches and business models will be discussed and tested for applicability under several technical, economical and legal constraints in the current German energy economy. The state of buildings in the commercial sector will be estimated by reproducing latest results from the growing number of research in this field.
Results show that there are potential cost savings related to demand response by additionally supporting grid operation. Market barriers and regulations in Germany need to be adapted to harness the full economical potential. The size of utilities, the variety of load shapes and high demand for heating and cooling highlights the commercial sector as prospective target for DR applications.
Editor: Florian Eichkorn
Tutor: Dipl.-Ing. Juliane Schmidt

Energy performance analysis of an institute building at the Technical University of Dresden
This thesis contains the setup and simulation of a theoretical comparsion model of the Informatik building of the Technical University Dresden. For this pupose the building will be transferred into a simplified geometrical model with the help of the CAD-input routine "TestNetz". Within this transfer the rooms with similar usage will be combined in zones. The magnitude of infrastructure of the building and the individual user characteristic will be represented as realistic as possible. For insufficient data available an adequate assumption under the help of available sources will be done. The simulation of the model will be done with usage of the numeric building simulation program "TRNSYS-TUD". Concluding the simulation results will be analysed, rated and compared with the given energy consumption values of the energy performance certificate of the building.
Editor: Hans Kaiser
Tutor:Dr.-Ing. Annina Gritzki, Dr.-Ing. André Kremonke

Development of a heat extraction module for use in a magnetocaloric cooling
unit

The development of magnetocaloric cooling devices is a promising technology for a more efficient way of refrigeration. This paper does the groundwork for the thermal and hydraulic design of the Heat uncoupling module of a magnetocalorical cooling device. The aim is the integration of this module into a DEC air conditioning system within the SOMAK project. For this purpose, the paper gives an introduction to magnetocaloric cooling and presents some concepts of devices. With this background, requirements for the fluid cycle and a thermal and hydraulic beneficial design of the magnetocaloric material are inferred. Afterwards various geometrical material designs are examined through analytical calculations.
For this aim an excel tool is developed, which outputs the effect of the variation of parameters on the thermal and hydraulic properties.
Additional a fluid cycle for hydraulic examinations is built up. Therefor suitable measurement technology is selected and calibrated in order to measure the pressure drop of produced probes of magnetocaloric material. The determined measured values enable the comparison with the calculated theoretical values. By means of the results, requirements on the quality of the produced magnetocaloric materials can be made.
Editor: Lukas Friedenstab
Tutor: Dipl.-Ing. Lars Schinke, Dipl.-Ing. Maximilian Beyer, PD Dr.-Ing. habil. Joachim Seifert

Analysis and investigations of control concepts of micro-CHP systems using emulation

In the context of the diploma thesis two different micro CHP systems for building ranges of one to two family houses are analysed energetically.
On the one hand, it is the system of the combination of electricity generation with a simultaneous provision of thermic energy for the sole building heating and on the other hand, it is the combination of electricity generation with a simultaneous provision of energy for heating purposes and drinking hot water.
For this purpose the micro CHP systems are analysed by a simulation. The test states are subsequently adapted to the specific functional requirements and the emulation tests are executed.
The resulting utilization ratios are compared correspondingly to the utilization ratios from the simulations as well as to the standard utilization ratio in accordance with DIN 4709.
Finally, the energetic analysis is considered critically.

Editor: Matthias Kunze
Tutor: PD Dr.-Ing. habil. Joachim Seifert, Dipl.-Ing. Paul Seidel, Dr.-Ing. Martin Knorr

Buildings as thermal energy storage

The present paper is concerned with the use of existing buildings as thermal energy storages. In order to attempt to deliver and use green energy, energy storages have reached a significant status on the market. Because of their high mass, buildings seem to be made for storing thermal energy. By using a simulation program, the thermal performance of a single-family house was examined over a period of one year. In addition to that, different variations of storing thermal energy were regarded, concerning their influence on the condition of the building. The detected energetic quality, the existing storage mass and the persistent storage effect labeled it as a potential thermal storage. Nevertheless the object of an usage is related to an optimal way of usage: By considering different scenarios it is now possible to draw up recommendations, regarding storage temperature and loading time. By that the usage can be detected as economical in certain circumstances.
Editor: Mathias Hauskeller
Tutor: Prof. Dr.-Ing. Clemens Felsmann

Integration of a water-cooled server rack in a heat supply plant

The company „Cloud & Heat Technologies GmbH” offers an energy-efficient solution in the field of heat recovery to minimize the high power consumption of data centres. This innovative idea is based on the use of waste heat from data centres. CLOUD & HEAT deals with the construction and operation of decentralized data centres, which are installed in residential buildings. These buildings are then heated with the data centre’s waste heat. The aim of this work is to design a supply concept for a housing complex, in which different water-cooled server racks are involved.		The difficulty of this project is that the server racks have different hydraulic properties. The idea of this supply plant is that it can additionally be used as the company’s test installation in which newly developed server racks can be tested. In the course of this work possible versions of the heat-related integration are presented and a preferred option will be selected. Subsequently, the major components of the selected version will be dimensioned and the pressure loss calculated.
Editor: Roque Salazar Alvear
Tutor: Dr.-Ing. Karin Rühling, Dipl. -Ing. A. Strech – Cloud & Heat Technologies GmbH

Optimization of the plant management for the heating and cooling system of a labor building

The aim of this research project is the examination and validation of the heating and cooling system of a laboratory building designed for analysis of municipal sewage and build in 2013 by the service unit “Stadtentwässerung” Dresden. A heat pump with hot- and cold-water tank provides heating and cooling power for the supply of the building. A district-heating connection of the DREWAG serves as a backup supply of heat. Whereas the hot-water tank is used as the heat sink of the heat pump, the low temperature heat source is either the cold-water tank or the primary clarifier. The performed examination provides an analysis of the function of the system, the set-up of an		installation diagram of the overall system as well as an examination of the deviations of the real plant parameters from the planning specifications. By means of records of measurement data an evaluation of plant components and their interaction is performed. An energy balance of the entire system and a consideration of the COP of the heat pump are used to determine the total degree of utilization and the COP in different modes of operation of the heat pump. A survey about the thermal comfort to be filled out by the employees is elaborated and evaluated.
Editor: Laura Fritsche
Tutor: Dr.-Ing. Karin Rühling, Dipl.-Ing. Thomas Schöniger, Stadtentwässerung

Research into model-based and empirical identification and optimization of the charging level of a storage made of salt hydrates using thermal CFD-simulation

The research project with the title Research into model-based and empirical identi cation and optimization of the charging level of a storage made of salt hydrates using thermal CFD-Simulation is elaborated by the Fraunhofer Institute IVI in cooperation with the Professorship of Building Energy Systems and Heat Supply of the Technical University Dresden. The aim of this research is to develop a prediction for the state of charge of latent heat accumulator devices. This heat storage unit uses sodium acetate trihydrate as a storage media and will be utilized in a self-su cient and oating residential building which is planned in the autartec® project.		In this student research project the transition change in a single package of the storage media which is used in the accumulator is analysed by thermal CFD-Simulation. The model is created by the multiphysics simulation tool COMSOL®. Based on this simulation further models of the whole heat storage device are developed and assessed. A test bench is designed for the validation of these simulations. The necessary structural, metrological and uidic components are de ned and the measurement data acquisition has been set up. To ensure a highly e cient execution of the validation tests a design of experiment study has been set up to evaluate the needed parameter settings.
Editor: Peter Bendix
Tutor: Prof. Dr.-Ing. Clemens Felsmann, Dipl.-Ing. Richard Kratzing / Dipl.-Ing. Christian Städel – Fraunhofer-Institut für Verkehrs- und Infrastruktursysteme IVI

Development of Heat maps and energy information systems

The objective of this paper is to examine the development of heat maps respectively energy information systems and to analyse maps, which already exist, of the city Dresden and its national and international environment. In the first instance the data which are required for the development of a heat map will be named and a description of various ways to estimate the heat requirement will be conducted. In order to complete an energy information system, several energy sources must be observed.		In this paper the determination of the industrial waste heat potential of different types of companies will be addressed in detail. During the following procedure of this paper, illustration facilities and applications of heat maps will be examined. Moreover, examples of Germany and other international countries will be analysed. It was determined that there are a few communes in Germany which have a heat map at this moment. The use of such a heat map for the communes in Saxony and also for Dresden is unknown.
Editor: Saskia Hübner
Tutor:Prof. Dr.-Ing. Clemens Felsmann, Dipl.-Ing. Jens Kaiser

Concept and draft design of waste heat utilization at a testing site

This paper explores the possibilities for re-using waste heat that is produced by a turbocharger testing center (TTC) in possession of the company Kompressorenbau Bannewitz GmbH (KBB). The objective was to find out whether such endeavor can be feasible. After characterizing the various kinds of heat sources and sinks at the site, technologies and components for industrial heat recovery were researched, presented and evaluated in terms of their usability for the application at KBB. Identified options were condensed into assembly modules, which then were combined to create the actual concepts for heat-recovery. For being capable of evaluating energy conservation and thus feasibility, key components had to be dimensioned at least roughly. Because the output of the most significant heat source (exhaust of the testing site with 0.15 ... 3.5 MW) is only available for some discrete hours during the day,		and because even during those hours, temperature and mass-flows are highly unsteady, a limited type of an optimization for the key components was also necessary. Respective approaches for dimensioning heat storage capacity and surfaces of the heat exchangers have been developed. A basic concept for supporting the heatening system and another one which upgrades the basic concept with a cooling function were found to be reasonable from an energetic point of view, energy savings with a magnitude of 500 MWh p. a. in fuel gas are achievable. Cash recovery periods and capital value have been calculated for various conditions. The feasibility of the proposed concepts depends on further optimization, the gas price and the attainability of a subsidy. Generally, pursuing the project of re-using waste heat at KBB is recommended.
Editor: Martin Schorcht
Tutor: Prof. Dr.-Ing. Clemens Felsmann; Oliver Schulz – Kompressorenbau Bannewitz GmbH

Sizing and Design of an evaporative cooler for energy self-sufficient buildings

The aim of this study work is the draft of the construction design and dimensioning of the power of an evaporative cooler for a self-sufficient residential building. The energy-independent building is realized by the autartec®-project planning. At first a short overview will given on the development of German cooling demand in the residential sector. Afterwards the autartec®-project planning is described and the cooling concept gets presented of a self-sufficient building. Following an energetic comparison of cooling technologies and a market research on current competitors on evaporative coolers takes place.		The description of a current application from the practice for the evaporative cooling concludes the chapter. Next, the recorded measured values are evaluated and modified an inappropriate set of formulas to describe the evaporation process in the case under consideration here. By using the modified Formula Werks a design tool is written in Matlab. With the help of the design tool the performance of the evaporative cooler is dimensioned. Finally, the design draft evaporative cooler is presented.
Editor: Lukas Zitzmann
Tutor: Prof. Dr.-Ing. Clemens Felsmann; Dipl.-Ing. Christian Städel, Dipl.-Ing. Ernst-Eckart Schulze, Fraunhofer-Institut für Verkehrs- und Infrastruktursysteme IVI

Energy related considerations about the economics of district heating

This assignment basically is an economic comparison of different heating technologies. The main focus is on the sector of private households. First there is an overview of the investments taken for a district heating system. The following chapter is a detailed analysis of the district heating market in Germany. The focus is on how the price formation works there. Especially the interlink of the district heating market and the prices of raw materials and other markets are analyzed.		Furthermore two distinct price models for district heating are introduced and analyzed for potential future efficiency. Also, there is an overview of modern technologies and their impact on the district heating market. The first part focuses on the economical use of district heating systems and the combined production of heat and power. The second part is about how to involve renewable energy systems with district heating.
Editor: Lydia Seifert
Tutor: Prof. Dr.-Ing. Clemens Felsmann

Thermal performance proof of cooling ceilings

The present research paper deals with a thermal performance proof of cooling ceilings. Basis therefore are the provided triples of temperature and the thermographic reports. The performance proof is performed by a thermal control of the temperatures and a screening of the thermographies.		Meanwhile influences and realisation of measurement are checked critically. It is the aim to establish a proof of 50.000 m² of perfect indoor climate control. Finally a guideline concept which should be used as an manual for similar projects is explained.
Editor: Robert M. Scharf
Tutor: Prof. Dr.-Ing. Clemens Felsmann, Herr Behrens - CANZLER GmbH Dresden

Cost comparison of heating systems

There is a large number of practicable heating systems for every building. A significant deciding factor for a heating system other than constructional conditions and technical requirements are especially the costs which are accompanied with respective system. The task is to create a cost comparison of typically used heating systems with the help of the annuity method.		Besides the investment and installation costs, the costs for technical maintenance of the heating system during the use also have to be regarded. The heating systems taken into account are adjusted for representative application in housing construction and are compared to each other.
Editor: Matthias Kunze
Tutor: Prof. Dr.-Ing. Clemens Felsmann

Development of coupleable calculation modules for smart heat networks

The thesis describes processes and modular calculations for the design and simulation of heat networks. The Purpose of the developed software is to create a program based on Microsoft-Excel with this programming environment “Visual Basic for Applications”. The software consists of individually programmed modules which are costumers, generators (including thermal storage) and the connection via pipeline structures. Through the connections of the calculations,		the program creates hourly load profiles of generators and an economic accounting of the heat network. The programmed software enables the user to give recommendations for the dimensioning of pipelines and to connect several generators from different geographic positions. The program is based on a few input values and standardized parameters. The user has the possibility to create individual project types. Finally the computations and visualizations are verified with a fictitious and a real heat network.
Editor: Eric Zimmermann
Tutor: Dr.-Ing. Stefan Gnüchtel; Dipl.-Ing. H. Wernecke – Ventury GmbH Energieanlagen, Dipl.-Ing D. Bigalke – Ventury GmbH Energieanlagen

Conception and dimensioning of the building energy system within conversion of the building complex „Universelle Werke Dresden“

In the matter of reutilizing the industrial complex „Universelle Werke Dresden“ this study offers a concept for the energy supply of the buildings. Therefor the old heating plant was investigated for any reusable parts and structures. A thorough inventory revealed the necessity for building a completely new plant, as neither parts nor structures can be reused.		The quantification of the heating demand was conducted by investigating the thermal shell and an exemplified heat load calculation. Furthermore a method for the thermal energy supply was examined. Additionally the need for a mechanical ventilation system was met by introducing a concept and discussing an exemplified dimensioning. The status quo of the concepts is presented and concluding methods of energy saving measures are stated.
Editor: Thomas Mehlig
Tutor: Dr.-Ing. Karin Rühling, Dipl.-Ing. Thomas Hoffmann – Ingenieurbüro Hoffmann Planungsbüro für Energie- & Haustechnik

Energetic Parameter Improvement of a PVT-Sandwich-Element by analytical Modeling

In this diploma thesis an analytical investigation of photovoltaic thermal modules (PVT) with water as heat transfer medium is developed to determine the electrical and thermal power parameters and their optimization. Two prototypes were examined with the special feature of using back affixed polypropylene capillary tube mats as heat exchanger. Therefore a complex analytical model was created which was validated with the help of an outdoor test station. On the basis of the newly created model it was possible to perform an energetic optimization of the prototypes' layout. In particular the influence of the heat conductivity and the thickness of the adhesive layer, the thickness of the rear insulation, the distance between the capillary tubes and the absorption coefficient of the photovoltaic inactive areas was determined. Furthermore the modules' angle of inclination, the concentration of antifreeze mixture, the inlet temperature and volume flow was varied. The collector parameters were optimized on the basis of the consequent changes of the energetic values and the estimation of the financial and technological practicality. The results were compared with the baseline values showing obvious improvements.
Editor: Carsten Pietzsch
Tutor: Dr.-Ing. Karin Rühling, Dipl.-Ing. Claudia Döhler, SMK Ingenieure GmbH & Co. KG

Reflections about the application of micro gas turbines as distributed CHP

This paper investigates the use of the micro gas turbine as decentralized cogeneration plant to describe conditions, operating limits and current developments. First, it explains the concept of cogeneration and the operation of a micro gas turbine. Subsequently, it describes the current market situation including conclusions of current. The practical implementation of micro gas turbine CHP (combined heat and power) is shown in examples based on the practical applications and complemented by practical examples of users.		It shows obstacles and barriers, as well as advantages and disadvantages in comparison to other CHP technologies. Finally, the paper undertakes an assessment based on energy, economic and ecological comparisons with other CHP technologies energy-economic assessment including a summaring recommendation highlighting the way forward.
Editor: Markus Arendt
Tutor: Prof. Dr.-Ing. Clemens Felsmann

Development of Model Descriptions for Solar Thermal Power Plants

This master thesis was written in partnership with the company ITI GmbH in Dresden, which develops software called SimulationX used for physical modeling, simulating and analyzing physical effects. In this thesis, the first component models for SimulationX have been developed in order to implement dynamic simulation of concentrating solar power plants. This paper particularly focuses on parabolic trough power plants. Component models for a steam turbine and parabolic trough collector were developed and the fluids molten salt and thermal oils were modeled.		To do so, the basics of concentrating solar power plants and a state of the art of the simulation in the solar thermal industry is explained. Then literature regarding the components, their modelling and validation for the steam turbine, collector and fluids is presented. Finally, a test loop for pressurized gas in parabolic-trough collectors of the Plataforma Solar de Almeria was modeled which studies CO2 as a heat transfer fluid in parabolic trough power plants. Simulation results are compared with measurement data. A sensitivity analysis was also carried out to study the system response regarding different input variables.
Editor: Marianne Biéron
Tutor: Dr.-Ing. Thomas Sander, Alex Magdanz – ITI GmbH Dresden

Development of Model Descriptions for Solar Thermal Power Plants

This master thesis was written in partnership with the company ITI GmbH in Dresden, which develops software called SimulationX used for physical modeling, simulating and analyzing physical effects. In this thesis, the first component models for SimulationX have been developed in order to implement dynamic simulation of concentrating solar power plants. This paper particularly focuses on parabolic trough power plants. Component models for a steam turbine and parabolic trough collector were developed and the fluids molten salt and thermal oils were modeled.		To do so, the basics of concentrating solar power plants and a state of the art of the simulation in the solar thermal industry is explained. Then literature regarding the components, their modelling and validation for the steam turbine, collector and fluids is presented. Finally, a test loop for pressurized gas in parabolic-trough collectors of the Plataforma Solar de Almeria was modeled which studies CO2 as a heat transfer fluid in parabolic trough power plants. Simulation results are compared with measurement data. A sensitivity analysis was also carried out to study the system response regarding different input variables.
Editor: Marianne Biéron
Tutor: Dr.-Ing. Thomas Sander, Alex Magdanz – ITI GmbH Dresden

Reduction of heat input for a gas pressure regulating stations through the use of thermal separation effect of a Ranque-Hilsch tube

This research paper deals with the reduction of preheating power in gas pressure regulation and preheating plants. A modified preheating plant with the usage of a vortex tube gets developed. This preheating plant uses the Ranque-Hilsch-Effect of the vortex tube to generate a heat flow from the ambient air.		The developed plant gets compared with an existing technology by comparing the energetic economization and the reduction of CO2 of an example plant. For evaluating the developed plant some requirements for gas grid operators gets defined. The evaluation shows, that the developed plant is an attractive and competitive way to reduce costs and emissions for gas preheating plants.
Editor: Florian Bauch
Tutor: Dipl.-Ing. Lars Schinke, Dipl.-Ing. Maximilian Beyer

Application of PV compared to other systems

The photovoltaics industry has experienced significant changes within the last decades. Benefits and cost structures have been changed profoundly due to different influence variables. This raises question about the benefit of local usage of PV-generated energy. The primary objective of this paper is to develop a comparative method for energy supply systems. The method is based on a utility analysis and is applied for the reference buildings single-family house, multi-family house and public administration building. Evaluation criteria, and structures are determined to generate the required value of utilities.		For each analyzed system the value of the evaluation criteria is formed in consideration of market and technology analyses as well as simulations in Polysun. To confirm the results informative value a sensitivity analysis is carried out exemplary for the single-family house. In order to understand the comparing method the first part of the paper deals with a detailed explanation of the utility analysis follow by basic information about components used for the energy supply systems. In the second part the method is applied to different supply systems for the reference buildings and a comparison based on the resulting utilities is drawn.
Editor: Florian Dallhammer
Tutor: Prof. Dr.-Ing. Clemens Felsmann

Redesigning Stirling machine

The present paper gives a general idea of the previous elaborations for the construction of a low temperature Stirling engine for driving a water pump and extends them. Therefore the mathematical background for the ideal dimensioning of the most important components was elaborated, conclusions for further arrangements to optimize the basic concept were drawn and a possible implementation was explicated and represented. Furthermore it gives an outlook about potential application cases, where it demonstrates, based on a comparison to competitive products, how the implementation of the elaborations could enable the planed low temperature Stirling engine to reach his ambition, to help people help themselves.		It has been shown that the existing elaborations mainly are well engineered, but in some regions they require further improvements. The implementation of the continuative improvements was illustrated in form of the construction of a second engine. The potential application cases are seen in promotion of well water and the watering of smaller fields in suitable regions. The comparison to other products carried out in the knowledge, that for a successful implementation, the planned low temperature Stirling engine could assert itself within the responded potential application cases.
Editor: Nils Niklas Müller
Tutor: Dipl.-Ing. Volkmar Lippert

Drinking Water Installations with Respect to the new General Requirements

In work, a compilation of rules and regulations and standards with essential content takes place in consideration of drinking water installations for water supply within a building. Compared the drinking water installations in a single family home and an apartment building, the calculation procedures DIN 1988-3, compare with DIN 1988-300 and DIN EN 806-3 ac-cording and show differences. For an apartment house with 6 apartments, the impact of the use of different pipe materials within a drinking water installation be examined on basis of a calculation of pipe network after DIN 1988-300		The design of the water pipes to the building and the water meter selection are compared with each other. Information about emission -, dwell - and waiting times in domestic drinking water networks for cold and heated potable water are represented. Referring to the European reference load profiles, policies and regulations to the retention time of heated drinking water are researched. The result is the appearance of a methodology to determine the residence time of drinking water in the drinking water distribution for different profiles of power take-off at the outlets of the considered apartment building.
Editor: Thorsten Lukas
Tutor: Dr.-Ing. Karin Rühling

Performance testing and optimization of a cascaded refrigeration plant

Currently, blood and tissues samples are frozen with liquid nitrogen, but this method does not meet the GMP demands adequately. The objective of the diploma thesis is the optimization of a three-stage cascaded refrigeration plant for freezing these samples. The machine was developed at ILK Dresden. Within the refrigeration plant, especially the middle temperature circle must be optimized. Therefore the refrigerating capacity must be increased to reach a temperature reduction from currently -30 °C down to -60 °C.		To find weak points, experiments were conducted with the device and the process was simulated with Refprop. Selected components of the plant were characterized and optimization measures were taken. The change of the condenser lead to a temperature reduction of 10 K. Furthermore, the air cooler was found to be too big and so the refrigeration plant does not reach optimal performance. Therefore the air cooler must be changed to guarantee the expected temperature in the refrigeration chamber.
Editor: Stefanie Bachmann
Tutor: Prof. Dr.-Ing. Clemens Felsmann, Dipl.-Ing. Björn Großmann – ILK Dresden

Excessive pressuriziation on the reinjection wellhead in partial load operations of geothermal plants

The production of thermal water in geothermal plants upsets chemically-thermodynamically thermal water equilibrium. The dissolved carbon dioxide that occurs due to this process tends to outgas. The effects can be directly detected by the occurrence of Scalings within the pipes. Therefore, an excessive pressurization in geothermal plants is needed to avoid the outgasing of carbon dioxide. The presented diploma-thesis focuses on the technical design of an excessive pressurization in geothermal plants and the restrictions of the plants in partial load operations. After the theoretical introduction of the topic, innovative pressure keeping systems are compared towards their versatility and effects for a specific geothermal plant project.		Based on the comparison, a recommendation for the most appropriate system to this project is given. Furthermore, a prognostic diagram is constructed to fasten up the decision-making process of choosing the most suited system for future projects. The diagram is based on only reservoir data and information about the heat consumption. The results clearly show that an injection turbine with a bypass string has the greatest potential for saving costs. This is due to the fact that the system makes it possible to regain electronic energy. Fully adjustable injection turbines could furthermore level up the potential to regain energy, but these technologies are still in the first steps of development.
Editor: Hannes Junker
Tutor: Prof. Dr.-Ing. Clemens Felsmann, Dr. -Ing. Frank Kabus - Geothermie Neubrandenburg GmbH (GTN)

2015

The effect of different ventilation solutions on noise, exposures and concentration performance of pupils in classrooms in elementary schools located in moderate climate

Ventilation in school buildings is accomplished either by natural forces (e.g. manually or automatically operable windows) or by mechanical forces (e.g. central or local ventilation system). The important criteria for retrofits are the investment and operating costs, whereas learning performance and wellbeing of pupils should become decisive criteria when school buildings are constructed or renovated. The purpose of this thesis was twofold: 1. to summarise the standards and regulations regarding ventilation and indoor climate for school buildings and reports about the performance of the ventilation systems; 2. to examine the influence of different ventilation systems in classrooms on air quality and learning performance by pupils. To address the first objective, the requirements by German regulations and standards are presented and existing studies about indoor air quality and learning performance in German speaking countries are surveyed. Examples of outstanding newly constructed and renovated schools are presented as well. These parts show that the CO2-concentration was above given limits and no consistent results regarding indoor climate and learning performance were seen.		To address the second objective, measurements were performed in a school building located north of Copenhagen retrofitted with different ventilation systems including: decentralised mechanical ventilation, hybrid ventilation (automatically opening windows with an exhaust fan), automatically operable windows and manually operable windows either in response to a visual feedback or at will. Conditions in all these classrooms were measured and they included CO2 – concentration, temperature, relative humidity and noise level. Pupils performed different cognitive tests and school-related performance tasks. Analyses showed that retrofitting the classrooms with the ventilation systems improved air quality as indicated by reduced CO2 and in many cases improved the performance of cognitive tests and school-like tasks. The results indicated that the effects of improved air quality (indicated by reduced CO2) were higher on the pupils who performed the tests less well, when the retrofitted systems were disabled. In conclusion, decentralised mechanical ventilation system and the hybrid ventilation system are recommended as they performed best regarding attaining CO2-concentration as required by German and European standards. Operation of the former systems brought also most consistent and highest effects on learning performance and it may be considered as an obvious choice for retrofits of schools in moderate climate.
Editor: Anne Hartmann
Tutor: Dr.-Ing. Claudia Kandzia , PhD P. Wargocki, Associate Professor (Dänemarks Technische Universität)

Energetic consideration for the renovation of air curtain taken into account the total energy consumption of a factory building

The diploma thesis is about two air curtains of the Audi AG which are energetically and economically compared to each other. One of the air curtains is an existing unit by the company Meissner und Wurst with high heating energy requirements. The second air curtain is by the Arwus company with lower energy requirements. First of all, both units are described in detail to get a deep insight into the operational behavior. After that, the yearly heat-loss-rate is being calculated, resulting in the change of air in an opened industry gate without an air curtain.		The change of air is being calculated by the differences in pressure that arise due to winds and thermals at the gate. For doing that, the recorded weather dates of the associated weather station are being used. In the following process the yearly heating energy consumption of both facilities is being determined, using the existing technical data. Using the air curtains results in different energetical losses in the space which can be determined and counted into the balance sheet. It includes the heat loss resulting from an insufficient shielding of the air curtains and intermixture deficits that arise from the mixing of air from the outside and the air rolls.
Editor: Konstantin Etzel
Tutor: Dr.-Ing. habil. Joachim Seifert, Dipl.-Ing. Lars Schinke, Dipl.-Ing. K. Graf (Audi) Dresden

Thermal mass savings in buildings

In this paper, the use of buildings as thermal storage is examined and generalizing assessments with regard to the effects load profile, peak load and heating requirements are sought. After consideration of the possible ways a thermal storage can be realized, constructional characteristics and conditions of building use on its probable impact on the storage potential of the building are analyzed. With the help of these preliminaries, a model of a detached house is varied in various aspects and then possible combinations of changes to the building and the management are simulated in TRNSYS.		The collected data of the loads and building temperatures are then investigated under introduction of comparative values with regard to the daily and yearly course and, by use of the comparative values, a classification and evaluation of building configurations concerning their storage potential are made. In addition, the variations are examined for their economic viability. Qualitative statements are made, which relate to certain indications in building configurations and identify key behaviors in the use of buildings as thermal storage and provide recommendations for operational management.
Editor: Marten Clauß
Tutor: Prof. Dr.-Ing. Clemens Felsmann

Development of a software tool applicable to §12 EnEV inspections of air conditioning and cooling systems

This paper deals with the creation of a calculation tool to perform and document the energetic inspection of air conditioning systems in accordance with the §12 of the German Energy Saving Ordinance. It considers the question of how the performing engineer can ascertain to perform the service “energetic inspection in accordance to §12 of the Energy Saving Ordinance” in high quality but at optimal costs and time. Defined goal of this paper is to make a tool available to the inspectors in order to perform the inspection within the meaning of the Energy Saving Ordinance respectively the Energy Performance of Buildings Directive and to provide improvement proposals for the system inspected		After clarifying the legal circumstances and becoming acquainted with evaluation procedure of DIN SPEC 15240, possibilities for the realisation of the calculation tools are discussed. The realisation of the evaluation procedure into a calculation tool, which is easy to use offers the possibility to become acquainted with the evaluation procedure in depth. Therefore the merits and demerits of the evaluation procedure of DIN SPEC 15240 are reviewed. In order to get more insights from the view of the inspector, the energetic inspection is performed for an existing air conditioning system. At last it is discussed to what extent time and cost efficiency as well as a high quality of the result of the energetic inspection can be provided by the calculation tool.
Editor: Nils Sachsenröder
Tutor: Prof. Dr.-Ing. Clemens Felsmann, Frau J. Szelig (Innius DÖ)

Development of a coil heat recovery loop system for decentralized room ventilation

In this work, a coil heat recovery loop system for decentralized room ventilation was developed, built and their ability to function demonstrated. The aim was to build a compact system that consists of components available on the market. As for suitable components have been researched: the heat exchanger HTFS2 3x120 LT from Watercool and the centrifugal fan DB12032B12L from M-Fan. The water circulation was realized with a stepping motor driven peristaltic pump.		To oparate the coil heat recovery loop system a controller has been developed and built. The interplay of these components achieved heat recovery rates of 0,55. To meet the requirements of the KfW or EnEV with values of at least 0,6 respectively 0,7, the components need further development. Moreover, the usable heat transfer area must be maxed out. Optimization potential is also offererd by the air ducts. With the achieved results a further development is recommended.
Editor: Miko Trusch
Tutor: Dr.-Ing. Markus Rösler, Dipl.-Ing. Lars Schinke, Dr.-Ing. K. Hackeschmidt, ILK Dresden

Power control of heat pumps

The climate change has a major impact on the environment and ecosystem. The efficient handling of the temperature variability is of challenging importance. Heat pumps need to cover a larger heating power spectrum and perform a greater amount of operating hours in part load. The present study evaluates the required power control of the heat pump and shows possible visibility in it's labelling. In order to gradually imply the power control to a heat pump, it's components are differently classified. The variable-speed compressor with the inverter represents the most efficient technology. An analysis of the calculation of the seasonal coefficient of performance in the DIN EN 14825 reveals a differentiation between the continuous and discontinuous power control.		The better performance of the continuous power regulation during the part load impacts on the primary energy consumption of the heating pump. This results in a better judgement through the energy labelling regulations. In conclusion, a realistic comparison confrims the progress made through the continuous power control. The better seasonal coefficient of performance leads to a reduction of electricity costs. In addition, government subsidies are provided to the benefit of the consumer. A fast amortisation of the acquisition costs are accomplished, which makes the continuous power control not only from an ecological point of view but also financially an attractive investment.
Editor: Justus von Rhein
Tutor: Prof. Dr.-Ing. Clemens Felsmann

Influence of Diamond Nanoparticles on the Heat Capacity of a Thermosyphon System

A thermosyphon is a heat pipe, which can be very effective to transport heat from the source to the sink. The thermosiphon is filled with a fluid, which are guaranteed by the phase change during evaporation and condensing a high heat flow density. Diamond nanoparticles were added to the fluid (water) to optimize the heat transfer. The evaluation of the measured results showed that the nanoparticles were able to reduce the thermal resistance of the thermosiphon only in the area of free convection. In the area of nucleate boiling no difference between the reference fluid and the diamond fluid was found.		. Other chemical testing after the test series showed that the diamond nanoparticles agglomerate and settle out and are no longer dispersed in the fluid. Also the formation of a porous layer on the inner pipe wall often described could not be found. A relationship between the thermal conductivity and a power function with the pressure and heat flux that is described in the literature could be refuted by the experiments. The use of diamond nanoparticles is not recommended under the chosen conditions.
Editor: Rico Günther
Tutor: Dr.-Ing. Karin Rühling, Dipl.-Ing. Martin Heymann

Weather forecast modeling in building systems

Predictive control methods in building automation systems under the use of weather forecast data is not only a theoretical potential anymore but already realized in numerous projects. This paper will summarize the latest information about the market situation of companies specialized in predictive building automation systems as well as about projects fitted with that technology. In order to understand the possibilities as well as the limits of modern weather forecast systems the first part of the paper deals with the creation and reception of weather data.		This part is followed by some basics of building automation systems as well as a market overview of companies specialized in weather forecast-based automations systems. In the second part of the paper theoretical fields of applications and realized projects are described. The characteristics of the projects are summarized equally to ensure an easy comparability. The paper ends with ideas for a conceptual design for a test rig at the TU Dresden.
Editor: Thorsten Krohn
Tutor: Prof. Dr.-Ing. Clemens Felsmann

Sizing and conceptual design of a heating plant

In the present work, a heating system for the Pressenhaus of the winery Hoflößnitz in Radebeul was designed. In the first step, the heating load was determined software based on the detailed procedures in accordance with DIN 12831, as well as under the simplified procedure according to DIN 12831 Attachment 3. The results were compared and discussed. Based on the heating load, structural conditions and users requirements, the components of the heating system were planned.		These included a gas boiler, radiators in the basement and attic and underfloor heating and door air curtain system on the ground floor. It also included a detailed planning of the piping and components assembly. Using the software Plancal Nova, the pipework calculation joined, whereupon the three heating circulation pumps were construed. In the end, the heating energy demand was calculated and classified.
Editor: Tim Böttner
Tutor: Dr.-Ing. André Kremonke

Production estimate for near surface geothermal energy

In the past years the number of installed geothermal heat pump systems in Germany has increased. A correct dimensioning is absolutely necessary for a high efficiency of such a system, since the correct length of a borehole depends on the power demand and the thermal conditions of the ground. Therefore the market offers a variety of simulation tools that are briefly presented in this paper		The aim of this paper is to find a simulation tool which could be used for teaching purposes. To compare the various applications, a simulation model is created. This is followed by a simulation of this model with the help of three selected tools. Based on the simulation results and a sensitivity analysis a recommendation is given.
Editor: Johannes Schrader
Tutor: Dipl.-Ing. Stefan Hoppe, Dipl.-Ing. Wojciech Kozak

Time series of wind energy production forecast in 2030

To compare different energy resources the primary energy factor is often used. With change to more renewable energy systems this system needs to be challenged. It seems to be necessary to have a better time resolution from the power input. Different systems are currently researched. On of this method called „time variable comparison of electric power“. This method gives the user an easy way to compare supply concepts from electric power using the supply behavior from power plants in an hourly resolution.		It is necessary to have a good forecast over the lifetime of new energy systems to be able to give a useful rating of these. The subject of this study is the forecast of wind turbines to the year 2030. The changeable power input of these plays a major role in the future energy supply. Especially the height of the rotor hub, the performance curve and the Betz's coefficient were part of this study.
Editor: Lukas Rothmann
Tutor: Dr.-Ing. Karin Rühling, Dipl.-Ing. Felix Panitz

Study on operating special wind turbines by using air flow induced in the area of runways

A new project idea concerns a wind turbine system, which uses induced current by an aircraft jet engine during take-off. The deployment of this system needs to obey the actual regulations and must not cause any risk at the airport environment. Coincident it should target a high yield too. Within this diploma thesis, only roughly described concepts shall be further investigated. In order to take action, relevant work packages for the whole project are defined.		However, the focus is put only on first modules due to generally limited time frame of a diploma thesis. After gaining results of numerical fluid dynamic calculations, a comparison with researched studies und publications is shown. For a better understanding of results, an observation based on typical faults in numerical fluid dynamic calculations is performed. Lastly, following steps are faced and discussed by providing some crucial considerations.
Editor: Patrick Arrue
Tutor: Dipl.-Ing. Andreas Herwig

Concept of a Solarthermal Pilot Plant on the roof of the ZET with Decentralized Feed-In into a District Heating Network

This thesis introduces and compares several regulating concepts in terms of covering a customers requirement of hot water via solarthermal systems and feeding the surplus in the district heating network. Furthermore it describes the concept of a solarthermal plant onto the roof of the ZET-Building. Analyzing the spatial conditions of the rooftop, a collecting duct system was drafted, which served as a basis for defining the characteristic of the hydraulic circle.		Subsequently several pumps get introduced that all can be deployed circulating the fluid. Additionally this thesis aims at forecasting the annual yields of the plant using Polysun and T-SOL as simulation software. As the model of the planned collector is entirely new, measuring data of an existing test field got evaluated, so that a simuation tool written in MATLAB could be validated.
Editor: Maximilian Leonhardt
Tutor: Dipl.-Ing. Martin Heymann, Dipl.-Ing. Toni Rosemann

Simulation of a DEC air conditioning system with a magnetocaloric unit

Within the framework of this work should be analysed how the new technology of the magnetocaloric unit can be integrated into a DEC air-conditioning system. It has been checked whether a magnetocaloric unit can be used as support for peak load cover in case of hot and humid outdoor climate. The check was carried out with the simulation program TRNSYS-TUD the source code of which has been enhanced. The newly developed simulation module has been validated with the help of comparative data.		The simulation results showed that the variant with a magnetocaloric unit is better able to cope with extreme outside air conditions (high temperature and humidity) than the variant with a classic air-conditioning system. That manifested itself in a lower room temperature. The simulation module will also be available for further investigations of ventilation systems in future.
Editor: Benjamin Perschk
Tutor: Dr.-Ing. habil. Joachim Seifert, Dr.-Ing. Markus Rösler

Energy performance evaluation and optimization of passive house

The passive house “Gerhard-Grafe-Sporthalle” in Dresden-Weixdorf built in 2009 is part of the development in the field of energy-efficient construction. In addition to a complex systems engineering with comprehensive environmental energy use, the building was designed to undercut the primary energy requirements of a passive house of 120 kWh/m²a by 50 %. A research project to the scientific evaluation of the building operation was initiated after completion of the construction. First results of the comprehensive monitoring could not confirm the ambitious planning objective, wherefore some optimization measures have been performed. In this work an energy requirement statement is realized of the gymnasium as a nonresidential building in accordance with the actual EnEV 2014.		The determined values are compared with earlier calculation results and the actual energy consumption of the sports hall. It is noted that a reliable energetic evaluation of a passive house building using the market EnEV programs is not possible. The determined values contradict the real consumption data. However, the compliance of the primary energy under 50 % of the passive house requirements could be confirmed on the basis of real consumption data. To study the improvements that are already made, a selected plant components are analyzed and evaluated according to measurement data. An improvement in the energy efficiency of the building could be determined, despite continued problems. In conclusion, further recommendations for optimization of plant operation are presented.
Editor: Susanne Klöditz
Tutor: Dipl.-Ing. Juliane Schmidt

Integration of a big sized solar thermal plant in an urban district heating system

The „Stadtwerke Zittau GmbH“ plans to replace 2 conventional block-type thermal power stations with a solar heating system. According to the regulations of the EEWärmeG (German Renewable Energies Heat Act) the solar heating system has to cover five percent of the annual production of district heating. At first the district heating performance of the years 2013 and 2014 is analyzed to make a founded prediction of the future production. With this information a future fictitious district heating annual performance is constructed. This performance is the basis for the following investigations of solar heating system.		At first a solar heating system without a store is inserted into the existing structures. After that it is replenished with a big hot water store. The calculations make clear that only the system with a store can appropriately be integrated into the district heating system. Finally the two versions of the solar heating system are comparatively evaluated. This study leaves to the result that a solar heating system with a hot water store is economic compared to the 2 conventional block-type thermal power stations.
Editor: Alessandro Hülser
Tutor: Dr.-Ing. Karin Rühling, Dipl-Ing. Thomas Große; Stadtwerke Zittau GmbH

Reflections about the application of gas-fired heat pumps

The environmental policy requirements of the Federal Government, to reduce the primary energy demand and the greenhouse gas emissions under increased integration of renewable energies, are aiming for a environmentally friendly, efficient as well as payable energy supply. The innovative gas fired heat pumps technology unifies all these requirements in one compact device. Towards conventional gas boilers and gas condensing boilers, another increase of efficiency in relation of the amount of the employed energy source, can be achieved. This seminar paper considers the actual heating market situation of the gas fired heat pump. In regards of this aspect, an extensively market overview of the		actual available gas fired heat pumps was made by thorough research work. Further, under consideration of alternative technologies, the different purposes of the gas fired heat pumps were examined. Finally, the future heating market situation of the gas fired heat pump was estimated as well as suggestions for the support of the further market development were submitted. Therefore, aspects like the high availability of natural gas, a well developed natural gas network as well as the wide distribution of natural gas applications at the heating market, indicate the large market potential of the gas fired heat pumps technology in Germany.
Editor: Sandra Giese
Tutor: Prof. Dr.-Ing. Clemens Felsmann

Literature study on electro-physical parameters of biofilms in drinking water piping systems

Through the process of biofilm development, bacteria change their way of live. That results in changes of their metabolism, as well as in changes of physical properties of the substratum. The work deals with the adhesion of bacteria to the substratum and parameters which influence biofilm properties. Furthermore it examines the influence of biofilm development on technical relevant aspects, like pressure drop, heat transfer and corrosion.		Afterwards some biofilm properties are presented which conduct to energy losses in water pipping systems. At the end a review of some biofilm monitoring techniques is given. The aim of this work is to show possibilities for new biofilm detection methods, which will give further information about biofilm development. Because the better understanding of processes, that lead to biofilm development will help to counteract biofilm development.
Editor: Alexander Bil
Tutor: Dipl.-Ing. Jan Löser

IT-basics for the design of energy strategies

This student research project describes the development process of energy concepts for districts. Initially the significance of energy concepts is evaluated. This is followed by the step by step description of the development process. Starting with requirements and conditions that are needed, the points are explained individually. Necessary information for the analysis is mentioned and their availability is discussed. In the course of the options for energy supply, various techniques of energy provision are presented and the potential is estimated. The focus lies on renewable energy sources such as sunlight, biomass and geothermal heat.		Furthermore, stakeholders are mentioned, that are involved in the planning process. Supported by a flow chart, the course of the process is examined in its entirety. Thereby the instruments and tools for the planning are specified, which may be helpful in the decision making. Finally the overall approach to the planning of energy concepts is summarized in a clearly arranged check list and briefly illustrated with the example of the campus of the Dresden University of Technology. This is not a detailed preparation of an energy concept, but rather an attempt to demonstrate its approach and first steps. Rounding of this project there is an outlook on possible future developments.
Editor: Tobias Kade
Tutor: Dipl.-Ing. Jens Kaiser

Conception, design and programming of a test rig for thermal characteristic testing of plate heat exchangers

This paper attends to the conception, the dimensioning and the setup of a test station for plate heat exchangers. In the beginning of this paper there are presented informations from technical literature and from the last decades' research regarding to the backgrounds and theories of heat exchange in plate heat exchangers. This is followed by a detailed description of the test station's setup and the programming of the control software which are the greatest parts of the practical work.		For the development of the test station existing parts should be used and a required space as low as possible. Furthermore the test station should work with as many as possible different types of plate heat exchangers. Also on both sides of the heat exchanger the water's parameters temperature and volume flow should be freely selectable in large ranges. The final goal was to reach a high grade of automation and the determination of Nußelt equations.
Editor: Carsten Pietzsch
Tutor: Dipl.-Ing. Jan Löser

Thermal and fluid mechanical Optimization of the Heat-Management of a short term Battery-Storage

The increase of renewable energy sources as part of the energy revolution requires electric storages, which are involved in local and global management systems, to ensure network stability. This flexible and rapidly deployable technology can take measures such as frequency control and load management. The "Belectric GmbH" realizes lead-acid battery systems in an international cargo container design with a maximum power of 1000 kW, which provide in connection with photovoltaic power plants grid services. In operation, the batteries produce depending on the power requirement, a significant thermal energy, which greatly speeds up the aging process of the cells.		In order to operate such a battery storage, especially in warm regions with high potential for solar power generation, an optimal heat management is necessary. In the thesis the existing air cooling system is studied and gradually optimized using computational fluid dynamics (Autodesk Simulation CFD). Furthermore, the fluidic verification of a new air cooling concept occurs. In addition, an alternative liquid cooling is designed and also examined fluid dynamical. The thermal load on the cooling variants and their effect can be demonstrated using the example of the prequalification procedure. In summary, the two concepts of air cooling and the developed liquid cooling are compared to identify a technical optimum.
Editor: Tobias Kämmerer
Tutor: Dr.-Ing. Karin Rühling, Dipl.-Ing. L. Fallant, BELETRIC GmbH Dresden

Energy saving caused by room temperature control

This paper is about the empirical research aims to deepen the energy saving potential of the room thermostat. The certification for the products of mechanical heating radiator thermostat is often achieved through TELL. TELL is an abbreviation of "Thermostatic Efficiency Labelling", which represents a classification scheme for energy efficiency labeling of Thermostatic radiator value. It is a voluntary energetic labeling system, which has been developed by reputable European manufacturers. E-United Valves, the European Association of valve manufacturer, assigned by the application to register the TELL label for thermostatic radiator valves. eu.bac.cert is a new procedure for the certification of electronic heating-regulator.		eu.bac is the acronym for "European Building Automation Control Association". This is a European association which was founded by the manufacturers and suppliers in the home and building automation in 2003. Currently, the members of eu.bac represent about. 95% of manufacturers in the European market. To check the previously described certification procedures TELL and eu.bac, in this chapter is a building in the city of Frechen considered as an example. With the simulation software "Building-Simulation 3D Plus" by the company Hottgenroth / ETU is a building and system simulation performed using the example building. By entering different set points of the room temperature is the heating energy consumption of the building with various individual room controllers simulated.
Editor: Ou Xiang
Tutor: Prof. Dr.-Ing. Clemens Felsmann

Impact of building automation and control on the energy performance of buildings

Automation and regulation have a significant impact on the energy efficiency and sustainability of buildings during their life-cycle. This thesis examined the operational parameters of building automation in accordance with the standards of DIN V 18599-11, which describes the contribution of building automation to energy saving. First of all, different digital models of buildings are created in consideration of various boundary conditions and factors. Then the final energy demand of Buildings, which is required for the calculation of the operational parameters, can be calculated via suitable software tools.		Thereby referring to the simplified method of DIN EN 15232, the calculated results are classified with the degrees of automation to make a more detailed comparison. Furthermore a plausibility check will be performed to determine the accuracy of the achieved results and the degree of automation. The question inevitably arises about how far the automation is implemented in software. The thesis will end with a brief outlook into the future aspects and future development of building automation.
Editor: Yipin Zang
Tutor: Prof. Dr.-Ing. Clemens Felsmann

Comparison of VDI 2078 (07.96, 2012 (blueprint)) and thermal simulation in terms of theoretical foundations and the achievable results

The completely revised VDI 2078: 2015-06, released simultaniously with this diploma thesis, generated controversial discussions among experts beforehand. Thus, its date of release was postponed from the end of 2014 to June 2015. Therefore, the objective of this paper was to verify the computational results obtained by the new VDI 2078 and to test the new possibilities. For this purpose the differences between VDI 2078:1996 and the		draft version used for this paper had been examined in terms of content first. Following this, the software for VDI 2078:2012, developed by SOLAR COMPUTER, was compared to a simulation program (IDA ICE) on the basis of simple examples and the results were examined through various manual arithmetic techniques. As a result, significant discrepancies were discovered in some cases.
Editor: Lukas Spörl
Tutor: Dr.-Ing. habil. Joachim Seifert, Dr.-Ing. P.Vogel (INNIUS)

Analysis of Modelica-based building simulation and co-simulation with TRNSYS-TUD

Modelica is an object-oriented and equation-based language to model complex physical systems. In the field of building simulation some Modelica model libraries are open to public uses. In the present thesis, after a brief presentation of Modelica and its development environment, I will realize an analysis of the possibilities for the dynamic simulation of building and facility systems. This analysis consists on the description of the model libraries and comparison from one to another based on the following parameters:		room simulation, heating, ventilation and air-conditioning simulation, weather simulation, internal heat gains and comfort. A step of this analysis was to study the possibilities of combinatory between the different model libraries. Then several already implemented in TRNSYS-TUD procedures of validation was selected, for implementation in Modelica, to compare the two simulation programs. Finally the co-simulation between Modelica and TRNSYS-TUD is considered.
Editor: Marianne Biéron
Tutor: Dr.-Ing. Alf Perschk, Dipl.-Ing. Sven Paulick

Modeling of humidification and dehumidification processes in HVAC systems

HVAC aspects in new buildings is becoming increasingly important. For the energetic evaluation of different plant-specific variations is an exact knowledge of the transfer behavior under static and dynamic aspects of great interest.		As part of the assignment should be created a literature review for existing models of humidifiers. The advantages and disadvantages of each model will be presented and analyzed. The humidifier will be handled programmatically to make it accessible into simulation environment TRNSYS-TUD.
Editor: Dmitrij Gorlovsky
Tutor: Dr.-Ing. habil. Joachim Seifert, Dipl.-Ing. Wojciech Kozak

Solubility analysis of water-glycol mixtures

As part of a research project, a test rig was developed, which makes it possible to experimentally determine the solubility of atmospheric gases in water-glycol mixtures. Initial analyses are now being extended for additional gases and solvents. The comparison with previous results is supposed to provide new findings as well as a broader basis for interpretations in addition to the further development of the test rig and the optimization of test procedures. The solubility of nitrogen and air has been examined, both in pure water-glycol mixtures of different concentrations, and in premixed liquids with corrosion-inhibiting additives which are used in practice.		This makes it possible to analyze the effect of these inhibitors in the premixed liquids on the solubility of atmospheric gases and to identify potential causes of problems in modern systems. On a total of 65 evaluable individual test days, relevant measurement data for the calculation of solubility was recorded and used for the analysis and interpretation of temperature and pressure curves. Moreover, the results of the investigation can be better evaluated by a simplified estimation of measurement uncertainty of different methods of calculation.
Editor: Max Pham
Tutor: Dr.-Ing. Karin Rühling, Dipl.-Ing. Felix Panitz

Creating a module structure for air conditioning system

Building air-conditioning and ventilation systems are getting more and more influence within the building technology. Especially in fields with great demands on convenience air-conditioning and ventilation systems were integrated more often. The systems were built increasingly into detached houses, mainly in low energy respectively passive houses. Against the background of increasing demands of the energy saving regulations (EnEV), concerning air tightness and primary energy consumption, ventilation systems and the		simulation of it will play an important part within the building technology. A suitable software for this simulation task is TRNSYS-TUD. In the context of this work the program got expanded by the feature of integrating air-conditioning and ventilation systems. The model enables the user to combine different component parts for simulations. As a result it is possible to draw conclusions out of the effects of different systems and to use them for further research.
Editor: Benjamin Perschk
Tutor: Dr.-Ing. habil. Joachim Seifert, Dr.-Ing. Markus Rösler

Design, construction and implementing of a experimental equipment for emulation of Micro-CHP systems

Currently used key figures to inform about the efficiency of micro-CHP-systems denote often not realistic attainable energy efficiency ratio as the used measurement method are only of stationary character. This leads to economic miscalculations and disappointed costumers, putting the diffusion of the micro-cogeneration-technology at risk. Tue goal of the paper at hand is therefore the creation of an emulation test rig to analyse such system in an transient state to determine the efficiency under operating conditions.		Here the dimensioning and design of the test rig is accompanied and the commissioning and initial measurements are performed. To validate the building model used for the emulation an inquiry into technical standards as weil as applicable literature is undertaken to compile statistic building key figure and the average user behaviour. Tue compilation is done for single and double-family houses, as micro-CHP-systems, due to their power category, are mainly in such an environment.
Editor: Franziska Pleißner
Tutor: Dr.-Ing. habil. Joachim Seifert, Dipl.-Ing. Lars Schinke, Dr.-Ing. Martin Knorr

Design of a heat pump system for heating swimming pool water utilizing waste heat and heat from the environment

In an indoor swimming pool plenty of shower water and water of a filtration installation accumulate during a year. By using a heat pump system, the waste heat can be recovered for heating the swimming pool and drinking water. Using waste heat is not sufficient for covering the whole heat demand. The remaining heat demand has to be completed with the existing district heating. It will be analyzed if it is more economic to utilize additional outdoor air to reduce the using of district heating in this work. The integration of waste heat and outdoor air in the heat pump system is realized with a hydraulic scheme.		A control system is created as a function of the incoming wastewater, the outside air temperature and the heat demand. The economy study shows that using only waste heat is not economic in comparison to the existing district heating. The integration of outdoor air in the heat pump system strikingly increases the heat production. The savings of district heating costs are much greater than the rising life-cycle costs. By the combined use of waste heat and outdoor-air savings up to 36.000 € can be reached per year.
Editor: Markus Vass
Tutor: Prof. Dr.-Ing. Clemens Felsmann, Dipl.-Ing. André Preuß, FWU Ingenieurbüro GmbH, Dresden

Layout of a study for the investigation of thermal comfort aspects on human subjects

The topic of this work is the layout of a study for the investigation of thermal comfort aspects in a newly established room for experiments of Dresden University of Technology, chair for building energy systems and heat supply in Merkelbau. With regard to the boundary conditions of this room for experiments the three parts such as interior decoration, subject groups and measurement equipment are discussed. As a first part a literature research with main attention on office rooms is done. The most important aspects are furnishing, lighting and acoustics. But also the colour is taken into account. In the second section facts regarding to subject groups are discussed. To this criteria belongs the acquisition, the selection of subjects, the conditioning before the experiments		in form of an information event and on the day of experiment like the briefing of the subjects as well as the activities during the experiments. In connection with the selection the quantity, important criteria and the combination of a representative sample are discussed. The topic of the third part is the decision of the measurement parameters based on existing models for thermal comfort, the selection of the necessary measuring instruments and the determination of their position. In addition the designed lighting system is metrologically controlled. Finally reflections towards the variation of the set-up of the experiment and consequent other possibilities for the use of the room for experiments were made.
Editor: Anne Hartmann
Tutor: Dipl.-Ing. Lars Schinke, Dipl.-Ing. Alexander Buchheim

Energy performance optimization and Sustainable Buildings

The research paper deals with the question of what sustainability is and how it can be implemented within the building sector. With the help of existing certification systems the attempt is made to make this optimization measurable and comparable. As part of the consideration, especially their energy-related aspects are moving into focus. The first chapter compares three common variants of evaluating sustainable construction in Germany. The organizations that stand behind these methods are examined closer and a first insight into the criteria will be granted.		The following two chapters are limited to one system and describe its approach to the assessment of selected points with energetic terms in detail. Therefor buildings and districts are considered separately. The fourth chapter concerns the conjunction of building simulation programs with the earlier described criteria. A suitable strategy is explained and pointed out the problems of a possible implementation. In the last chapter, the gained knowledge is applied and the sustainability evaluation of certain buildings carried out by way of example.
Editor: Sebastian Gruber
Tutor: Prof. Dr.-Ing. Clemens Felsmann

Contribution to Modelling and Testing of Decentralized Solarthermal Feed-In in District Heating Networks

In the first part of the study a solar thermal plant model has been developed. The dynamic behaviour of the model is validated with real system data. As simulation environment MATLABSimulink is used with components of the CARNOT-Toolbox. The results of the model are validated and evaluated with two different approaches: the step response of three different input data and the annual simulation. In the second part measurement data of two district heating stations: Gartenheimsiedlung (Dresden) and M¨unchner Ackermannbogen have been prepared.		For both district heating stations highresolution load profiles for the typical-day procedure are generated. The data could be used for the emulation of heat consumer or added to an existing database. In the third part a CARNOT-HANEST-model with state flow automatic and hydraulic separator is implemented into the simulation environment MATLAB-Simulink. The interaction between HANEST and district heating grid is not put into focus. The CARNOT-HANEST-model is evaluated with a typical-day. Finally prospects for future work are given.
Editor: Lisette Hähnel
Tutor: Dr.-Ing. Karin Rühling, Dipl.-Ing. Martin Heymann, Dipl.-Ing. Toni Rosemann

Analysis of the ASHRAE-based energy simulation software Sefaira with respect to its applicability for building design in the context of the German standardization

The American start-up company Sefaira offers a same-named web application which integrates sustainable, energy-efficient building design into the building planning process to determine the expected energy demand of buildings. The objective of this study is to access whether the ASHRAE-based web application Sefaira can be applied as a pre-assessment measure for the DIN V 18599-based energy pass. Sefaira's scope of performance is compared to that of the DIN V 18599-based software SOLAR-COMPUTER.		The calculation-based results of Sefaira were compared to those of SOLAR-COMPUTER using three different office buildings. Subsequently, an analysis addressed the determined differences and their potential causes. The final evaluation advises against the utilization of Sefaira as a pre-assessment measure for the DIN V 18599-based energy pass. Sefaira's limits are also discussed as well as its further potential applications.
Editor: Kristin Küther
Tutor: Prof. Dr.-Ing. Clemens Felsmann

Hydraulic of heating systems

Hardly an electronic program supports the calculation of part load conditions in heating pipe systems. Circulating pumps are selected after the maximum point of its heating system. Choosing the pump occurring the load conditions will help to work in better conditions. The circulation pump consume less energy, without compromising the security of supply.		This saved several hundred euros at an office building. In existing buildings the potential savings can be considerably greater. The exchange of the heating pump against a high-efficiency pump pays for itself in a detached house after 2 to 7 years. Also several hundred euros could be saved over the entire lifetime.
Editor: Rico Günther
Tutor: Prof. Dr.-Ing. Clemens Felsmann, B. Götze, Cofely Deutschland GmbH

Numerical calculation of indoor air flow in a scale model based on a Lattice-Boltzmann-method

An indoor air flow investigated in 1995 by a model experiment is recalculated using the Lattice Boltzmann method. The numerical results are verified with the measurement data. The fundamental principles and practical configuration of the simulation are explained in detail.		Many discussions about the numerical accuracy and stability are included. Numerous insights and experiences are documented. While the second half of the thesis is more practical, the theoretical foundations of the method are described systematically before that.
Editor: Xunzhang Yuan
Tutor: Dr.-Ing. Ralf Gritzki , Dr.-Ing. Markus Rösler

Optimisation of a p-dot µc-SiOx-layer in a-Si/µc-Si tandem solar cell for improvement of light management

In the frame of this work, p-doped microcrystalline silicon oxide layers, with variable stoichiometry, were optimised. The optimisation goal was to lower the refractive index while maintaining the electrical properties of the layers. The maintenance of conductivity through the layer, by forming microcrystallites is particularly important. The influence of precursorgas-composition to optoelectrical and structural properties of the layers was investigated. The investigation lead through a series of experiments considering carbondioxide proportion, hydrogen dilution and total gas flow. It was possible to lower the refractive index by increasing the carbondioxide proportion, which also leads to a lower chrystallite generation and lower layer conductivities. By increasing the hydrogen dilution it was possible to lower the refractive index and to increase the chrystallite proportion.		It can also be shown that increasing total gas flows lead to raising refractive indices, but also to higher chrystalline proportions and fewer defects in the layers. Promising layers were used to fabricate thin film tandem solar cells. The cell parameters of the resulting cells were investigated. It was possible to fabricate layers with lower refractive index and a higher conductivity in comparison to the reference. The best cell has an 0.4% increased stabilised efficiency, which is a 4% relative increase to the reference cell. The results of this work can be used as a basis for further investigations, like the implementation of a Bragg-reflector into a thin film tandem solar cell, for which it is only necessary to optimise the thickness of the layers.
Editor: Patrick Krüger
Tutor: Dr.-Ing. Karin Rühling, Dr.-Ing. Simon Kirner,Helmholtz-Zentrum Berlin f. Materialien u. Energie GmbH

Evaluation of the design and construction process using the example of a research institute building

The following interdisciplinary project work deals with the issue of „Review the planning and construction processes using the example of a research building“. The center of Radiopharmaceutical Research tumor (ZRT) was here named as a concrete object. First deals with the description of the project in general and in particular. Then specific planning tools are introduced which are used to support the planning phase.		Within the planning phases occur which are addressed in section 4 of the work changes. Finally, a year will be cost estimates for selected areas of technical building equipment. Summary results for the planning of the project ZRT an extensive and comprehensive task to the specific technical requirements and resulting.
Editor: Julia Scholz
Tutor: Prof. Dr.-Ing. Clemens Felsmann

Numerical calculation of indoor air quality and ventilation efficiency in the vicinity of persons comparing different concepts of mechanical ventilation

Aimed at survey of air quality and ventilation efficiency in direct vicinity of persons, an office with two workstations is modeled in a CAD model. The persons are modeled by a 3D-scanner. Two conventional ventilation concepts namely mixing ventilation and displacement ventilation as well as one personalized ventilation concept are designed and applied for the indoor-ventilation of this office. After modeling and meshing of the compact model, a coupled simulation of building, equipment and airflow is performed with this model. A phase of 15 days for each ventilation concept will be simulated respectively in the winter and summer case. Using the numerical simulation methods, all state parameters of indoor air at any location in the office can be calculated over time, including air pollutant concentration and air age, which are necessary for investigation of air quality and ventilation efficiency.		Criteria for ventilation efficiency in the direct vicinity of persons are drawn up from general criteria for ventilation effectiveness. With these criteria, the data of simulation results of the six basic cases are analyzed in order to evaluate the three concepts. Every basic case will be simulated several times with the sensor established at different positions and different proportion-factors for temperature automatic control, in order to explore the optimal sensor-positioning and analyze of the sensitivity of the system. In addition, the energy costs of the three HVAC-systems for the applied conditions and thereby achieved thermal comfort will be analyzed and compared with each other. At last, the possibility of airflow-reduction at personalized ventilation concept is investigated.
Editor: Zheyu Wang
Tutor: Dr.-Ing. Claudia Kandzia , Dr.-Ing. Markus Rösler

Setup, analysis and optimization of an alternative CHP concept

The tremendously high CO2 emissions resulting from many decades of unsustainable generation of electricity and heat from fossil fuels are widely recognised as the main cause of climate change, today’s biggest threat to the environment. There is an urgent need for the deployment of more sustainable energy technologies. A promising option for a more sustainable energy supply of residential buildings are CHP systems for the combined production of heat and power that operate at a very small scale and are located close the point of consumption. Considering the decentral location of the landed property and also the periodical disruption in electric power supply by the local power authorities in the Allgäu the purchase of an emergency power unit seemed reasonable. By calculating the power input the question of supply guarantee in case of a power failure appeared. Furthermore one has to consider questions like: How much energy would one need? In a case of emergency: Is one source of light enough? Should there be enough power to continue the roast in the oven, and even, should there be enough electricity for maintaining the working capacity in the workshop down in the basement. The research throughout the sale platforms on the internet offered various affordable alternatives for almost every possible case. Due to my previous training as a commanding officer and my experiences as an officer of maintenance parameter like creeping strength and		maintenance requirements are considered as important terms for my professional work. For securing warm water supply, processing water and also to provide central heating there was already installed a plate heat exchanger, holding a volume of VP = 1m3 , and an aligned solar panel in 2008. As a result the decision for a water chilled emergency power unit which additionally secures processing water was made. Currently there was operate a 4.4 liter Perkins diesel engine which fuels a synchron generator with a maximum power of Pel = 30 kW. Throughout The following assignment will constitute why this option was favored. Furthermore a self-adjusting approach of the volume flow rate concerning the cooling water was developed and designed. The Performance was measured and reviewed. In order to use the effective heat capacity of the emissions there was also calculated and crafted an emission transmitter. One of the most important things concerning this project is an effective utilization of the primary energy. The often promised high efficiency rate of η ≈ 90% of oil and gas heating for generating warm water is mathematical correct, but they conceal the term exergy. After the initiation of the system it was equipped with the necessary process measuring and also control-technology to detect its efficiency and capacity factor in order to compare it with commercial off-the-shelf products.
Editor: Rainer Dietrich Jung
Tutor: Dr.-Ing. habil. Joachim Seifert, Dipl.-Ing. Paul Seidel

Basic analyzes for modeling of complex gas-networks

The objective of this work was to collect the bases for the calculation of pressure drop in gas networks for the software TRNSYS-TUD. First there was developed an equation to calculate the pressure drop and a formula for calculating the heat transfer. For both calculations formulas were collected to determine the material properties. In a last step before the implementation, the theory of network calculation and the with this connected terminology was explained.		An algorithm created from those theories and written for controls in VBA. In this way could be tested in two examples first that the algorithm gives correct values, and then in a second example, that the algorithm has been implemented correctly in TRNSYS-TUD. This work concludes then with a comparison of the values.
Editor: Karl Eugen Wolffgang
Tutor: Dr.-Ing. habil. Joachim Seifert, Dr.-Ing. Alf Perschk

Investigations on a window integrated ventilation system with heat pipe heat exchanger

In this thesis, a prototype of a decentralized window ventilation system with heat recovery was developed. The focus laid on to use only one fan and perform the heat recovery using a heat exchanger made with on the market available heat pipes. By using only one fan is to be achieved, that the equipment operates quietly. The reverse air is then free to flow in. As a further objective was to fulfill the requirements of the Renewable Energies Heat Act for the use of heat recovery as replacement measures of renewable energy.		Therefor various heat exchangers were constructed and measured, as well as various types of fans were tested for air flow and noise emission. The measurements have shown that the evaporator capacity of the investigated on the market available heat pipes is for the used temperature range too low. The requirements of the Renewable Energies Heat Act could not be reached. The design with only one fan and supply air then resupplied not proven to be feasible if the leaks in the room are too large. For further constructions it is recommended to use always one as quiet as possible fan for air intake and outlet.
Editor: Miko Tusch
Tutor: Dipl.-Ing. Lars Schinke, Dr.-Ing. K. Hackeschmidt, ILK Dresden

Realistic Infiltration and Window Ventilation for the Simulation TRNSYS-TUD

This research paper examines the theoretical background for window ventilation and infiltration of the building simulation software TRNSYS-TUD [2] (expansion to TRNSYS, version 14.2). In the first place the inhabitants behaviour towards window ventilation of residential buildings is analysed. Based on this knowledge, several window ventilation schedules will be developed in this examination. This work is especially based on the research of KLESSE [1] about window ventilation. In the same chapter is then explained how the currently used and already implemented method of TRNSYS-TUD works, to		make the simulated air renewal conditional on weather influences. Subsequently, a method from DIN EN 15242 is implemented and prepared to be used to make infiltration air renewal in TRNSYS-TUD conditional on weather influences. At the end simulations, using the results of this work, are evaluated to complete this examination. Literatur [1] Andreas Klesse. Modellierung und Bewertung unterschiedlichen Nutzerverhaltens in hochwarmegedämmten Einfamilienhäusern. 2012. [2] Alf Perschk. Gebaude- und Anlagensimulation - Ein "Dresdner Modell". GI- Gesundheitsingenieur, 131:178-183, 2010.
Editor: Mathias Hummel
Tutor: Dr.rer.nat. Christoph Schünemann, Dr.-Ing. Alf Perschk

Conception of a biomass- an biogas-based district heating network

Motivated by increasing prices for land, it is aspired to improve the profitableness of an existing biogas plant in northern Germany. In 2012 Germany consumed about 34 % of its total energy demand by space heating and generating domestic hot water. The governmental promotion of biogas plants created a huge potential in the rural areas for heat supply by renewable energies. This thesis shows the potential on the basis of a 721-people-village for the already existing biogas plant to provide in basic load, combined with a woodchip boiler for the peak load, an amount of heat of 2,4 MWh per year via district heating. The developed district heating systems combines preinsulated bonded pipes and polymer medium pipes.		The maximum flow temperature is limited to 85 °C, the maximum operation pressure is limited to 6,5 · 105 Pag. The delivered heat shows a specific primary energy factor of 0. The stretched structure of the village has according to the middle heat turnover of 530 kWh/ma a negative influence on the investment costs and the heat losses during operation. Although the energetic positive project would be promoted a lot by the government, the estimated financial return is too low to start the project immediately. Basically the until the year 2025 limited promotion of selling electric energy by the Renewable Energy Law is decisive, because of its big share in the financial concept. Another detailed economically analysis is necessary.
Editor: Jan Lobsien
Tutor: Dr.-Ing. Karin Rühling

emulation of the transient thermal behaviour of a building wall

In the present work, the basis for realistic boundary conditions for thermal comfort studies was created with the construction of an information network from numerical building and system behavior simulation and control software of the test room at the TU Dresden.The concept of emulation, the replication of simulated building and system behavior in a real-world test rig, it needs information about real-world surface temperatures. To this end, a building model was created in which a room reflects the total of n=74 individually temperature controlled areas of the real test room.		Through the implementation of the building model in different insulation levels, different thermal states of the enclosure construction be considered. In simulations of those building models using TRNSYS-TUD a database was created, with a selection of typical operational scenarios and the definition was performed by real-world application limits. With an emulation of the selected scenarios, the function of the Information Network was detected and identified temperatures or temperature changes could be realized. The present work concludes with an outlook on the expansion of the information networks with the full study room and proposals to extend the used software.
Editor: Martin Henkner
Tutor: Dr.-Ing. Alf Perschk, Dipl.-Ing. Alexander Buchheim

2014

Smart Grid integrated heat pumps

The research focus and general interest in the concept of Smart Grid have risen in view of the nuclear phase-out and the growth of renewable energies in recent years. Optimal storage capacities are sought in order to ensure fluctuating electricity feed-in. The heat pump as a controllable power consumer could provide a solution. A review of manufactures is given and communication problems between the heat pump and electricity grid are shown. Furthermore pilot projects in different European countries are described. The final part of the student research project illustrates fields of application for heat pumps in connection with the availability of heat sources and the cooling of the building. Consequently heat pumps in Smart grid could be an opportunity for intelligent load management. Manufactures apply diverse solutions for making		the heat pump suitable for Smart Grid. The communication structure, that measures energy exchanges in two directions, constitutes a serious problem. Uniform general conditions for intelligent counters in low voltage networks are still missing. The German Federal Office for Information Security takes a pioneering role and has developed common safety standards for measurement counters. Heat pumps are only used as border line technologies in Smart Grid projects. They are expected to supply new information for later projects. The costs of heat pumps have to be worthwhile for owner. Network operators should receive the possibility of easy integration of heat pumps in Smart Grid. New business models with advanced incentives for nationwide use of heat pumps in Smart Grid become more important in the future.
Editor: Fabian von Bienenstamm
Tutor: Prof. Dr.-Ing. Clemens Felsmann

Numerical studies of the fluid flow pressure loss in case of heat exchangers within gas cyclic processes

In this thesis numerical studies of the fluid flow pressure loss in case of heat exchangers within gas cyclic processes is presented. The findings can then be used for design and operation of machines which use these heat exchangers. In a first step an overview of gas cyclic processes is given. On this basis, the heat exchangers of built machines are examined and the conditions for the numerical simulations are derived. After that, based on the preliminary investigations and a literature study, a simulation model is examined, which enables the calculation of fluid flow pressure loss under the boundary conditions of the oscillating flow.		On the basis of the simulation model a parameter study is conducted, to examine the influences of the variation of the parameters on the pressure gradient. The results are then compared with correlations, which are typically used in practice for models of gas cyclic processes, for example the quasi steady approach. It is found that for a given mass flow the medium version of the three examined geometries is the optimum in the turbulent flow region, where most of the machines are operated. The smaller version has a larger pressure loss because of the larger surface and the bigger version because of the higher oscillatory influence.
Editor: Robert Heidrich
Tutor: Dipl.-Ing. (FH) Torben Möller

Energy perfomance optimization of an office building with special focus on geothermal applications

The building sector comprises an immense potential for energy savings and efficiency enhancements. A versatile possibility for exhausting this potential is posed by the geothermal utilization of the underground with heat pumps. This paper analyses an innovative energy concept for heating and cooling an office building using this technology. It attempts to identify optimization potentials for every component. Therefor data from different sources is collected, processed and analyzed.		These data sources are the installed energy meters, fiber optical measurements on some borehole heat exchangers, a power measurement on the heat pumps and the available historical data from the central building control system. It is pointed out that an adapted monitoring is needed for the implementation of a continuous optimization process. Recommendations for its realization are made. Furthermore, it is made clear that the development of a specialized software tool can simplify this optimization process considerably and make it widely applicable in an economic fashion.
Editor: Lukas Reimer
Tutor: Dipl.-Ing. Stefan Hoppe, Prof. Dr.-Ing. Clemens Felsmann

Investigations on the impact of atmospheric gas on efficiency and pressure loss of solar thermal collectors

For solar thermal circuits negative effects of free gases in the solar fluid, like incorrect circulation and reduced heat transfer, are assumed. For lack of measured data corresponding to the effects described in literature there is a need of experimental investigation. Therefore in this work the effetcs of a discrete gas load on the efficiency and the pressure loss of a solar thermal collector had been tested using an indoor testing device. First, known input mechanisms of atmospherical gases as well as their form of occurence and their assumed effects will be pointed out. Afterwards for the planning of the experiments theoretical basics regarding the solubility of gases in the solar fluid, the measurement of the efficiency and the pressure loss and the applied methods of detecting dissolved and free gases during the experiments will be presented. This knowlegde had been used to carry out necessary modifications to the indoor testing device, like the installation of a gas impinging unit. Therefore, the testing conditions according to DIN EN 12975-2 had been taken into account. Subsequently, pre-experiments with varying flow rates, temperature differences and gas loads had been carried out to determine the limits of the test parameters.		The results had been used to measure and to compare a reference case without gas load and a case with maximum gas load with focus on the efficiency and the pressure loss of the solar thermal collector. On the one hand the results show a dependency of the efficiency of the collector from the flow rate of the solar fluid. On the other hand an influence of the free gases in the collector on its efficiency can be supposed particularly for high flow rates of the solar fluid. For low flow rates of the solar fluid a deviating stagnation behaviour could be observed. Regarding the pressure loss a negative influence of the free gases could be detected. However, no tendency regarding their quantity can be given yet. In general, the dependency of the efficiency and the pressure loss from the amount of free gases in the tested solar thermal collector cannot be quantified yet as there is too little measured data. Hence, there is a need of further investigation. A long term aim of this work can be to predict the occurring loss of a solar thermal collector during its running by knowing just a few operating parameters and an appropriate mathematic model and to assess whether the solar fluid should be degased.
Editor: Luise Umbreit
Tutor: Dr.-Ing. Karin Rühling, Dipl.-Ing. Martin Heymann

Economic Evaluation of Passive Houses in Comparison to Buildings Regarding EnEV

In this thesis comparable single-family homes with different energetic standards are evaluated – according to their total costs during a fix time period. The key question is – under which conditions it is more economical to build a passive house than to build a house according to the energy savings decree (EnEV14). In total there are twelve different building-heating-system combinations economically compared to each other.		The advantage of buildings with a high energetic standard is shown: The costs of the higher thermal quality of the building design are compensated by the lower investment on heating systems and less energy consumption costs. The passive house, with an optimized system considering a yearly energy increase of more than 3%, is the most economic and advisable building version.
Editor: Eva Boog
Tutor: Dr.rer.nat. Christoph Schünemann

Conceptual Design for a geothermal project

This seminar paper deals with conceptual considerations for a deep geothermal project in the area of Dresden. In the first part of this work the geological characteristics of Dresden will be analyzed and different potentials uses are shown. Estimations of reachable temperatures, mass flows, and thermal power of the plant will be presented. Additionally, the question of the contribution of the overall energy supply through a deep geothermal system and the connection to the district heating system of the DREWAG Stadtwerke Dresden GmbH will be answered. The second part of the paper shows some system variants for heat- and/or electric power generation. They will be examined in terms of the boundary conditions of Dresden relating to the first point. Withal, a variant of exclusive heat using and a combined heat and power (CHP) will be compared. At the end, the main components of the most suitable system are explained and measured roughly. To get an economic view to the project there will be an analysis of the sensitivity of the temperature and mass flow in the next part. Besides, the heat generation costs of the plant will be calculated. Subsequently, there is a discussion of possible risks of the deep geothermal project with		connection to the boundary conditions in Dresden. Results of the paper reveal that the deep geothermal potential of Dresden can be - as a result of the geologic crystalline structure - used by a petrothermal system only, the Enhanced Geothermal System (EGS). It is necessary to reach depth of 5000 m to get useful energy sources. The maximum temperature is roughly 116 °C, the mass floss is around 60 kg/s, and the generated heat power amounts to 11,5 MW [1]. Besides, a combined heat and power generation considering the conditions of the temperature and mass floss together with the high heat load of Dresden is not reasonable. Due to higher efficiency of the heat generation it is better to go with an exclusive heat use. The analysis of sensitivity shows the particular dependency of the thermal power on the pumping temperature. The heat generation costs of the plant are approximately between 40 €/MWh and 65 €/MWh. The result of the discussion of the project risks claims a special treatment of the induced seismicity because of the micro electric industry and the sensitive historic building structure in Dresden.
Editor: Marco Reinisch
Tutor: Prof. Dr.-Ing. Clemens Felsmann

Thermodynamic and hydraulic design of MED-plants with decentralize feed-in of untreated water

There are different treatment processes, which can be applied for the desalination of seawater to produce drinking water or process water. The presented thesis examines the thermodynamic design as well as the optimization of sites based on the multi-effect-distillation (MED). First of all a simulation program for the calculation of specific values of MED-sites with plate heat exchangers is developed, using underlying theoretical basics. In connection with this simulation tool follows a model validation by means of a prototype at the ILK Dresden, which is be used as a test plant for studies of different heat exchanger designs. A comparison between the theoretically simulated and practically measured specific values of different heat exchangers leads to the conclusion,		that the simulation tool achieves a sufficient accuracy relating to the analyzed parameters. In the last section, the impact of a decentralization of the raw water supply of a Double-Quattro-MED site is analyzed theoretically and practically. Based on the developed simulation tool, the benefits of a decentralized raw water supply are investigated and valued as positive. Afterwards, the decentralized raw water supply is structurally realized and analyzed using various different measurement series. A comparison between the test series of the decentralized and the primal central raw water supply is emphatic that the decentralization leads to an increase of the specific distillate production of more than 10% and hence the systems energetic efficiency can be improved.
Editor: Andreas Meurer
Tutor: Dr.-Ing. Karin Rühling, Dr.-Ing. Bodo Burandt; ILK Dresden gGmbH

Power to gas-to-power development and evaluation of an energy concept

The fluctuating and thus temporally unreliable power generation from renewable energy sources, such as wind and solar, raises the question of how the electricity should be stored. Therefore the paper at hand analyses the concept ,,Power to gas to power". A concept, in which electric energy is transformed into chemical energy of an synthetic gas through electrolysis and is subsequently retransformed into electricity. The fundamental chemical processes electrolysis and methanisation are considered and the necessary substeps of the power to gas technology are examined as weil. Advantages and disad vantages of these substeps are evaluated and the energy and material flows are explored.		Additionally possible process variants are narned and current projects are presented. A subsequent evaluation of the cost effectiveness led to the conclusion that an economic utilization of the ,,Power to gas to power"- technology is rarely achieved. Compared to other techniques of electricity storage the technology under scrutiny exhibits certain advantages and disadvantages, which are highlighted. The paper con cludes with an overview about inherent chances and obstacles of the concept. The paper conclusively recognizes, that the „Power to gas to power"-technology offers great chances, to pave the way for a solely renewable energy generation, but at the present moment the economic drawbacks hinder an wide application.
Editor: Franziska Pleißner
Tutor: Dr.-Ing. habil. Joachim Seifert; Dr.-Ing. M. Göbel, Dr.-Ing. J. Hartan (VNG Gasspeicher GmbH)

Potential analysis and evaluation of smart home concepts

The smart home (SH) concept is a new possibility to the end user to control the energy consumption in a home. The SH is attributed with great advantages in energy efficiency and comfort. A potential and economical analysis is performed in this investigation with focus on the field of energy management. Several marketable SH solutions are already available in a market which is predicted to reach 5 billion Euro in 2017. A building simulation examines both the area of heat supply and devices and applications.		Results of the study show that especially buildings with high energy requirements due to low energy performance of buildings and low energy efficient devices are suited for an economic SH solution. In particular, the intelligent heating control achieves an investment recommendation in many cases. Whereas the intelligent devices and light control gets no investment recommendation. Finally, the SH solutions is compared to other measures of energy and CO2 emission reductions. In particular the SH heating solution can be superior in its abatement costs to other solutions like an entire modernisation of a heating system.
Editor: Stefan Ubben
Tutor: Prof. Dr.-Ing. Clemens Felsmann, Prof. Dr. D. Möst

Counter Flow Cooling Towers – Identification of an Operation Strategy Minimizing Primary Energy Input (Case Study: „Maschinenhalle Nord EVC 1, Dresden)

The Energy Center in Dresden Wilschdorf provides since 1998 for the semiconductor manufacture of Globalfoundries electricity, hot, warm- and cold-water. 2006, the power plant had to be extended to include six additional turbo chillers to cover the growing energy, which the consumer needs. Cold water has to be supplied in 5/11°C- and 11/17°C- operation. The cooling circuit of the turbo chiller was designed with 27°C inflow- and 34°C outflow- temperature to preheat hot water from another process. The investigations of this study shows that the current mode of operation could be replaced by a more efficient coupling of chiller, cooling water pump and cooling towers and so a considerable amount of primary energy can be saved.		The theoretical part examines the mechanisms of action of the refrigeration system. After this, the operational characteristics of the machines, who are used, are determined by contact with the manufacturers. Tests analysed and verified them. After measuring all operating points were proved unfeasible, a simulation model was developed, which takes the problem of the complex dependence of the various factors into consideration with each other. The target size, the sum of compressor power, pump power and fan power, was minimized in this work as much as possible. The savings potential was calculated.
Editor: Felix Pfeiler
Tutor: Dipl.-Ing. Elisabeth Eckstädt; Uwe Püschmann, Dipl.-Ing. Matthias Schmidt, Dipl.-Ing. Sophie Fischer, Energieversorgungscenter, Dresden-Wilschdorf GmbH & Co. KG

Modeling of cooling energy storages

In stratified chilled water thermal storages, cooling capacity gets lost because of mixing. As the cold, usable water mixes with the warm return water at the top of the tank, it cannot be used anymore if it exceeds a specific limiting temperature. Additionally, capacity is lost through heat gain from the ambient. In this paper, an Excel calculation was developed to estimate the losses through heat gain from the ambient approximately. The ratio of the energy gain from the ambient to maximal cooling capacity for an exemplary chilled water storage tank was very small. Thus the assumption made in the literature to neglect the losses from the ambient could be confirmed.		For the evaluation of the other losses occurring in chilled water storages (mainly through mixing) two models from the literature were presented. In the first model two metrics for the thermal performance are introduced. A CFD model was developed and validated. First order correlations relating thermal performance to storage parameters were derived from the results of the CFD model by applying a factorial design experiment. In the second presented model the unsteady energy equation was solved analytically. The resulting equation for the time- and position-dependent temperature profile was used to calculate the first law efficiency of the storage tank. To conclude the paper, comments concerning the application of the models were made.
Editor: Christina Kirschstein
Tutor: Dipl.-Ing. Elisabeth Eckstädt

Operation and measuring of a low power heat pump and preparation of a laboratory experiment for students

The heat loss in water heating facilities caused by the ciculation may constitute up to 50% of the total requirements for the heating facility. As a step for reducing those losses, a circulation heat pump was developed at the institute for energy engineering in cooperation with an industrial partner.		The variable heat sources, its high level of measuring equipment and an easy accessibility predetermine this heat pump for using it in student education. In this work the heat pump has to be resumed and integrated in the existing periphery in the center of energy technology. Basing on experimental series proposals for improvements shall be elaborated and implemented.
Editor: Felix Werner
Tutor: Dipl.-Ing. Stefan Hoppe, Dr.-Ing. Karin Rühling

Solar Domestic Hot Water Generation with Photovoltaics

This paper focuses on domestic water heating through the technologies photovoltaic and solar thermal. The question of this paper is due to which aspects and corresponding circumstances one of these technologies can be preferred. The goal is to show how the unusual photovoltaic power generation for the use of heating in detached houses is profitable, using primary energetical, economical and ecological aspects. The answer of the leading question is founded on specific norms and guidelines as well as current literature and is described and discussed in this paper.		Using an additional data source with exact to the hour weather data, provides an even more detailled illustration of the results. The results show that solar thermal has lesser energy acquisition costs compared to photovoltaic plants and thereby being the appropriate option for domestic water heating. The integration of the technologies on the basis of the mentioned media into an overall system leads to a detailled examination of further system components. This shows that the selection of the drinking water and battery storage has great relevance when analyzing the economic assessment of the system.
Editor: Marc Kissling
Tutor: Dipl.-Ing. Elisabeth Eckstädt

Energy management and Building automation

The fight against climate change is ubiquitous, especially in the area of technical development. Alternative energy sources are expanded, researched and developed. But society is faced with a problem. They do not economize with the available energy so far. The trend of energy moves towards decentralization, which one day causes a limitation of available energy. To pass this challenge, high energy efficiency is needed, on the one hand by consumers themselves, on the other hand of the technical systems that surround them. Energy management systems are an important basic requirement for it.		Due to such systems energy savings are discovered in buildings, which lead to improvements of the energy performance in turn by taking appropriate measures. The DIN EN ISO 50001 largely describes the organizational implementation of an energy management system. This paper examines evidence, for which building types energy management systems are particularly suitable and what automation installations the building should be equipped, to accomplish the requirements of the norm. Furthermore, it is analyzed, how far the Technical University of Dresden is implementing such a concept and to which extent the implementation of an energy management system makes sense for a smart home concept.
Editor: Tobias Kämmerer
Tutor: Prof. Dr.-Ing. Clemens Felsmann

Transient thermal performance of buildings using simplified building mode

Dynamic thermal building simulations are useful and efficient tools to analyze and optimize building specific supply installations. Nevertheless necessary parameterization and computation efforts (long simulation time) of such building models often exceed a practical limit. In this context the purpose of this study is to investigate possibly ways to simplify multi-zone building models in order to reduce these computation and parameterization requirements considering the trade-off between reliability, accuracy and time.		In addition to the simple heating energy demand especially the heating load curve are of interest describing the building as a consumer of thermal energy. Therefore the TRNSYS Type 56 was used in this thesis to analyze different approaches of building model simplification methods. Finally the results are compared to the usage of building models in accordance to the guideline VDI 6007 (based on an r-c circuit).
Editor: Tobias Schlosser
Tutor: Prof. Dr.-Ing. Clemens Felsmann, Dr.-Ing. Alf Perschk

Design of a measurement concept, a survey and a database structure for the detection of subjective and objective comfort criteria

Subject of this paper is the long-term study of thermal comfort at office workstations. For this, a concept was developed, that serves the gathering of both physical measurement data and data generated from surveys amongst the office workers. It is designed to be flexible so that additional sensors, questions, questionnaires, offices for measuring and probands can be added at any time. First, the state of research in thermal comfort was outlined, with the goal of identifying reseach questions that appear to be particularly interesting. A list of physically measureable data was created, with items which do or might influence thermal comfort.		The list was then filtered and sorted into modules, which are in accordance with the afore identified reseach questions. Some basics for applying questionnaires were presented and questions chosen. The positioning of measuring equipment in the offices was described, their linking with a server shown and a database architecture designed. For the appliance of radiation heatening systems suggestions, inspirations and approaches were added to support evaluating those systems and for making comparisons toward convection heating more tangible for the future.
Tutor: Martin Schorcht
Editor: Dipl.-Ing. Jens Haupt

Optimization of the use of heat pumps

This work includes studies on thermal storage effects in the building with the use of current-controlled and solar-controlled heat pump operation. Through the use of intelligent control algorithms, the cost of electricity purchased from the public network can be lowered by taking advantage of variable electricity rates or by increasing the proportion of self-used photovoltaic electricity. In the scope of this work, the achievable energy management measures are investigated for two building types. On the basis of the rising penetration of renewable energies into the electricity grid, whereby frequency and voltage fluctuations occur, the resulting potential with regard to flexible power demand should also be assessed.		The investigations showed that, by participating in load management, the developed algorithms cause savings in annual operating costs for the heat pump owner. With this, the introduction of load-variable electricity tariffs for end users is necessary for current-controlled operation. The potential of a single heat pump for the stabilization of the frequency and voltage fluctuations relative to the entire power system are rather low, but can result in a high efficiency due to the large number of available decentralized heat pumps. Therefore, the creation of a price incentive is a good activator.
Editor: Rene Kronenberg
Tutor: Prof. Dr.-Ing. Clemens Felsmann, Dipl.-Ing. Felix Panitz

Self Consumption of Photocoltaic Power – Hourly or Minute Based Values?

The temporal resolution of the power generation from PV is one of the parameters affecting the simulation of PV systems. In this work, the influence of temporal resolution on the power demands of the electricity produced, the self-consumption and self-sufficiency and share the overall cost of PV power are considered. Therefore, the different temporal resolutions of power generation and demand of 1 minute, 15 minutes, 30 minutes and 1 hour are examined. The high temporal resolutions lead to a high power fluctuation, while the lower resolutions flatten the power profile and can reduce and hence neglect peaks of power demand or supply.		These effects influence the self-consumption and self-sufficiency ratios, reduction of the power purchased from grid and also increasing the supply revenues. The lower the temporal resolutions, the larger the deviations of self-consumption and self-sufficiency ratio from the reality might be. However, the investigation shows that the average values do not differ significantly for different time resolution of 1 to 60 minutes for the period of a whole year. On the other side, to gain accurate self-consumption and self-sufficiency percentage ratios the time step should be lower than 1 minute.
Editor: Anchalee Prapatsornpittaya
Tutor: Dr.rer.nat. Christoph Schünemann

Energy efficient circulators for the state capital Dresden

Circulation pumps offer an enormous potential of saving power. Most of them are not only oversized but also very old and technically not up to date. To quantify the latter, 47 pumps in 13 buildings of the city of Dresden were analyzed and replaced by a fitting modern pump. With this comparison, the reduction of power consumption and carbon dioxide emissions as well as the time of amortisation and saving of costs within 15 years could be calculated.		All pumps showed the expected technical potential but both power tariffs of the city were so low priced (compared to a private house owner and power customer) that they became the most important factor of the replacement analysis. The electricity tariff and its increase over the years are the essential part of the calculation of profitability. Although the calculations and results are not as close to reality as they could get, the possibilities and problems of a pump replacement could be determined and quantified.
Editor: Johann Rüdiger
Tutor: Prof. Dr.-Ing. Clemens Felsmann

Energy recovery in building facades

A huge part of the German population favored a development of using renewable energy and also the federal government Germany and the UN Intergovernmental Panel on Climate Change (ipcc) force the extended development. To achieve that aim, technologies had to enhance and new useful areas had to make accessible. This paper deal with technologies that develop energetically the mostly passive used facades. These technologies are: photovoltaic, solar heating, translucent insulation, photobioreactor, and the project Windrail and they get research on the aspects of energy efficiency, conditions governing locations, the construction-related effort and the economic feasibility.		The target of this work is to get an overview of different technologies for develop energetically facades. The costs of many technologies for using renewable energies drop increasingly, in the same time you can register a growth of the energy efficiency. That fact abets popular development renewable energy systems also at evadable bad locations like a vertical façade. The using of energy systems at facades getting more and more lucrative, however it is important to check the conditions governing locations to use the technology meaningful.
Editor: Tom Eckhardt
Tutor: Prof. Dr.-Ing. Clemens Felsmann

Conception, dimensioning and setup of a test and practicum station for the combined heat and power unit

This paper attends to the conception, the dimensioning and the setup of a test and practicum station for the combined heat and power unit Viessmann Vitotwin 300-W. The preliminary consideration goes into detail about the themes combined heat and power (CHP), the micro cogeneration, stirling engines, sankey diagrams and the combustion calculation. This is followed by informations about the used components of the test station, the planning, the setup of the system and eventually the first practicum experiments.		The measurement equipment was from special meaning. At the end there is a summary and some prospects. In the appendix there are certain documents which are developed during the creation of this paper for example the piping and instrumentation diagram, the list of measuring and regulation points, the practicum documents with solutions and finally excerpts of the online documentation's wiki pages.
Bearbeiter: Carsten Pietzsch
Betreuer: Dipl.-Ing. Jan Löser

Time variable benchmark for electricity considering fluctuating renewables energy sources

Buildings' energy efficiency and cogeneration of heat and power are evaluated using annual mean values for primary energy factor, share of renewable energies and greenhouse gas emissions of electricity generation. Fluctuating renewable energy sources are so far not being considered. Therefore this seminar paper examines the influence of fluctuating power generation on a buildings' energetic benchmark. In chapter 3 the data basis is elucidated, assumptions and simplifications are introduced and justified and the used formulas are derived. Furthermore time variable benchmarks are illustrated, phenomenons are explained using weekly and daily resoluted graphs and temperature dependency of the primary energy factor is highlighted.		In chapter 4 a method to calculate time variable benchmarks for the forecast years of 2020 and 2030 is introduced and differences between present time and the forecast years are explained. In two examples in the 5 th chapter the hypothetic buildings' primary energy consumption of one year is compared, once using time variable benchmarking and once using mean values. The resulting deviations of 2.8 to 3.39 % for present values of the primary energy factor in the different examples indicate that nowadays time variable benchmarking is not yet necessary. However, deviations are much bigger in the forecasted years (7.8 to 8.8 %). The author concludes that Demand Side Management that regards favorable primary energy factors could even increase deviations between time variable benchmarking and regular benchmarking considerably and thus give more importance to the time variable benchmarking.
Editor: Andreas Odenkirchen
Tutor: Dipl.-Ing. Felix Panitz, Dr.-Ing. Karin Rühling

Options and potentials for energy recovery from water supply and drainage systems in buildings

Ever since their erection in the 19th century, the systems for drinking water distribution and waste water collection are serving Western and Central European cities reliably. Simultaneously, not only large hydroelectric power plants were constructed, but also medium-sized hydroelectric power plants, devices for micro hydro energy harvesting, and technologies for the utilisation of thermic energy in buildings. It may be taken into question which of these technologies work effectively and efficiently enough to provide significant economic and ecologic benefits. Hence, this thesis investigates the systemic prerequisites for utilising energy recovery technologies in systems of water supply and water disposal in buildings.		To that end, a building classification is introduced which takes into account the dimensioning of the building’s connection to the drinking water network. Also, the problem of different patterns in the fluctuation of consumption for the respective building classes is discussed. Following a detailed description of different technologies for energy recovery from systems of water supply and water disposal, these technologies are evaluated in regard to their respective technological and economic utility. Consequently, the technologies are compared among each other and in regard to their respective suitability for efficient deployment in the different building classes.This reveals previously unused potentials, as well as ways to identify limitations of currently used technologies.
Editor: Mathias Poetzsch
Tutor: Prof. Dr.-Ing. Clemens Felsmann

Sustainability Analysis of Solar Electricity Storage Systems in Buildings

The student research project titled “Sustainability Analysis of Solar Electricity Storage Systems in Buildings” examines the usage of a solar electricity storage system concerning their sustainability referring to primary energy demand and greenhouse gas emissions. All energy produced by the photovoltaic plant, which cannot be used directly, should be stored in the battery. Two different types of storage systems are considered: lead – acid batteries and lithium – ion batteries. In addition the battery management system and during the further process of this project the integration of the battery into a family home with a photovoltaic plant are analysed concerning their sustainability.		The conventional method without a storage and therefore low internal consumption but on the other hand with a higher share of supply into the public grid is used as a reference. The main result of the investigation is that solar electricity storage systems in family homes are more ecological than systems without storage. This statement is valid for both types: lithium – ion and lead acid batteries. Systems with storage need up to 50% less primary energy compared to systems without storage. The sensitivity analysis shows that the sustainability of a solar electricity storage system is also guaranteed for a lower primary energy factor of the German electricity grid in 2016.
Editor: Catrin Weyers
Tutor: Dr.rer.nat. Christoph Schünemann

Investigation on a novel method for storing electrical energy

Because of the current discussion on the use of systems to store electrical energy this seminar paper is concerned with a certain technique based on the patent description “Method for converting and storing regenerative energy”. This technique stores energy by compacting a working fluid above its precipitation point. The compacting is achieved by displacing the working fluid by water pumped into the vessel. During the outtake of electrical energy the evaporation of the working fluid ensures a constant pressure while leading the water through a turbine.		The focus of this seminar paper lies on the practicability of the technique. Therefore the feasibility of the thermodynamic process was analyzed using the program for material characteristics “FluidExcel”. Having compared the results the energetically best option was used to do a constructive design of the storage system based on the construction of the turbine and the engine. This was compared to a design based on energy economic parameters. In conclusion the possibilities for integrating the technique into energy network systems were analyzed.
Editor: Fiona Dominique Lüdecke
Tutor: Dipl.-Ing. Felix Panitz, Dr.-Ing. Karin Rühling

Sustainability Analysis of Constructing a Passive House in Comparison to an EnEV09 Standard Building

This student research includes the primary energy demand and the resulting greenhouse gas emissions of the production of building equipment for heating and building insulation. It is compared to the savings of the energy consumption during the use phase. New buildings by the Energy Conservation Ordinance (EnEV14) are compared to passive houses with different ecological equipment and building insulations. The special feature is the inclusion of the production energy demand of the equipment and the usage of different sources for the		primary energy demand and the resulting greenhouse gas emissions of the production of insulation materials and therefore can be said it ensures precise results. The use of organic insulating materials, such as Cellulose and the installation of systems with low fossil fuels and electricity consumption are sustainable measures to reduce the primary energy demand and greenhouse gas emissions. These measures make possible that an EnEV14 standard building can nearly reach the primary energy consumption and the resulting greenhouse gas emissions of a passive house during 20 years.
Editor: Adrienne Gehre
Tutor: Dr.rer.nat. Christoph Schünemann

Intelligent Integration of Thermal Storages to Enhance the Usage of Photovoltaic Power in Domestic Buildings

This paper includes a study on the use of intelligent control algorithms for heating buildings and drinking water. These algorithms are intended to increase the self-consumption of the electricity generated by the photovoltaic plant. Because of the falling buyback price for photovoltaic electricity, self-consumption is more profitable than feed in the electrical grid. Accordingly in this paper it is investigated which effect wall mounting has on the cooling behavior of the building and thus how it affects the possibility to shift the heating load. Additionly it is examined which systems engineering is most suitable for this application. Furthermore, methods will be developed which should help to make the algorithms as efficient as possible for example by estimating the heating requirement.		The study showed finally that the developed algorithms are currently not yet efficient enough to compensate the increased financial costs of additional systems engineering. However the developed intelligent control algorithms have a lot of potential, if further optimizations will be done and the future development of the electricity price is considered. The algorithms could decrease the heating costs and following the investment of a photovoltaic system would be made more profitable. Furthermore, it was worked out that the use of direct electric heating elements, although it increases internal consumption, but in conjunction with the intelligent control algorithms the total consumption of electricity is significantly higher than in the reference scenario. This was rated critical.
Editor: Korbinian Hörfurter
Tutor: Dr.rer.nat. Christoph Schünemann

The use of geothermal energy : an energy-economic review

The energy revolution and increasingly important climate change commitments call for a rapid expansion of renewable energies, for example of geothermal energy. The seminar paper deals with the economic potential of geothermal energy, especially for heat supply in Germany at present and in the future. A detailed research work has been done to analyze technical and scientific, as well as economic and political conditions.		The near-surface geothermal energy is already an effective method to provide heat for heating purposes. Mainly due to high costs and a low state of research, however, deep geothermal energy is still not of economic interest for electricity and heat supply. The great geological potential and promising environmental aspects are an incentive to promote geothermal energy in the future. It is still unclear how long it will take geothermal energy to make a significant contribution to the German energy supply.
Editor: Kristin Wiegand
Tutor: Prof. Dr.-Ing. Clemens Felsmann

Renewable Energies for Cooling in Buildings

The cooling demand of buildings is increasing steadily for some time now and this progress is expected to continue. This causes inevitably a high energy consumption and great cost. Renewable energies could be a solution for these problems. This paper examines, to what extent they can be used to limit both cost and energy consumption. For that purpose two principles were considered. They either use indirect thermal or electrical drive energy or a directly available heat sink. Two building models worked as an auxiliary tool for the calculations. The first is a one family house and the second a three-floor office building. A simulation using meteorological data provided of the Germen Weather Service was applied to generate a demand profile for a one year period. Manufacturer’s data made it possible to calculate cost and energy demand for the following systems: The cooling of a building using a conventional compression refrigeration machine and current from the mains as reference. A photovoltaic system that provides the electrical energy required for the compression refrigeration machine. An adsorption refrigeration machine in combination with a solar-thermal energy system. Passive cooling with geothermal power - using a collector for the one family house and probes for the office building. Besides, ventilation systems were discussed, that however were not able to cool the buildings entirely. Nevertheless, an improvement in comfort is possible.		A precise calculation was beyond the scope of this paper, which makes an informative comparison to the other systems difficult. The study demonstrated that each of the systems can have advantages over the conventional method. This highly depends on type of building, location and the environmental conditions. For the one family house a geothermal system is the most profitable, taking into account that the soil has to be suitable. The systems using solar energy can have advantages concerning cost and energy consumption over the conventional system as well, when the energy surplus is turned to account.Regarding the office building, the combination of a photovoltaic system and a compression refrigeration machine supplies the best results. One reason for this is the fact that this type of building ist usually already equipped with this type of refrigeration machine and therefore a retrofitting can easily be realised. The solar-thermal energy system was very expensive due to high investment costs. Besides, much of the produced energy is left unexploited because it is generated on weekends, when the energy demand of the building is very low. The geothermal power system causes great cost as well, because the drilling is very expensive. By using the system to heat the building in winter as well, maybe this disadvantage ought to be compensated. To evaluate the different possibilities more precisely, the examination of a system that includes cooling in summer and heating in winter would have been necessary. A separation of these two cases of application inevitably causes misrepresentation. Because of limited scope, further calculations could not be accomplished. However, an evaluation of the presented renewable energy systems for cooling of buildings was possible.
Editor: Vera Volmer
Tutor: Prof. Dr.-Ing. Clemens Felsmann

Contribution to the Modelling of Scenarios for new Constructions of inner-city District Heating Networks

This diploma thesis with the subject "Contribution to the Modeling of Scenarios for new Constructions of inner-city District Heating Networks" includes an investigation of a local heating network in a suburb of Dresden, which is classified as uneconomical because it is too far away from the main-pipes of the district heating network of the urban supplier DREWAG. For this there was made a conception of six different network variants with the software tool STEFaN,		a calculation of the heat losses in this networks, an investigation of the development of the annual heating requirement for the designed network and a selection of suitable pumps. Subsequently there was made a determination and a calculation of the energy system management and the running costs of four suitable heat generator variants with the software FreeOpt, that are fitting to the defined and given boundary conditions. The diploma thesis is a basis for a profitability analysis, which is necessary in the wake.
Editor: Marco Meiling
Tutor: Prof. Dr.-Ing. Clemens Felsmann, Dr.-Ing. Karin Rühling, Dr.-Ing. Stefan Gnüchtel; Dipl.-Ing. U. Gedrich, DREWAG NETZ GmbH

Validation of models for radiant heating and cooling systems

Simulation programs are an essential tool for the interpretation and optimization of building services engineering and systems engineering. Because software is always a developing process it is essential to validate it regularly for getting a high level of quality. Within this paper extended possibilities of validation of the program system TRNSYS-TUD of the professorship for building energy systems and heat supply are realized. Within a first step different test cases of the project RADTEST of the IEA/SHC		are described and transformed into the TRNSYS-TUD program. Within this tests the TRNSYS-TUD program got a very high coincidence with other programs with only some exceptions. It is not possible to define the reasons for this exceptions at this time. Within the further work an empirical validation was done by usage of a test stand with integrated floor heating and its simulation within the TRNSYS-TUD program. There was no coincidence observed between simulation and measurement. Possible reasons could be found in the technical design of the test stand and the evaluation of the measurement data.
Editor: Hans Kaiser
Tutor: Dipl.-Ing. Katharina Huck, Dipl.-Ing. Sven Paulick, Dr.-Ing. Alf Perschk

Investigation of operational scenarios of a RVK by numerical simulation

This report deals with a series of static measurements, designed to evaluate the properties of a new combined heat and power unit (CHP). In a second series a set of indicators were determined in a standard test cycle, specified in the DIN standard 4709. The examined CHP-unit is an EcoPower 1.0 of the Vailant Group. Furthermore a numeric simulation tool was created to simulate a large quantity of CHP-units operating in a virtual power plant.		Based on some research about possible application of regional virtual power plants, test scenarios were created. These were calculated with different composed versions and interpreted. Based on these results requirements for CHP-units participating in a virtual power plant were described. Also conclusion about the possible chances and limitations of virtual power plants were drawn. The report concludes with an outlook about further developments and applications of the tool.
Editor: Felix Glöckner
Tutor: Dipl.-Ing. Jens Haupt, Dipl.-Ing. Paul Seidel

Elaboration of a design planning for a heat-supply system in a medium-sized building with varied user characteristics

Integrated Design planning is part of any serious planning of technical installations in buildings. It requires the mutual coordination of planning services all disciplines in all phases and thereby enables the timely execution of the project and its adaptation to the requirements of the client. These objects will be achieved with the help of suitable planning tools. A technical design of heat supply systems for a medium sized building is to be worked out as part of the interdisciplinary project work. Special consideration at that subject is to get the planning coordination with other trades.		The focus of the work should be in the preparation of planning documents. The aim of this work is by independent working and deepened research to develop an overarching understanding and overview of service-design phase of a project planning by schedule of services and fees for architects and engineers (short HOAI) and to make with the obtained knowledge decisions on the current project itself and therefore to use the experience gained from my studies on a task of professional life of a Technical facility equipment engineer.
Editor: Dmitrij Gorlovsky
Tutor: Dipl.-Ing. Wojciech Kozak, Lars Dobberstein (ARUP)

Continuation of renewal of solar radiation processor in TRNSYS-TUD

In this work the TYPE116 was transferred to a C++ code and its functionality was confirmed in a test case. Moreover, new models of computation for tilted surfaces were added. By the implementation it was taken care to write a legible and fast code. This is necessary, because the computation time of larger models considerably exceeds the time which can be saved through code optimization, what stands out primarily for large simulation periods with high resolution and many surfaces. The calculation of a time step runs algorithmically: first the data conditioning and then the calculation of area-related variables.		The pure calculation time of the data processing for each time step is independent of the number of faces. Considered over the whole simulation time, the data processing time is only dependent on the time resolution of the simulation. The total computation time required for area-related variables, however, is proportional to the number of surfaces, since the surface quantities are calculated serially. One possibility for the reduction of this time could be at this point the parallelization of the computation.
Editor: Miko Trusch
Tutor: Dr.-Ing. Alf Perschk, Dr.-Ing. Markus Rösler

Inspection and Optimization of the building automation and control systems in an office building

Subject of this thesis is the analysis of the building automation system of the office building “Haus V“, owned by urban drainage Dresden, as well as the suggestion of possible improvements. The operation of „Haus V“ is difficult due to two reasons. Building physics and the installed system lead to different energetic demands in the rooms of the former digestion towers. Furthermore, these different energetic demands differ from the demands of the rooms belonging to a connection building, whose facade is mostly made of glass. Additionally, it is not possible to condition single rooms with the installed heating/cooling and ventilation system. The resulting discomforting indoor climate, leads to the employees’ dissatisfaction during most of the working time, as well as high energy consumption.		This thesis follows three approaches to increase thermal comfort in the rooms and to reduce the building’s energy consumption: an extensive data analysis, measured by a local building control, the assessment of the building automation and control system with a new certification scheme by the eu.bac association and lastly an analysis using the dynamic building simulation software TRNSYS-TUD. This thesis comes to the conclusion that the complaints by the employees are justified, since the rooms do not comply with the requirements of an acceptable indoor climate. This problem can be ascribed to a wrong setting of the flow temperature. The simulation reveals a high improvement of thermal comfort by replacing the old heating curve, which also leads to energy savings. Additionally, other improvements, based on data analysis and optimisation suggestions by the eu.bac certification scheme, are presented.
Editor: Niels Rauland
Tutor: Prof. Dr.-Ing. Clemens Felsmann; A. Eisele, Sauter-Cumulus, GmbH, NL Dresden

Modeling of a vertical evaporator

Compared to the secondary loop systems the geothermal probe with directly evaporating (EWS) has higher coefficient of performance (COP) for the heat pump. The problems by EWS are the wetting of evaporation surface and break down of the liquid film, when the parameters of the film are outside of the stability region. In this study, a mathematical model for the evaporator is presented in order to simulate the heat transfer in the evaporation and to characteristic the liquid films. The intent of the work is the theoretical analysis of the restrained wetting and the thermodynamic processes during the evaporation of the refrigerant. To solve these problems EWS with simple		and multiple injections was modeled under the assumption, that heat flux density was acquainted. The model and parameter calculations were with EXCEL, and they were carried out with the refrigerant - ammonia. One important result of this work is, that the flood limit even for small pipe diameters is hardly achieved, below which a two-phase countercurrent flow is possible. Moreover, the maximal heat flows from soil increases with an increasing tube diameter and tube length. The studies with multiple injections system shows, that the multi-injection has no positive effect on the maximal heat flow.
Editor: Xiaojing Wang
Tutor: Dipl.-Ing. Elisabeth Eckstädt, Dipl.-Ing. Chr. Edler, Dr.-Ing. D. Vollmer; ILK Dresden

Development of an Excel® based Model for the Optimized Operation of CHP Units in Combination with Heat Storage as a Tool for the Layout of the Storage

In the Federal Republic of Germany, during the last years, the extension of renewable energies has been expedited increasingly. The energies’ volatile availability has led to a more and more discontinuous feed-in of electric energy and has caused fluctuating stock market prices for power. As a result, fossil-fueled power stations have more often been pushed into economic straits. Especially, highly efficient CHP plants in charge of district heating are challenged by the task to ensure an economical operation without endangering the heat supply. These circumstances render the use of heat accumulators interesting, since they extend the operating time of these plants. The task of this diploma thesis will be to survey the effects of fluctuating electricity rates on the operation of a CHP plant supplying heat with a non-pressurized hot water accumulator and deduce conclusions about its ideal storage size.		The optimum can be determined by offsetting the budgetary surplus generated by the use of an accumulator against the related investment costs. On this, a simulation model will be created which contains the important economic and technical boundary conditions. The result of the simulation reveals that the size of the storage gets smaller the less the electricity rates vary. The storage optimum, however, lies below the anticipated dimensions and does not correlate with comparable projects already realized. This circumstance is due to the fact that the budgetary surplus cannot be increased to such an extent that the investment costs for increased storage size are covered. The analysis of the causes indicates that the provident consideration of electricity rates in the load management has to be applied more efficiently. Furthermore, the economic boundary conditions need to be extended and decisions about choosing alternative CHP plants have to be made.
Editor: Georg Hamann
Tutor: Dr.-Ing. Thomas Sander, Dr.-Ing. Robert Huhn, KEMA-IEV GmbH Dresden

Integration of OpenFOAM into the program system TRNSYS-TUD/ParallelNS

This thesis describes the integration of the CFD software package Open- FOAM into the program system TRNSYS-TUD/ParallelNS. The purpose of this integration is to establish a new software system based on external coupling strategies for building performance simulation. By combining these specialized programs together, more realistic simulation results are expected.		The thesis first demonstrates the chosen OpenFOAM solver to be coupled with. After studying the existing boundary condition classes in OpenFOAM, a new boundary condition type pvmbc is designed and implemented, which works as a data communication interface. The data transfer between the different programs relies on the software package Parallel Virtual Machine. After testing and debugging the new interface, a test case is calculated and evaluated.
Editor: Xunzhang Yuan
Tutor: Dr.-Ing. Markus Rösler, Dr.-Ing Ralf Gritzki

Opportunities, capabilities and economic efficieny of waste heat recovery system in combination with a sorption machine

At first this thesis offers an overview of the current possibilities of thermal cooling. The main focus is placed on the use of waste heat from industrial companies. Furthermore, criterias for the use of a sorption machine are defined. These criterias were used to analyse the potential of using waste heat with a sorption machine in a concrete object. Based on this, different variants of thermal cooling will be presented.		Afterwards, their economic efficiency will be analyzed in comparison to the reference system, consisting of a combination of compression chiller, dry cooling tower and air-conditioning split units. Therefore, the annuity method based on the guideline VDI 2067 is used. Finally, a possible structural implementation of the preferred alternativ thermal cooling system is presented.
Editor: Tobias Schlosser
Tutor: Prof. Dr.-Ing. Clemens Felsmann, Dipl.-Ing. R. Dittrich, DZH Dresden

Energieeffizienter Campus

This article offers the readers an overview of the energy-consumption-analysis of the TU Dresden campus. As per the Energy Saving Ordinance 2009 all buildings of the campus can be classified into 5 categories. For the 5 categories (e.g. gymnasium) one building was compared with high and low energy consumption. The reasons for the deviation were presented. The energy pass is an energy-evaluated-document for a building. With the help of the program dena, man can issue the energy pass.		In this article the new energy pass of 6 extra buildings (e.g. Tillich-Bau) were issued. The second part of this article was regarded as the heat-density-map. Man can easily identify with the heat-density-map, that which buildings of the TU Dresden are energy-saving and which are problematic according to the energy-consumption-analysis 2009. In the end, the energy-redevelopment-measures come into being. The suggestions for the new roof-structure of Mollier-Bau were developed in the article.
Editor: Wenfeng Shao
Tutor: Prof. Dr.-Ing. Clemens Felsmann

Conception of an air change rate measurement with mobile CO2-Sensors

Indoor air quality is of great importance for the human health and comfort. An adequate air exchange should be guaranteed by proper ventilation, in order to supply fresh air to the occupants, lead indoor air pollutants and thermal loads away. In this paper, an experiment will be designed to identify the air change rate with tracer gas measurement and with CO2 as tracer gas. The experiment will be performed in the classroom Merkelbau 102c. During the experiment the temperatures and CO2-concentrations at three test-points in the room will be recorded.		The air change rate can be evaluated from the profiles of the concentrations with adoption of the algorithms, which are deduced based on different ventilation conditions of different measurement-methods. Due to the fact that this experiment serves as a demonstration experiment in the course Ventilation and Air Conditioning, the recording of the measured data will be visualized on a screen in the next room. Three mobile CO2 sensors will be used for the measurement and a network-data-adapter realizes the data acquisition and visualization. The other possible implements will also be presented in this paper.
Editor: Zheyu Wang
Tutor: Dr.-Ing. Markus Rösler

Hydraulic and energetic investigation at a DHW circulation test rig

In the Complex R of the “Zentrum für Energietechnik” (ZET) at the TU Dresden a test rig with extensive measurement and control technology was built, that emulates the domestic hot water construction and its circulation lines for a multi-family building with real line lengths and real heat losses and allows setting any draw-off cycles. The aim of this work is to investigate and to compare different circulation concepts experimentally. Initially, the measurement was extended to detect all pertinent data for the evaluation. Then in an extensive hydraulic characterization of the test rig a tool was developed that makes it possible to simulate different		scenarios and to output the resulting pressure losses and flow conditions. At a total of 47 evaluable test days two circulation systems were practically tested and evaluated at different temperature levels both in circulation mode without any draw-offs, as well as in the combined tapping and circulation mode. Energy balances were compared with each other through a theoretical and experimental determination of the occurring heat losses for different modifications of experiments. Furthermore, recommendations are provided helping to optimize.
Editor: Max Pham
Tutor: Dipl.-Ing. Felix Panitz, Dr.-Ing. Karin Rühling

Energetic analysis of a heatpump-Ice storage-system

In this thesis a supply concept has been examined, in which an ice storage functions both as heat source of a heat pump and as a heat sink for the heat that has been absorbed by the cooling system. The ice storage is a seasonal cold storage and low temperature heat storage at once. A plant model of a heat pump ice storage system has been created in Dymola/Modelica and was simulated with various boundary conditions. The results have been compared with a conventional reference system composed of a condensing gas boiler and a vapour compression chiller with free cooling. The simulation shows that the heat pump ice storage system has a significantly lower primary energy demand than the conventional system.		While the cost of energy for the heat supply is almost the same, the cost of energy for the refrigeration supply could be reduced. Furthermore it was revealed that the achieved savings essentially depend on the heat requirement. Increasing heat requirement results in increasing ice volume, which can be used for free cooling. The economic estimation shows that the capital costs are amortised by the savings achieved. The pay-off period lies between 10 and 15 years, depending on the load profile. Moreover the calculation indicates that the assumed development of energy prices have a determining influence on the pay-off period.
Editor: Patrick Eggers
Tutor: Dipl.-Ing. Thomas Kretzschmar, Dr.-Ing. Bruno Lüdemann, Imtech Deutschland GmbH & Co. KG

Evaluation and interpretation of complex technical building systems

The construction of a new building requires comprehensive planning services, depending on the complexity of the building project. In addition to architectural and structural services, the construction of technical plants and supply systems is very important. The schedule of services and fees for architects and engineers (HOAI) classifies the technical planning services into nine phases of planning. In this seminar paper parts of the planning services of complex technical building supply systems are investigated by three examples.		The first task is an acoustic evaluation of the air conditioning supply concept of the Sempergalerie in the Zwinger in Dresden by the example of one exhibition room as part of the design planning stage. A second task is to analyse the transfer of two rotary offset presses with regard to the fluids and supply rails that have to be provided at the new location. There is also examined which contructional conditions result. As an example for the planning step „facility management and documentation“ a stocktaking to generate a digital room book for the operation of buildings is executed.
Editor: Claudia Buth
Tutor: Dr.-Ing. habil. Joachim Seifert, Dr.-Ing. P. Vogel (INNIUS GTD GmbH)

Development of a concept for the design and operating mode of an air conditioning system to supply a climate chamber

This student work deals with the design of the HVAC system of the planned test rig at the Department of Energy Management in Buildings and heat supply of the Dresden University of Technologie. For this purpose, the requirements for the air conditioning system for studies on thermal comfort were determined. The results of a literature search to similar test rooms and their facilities and operating concepts are presented in the work. On the basis of the existing plant concept, the dimensioning of the HVAC system is performed. With the obtained results, the system components for air conditioning were selected		and a concept for a flexible and easily adjustable air duct system developed. The required measurement and control devices were identified and an integration into the already developed measurement and control concept of the test stand determined. Subsequently, the calculation of the pressure loss is carried out in the design case and a system curve created. The concept of the HVAC system is discussed and possible modes of operation are listed. A study on the application limits of the HVAC system in interaction with the surrounding surfaces of the test stand completes this work.
Editor: Martin Henkner
Tutor: Dipl.-Ing. Lars Schinke, Dipl.-Ing. Alexander Buchheim

Modell Based Analysis of SOFC/Battery Hybrid Systems for the Domestic Electrical Energy Supply in India

The Fraunhofer-Institut für Keramische Technologien und Systeme (IKTS) develops by order of an industry customer a solid oxide fuel cells (SOFC) system. This shall be used for the electrical power supply of Indian households. The SOFC system shall be connected with the public electricity grid and furthermore battery storage shall be used for compensating power fluctuations. During a power failure of the grid, the SOFC battery hybrid system should supply the consumer independently.		In this thesis a model is developed, which represents all components of the SOFC battery hybrid system. The model calculates power flows of the system. For an appropriate system configuration and operation, parameter studies will be carried out. The acquired results will be summarized in a technical recommendation for design and size of the SOFC battery hybrid system.
Editor: Benjamin Gleichner
Tutor: Dr.-Ing. Thomas Sander, Dipl.-Ing. Thomas Pfeifer Fraunhofer IKTS Dresden

Studies on the effect of air ionisation in mechanically ventilated rooms

Topics of this paper are studies about the effect of air ionisation on mechanically ventilated operating rooms and office rooms. The paper is structured into four parts. First of all a literature research about the functionality of ionisation methods, the effect on the human organism and the building related requirements is necessary. On basis of this research the following experiments are established. The main point of the second part of this work is the research on the possibilities of the precipitation of particles in the office room C5 in the center of integrated building systems (ZIG) at Lucerne University of Applied Sciences and Art (HSLU-T & A) in Horw (Switzerland).		At the beginning an experiment in an empty office room und later a four week measurement with normal use is done. Afterwards the precipitation of particles in a faithful full-scale replica in the laboratory of the HSLU is analysed. The number of particles in the source, the relative humidity, the air volume flow, the earth and the number of ions are modified. Finally a study about the feeling of comfort of the users under the influence of air ionisation in the room C5 is investigated. Apart from the measurement of temperature, relative humidity, CO2-concentration and the number of ions a survey with the users is done. The results and reflections about further need of research are outlined.
Editor: Anne Hartmann
Tutor: Prof. Dr.-Ing. Clemens Felsmann; Prof. R. Külpmann, Hochschule Luzern

Investigation of the Reconstruction of a Cooling System with Emphasis on Energy Costs

A company wants to expand. Due to the extension of production area, there is a higher requirement of refrigeration to climatize the building. The previous chiller cannot provide the increased refrigerating capacity. It shall be replaced by a new refrigerating machine with a higher efficiency.		The new chiller provides the opportunity of free cooling. This document shall give an exact way to calculate the energy consumption of the previous and the new plant. In Addition to the higher efficiency there will be shown the huge effect of the free cooling for saving energy.
Editor: Marco Radehaus
Tutor: Dipl.-Ing. Elisabeth Eckstädt

Building and system simulation of the new construction Elbland hospital Riesa- Großenhain with IDA Indoor Climate and Energy

Simulation programs are increasingly being used in the area of technical building equipment. They allow to optimize the systems engineering, especially for larger buildings, and thus help to reduce the energy consumption. Especially in hospitals, it is to ensure that the indoor climate is not affected because of the optimization. Based on this observation, this thesis investigates the indoor climate and energy consumption of the new extension at the Elblandklinik Riesa-Großenhain with the help of the simulation program for buildings IDA Indoor Climate and Energy.		In a first step, the suitability of this simulation tool was examined. The influences of the environment, the user behavior and the system design on the indoor climate are described on the basis of selected zones in a next step. In a last step, the simulation results are evaluated regarding their thermal comfort within the building as well as the energy consumption of the system design.
Editor: Susann Klöditz
Tutor: Dr.-Ing. Markus Rösler; Dr.-Ing. Matthias Radenz, Brendel Ingenieure Dresden GmbH

Generation and validation of a new model for gas adsorption heat pumps within the numerical simulation program TRNSYS

The aim was to integrate a model for gas adsorption heat pumps into the simulation programm TRNSYS-TUD. Gas adsorption heat pumps represent a possibility to further develop gas heaters. On the one hand the efficiency is even higher compared to condensing boilers, on the other hand regenerative proportions contribute to the heat balance by using the heat pump process. As a consequence they reduce the amount of gas needed and also reduce the emissions of CO2 into the atmosphere.		For that reason the simulation program TRNSYS-TUD was extended. It now includes the option for modeling the gas adsorption heat pumps. It enables the user to compare energetic aspects of gas adsorption heat pumps and existing systems. The theoretical background of gas adsorption heat pumps was described. This includes the processes during the adsorption and desorption phase. The results of the heat pump model were validated with the information provided by manufacturer. The characteristics were tested under simulation conditions.
Editor: Benjamin Perschk
Tutor: Dr.-Ing. habil. Joachim Seifert

energetic and economic optimization of an ultrapure water processing plant

One determining factor for the POU (point of use) of an ultrapure water plant is the temperature. In the end of the concerned ultrapure water processing plant (Polishing), there are “cold” manufacturing tools which require a temperature of 21,5°C ± 0,5°C and “hot” manufacturing tools which require a temperature of 60°C ± 0,5°C. Plate heat exchangers designed as recuperator, heater or cooler are used during the process engineering circuit in order to transmit the necessary heat flows.		The “hot” sub-process of the existing ultrapure water processing plant right before the manufacturing tools were checked for energy efficiency and energy savings potential. The objective was to reduce the necessary cold and hot volume flows on the secondary side of the plate heat exchangers and yet to realize the required temperatures at the primary exit of the plate heat exchangers.
Editor: Johannes Nebauer
Tutor: Prof. Dr.-Ing. Clemens Felsmann; Dipl.-Ing. Klaus Wohlmann, Arcade Engineering GmbH

Collection, archiving and evaluation of measured values

The shift-induced utilization of renewable resources not only requires to develop new concepts in energy deployment but also to examine the effects on energy transport systems in place and to re-evaluate their stresses and design. In context of this paper methods are evolved to draw conclusions from available measurement data about operating characteristics of district heating grids in common strain as well as with additional solar thermal energy feed-in. Thematic priority is the preparation of the measurement data and examining the data with regard to full load changes and simultaneity.		The preparation of the measured data is focused on a high degree of automation and repeatability in order to load the different file formats into the database system with low effort and after checking them. The examination of full load changes is made by the means of a rainflow algorithm to especially show the differences in additional solar thermal energy feed-in. For the examination of simultaneity data of different measuring stations of one district heating grid is used to create and compare single day profiles categorized by day classes.
Editor: Christian Meyer
Tutor: Dr.-Ing. Stefan Gnüchtel

Application Limits of Droplet Separators

The project work describes the conceptual design and the construction of a test bench to investigate the entrainment of condensate at heat exchanger, as well as the measured proceed and the results of this measurement. The aim of the investigation was to validate the empirical assumption of the GEA Air Treatment GmbH about the entrainment boundary to identify the application limits of droplet separators. This assumption forsees that for an air velocity of 2 m/s in the free crosssection of a heat exchanger a droplet separator is necessary.		Beside the air velocity, the condensate quantity and fin spacing of the heat exchanger were also analyzed and defined as the main determinant factors. The measurement results show, that the dependence of the fin spacing can be proved only partly.
Editor: Konstantin Etzel
Tutor: Dr.-Ing. Karin Rühling; Dipl. Ing. (FH) Julian Appelhoff, GEA Air Treatment GmbH

Design and verification of a natural gas distribution system for a factory

A new aluminium recycling factory is established in Nachterstedt. To provide a capacity of about 400.000 tons of aluminium rolling ingots per year, two severally working production lines are being created. Also a gas connection has been created by the gas supply company to run the factory with natural gas.		The assignment was to check the planned pipe dimensions, conceived by the company “AIC Ingenieurgesellschaft für Bauplanung Chemnitz GmbH”, on functionality and conformity to existing national standards and rules. Therefore the entire pressure drop calculation has to be executed, and it should be noted that all conditions and guidelines are observed.
Editor: Matthias Kunze
Tutor: Dr.-Ing. habil. Joachim Seifert, Dipl.-Ing. Paul Seidel

Analysis of the Part Load Behaviour of a µ-Solide Oxide Fuel Cell System

The present paper deals about the analysis of the part-load capability of a high temperature fuel cell system for reliable off-grid power supply which uses propane gas. By flexible power modulation a broadest possible requirement profile for usage shall be covered. For this basic chemical and thermodynamic relationships and requirements are characterized. Operating values will be explained and on a simulated performance their dependence from each other is demonstrated. After description of the test item as well as the test bed the presentation of the experimental design and its execution will be shown. For different fuel gas supply at various electrical load follows the detection of thermally stable operating points and their energetic balance.		Therefor the consumption of the balance of plant and thermal losses are determined. Furthermore the effects of a changing operating point or deviant operating variables are identified with thermochemical software. An additional analysis of former experiments shows that a deviation of the air flow supply to the partial oxidation reformer has the greatest influence to the heat value of the synthesis gas. As a result of the work a first characteristic field will be developed from all detected operating points, in whose area the fuel cell system can be operated thermally stable.
Editor: Martin Sicker
Tutor: Dr.-Ing. Thomas Sander

Energymanagement with heat pumps

Currently, the increasing renewable energy use and the increasingly decentralized Feeding in the private customers’ area lead to fluctuations in the power production. In the electricity grid of the future load management and storage have to introduce to the generation and consumption. In order to stabilize the system in the future permanently, and also about the green power to utilize more effective, therefore got an idea that, to store excess electricity in order to retrieve it again, if the demand is greater than the power generation.		On this basis, the conversion of electrical energy into thermal energy by heat pumps and storage has a special meaning for load management. Subject of the thesis is to analyze the technical condition, possibilities of implementation, as well as the experiences derived from the energy management economic and ecological potential and to describe. The main contents include the analysis of the current and future potential of heat pumps for load management from an economic and environmental point of view.
Editor Yang Danquan
Tutor: Prof. Dr.-Ing. Clemens Felsmann, Dipl.-Ing. Andrea Meinzenbach

Heat Exchanger for Desalination Plants – Comparison of Constructions and Cleaning Methods

The research paper describes the need for fresh water due to the limited natural occurrence. The possibility of generation by desalination plants will be shown, as well as the consequences of a lack of drinking water supply. The first chapter deals with the purification of such a system. First, the effects and origins of soiling will be explained to the plate heat exchanger used in the desalination of seawater. Further the practical process of cleaning and its evaluation is described.		In the second chapter the development of the heat exchanger construction is compared with its predecessor version. The description amplifies the changes in the water and material flow management in terms of volume currents and flow rates. The last chapter describes the construction and test of the new heat exchanger. Furthermore it discusses the commissioning of a specially developed test rig and there is an evaluation of the new design.
Editor: Sebastian Gruber
Tutor: Dr.-Ing. Karin Rühling; Dr. B. Burandt, ILK Dresden

Development of an energy strategy for a group of residential buildings as a passive house

Against the background of the ever increasing energy demand of mankind, energy-saving building concepts gain in importance both energetically and economically. Especially the passive house standard has shown that high energy savings can be achieved without any loss of comfort and with economic success. The realization of larger buildings and residential apartment complexes however often requires special solutions and is therewith incorporated with a lot of planning effort. This work shows the state of technology within the area of passive house residential complexes.		The thermal hull and the supply technology are examined closely in connection with specific examples. On this foundation an innovative energy supply concept with the goal of a maximized utilization of solar energy for a planned residential complex is introduced. A critical energetic analysis of the single parts of the system is conducted to evaluate the primary energetic potential. It is also shown that solar energy can be utilized at a high percentage either directly or indirectly. Additionally efficiency enhancements are revealed due to mutual positive influences of the components.
Editor: Lukas Reimer
Tutor: Prof. Dr.-Ing. Clemens Felsmann; Dr.-Ing. Stefan Scheffler, IB Dr. Scheffler und Partner GmbH

Design of an Energy Efficient Cold and Heat Supply Plant for a Conference Centre based on Solar Thermal Energy

Especially in sunshiny and hot regions, the solar thermal supply of cold represents an effective and economic way to reduce the consumption of fossil energies. This paper illustrates the development of a solar thermal installation for a technology center in Ankara. By using parabolic trough collectors, the solar Irradiation provides thermal energy, which will be used to operate an absorption chiller.		During the winter, the installation will be used to support the building’s heating. After an introduction, illustrating some basic boundary conditions, the paper describes the basic components which are necessary for the operation. The key aspect is the detailed design of the collector field. Finally, an ecological and economical analysis confirms the benefits of the supply of cold and heat via concentrating solar power.
Editor: Andreas Meurer
Tutor: Dr.-Ing. Karin Rühling; Dipl.-Ing. Christian Gunkel, SOLITEM GmbH

Conceptual design of a CO2 heat pump with super critical operation mode and comparisons against conventional heat pumps

Carbon dioxoide as a natural refrigerant shows thermodynamic properties, which predetermines it for heatpump applications. While using it on transcritical parameters, high output flow temperatures can be reached in combination with a high coefficient of performance.		In this work a heatpump series was developed using piston compressors as fundamental. The choice of components and pipeline management are displayed. In Addition, these transcritical heatpumps are getting compared regarding to their economics and fields of application with conventional heatpumps.
Editor: Felix Werner
Tutor: Dipl.-Ing. Thomas Kretzschmar, Dipl.-Ing. Stephan Leideck, compact Kältetechnik GmbH

Simplified design of heat pumps in combination with photovoltaics

The improvement of a system design consisting of a heat pump, buffer storage combinated with photovoltaics will be the topic of this project work paper. The system uses solar electricity in order to supply the heat pump and can create new stimuli for using photovoltaics because of decreasing feed-in compensation. A calculation of the heating load, which is necessary in order to determine the dimension of the system’s parts, will be accomplished via simplified procedures. These, namely the method of employing an enveloping measurement surface and two comparative methods, will be applied at reference buildings to allow comparison.		Procedures will be tested for their practicability when data is missing especially, since existing buildings, which are under reconstruction, were chosen as the object of investigation. Advantages and disadvantages of the procedures will be displayed as well. Furthermore, the proposed measures of reconstruction will be taken into account. Lastly, the effect of the heating load on the program, which simulates the proposed system over an extended period of time and thereby scales the system’s components, will be examined.
Editor: Anika Steinbart
Tutor: Prof. Dr.-Ing. Clemens Felsmann; Frau Hischke, Belelectric Solarkraftwerke GmbH

Cost optimal heat supply integrating renewable energy sources

In this work, a program was developed that simulates the operation of a heating system for any building. The system consists of a heat pump, a heat reservoir, an optional secondary heat generator and a photovoltaic installation. To better manage costs as energy prices increase, these components should interact with an intelligent control. The motivation for this control is to improve the efficiency in the provision of useful energy (electricity, heat), while employing maximally cost-effective primary energy sources. Both are to be realized through the combination of photovoltaic generation and heat pumps.		To achieve this increased efficiency, the heat pump draws most of the required energy at times of optimal weather conditions and stores it in a special-purpose water-based heat reservoir. The cost minimization and stability is achieved with the photovoltaic installation. Once installed, it delivers electric energy mostly when demand from the heat pump is greatest, namely during the day under high irradiation and milder temperatures. Lastly, the cost-optimal combination shall be determined by varying the system components in terms of their rated power or storage capacity.
Editor: Martin Arndt
Tutor: Prof. Dr.-Ing. Clemens Felsmann; Dipl.-Ing. L. Fallant, BELETRIC Solarkraftwerke GmbH, Zweigst. DD

Investigation of the building structure in the city of Jena and prediction of the heating demand with a numerical building and system simulation

Due to the expiring contract between E.ON Thüringer Energie AG for district heating supply of the municipal utility company of Jena GmbH Pössneck, different scenarios which guarantee the future heat supply for the city shall be analyzed. The needed building heat demand for Jena have to be closely investigated. The objective of this work is to determine the heat demand for various building ages and size classes of residential buildings in order to represent the majority of the housing stock of Jena. Characteristic reference buildings for the city are therefore being determined and typical for the epoch wall constructions for those buildings are being calculated on the basis of an extensive research.		By a numerical building and system simulation with TRYNSYS-TUD the annual heat demand for various building ages of the reference buildings is being determined. The simulated heat demand is compared with current studies for the heat consumption of Jena and building typologies to estimate whether the selected wall structures are representative. In addition, a heat distribution system of one reference building is implemented in order to investigate the feedback between the building supply and the existing supply system technology of the building as well as the derivation of possible connections and boundary conditions.
Editor: David Scherzer
Tutor: Dr.-Ing. habil. Joachim Seifert, Dipl.-Ing. Lars Schinke, Dipl.-Ing. Paul Seidel

Regional Virtual Power Plant – operating concepts for networking of CHP-systems in buildings

The energy policy of the federal government plans the restructuring of the energy supply until 2050. In order to reduce primary energy consumption and greenhouse gas emissions in Germany, extensions of highly efficient and renewable energy production systems would be required. Decentralised combined heat and power (CHP) clearly supports defined political objectives by combining production of electricity and heat. Micro-CHP technology for buildings has been available on the market for for a few years. This technology is designed to cover the total heating requirements of a single-family house and can generate up to P = 15 kW electrical power.		This paper will analyse the potential of Micro-CHP units in buidlings. The aim is to formulate operating concepts for virtual networking of numerous generation systems. For this purpose a dialogue was conducted with 24 regional electricity network operators and energy providers to investigate conflict potential of low decentralized electricity input in the low- and medium-voltage grid. This analysis facilitates the exchange of know-how between public utilities and the research sector and serves the model preparation of a Regional Virtual Power Plant based on mini and micro CHP-technology.
Editor: Philipp Oehmgen
Tutor: Dr.-Ing. habil. Joachim Seifert, Dipl.-Ing. Andrea Meinzenbach, Dipl.-Ing. M. Preißner (VNG AG)

Thermal comfort under investigation of flexible energy supply

In the future the rising of the decentralization of energy production (cogeneration, ...) and the integration of feature-dependent renewable energy sources (wind power, solar power, ...) will place new demands on the energy supply structure. The load management in the building sector may minimize arising deficits between power generation and energy consumption. It will offer an incentive for load transfer taking into account the passing of volatile energy prices on the end costumer. This paper focuses on a price-based, electro-thermal load management by utilization of a building as storage medium and the compliance with established criteria of thermal comfort. On the basis of a literature research permissible boundary conditions of thermal comfort were identified and used for further considerations.		Models of selected configuration of the building which are typical for the era (standard of insulation, masses of building materials, ...) can be examined with the building simulation program TRNSYS-TUD. Different usage profiles were implemented into the software and with the results of the thermal comfort chapter simulated for the heating mode. Following the results of the needed heating demand for an ideal heating system were linked by the mode of the heating system to the energy prices. Finally, the paper ends up with an assessment of the so far unused saving potential of a strong intermittent mode of the heating system and also outlines further key issues.
Editor: Christine Knaus
Tutor: Dipl.-Ing. Alexander Buchheim, Dipl.-Ing. Juliane Schmidt, Dipl.-Ing. Claudia Kandzia

2013
Heat storage in the energy sector

The focus of this student work is on the subject "heat storage in the energy sector" and considered different aspects. The capitals lead the reader in a logic order from the necessary of heat storage over the fundamental functionality and available storage concepts to the analysis and rating of itself which is based on particular strengths, weaknesses and actual application in practice. The main aim was not the selection of a certain storage concept but a clear and		informative view of available heat storage technology and the investigation about a possible usage of certain storages in a heat powerhouse. The notion of thermodynamics regularities and relevant parameters of heat storage permit a widespread insight. An additional aspect is a list of commercial producer and provider of heat storage which contains as much as possible information about the product. In this way the reader is able to inform about a certain heat storage and can parallel look for a suitable producer.
Editor: Patrick Arrue
Tutorr: Prof. Dr.-Ing. Clemens Felsmann; S. Schneider, Vattenfall Europe PowerConsult GmbH

Thermodynamic Analysis of a small sized MED-Prototype plant under in-situ conditions

The assignment starts initially with an insight of seawater desalination and technical terms are clarified. The measurement data are analysed according to the description of the field test plant. The special consideration is paid to the heat exchangers. It deals less with the distillation yield or the electric energy consumption which is necessary for operation.		The main part includes the irregularities during operation time. This will be illustrated and discussed. Sticking to that point the calculation of the thermal transmittance coefficients is the most important part. For the support of further developments the thermodynamic consideration is necessary to identify and resolve problems.
Editor: Nico Wessely
Tutor: Dr.-Ing. Karin Rühling; Dr.-Ing. Bodo Burandt, ILK Dresden GmbH

Evaluation of the Energy Economic Conditions and the Legal Framework of Electric Energy Storage in Germany

This diploma thesis was done within the context of the German energy transition, which restructures the whole electricity supply chain. Integration of large intermittent renewable energies in local and central positions, reduction of CO2 emission and nuclear phase-out are pressing the development of new grid infrastructure. Energy storage technologies are usually new technologies except for pumped storage hydropower plants. They need further research and development but most importantly more pilot-projects to improve and test performance in real environments. First commercial products are coming into the market, especially flywheels, batteries and power to gas solutions. An overview of the status and characteristics of energy storage solutions is given in this report. The transformation of the electricity supply system creates a new North-South gap between generation and consumption loads. In the North, there will be an overcapacity of wind generation with 28 GW onshore and until 40 GW offshore installed in the near future (2013: 3 GW). Furthermore the balance between construction and depletion of conventional power plants (nuclear power plants included) is positive in the North with a creation of 6,4 GW by 2018 and negative in the South with a reduction of 5,4 GW by 2018. In the South, wind is less dominant than in the North, but still has an oversupply of photovoltaic with 14 GW installed. In addition, the South concentrates two large centers of industrial consumption in Bavaria and Baden Württemberg. New transmission network is imperative but its development is often delayed. Moreover, grid system operators experience increasing congestion cases.		Ancillary services provide security services and could be adapted for the integration of new flexibility options. The development of energy storage could then be considered in the framework of flexibility supply. Regulatory framework and revenue streams for storage are still not clearly defined. Some technologies are exempted from taxes contributions but there is no specific strategy to incentivize storage or other flexibility options. However, ancillary services could be an option for developing storage business cases in the current electricity market. For example, a 1MW/500kWh Li-Ion battery can respect the prequalification requirements under certain hypothesis and participate on the primary reserve. This already appears a lucrative possibility. Stationary storage is hampered by the current mistrust of investors regarding revenue streams, which actually are already there. Therefore, to incentivize the development of the storage sector and to create trust in investment, we propose four possibilities: Pilot projects with private investors should be incentivized Regulatory framework of storage should be clarified and storage should not be considered as an end-user Existing ancillary services should be rapidly adapted to allow the participation of other flexibility options by reducing the prequalification requirements and opening other tendering procedures to ancillary services such as supplying reactive power Market should to reward flexibility: monetizing asset dynamics could be a response to increase of intermittent renewable generation.
Editor: Yann Briand
Tutor: Dr.-Ing. Thomas Sander; PhD. Michael Salomon, Clean Horizon, Paris

Transient temperature field sensing in a hot water heat storage tank using a distributed temperature measurement system

The topic of this report is the Transient temperature field sensing in a hot water storage tank using a distributed temperature measurement system". Therefore experiments at a testing device at the Dresden University of Technology, chair of Energy Technology in Building and Heat Supply, had been carried out. Distributed Temperature Sensing (DTS) is a new measurement system which uses a fiber optic sensor to capture three-dimensional temperature fields. For this work the system has been used for the first time to measure the spatial temperature distribution of a hot water storage vessel located at the Centre of Energy Technology (ZET - Zentrum für Energietechnik) at the Dresden University of Technology. Therefore the heat storage vessel had been equipped with radial jets for the charging and discharging of the vessel. In this report the conception and the installation of the measurement system is depicted.		Experiments with varying parameters have been carried out. The three dimensional post-processing of the measurement data with the software ParaView is used to visualize the evolution of the thermal stratification and to capture transient phenomena as well. The analysis is of the experimental data was made especially with respect to the rotational symmetry of the current exiting the jet and the developing temperature profiles. Furthermore for some charging and discharging parameters an influence of the composition of t he measurement system on the current is proven. The gained experience can be useful for the investigation of a big heat storage vessel containing a volume of several tens of thousands cubic meters. ln addition the measurement data obtained within this report may serve as a first approach for the generation of a data basis to validate CFD simulations.
Editor: Luise Umbreit
Tutor: Dipl.-Ing. Andreas Herwig

Economical Evaluation of Solar Energy Usage in Buildings

In this thesis the technologies photovoltaic and solar thermal energy for the use of solar energy in buildings are compared from an economic and social point of view. For this purpose, two different systems for the energy supply of buildings are designed. The first system is designed for the use of solar thermal collectors and works in collaboration with a gas condensing boiler and underfloor heating. The second system, which is designed for the use of photovoltaic, uses electric underfloor heating in conjunction with a heat pump for hot water supply. For reasons of better comparison both systems are analyzed with each of the technologies as well as without the use of renewable energies. Energy consumption and generation are compared with each other so that the cost of energy supply can be calculated. Along with the investment cost which is reduced by government grants the total annual cost for the energy supply of residential and office buildings with different standards such as passive house and EnEV 09 house is calculated with the annuity method and compared.		The calculations show that a system using photovoltaic and a gas boiler results in the lowest total cost, which is mainly explained by the price difference between electricity and gas and the limited ability to store solar thermal heat. The subsequent analysis of greenhouse gas emissions and air pollutants from a social perspective, states that all analyzed renewable technologies result in less emissions. Photovoltaic systems exhibit the lowest emission values, which is caused by both the system boundaries as well as the lack of a possibility to feed in redundant heat in a public network. In contrary, a study of the degree of autarchy of the systems leads to the conclusion that solar thermal systems generally have a higher degree of self-sufficiency. The final consideration of the efficiencies of the subsidy programs shows that on average less public money has to be spent for a unit of generated energy by solar thermal technology than energy from photovoltaic systems. Finally underlying assumptions for the calculations are reviewed and the effect of deviations of these values are analyzed which confirms the relevance of the results of this thesis.
Editor: Daniel Peschel
Tutor: Dipl.-Ing. Felix Panitz, Dr.rer.nat. Christoph Schünemann, Dr.-Ing. Karin Rühling, Dipl.-Kfm. André Gräning TU Dresden, Fak. Wirtschaftswissenschaften, Professur für Wirtschaftsinformatik

Metrological analysis of a tempered wall element to be applied in a test rig for investigation of control strategies for HVAC systems

This thesis deals with the hydraulic and thermodynamic analysis of a temperature-controlled surface element. Such elements will be used in a prospective test rig to set an uniform surface temperature. Three capillary tubes, which can be heated or cooled independently, are integrated in the surface element.		As part of the thesis, an experimental set-up has to be constructed and equipped with the necessary sensor technology. In serveral experiments at laboratory conditions various parameters are analysed and evaluated to characterize the surface element. This thesis concludes with an outlook on future studies.
Editor: Maximilian Beyer
Tutor: Dipl.-Ing. Lars Schinke, Dipl.-Ing. Alexander Buchheim, Dipl.-Ing. E. Demisch - Fa. ILKAZELL
Estimation, modeling and optimization of a supermarket estate’s heating and cooling supply systems
Food markets are one of the most energy intensive types of commercial buildings. In consequence of rising energy prices together with ecopolitical climate protection goals the importance of energy efficiency is increasing. This paper has been written as in the context of an internship at kke GmbH. Analysed was an already existing supermarket. In first sequence the heat supply of the supermarket is covered by the heat recovery of the refrigeration system, in second sequence by the VRF-System which functions as an air source heat pump. The supply system has been analysed, estimated and modulated with MS Excel VBA based on the accessible measured data. Using the measured data as boundary conditions the system could be calculated based on these models for a defined timeframe.		In the second part of this paper an optimised modification of the system has been elaborated. The key point is floating condensing pressure. The waste heat of the refrigeration system is now used as a heat source of the VRF-System. Both systems – the refrigeration and the VRF-System – are now connected by a heat exchanger. The modified system has been calculated by using the created calculation model. The results show that the electricity consumption of the refrigeration system could be lowered by 15 %, while the electricity consumption of the VRF-System increases by 26 %. The total electricity consumption of both systems in total is lowered by 12 %.
Editor: Patrick Eggers
Tutor: Dipl.-Ing. Thomas Kretzschmar, Thomas Nickel, kke GmbH

Economic analysis and design of a PV-based PtG

With the ongoing development of renewable energies a power overspill is expected to result from natural changes in weather. For an adequate integration of those energies, efficient storages will be required. To make that energy storable and transportable on the long term, the hereby researched power-to-gas-process (PtG) appears to be one of the forward-looking models. It uses power from a regenerative source to split up water into hydrogen and oxygen by electrolysis. The hydrogen can be used as a long-term storage for energy and can then either be sold as a product of its own or be converted to methane as a direct supply for the gas distribution system. For the process of producing hydrogen, the three conventional types of water-electrolysis will be discussed in this paper.		Due to its highly dynamic operation, the proton-exchange-membrane-electrolysis (PEMEL) is considered as the most appropriate for the use within the investigated, PV-energy-driven PtG-construction. In consideration of the specific characteristics of hydrogen, arrangements for safety engineering refer mainly to explosion prevention. In terms of economic aspects the gas- and automotive industry as well as supplier of electric energy are the main interested parties for a commercial use of hydrogen out of the PtG-technology. Another important field is the operating reserve for electricity networks, which can be served by PtG. Yet, a promising realization of the PtG-concept has only been proven within subsidized test systems.
Editor: Philomena Apitzsch
Tutor: Dr.-Ing. Karin Rühling, M.Sc. Michael Zipf, Dr. rer. nat. Dirk Caspary, MR SunStrom GmbH

Practice of Predictive control in buildings

Today, it is possible to use weather forecast in control strategies of HVAC-systems. This paper gives an overview about the current usage of this strategy and examines the possible effect of incorrect weather forecasts on the system. In order to judge on the influence of incorrect weather forecasts, common models of weather prediction are introduced and the development of a prognosis is explained. The next part summarises the market activities of companies who offer control systems based on weather forecasts. In the following, scientific demonstration objects as well as concrete savings of different systems used in real existing objects are presented.		In the last part of this paper, the flow temperature control algorithms by Sauter are analysed in detail. The simulation tool TRNSYS-TUD is used to demonstrate the differences between the usage of a real and a perfect weather forecast. Furthermore, the meteorological data are systematically manipulated within an offset. To show the direct influence of different forecastfactors (e.g. temperature, radiation, etc.) on the room temperature or the flow temperature, the simulation is repeated with those manipulated factors.
Editor: Niels Rauland
Tutor: Prof. Dr.-Ing. Clemens Felsmann; Andreas Eisele, Sauter-Cumulus GmbH, NL Dresden; Dr. Andreas Wetzel, Sauter-Cumulus GmbH, Zentrale

Concept development and implementation of automation of a heat-pump-compressors test stand

The goal of the present work is to develop and implement an automation concept capable of executing automated measurements on refrigerant compressors according to generally accepted engineering standards. The automation concept is based on an existing test rig, designed as a refrigerant circuit, which was already used for measurements on refrigerant compressors in manual operation mode. Hence, the thermodynamic principles and the principles of feedback control systems related to refrigerant circles have been worked out first followed by an investigation according to the test standards subsequently as the concept of the regulation has been developed and implemented in the graphical programming language Labview.		For the regulation concept it was necessery to configure control units capable of setting the necessery conditions for compressor measurements. The automation concept includes the initialisation of the test rig, the batch processing of measurement points, and the automated analysis of the recorded data according to the operating figures of compressors. A key point of the concept was the monitoring of the sensible points during the test operation. Furthermore the test bench software includes a possibility to execute measurements in a manual operation mode. Through a series of final tests an evaluation of the implementation shall be possible and afford possibilities to improve the qualitiy of the test bench automation.
Editor: Tobias Müller
Tutor: Dr.-Ing. habil. Joachim Seifert

Energetically assessment with EnerCalC

The Gerhard-Crafe gymnasium is a club and school sports hall of the sports community Weixdorf Registered Charity. This building is located in Weixdorf, a town and a statistical district of Dresden. It’s the first gymnasium which is built according to the standard of passive house and at the same time regarded as the most modern building in Free State of Saxony. The passive house "AmPulverturm" is a passive house concept, which was designed by me and two classmates: Andreas Matloch, Gerit Hüte, from the module BIW4-72 Sustainable Building.		This project work is on one hand in line with the research of optimization of building and facility operation on weixdorf gymnasium. The object is a total balance of energy with the help of the calculating tool EnerCalC which is based on EXCEL. The calculating program allows a simplified balance of energy of the building as per the DIN V 18599. On the other hand the calculating programs EnerCalC and ZUB are compared with other through the example-based application on the passive house „Am Pulverturm“ in oder to evaluate the practicability of the calculating methods.
Editor: Ou Xiang
Tutor: Dipl.-Ing. Juliane Schmidt

Comparative analysis of hydraulic and auxiliary energy consumption in energy supply systems for buildings using free environmental energy

The usage of heating- and cooling systems for HVAC purposes that are using environmental energy, have the advantage of a reduced primary energy consumption compared to conventional systems. An essential requirement to achieve a technical advantage of environmentally used systems is the efficient distribution of the thermal energy in buildings. In this thesis the energy supply systems of ten non-residential buildings were analyzed for their weaknesses and strength. At first the typical hydraulic characteristics of thermal distribution systems were classified and based on this classification, the systems were assigned to this classification. Steady state pressure drop calculations were carried out and analyzed in order to locate deficits in the hydraulic systems.		The results imply a potential saving rate of the auxiliary power of more than 70 %. In the second part of the thesis Measurements are used to investigate the hydraulic and thermal control strategies currently used and their impact on the thermal distribution system seasonal performance factor and the specific hydraulic power consumption. Finally, a dynamic model of the thermal load circuit is developed using the software Dymola. Based on the model recommended, improvements of the system design are investigated under non-steady-state conditions. After implementation of the improvements the efficiency of the system increased fivefold.
Editor: Christoph Kaatz
Tutor: Dr.-Ing. Ralf Gritzki, Dipl.-Ing. Paul Seidel

Efficient Design of the Power and Heat Supply of Company Buildings

In the thesis the energy supply of the 20 years old company building of the GOEDE group in the Bavarian Waldaschaff will be examine and introduce Possibilities for improving the energy supply. First, the structural physical thermal energy demand of the building is determined and evaluated according to the monthly balance method of DIN V 4108-6 by using a simplified model of the thermal envelope. In addition, the losses of the current technical building equipment will be determined according to the detailed procedure of DIN 4701-10 and analyzed. The data thus obtained are used for the development of measures to reduce the building-side energy loss and it will be make statements about the cost of a renovation of the building envelope.		Another important part of this work is the development of strategies for the reduction of heating costs. First the yearly system-side natural gas and building-side electrostatic energy demand is collected and processed. In addition, suggestions are made for alternative heating systems. The cost of multiple combined heat and power in different sizes of performance and the cost of a condensing boiler heating system are checked and it will be shown funding opportunities for CHPs. To determine the required heating power, the design heat load is calculated according to DIN EN 12831. Similarly, the impact of a planned photovoltaic system is determined on the use of a combined heat and power unit. Due to the plant ages the cleansing and purification of the heating system are presented.
Editor: Steffen Rex
Tutor: Dr.-Ing. Thomas Sander, Dipl.-Ing.(FH) Eberhard Zentgraf GÖDE, TEC-Institut Waldaschaff

Development of a technical solution to meet the indoor air quality requirements of microscopy-rooms

One of the Clusters of Excellence of the University of Technology Dresden while the German government's Excellence Initiative is the Center for Advancing Electronics Dresden (cfAED). The Cluster shall be integrated at Barkhausen- Bau on Campus of the University. Regarding the building services technology the building doesn't reply with the current state of the art and shall be updated. One of the major elements of the arising centre of the Cluster of Excellence is a microscopy, which will be an important location of research even beyond internal cluster research.		The requirements to indoor climate of this part of the building are very high. Namely the required temperature stability of 0,1K/ h presents a special challenge to building service technology. Part of this work is to describe basics of ventilation and air- conditioning technology and to identify user requirements of the microscopy, which subsequently are used to develop a concept to implement the requirements on indoor climate. Finally the resulting concept is summarised and evaluated. The following perspective gives suggestions for the further course of engineering of the building's service technology.
Editor: Ramona Nosbers
Tutor: Prof. Dr.-Ing. Clemens Felsmann, Herr A. König, KLEMM Ingenieure GmbH & Co. KG

Economic and ecologic perspectives of district heating based on biogas plants in rural areas

Small district heating networks play a leading role in the transformation of the energy supply to renewable energies. They open the chance for an economic and ecologic sustainable heat supply. In this diploma thesis it is analyzed in how far small district heating networks based on biogas plants in rural areas are complied with these criteria currently and how the conditions might look therefore in the future. For this purpose existing small district heating networks will be proved and compared, based on a data collection through chosen indicators.		The thesis shows that operating heating networks ecologically und economically is possible right now. After highlighting that, the data will be evaluated and put into the context of future development scenarios. It will be recognizable that energy saving and population decrease can threaten the economic efficiency of this projects. Based on this, strategies will be developed which ensure the economic efficiency in the long-term.
Editor: Christoph Runst
Tutor: Prof. Dr.-Ing. Clemens Felsmann, Dr. T. Schmidt-Baum (DBFZ)

Evaluation of the energy performance of a ventilation system

This paper aims to select a favorable combination of fans and a heat recovery unit for a ventilation system under energetic and economic aspects. The system shall replace an existing but out-dated version. The state of art was researched and presented, components of highest energy efficiency pointed out. In order to find a combination of these components that performs at a possibly low consumption of energy, a preselection was made using suitable parameters.		The preferred devices were evaluated energetically using the method of ventilation degree hours with consideration to the user's behavior. By converting the values of different forms of energy into accumulated energy expenditure (Ger. abbrv. KEA), the device constellation which allows the highest potential for energy saving became visible. Eventually an economic evaluation was undertaken, using the Net present value method. Rising energy prices were taken into account. Thus a relation between energetic and financial efficiency is apparent.
Editor: Martin Schorcht
Tutor: Prof. Dr.-Ing. Clemens Felsmann

Optimal operation mode of an urban combined heat and power supply system with a major heat accumulator, a solar thermal system and heat pumps

The present thesis „optimal operation made of an urban combined heat and power supply system with a major heat accumulator, a solar thermal system and heat pumps” describes the performance of a resource planning process for a power plant complex. The exemplary power plant complex consists of a cogeneration plant and a daily storage. It produces heat as well as electricity. During off-peak times of district heating, economic-technical parameters arise, which question the marketability of the CHP plant. Therefore, the power plant complex should be extended by a large heat storage, a solar thermal system and a thermal heat pump. The aim is the adjustment of the plant to the progression of the electricity price and the increase of the total proceeds.		That signifies that the heating power plant can operated with a low performance during weekends due to low electricity prices and the supplied heat by the large heat storage. The optimal operation mode is based on the optimization of the total proceeds. With the help of the optimization program FWOptD the resource planning was implemented for different scenarios. That leads to a series of results, involving varied parameters. Over the course of application planning a validity check as well as the documentation of the analysis was transacted. The analysis of the results of the resource planning showed certain regularities, for instance a better fuel efficiency and a better adaption to the progression of the electricity price. Hence the profitability of the power plant process can eventually be increased.
Editor: Florian Kuhla
Tutor: Dr.-Ing. Sebastian Groß

Development, implementation and testing of a set and control concept for a modular climate chamber

To target the issue of the assessment of thermal comfort under transient conditions a climate chamber is currently in development at the Technical University of Dresden. The adjustment of the surface temperature of the walls is a characteristic feature of the test facility. Cold and hot water is locally mixed to temper the surface of the wall. The main aspect of the work is the development of the measurement and control concept.		The researched hardware concept is able to realize the measurement and control of the wall surface temperatures. Based on a thermodynamical model of the wall, the system is simulated in order to predetermine control accuracy and configuration of the controller. The simulation is also used to test the programmed control device in the loop. The adjustment of the supply flow temperature is discussed. The found solutions are rated by their suitability.
Editor: Toni Rosemann
Tutor: Prof. Dr.-Ing. Clemens Felsmann, Dipl.-Ing. Jens Haupt

Ecological Valuation of Buildings in the Context of Sustainability and Life-Cycle Analysis

In the life cycle of a building comes the time, when the building can not longer be used and has to be demolish. The consequences for an abandonment with predefined criteria - material recycling and emission - have been investigated and illustrated with examples, in cooperation with the Institut of		Building Energy Systems and Heat Supply of the Technical University of Dresden and the Gundlach Group from Hanover. The results provided information about changes in construction for a new building and its operation, if already in the planning stage will ensure an ecological abondonment.
Editor: Andreas Matloch
Tutor: Prof. Dr.-Ing. Clemens Felsmann, Dr.-Ing. Thomas Sander, Herr Gerbens, Fa. Gundlach, Hannover

Experimental Study on the characteristics of a heater for domestic hot water using the storage charging principle

The present work investigates a heater for domestic hot water using the storage charging principle. For the first time distributed temperature sensing based on the Raman effect is employed in the ZET. A custom construction is used to monitor the temperature layers of the water during various operating states of the heater.		Using this measuring approach, it is possible to analyze and evaluate the heater. Based on these experiments we could discern appropriate parameters to operate the heater and we were able to calculate its expected service capability. For this purpose we performed multiple experiments. The investigated operating states are loading and tapping, each with active and inactive circulation.
Editor: Sabrina Uhlig
Tutor: Dr.-Ing. Karin Rühling, Dipl.-Ing. Felix Panitz, Dipl.-Ing. Jan Löser

Experimental investigations of the pressure drop of a mixture of water-ice

In ILK Dresden is testing a new system for the production of ice suspensions (Vacuum-Ice). There are two special feature of this system. The first is that, water in this cold production process the same time as the refrigerant and solution. And second, ice crystals are not formed by heat transfer in a heat exchanger, but arise in the direct evaporation of water in a very low pressure (near vacuum). This process is called Vacuum-Ice Process. After generating the ice suspensions will be able to pump to the consumers.		After generating the ice suspensions will be able to pump to the consumers. But in this transport process have some pressure loss. Therefore, we have to understand the relevant knowledge about how to reduce the pressure drop. The flow properties of ice slurries are dependent on the ice content, the flow speed and the pipe diameter. In this project, we will measure the pressure drop at different ice content, flow velocity and pipe diameter. Purpose is to understand the flow properties of Vacuum-Ice.
Editor: Yang Danquan
Tutor: Dipl.-Ing. Lars Schinke, Dipl.-Ing. Marcus Honke (ILK Dresden)

Solubility analysis of solar liquids

To evaluate the cycle of solar constructions and to construct the components, the data on chemical media are necessary. Therefore experimental equipment is given, where experiments for liquid solubility were done. In solar systems absorption and desorption processes are important as well. The speed of these processes is described by the diffusion coefficient. This coefficient should be defined with the help of the given experimental equipment. An analysis of the existing experiments for diffusion coefficients was done to give an overview.		The theoretically base was fleshed out and specialized for the experiment. A routine for the experiments was prepared and used for all trails. The equipment was calibrated, which allows to correct the following measuring results. The experiments were done for different solar liquids. Out of this, the diffusion coefficient could be defined for the researched liquids. Following the results were summarized and assessed. A forecast for future experiments and developments of the equipment finishes the work.
Editor: Sebastian Unger
Tutor: Dr.-Ing. Karin Rühling, Dipl.-Ing. Felix Panitz

Commissioning and thermal performance analysis of a new latent-heat storage unit

The growing use of renewable energies, paralleled by increasing energy efficiency and the reduction in dependency on energy imports, results in potential applications for thermal storage systems. The present work deals with the characterisation of an innovative latent heat storage system. The eutectic mixture of potassium/sodium nitrate is utilised as storage material. For charging and discharging the storage, an existing oil circuit is used. Based on temperature measurements of the storage material and in the oil circuit, the thermal performance of the storage is examined at two different flow rates and three temperature ranges. The tests conducted show that the discharging process takes much longer than the charging procedure due to a layer formation during solidification.		By inserting a thermally conductive heat transfer structure into the salt, the heat transfer is to be further improved. Further, the software ANSYS Workbench is used in order to create a simplified simulation model of storage that allows the simulation of the melting and solidification processes. The model is validated by means of the measurement data. Based on the validated model, various heat transfer structures are simulated and one structure is selected for testing. The structure of choice is a zigzag sheet, which is constructed and installed in the storage. For the thermal characterisation, the experimental conditions remain the same as in earlier experiments.
Editor: Torsten Klemm
Tutor: Prof. Dr.-Ing. Clemens Felsmann, Dipl.-Ing. Andreas Herwig

Numerical studies of the fluid flow pressure loss and heat transfer in case of regenerators within gas cyclic processes

In the context of the investigation of Stirling engines at the TU Dresden further information was required on how the ﬂow conditions in regenerators are. Generally speaking, the regenerator’s main purpose is to supply a temperature difference between the compression and expansion space in closed regenerative cycles with gaseous working ﬂuids. In this study, several CFD models have been developed for woven wire screen meshes.		The aim was to ﬁnd a suitable description of regenerators by making realistic assumptions related to the geometry and the physical conditions. At ﬁrst, the models have been analysed with constant inlet ﬂows. Later on, oscillating ﬂows were implemented as well. In order to validate the models, their values for pressure drop and heat transfer were compared to empirical studies of other authors.
Editor: Markus Blank
Tutor: Dipl.-Ing. (FH) Torben Möller

Design related and fluid dynamic aspects of solar thermal collectors made of ETFE-foils

In the context of the increasing use of transparent building materials in modern architecture, the application of pneumatically stabilised Etylene Tetrafluoroethylene (ETFE)-foil cushions is more and more common. Whilst these satisfy the need for transparent roof and façade constructions, their high transmittance leads to an increased heating of the building’s interior and therefore to a higher demand for air-conditioning. In the pursuit of developing an effective shading system, the application of fluid flowing through the cushion middle layer is explored. Furthermore the potential for the possible utilisation of the thermal energy absorbed in the fluid is being aimed for. Simplified models of these collectors have been designed and manufactured by welding together two ETFE foil layers. Possibilities to expand the generated capillary structures have been tested and evaluated. Applying radiation energy to the models, the loss of pressure across the structure during flow-through tests as well as the warming of a		coloured and a transparent solar absorber fluid have been determined for different parameters. This was accomplished with a specially designed array of measuring and logging devices. In several iterations, the design of the solar collectors has been evolved by applying their geometries and connection alternatives. It was possible to create structures which could be expanded when passed through by a flow-through of a hot fluid which showed a loss of pressure of only a few milibar. The energetic potential that has been identified in thermo-hydraulic tests is very small in comparison to standard solar collectors but is already clearly recognisable. The established temperature increase of more than 5 Kelvin can be further increased by enlarging the collector area, enhancing the absorbing properties of the solar fluid as well as reducing the heat loss of the collector by the ETFE-foil cushion that would encase the collector in practice.
Editor: Sebastian Dietrich
Tutor: Dr.-Ing. Karin Rühling

Numerical study of the air flows and temperature stratifications within the atrium/PIK-research new building Potsdam

In context of energetic evaluation and optimization of the research new building of the Potsdam Institute for Climate Impact Research this study provides an analysis of the ambient air conditions in the atrium and its adjacent corridors.		Using numerical models, the effects of environmental conditions and HVAC characteristics on the air flows and temperature distribution were analysed. Likewise a part of this work is to study the thermal comfort conditions for estimating the risk of overheating in summer.
Editor: Erik Siebert
Tutor: Dipl.-Ing. (FH) Torben Möller

Development of an energetically concept "Campus Bildungszentrum Handwerk"

The development and documentation of an energetically concept for the new build of the Handwerkskammer Dresden was the task of the following research paper. The development of the concept based on the criteria given by the building contractor, regarding the needs of primary energy, profitability and innovation of the facility engineering. At first a short introduction to the construction plans of the new built is given. The construction plans were designed by the archtitect`s office translocal Architecture. Based on the defined demands on the providing of warmth, cold and ventilation, the basic conditions are presented. In addition the local geological and meteorological conditions are presented and estimated.		Hereafter the needs for warmth, cold and ventilation are worked out of the preliminary considerations. In the following literature research various technologies for generation and storage of different kinds of energy are presented. On the basis of the preliminary considerations the working out of the energetic concept takes place. After a critical look at profitability and applicability of the technologies, which were presented in the literature research, the selection of devices takes place. The energetic concept includes the supplying of warmth, cold and ventilation, followed by a short assessment of the power supplying, the level of automation and the costs of the building energy systems. Finally a summarising assessment and prospect on the energetically concept is given.
Editor: Christian Schwind
Tutor: Dr.-Ing. habil. Joachim Seifert, Dipl.-Ing. Paul Seidel

Design and validation by measurement of a heat pump test facility

The aim of the project is to analyze the performance characteristics of a test facility for measurement and efficiency validation of air-water-heat pumps. Therefore the test facility is investigated in its former structure, flaws are worked out and afterwards it will also be expanded. This means the design and construction of a hydraulic module to deliver specified parameters on the heating side of the heat pump. For this part a broad hydraulic dimensioning, calibration of sensor systems and integration in the facility has to be performed.		Furthermore the air-side connection of the device under test with all sensors and components is being investigated in detail. In the next step the whole system is being tested for its applicability for efficiency measurement of heat pumps under testing conditions specified in the DIN EN 14825. This also includes a metrological analysis of the actuator characteristics, efficiency test and analysis of error. Eventually a critical assessment of the present situation of the test facility concerning the normative specifications will give an overview of what is possible in this state and a perspective on future projects with relevant ideas of improvement.
Editor: Christian Scheer
Tutor: Dipl.-Ing. Stefan Hoppe

Fault Detection and Diagnosis at cooling systems

With regard to the expansion of renewable energies and the planned exit of nuclear power generation emerging a trend of German energy policy to draw back from energy efficiency. The quest for an environmentally conscious image of a hand, and rising energy costs on the other hand, slowly raise with the operators, but determined the needs, process engineering systems including refrigeration construed energy efficient. Therefore, the optimized management in the future is necessary. Aim of this study is the potential for energy savings in existing commercial refrigeration		equipment lying to the supermarket and in Germany activate because the cooling systems of power consumers are important in the food trade. On based of a study shows, that only in existing installations, a savings of 859 GWh per year, 10% of the total needs of supermarket refrigeration systems exists. A significant part of the energy demand can often be saved by simple measures. One of the necessary measures for an operational market monitoring to optimize operations is error early to recognize (FFE) and diagnose.
Editor: Xiaojing Wang
Tutor: Prof. Dr.-Ing. Clemens Felsmann, Dipl.-Ing. Elisabeth Eckstädt

Experimental investigation of a hybrid device from Absorption heat pump and condensing gas boiler

Saving energy for existing buildings will play a major role in the future of climate- and energy policy. Beside insulation, modern heating techniques will offer huge possible savings of energy. Therefore, a newly designed hybrid device consisting of an absorption heat pump and a condensing gas boiler is under development at the corporation, where the internship to this project thesis was done. In this work, several prototypes of this hybrid device were analyzed and improved. After discussing the absorption process theoretically, several measurements were performed. The currently used calculation method to determine the hybrid efficiency of		absorption heat pumps without peak load was improved. In a comparison, the effect of two different peak load boilers on the heat pump was investigated. The influence of the temperature on the absorption process and the overall heating power of the absorption heat pump were analyzed, by varying the volume flow rate at constant flow temperature and thermal output. The influence of the improvement of several machine components on the overall performance of the machine was shown in a comparison of two hybrid devices of different levels of development. Furthermore, different control methods on the hybrid machine were optimized.
Editor: Martin Henkner
Tutor: Prof. Dr.-Ing. Clemens Felsmann, Dr.-Ing. Martin Knorr

Basic analysis of a campus energy concept

The heat supply system for the campus of Burg Giebichenstein University of Art and Design has to be renewed due to the high energy costs and the current energy policy. The goal is to save costs and use renewable energy. In this project, a possible methodology is shown how to solve the task of heat supply for a campus with a local heating network and renewable energy. First, the existing supply systems are analyzed and the consumption data are evaluated. Based on the evaluation results, the local heating network is developed.		Specific tasks involved are for example the study of supply tasks, the dimensioning of pipelines and generating units, and a rough estimate of the investment costs. Then, the new heat supply system has to be environmentally and economically investigated. The studies show firstly a clear reduction of CO2 emission. The economic calculation shows that the local heating network would pay off, despite its high investment costs. The promotion policy for renewable energy has made green technology even more attractive.
Editor: Xunzhang Yuan
Tutor: Prof. Dr.-Ing. Clemens Felsmann

Prediction of the effects due to changed absorber materials for a solar thermal flat plate collector

Because the performance of the solar thermal flat plate collector at the market lie close together, it will attempted to generate a benefit at the market with some products through the encouragement of alternative materials. This should happen though the lowering of the price and the weight of the collector. In this project select effects of the changed absorber materials for a solar thermal flat plate collector will predicted. That happens on the example of the FKA 200 V of the company STI GmbH. At first the regarded collector should compare with other concurrently products they are available at the market.		Next the constructive and material technical alternatives by the absorber design will work out. At this it will gone bust detailed of the absorber variants and their components. The components of the tube system will subjected to a flow analyse and a durability approval will be made. In addition an energy balance will made over the total collector, during an irradiation experiment in accord with DIN EN 12775-2 and the efficiency and other results of the respective product variant will comprehend. Additionally analytical and metrological thermal and hydraulic parameters will work out and confronted.
Editor: Sebastian Wittig
Tutor: Dr.-Ing. Karin Rühling, Prof. Dr.-Ing. Clemens Felsmann

Storage technologies for heat pumps and micro-CHP systems

This paper gives a first review of latent thermal energy storage systems in buildings. For this purpose relevent phase change materials (PCM) were collected for the use in a thermal energy storage system in combination with a heat pump or a micro-CHP system. After that a comparison of the different groups of PCM’s were made and a selection of five PCM’s were defined for an implementation of TRNSYS.		To realize a first simple model, the already existing TYPE75 were modified. This prototype takes into account a maximum mass fraction of PCM of 50 percent and a vertical heat transfer. Convection in the liquid phase of the PCM, hysteresis and subcooling could not be realized at this moment. Finally first functional tests were undertaken.
Editor: Tobias Schlosser
Tutor: Dr.-Ing. habil. Joachim Seifert, Dipl.-Ing. Lars Schinke

Extension of validation capabilities of TRNSYS-TUD

With respect to the design and optimization of buildings and technical installations, simulation programs apply to a broad field of application. The software used for this purpose must be checked regularly with regard to quality. In this diploma thesis possibilities to validate the programme system TRNSYS-TUD, which was further developed by the Professorship of Building Energy Systems and Heat Supply, are extended. At first different methods of standardisation and projects of the IEA/ECBCS are described and several test cases for the implementation in TRNSYS-TUD are selected.		During the study of the boundary conditions partly contradictory definitions occur, so reasonable assumptions are made for the implementation into the programme. The implementation of the parameters is exactly documented. To compare the results of the performed simulations reference values, analytical solutions or results from other programmes are available. The compliance of the figures is different according to the validation method used and the precision of the test descriptions.
Editor: Katharina Huck
Tutor: Dr.-Ing. Alf Perschk, Dr.-Ing. Markus Rösler

Actualisation of the Energy Economic Market Review and the Impacts on the Operation of Power Stations

The Federal Republic of Germany is the fourth largest economy in the world and needs, as it is an exporting, developed nation, about 600 TWh of electric energy per year. The steady supply of energy is essential for the preservation of economic power and is the responsibility of an electricity supplier. In light of the expansion targets for renewable energy sources of the federal government new challenges occur along the entire value-added chain of energy supply. Market reviews are one instrument for sustainable management in times of change. The present work deals with the development of an Excel tool allowing the user an efficient preparation of a clear market review.		In addition, the backgrounds of the energy market are explained and the content of the market review is based thereupon presented and evaluated. It is of prime importance that such an evaluation is used in the strategic alignment of an electricity supplier with the aim to remain competitive. Here, the focus of the electricity supplier lies on the one hand on the marketing of the electricity generated and on the other hand on the adjustment of the generation portfolio. In this context, the present work examines the added value of an upgrade of the power plant Jänschwalde in terms of a lower technical minimum load. For this, the benefits of a greater flexibility are compared with the investment costs in a net present value calculation.
Editor: Dirk Richter
Tutor: Dr.-Ing. Thomas Sander

Approximation des konvektiven Wärmeübergangs in der dynamischen Gebäude- und Anlagensimulation

Thermal building and system simulation is an important tool to determine the energy requirement of buildings. Through a better calculation of interior convection coefficients the accuracy of building and system simulation can be significantly improved.		The purpose is to find suitable approximation equations through a literature review and to analyse these equations and its robustness. After that the equations will be implemented in TRNSYS-TUD and analysed for a test chamber developed by Awbi-Hatton and for a room of an one family house.
Editor: David Scherzer
Tutor: Dr.-Ing. Alf Perschk, Dr.-Ing. Markus Rösler

Evaluation of unsteady effects on thermal comfort

Today, the majority of citizens spend several hours in buildings and public means of transportation. Therefore, it is important to satisfy the needs of human beings indoors and to understand the effect of air-conditioning on people. Currently there is a lack of research in understanding these complex factors and their relations. Available studies in research literature already contributed first results, but are not sufficient for a comprehensive understanding. This thesis analyses the current state of research and concludes the boundary conditions		(experimental design) for a planned user study focusing on unsteady terms in the winter. The effect of unsteady boundary conditions on the performance of subjects doing their office work during several hours is determined in a realistic office environment. The air temperature in the laboratory varies within different ranges. In addition to the exposure of physical and physiological parameters, the personal rating of the proband is recorded with the help of a questionnaire.
Editor: Christine Knaus
Tutor: Dipl.-Ing. Alexander Buchheim, Dr.-Ing. Markus Rösler

Design and engineering of a test rig for investigation of control strategies for HVAC systems

A projected test rig at TU Dresden deals with the thermal comfort assessment under transient conditions. Two superposed test rooms were designed. The inner wall surface temperature is adjustable. This is realized by modular wall elements with integrated capillary tubes. The test rooms can be expanded to a large room through removing the ceiling between them. The work presents the results of the literature research on existing test rigs with similar objects of investigation.		They are compared with the concept of the TU Dresden. The main chapter includes the dimensioning of the water supply, which requires the capillary tubes, and ventilation system, which is used to set defined ambient air conditions. For better understanding a 3D model including the networks of water pipes and air ducts was designed in SolidWorks. The solution is evaluated for its suitability.
Editor: Maximilian Beyer
Tutor: Dr.-Ing. habil. Joachim Seifert, Dipl.-Ing. Alexander Buchheim, Dipl.-Ing. Lars Schinke

Commissioning and testing of the „Combined Energy Lab“

Within the scope of an multidisciplinary research project at the institute of power engineering in cooperation with the institute of electrical power systems and high voltage engineering a test field is being developed that is capable of investigating both the thermal as well as the electrical performance of power generators. A grid emulator is therefore being developed in order to emulate an electrical grid. The present work shall go along with the start-up of this “Combined Energy Lab”. For this purpose it is necessary to prepare the existing test field for its prospective use, to calibrate the measuring instruments and to prepare them for automated long-term testing. Furthermore, the analysis of the existing “gas measuring track” and the evaluation to which		extent a new gas flow meter and gas analyser can add to improving measurement accuracy shall be a focus of this work. Main parts are screening of existing possibilities, revision of found solutions and to invite offers from producers. A design drawing shall be the preparation for the construction of the new gas measuring section. In addition, interfaces between the thermal emulator and the grid emulator are defined. In essence, an automated data analysis concept shall be developed. Therefore commercial software solutions shall be analysed as well as an alternative in MatLab shall be developed. In a final step first tests with the thermal emulator will be achieved.
Editor: Tobias Müller
Tutor: Dr.-Ing. habil. Joachim Seifert, Dipl.-Ing. Paul Seidel

Studies on the energy efficiency development of selected compressors by means of trend analyses evaluation basing on measured values

The Institute of Air Handling and Refrigeration in Dresden executes performance measurements for refrigerant compressors for many years. Up to now all the data was stored in single Excel-Files. A MS Access database is developed to perform evaluations more easily and to achieve the data in consistent way. In the first part of the thesis theoretical background about databases and database development is mediated. Afterwards the structure of the complete refrigerant compressor database is explained. In addition the range of functions and the graphical user interface is described. The second part of the research paper deals with the theoretical background of compressors in a compression refrigeration system. The most important parameters regarding efficiency are compression efficiency, isentropic		efficiency and coefficient of performance which are described in detail. Furthermore the method how to gain these parameters based on DIN EN 13771-1 is explained. The focus is set on the evaluation of refrigerant performance measurements from the years 2003-2012 of piston and scroll compressors regarding their performance. It can be stated that large differences in performance still occur between different manufacturers. Moreover it is remarkable that the progression in efficiency of piston compressors stagnated within the last ten years. Even a little decrease of the parameters compression efficiency and isentropic efficiency can be observed. However the substantially newer scroll compressor technology is still showing a little increase in efficiency.
Editor: Tim Weippert
Tutor: Prof. Dr.-Ing. Clemens Felsmann, Dipl.-Ing. Christian Edler (ILK Dresden), Dr.-Ing. Matthias Böhm (ILK Dresden)

Experimental Evaluation of the Intermittent Operation of a District Heating System

As part of the E-Energy project "Modellstadt Mannheim", the heating supply of residential buildings over a district heating system has been temporarily reduced by means of a certain control strategy. In this way it was possible to examine the effects of temporary undersupply on the behaviour of buildings and district heating systems. In the present study the practically implemented reduction tests are being analyzed and evaluated in various aspects.		The main topics are considerations of the thermal state of the buildings as well as the hot water supply. Furthermore, the conditions in the district heating system regarding increased stress and wear are being examined and potential problems are being discussed. The recommendations and conclusions of this study represent a supporting contribution for a more flexible energy production in the future.
Editor: Max Pham
Tutor: Prof. Dr.-Ing. Clemens Felsmann

Evaluation of building energy performance using EnEV easy

In the first part of the paper, the approach “EnEV easy” is analysed in detail. It deals with the creation of energy passes for residential buildings and was developed by the German Federal Ministry of Transport, Building, and Urban Development. EnEV easy is introduced, explained, and commented in the following, as well as used to create the energy passes for two virtual buildings. Albeit, the application of the approach is due to constraints concerning the characteristics of the buildings (geometry, systems etc.) not permitted, it is still used in order to gain experiences. The results are compared to calculations in accordance with DIN V 18599.		The first part ends with an evaluation of the EnEV easy method by the author. In the second part of the paper, an excel file is created with which it is possible to generate Sankey diagrams automatically from measured energy flows. The energy flows were measured between 12.07.2012 and 31.01.2013 at the Gerhard-Grafe-sportshall in Dresden. The discussion of the created Sankey diagrams reveals weak-points of the installed energysupply-system. These weak-points require a more detailed analysis, which is not part of this paper.
Editor: Niels Rauland
Tutor: Prof. Dr.-Ing. Clemens Felsmann

Energy certification and energy calculation

According to the EnEV (Energieeinsparverordnung - energy conservation regulations) the energy demand of buildings is calculated with the DIN V 18599. In this paper the results of these calculations will be compared to the results of a dynamic building simulation and to the actual energy consumption of a building. A single-family house and an apartment building have each been calculated with two different Thermal Insulation Standards, and were compared to the simulation results. The Energy Certificate under public law requires certain boundary conditions. The boundary conditions used in the simulation differ from these. Therefore each variation was calculated twice, once with standard boundary conditions		and once with conditions adapted to the simulation. The calculation using standard boundary conditions showed big differences between the calculated energy demand and the simulation results. By adapting the boundary conditions, the calculated energy demand decrease significantly and approached the results of the simulation. The comparison of the calculated energy demand with the actual energy consumption of the Merkel-Bau showed big differences as well. Because important building information were missing, it was impossible to analyse to which extent these results are caused by the calculation algorithm of the DIN V 18599 or by an incorrect projecting of the building.
Editor: Patrick Eggers
Tutor: Prof. Dr.-Ing. Clemens Felsmann

Design and construction of a surface-integrated heat exchanger

The conventional heating systems of buses are no longer on the current state of technology. A major problem is the susceptibility to maintenance the used convector-technology. In addition hybrid and fully electric vehicles produced significantly less rejected heat than vehicles with conventional combustion engines. For these reasons the “Fraunhofer Institut für Verkehrs- und Infrastruktursysteme IVI” started working for developing new heating technologies which fulfill the new requirements. With help of the AutoTram Extra Grand which is an experimental vehicle from the “Fraunhofer Institut für Verkehrs- und Infrastruktursysteme IVI” a surface-integrated heat exchanger is designed and constructed in the following paper.		According to theoretical considerations (previous heat-systems of buses, requirements on air-conditioning of buses etc.) the heat demand of the bus-cabin will be compare with the heating power of a surface-integrated heat exchanger. The comparison is carried out at an external temperature of -15°C. The result of the comparison indicate that the heating power doesn´t suffice to heat the bus-cabin up to 18°C. After the design and construction of a surface-integrated heat exchanger there will be make proposals about other necessary heat-systems and components to realize surface-integrated heat exchanger in buses.
Editor: Markus Vass
Tutor: Prof. Dr.-Ing. Clemens Felsmann, Dr.-Ing. Martin Knorr

Design and Mode of Operation of High Efficient Cogeneration Plants with District Heating Storage in Consideration of Increasing Renewable Power Generation

The determination of the influence of the increasing renewable power on the mode of operation and therefore also on the profitability of a CHP plant is the goal of this thesis. The investigation is conducted based on an combined cycle plant (gas and steam), which supplies district heating for a selected city. The analysis of the power grid parameters and its resultant forcast until 2030 shows that more and more frequently the renewable power plants are able to cover the required power load without the support of conventional power plants. Due to the power surplus in the grid the considered CHP plant can not be put in operation in these periods. Installing a district heating storage is reasonable to avoid the additional employment of a heating plant during these times.		It turns out that solely the use of the storage increases the profitability of the system significantly. Furthermore two contemplable types of gas turbines are considered. The effects of an additional grant by the state are listed in the review as well. In addition, the integration of an electrode boiler into the system “CHP plant – district heating storage – district heating system” is examined. The results show, that under the given conditions such boiler can already be positioned economically viable in the electricity balancing market. If the electric energy is bought to low prices at the electricity wholesale market, then profit is generated only under certain conditions.
Editor: Christian Nawrodt
Tutor: Dr.-Ing. Thomas Sander

Building energy management in company

The lack of systematic configuration of the energy-consumption leads to blindness and inefficiency of the Commercial Building Operation Optimization for most enterprises. In order to assemble the energy relating data in the building in real time, and to improve the employee’s sensitization of saving energy with up-to-date visualized energy distribution, we set the visualization of the building energy consumption an important task in our Technical Energy Management Platform project, also the main focus of my internship work. To realize it, a 4-stage dataflow corresponding approach is developed:		Data-recording by counters and sensors, data-collection by gateway, data-transmission to the database and data-presentation using JSP development tool. With three M-Bus electricity counters, two Z-Wave temperature-and humidity sensors, one Modbus heat flow meter, a demo-Hawk from Tridium as bus-gateway, Niagara Framework as operation system, MySQL as database, Eclipse as JSP development tool, I committed myself to the visualization of the energy consumption in our own office building and a logic-controlling using the Niagara modules. In this dissertation, I will mainly expound the realizations of these two approaches.
Editor: Wang Zheyu
Tutor: Prof. Dr.-Ing. Clemens Felsmann

Thermoelectric heating and cooling of residential buildings

The heat demands for space heating will decrease in the future because of higher insulate standards. This fact makes it possible to use alternative heating systems with a lower power, especially for residential buildings. The aim of the present paper is to analyse possible applications of thermoelectric heat pumps. Peltier-elements are known as thermoelectric heat pumps. An advantage of Peltier-elements is, to make cooling in summer possible. It increases the convenience of living.		The operating performance of Peltier-elements and the heat transfer to the air will get analysed. Another point for research is a possible combination with a heat recovery system. The heat transfer will confirmed with a simulation, working with the finite element method. The most important results of the present paper are facts about operating conditions, limits of using and reachable Coefficients of Performance (COP).
Editor: Nico Wessely
Tutor: Prof. Dr.-Ing. Clemens Felsmann

Advance of the Energy Efficiency of the School Complex in the City Kremmen

The buildings energy efficiency aims to the optimization of energy resources. The first step is to complete an analysis of the buildings state: energy loss, energy consumption and the structure of the technical installation. Then we have to assess the potential of amelioration and the real energy needs. Now we can develop an energy concept for the building which has to save the energy consumption. We propose finally two actions for the canteen of the school: a first one which solves the basics problems		and represents at least a first level of efficiency and another one which designs an energy concept for the renovation particularly of the heat supply and achieves a good level of efficiency. During this study we have to notice that citizens are not really ready for an energetic transition, because most of them don´t know the simple energetic principle and also don´t understand. The first level of efficiency is soon completed and the second one is now being worked on by an engineering office and has to be assessed for a future investment.
Editor: Yann Briand
Tutor: Dr.-Ing. Thomas Sander

Modeling and optimizing of the hot water supply for Globalfoundries by Energy Supply Center (EVC) Dresden

The development and production site for semiconductor chips of Globalfoundries in Dresden is supplied with electric energy, hot water and cold water by the EVC. The whole generation system is highly networked in order to implement the combined heat and power and cooling production as efficiently as possible. In this work a calculation model is developed, which enables the simulation of any operating states of the EVC.		Using the model, there are investigated several operation states of the hot water supply system. From the analyses are identified the optimal sequences of operation of the hot water supply systems components. From the studies arise concrete evaluation parameters, which characterize the optimal sequence of operation of the hot water supply systems components of the EVC. Prospectively the calculation model can be used to optimize further systems of the EVC.
Editor: Andre Burchardt
Tutor: Dr.-Ing. Thomas Sander

Technical and ecological comparison of furnace systems for dry lignite and natural gas (state of the art)

This report contains a comparison of coal and gas as energy sources. Their use is heavily disputed, but currently they are both indispensable. The study focuses on combustion processes of coal and gas firings, examining their advantages and disadvantages. Various combustion techniques are evaluated with respect to their influence on the caused pollution. To this end various fuels and burners are considered and different approaches to handle the occurring flue gas are introduced.		These approaches are generally categorised in primary and secondary procedures. While primary procedures are mostly implemented during construction of new equipment, secondary procedures can be used to upgrade existing equipment. The pollutants considered in this report are nitrogen oxides, sulphur oxides, carbon oxides, water vapour, dust, and ashes. In a concluding review the generated results are assessed and a discussion concerning the ongoing use of fossil fuels in Germany is presented.
Editor: Sabrina Schmidt
Tutor: Dr.-Ing. Karin Rühling, Dipl.-Ing. Jan Löser

Development of a self –acting control system for freeze protection for animal drinking trough

In agriculture it becomes increasingly important to reduce the water and energy consumption for both economic and environmentally conscious reasons. The current systems for freeze protection for animal drinking troughs and their connection pipes are predominantly operated by electricity. A system for freeze protection which operates without electricity provides the opportunity to replace or to supplement the electric heating systems and to reduce the power consumption.		A frost protection valve that operates without auxiliary power is practically established in the animal breeding. In order to achieve the independence of this patented frost protection monitor, an alternative solution is developed and implemented constructive in this thesis. The thermostatic radiator valve of the building technology serves as a model. Furthermore, the main focus is on the one hand the minimization of the water consumption and on the other hand the adaptation of the valve to the prevailing surrounding conditions in the stable.
Editor: Susann Klöditz
Tutor: Dr.-Ing. habil. Joachim Seifert

2012
Impact of user behavior on the results of building and system simulation

In this study the influence of user dependant processes on the results of building and system simulation is investigated. At first the basis for calculation of the internal heat sources and the air change rate are explained to describe them in the simulation. In addition investigations to profil schedules are presented. Next, a method is described which allows creating profile schedules with Microsoft-Excel 2008 to simulate running processes with TRNSYS-TUD. By classifying the profile schedules for internal heat sources and the air exchange rate in building various simulations with a period of a year have been performed.		After the execution of various simulations different results obtained and are examined critically. These results relate on the expended annual heating energy, on the temperature gradients and the ventialtion behavior in the diurnal cycle. During the processing of this study it has been shown, for more detailed description of user dependant processes more complex profile schedules are produced. In this way the handling of creation and simulation with the described method aggravates.
Editor: Enzmann
Tutor: Dr.-Ing, Alf Perschk, Dr.-Ing. Markus Rösler

Economic evaluation of Renewable energies using the example of Geothermal energy

The development of renewable energy sources (RES) is supported by the German government in the electricity as well as in the heating sector by implementing incentive systems and support schemes. In this context this Master thesis discusses the geothermal heat and electricity generation for geological conditions available in Germany. For this purpose the costs of electricity and heat generation are calculated for geothermal energy applications using dynamic methods for investment appraisals. The aim of these calculations is to assess the competitiveness of geothermal energy applications in the German electricity and heating sector as well as to evaluate the efficiency of government supporting systems related to geothermal energy. The analysis considers technical and economical aspects of geothermal energy applications using both shallow and deep heat sources.		Taking into account the characteristics of geothermal energy generation, for the interpretation of the results it is necessary to distinguish between the supply of thermal and electric energy. The existing support measures for geothermal heating applications near the surface and in deeper areas can be evaluated as efficient. Taking into consideration the government support, geothermal heating applications can reach competitiveness in the German heating sector. Still this requires good geological and technical conditions, like a good annual performance factor of the heat pump or a high temperature of the geothermic water. For the generation of electricity by geothermal energy the following conclusions can be made. In case of not taking into account the incentives provided by the Renewable-Energy-Law, geothermal power plants can work economically only by a combined generation of heat and power. Important requirements for running these plants economically are good local conditions, like a high temperature of the geothermic water. The support measures for geothermal power plants within the Renewable-Energy-Law can be evaluated as inefficient.
Editor: Volker Seifert
Tutor: Prof. Dr.-Ing. Clemens Felsmann

The use of Peltier-Heat Pumps with special focus on application in building energy systems

This document will examine the use of Peltier heat pumps with special emphasis on applications in building. Objectives and steps of the present study are: First, the physical laws and principles are described that must be followed in order to build efficient Peltier heat pump system building. To this end, prior to the presentation of the basics of thermoelectric is a brief introduction to heat transfer and heat transfer, as they are essential for building the system discussed in the following sections for explanations Peltier heat pump. Then the applications and operating experience for Peltier element are given. e.g. different type of Peltier element for various industrial applications. The focus of this article is to comparison of different building systems for residential unite, therefore, need to design two different systems. Air-conditioning and heating systems with compression heat pump Air-conditioning and heating systems with Peltier heat pumps		And then the new building system (Peltier heat pump system) with respect to reproducibility, production costs and efficiency compared to the current state of technology (compression heat pump system) to be compared. By comparison with a compression heat pump system, the possible application of Peltier heat pump system will explore as home air conditioning and heating systems. At the end is an introduction to the thermoelectric. Important parameters such as quality of materials are presented and described its impact on the efficiency of thermoelectric generators. Finally, two thermoelectric combined systems are given. These are: Generators in solar thermal systems Thermal generators with heat pipe combination.
Editor: Danquan Yang
Tutor: Prof. Dr.-Ing. Clemens Felsmann

Implementation of a concept for measuring of the thermal behaviour of ground-coupled heat exchanger field in Centrum of Energy Technology of the TU Dresden

Since the Renewable Energy Sources Act (EEG) came into force heating systems with heat pumps have become of paramount importance. Brine-water heat pumps have the potential to provide thermal energy by exclusively using renewable energy sources throughout all seasons. Therefore heat out of the near-surface soil is often used with a vertical borehole heat exchanger. The optimal performance as well as thermal simulation of a system like this require precise knowledge of the surrounding soil conditions. For this purpose a Thermal Response Test (TRT) is carried out with the newly built borehole field at the Centre for Energy Technology of the TU Dresden.		Therefore various measurement components, including a fiber-optic temperature measurement system, are added to the test rig. It is developed a measurement software, which is capable of uniting all the measurement devices, recording measurement data and sending control signals to the test rig. Finally the test data is analyzed by using common TRT-evaluation methods. The thermal properties of soil in the near heat exchanger environment are determined by comparing measured and simulated (TRNSYS simulation) temperature data. The results are evaluated in consideration of similar tests found in literature sources and property specifications in VDI-guideline 4640-1.
Editor: Stefan Hoppe
Tutor: Dipl.-Ing. Jens Haupt, Dipl.-Ing. Wojciech Kozak

Validation in building and system simulation

Building energy simulation programs are useful tools for planning and modernizing buildings, and their technical installations. For the acceptance of simulation results it is essential to validate the programs regularly. The concern of the present study is a validation of the program TRNSYS-TUD according to the instructions of DIN EN ISO 13791 (2010-03). At first various validation options and projects about that topic, that have already been completed, are described.		This is followed by a closer examination of TRNSYS-TUD. Then the program is validated by some methods of DIN EN ISO 13791. In addition to that the results of various simulations in TRNSYS-TUD are compared with those of other simulation programs. TRNSYS-TUD meets the demands of the standard very well. In comparison with other programs partially differences between the results have occured. Reasons for the differences can not be defined precisely.
Editor: Katharina Huck
Tutor: Dr.-Ing, Alf Perschk, Dr.-Ing. Markus Rösler

Development of electrically heated high-temperature components used in fuel cell test rigs, based on experimental results and models

The research of SOFC fuel cells requires the verifying and operation of the stacks in special test rigs that are developed for this purpose. Within the scope of this diploma thesis the further development of the components air and gas preheater as part of these test rigs will be approached. These components are subjected to high thermal stresses due to the operation in high-temperature area, eventuating in an increased attrition. The used principle of electrical heating with heating wire will be followed up in this development and optimized in terms of material selection, flow design and the supply of power.		In particular the heat transfer is improved by appropriate measures, including in addition to the increase of the convective heat transfer the heat radiation. The power supplied in the form of heat is realized in steps along the flow path, resulting in a decreased stress of the heat wire material in the hotter section near the outlet and consequently reducing the attrition while getting a longer life. Furthermore, the requirement of higher heating rates shall be accomplished in this way. The permanent thermal loads lead in addition to the usage of alternative materials that can satisfy these requirements.
Editor: Sven Paulick
Tutor: Prof. Dr.-Ing. Clemens Felsmann, Dipl.-Ing. Jens Haupt

Design and Test of an NCG-Exhaustion of a MED Test Facility

The diploma thesis analyzes theoretical and experimental the desorption of not condensable gases (NCG) and the exhaust of those out of a MED-trial station with small capacity, with the aim of developing an improved exhaust system. After the theoretical detection of the NCG volume the exhaust system of the trial station is divided into components and analyzed.		From the findings suggestions for improvement are derived and evaluated in order to put them together to an optimized exhaust system. A systems engineering, which guarantees realistic gas content in the raw water tank is developed as test preparation. Finally the NCG volume its distribution and the single components of the exhaust system are analyzed experimental by a series of test.
Editor: Marko Hähnel
Tutor: Dr.-Ing. Karin Rühling

Investigations on Heat-Pipe Vacuum-Tube-Collectors in Drain Back Systems

Subject of this thesis is the development of a new type of solar thermal system that is based on the Drain-Back System. The development is focused on the combination of an open Drain-Back System (DBS) combined with an atmospheric water tank manufactured out of glass fibre and efficient Heat-Pipe Vacuum-Tubes. In opposite to previous open DBS the draindown tank prevents the direct contact between the air of the System and the surrounding atmosphere. Thus the danger of corrosion is minimized.		To design the system there are suggested some calculation models. The dimension of the draindown tank can be estimated using the ideal gas equation according to the volume of gas in the system under different conditions. The calculations of thermal and hydraulic aspects are calculated according to the extended Bernoulli equation. To evaluate the capability of the new DBS a test system is designed. The test system consists of the DBS and a usual designed pressurized solar thermal system using a mixture of water and frost protection agent.
Editor: Thomas Plaz
Tutor: Dr.-Ing. Karin Rühling, Dipl.-Ing. Martin Heymann

Life-Cycle-Analysis in building energy systems

The investor’s selection of building energy systems is based among other things on their economic efficiency. For that the investment costs as well as all expenses that occur during the runtime of the equipment are considered, but until now the temporal development of operation-depending costs are not considered. Though, electricity and resource prices are subject to strong changes in the coming years.		This paper deals with the total economy, especially for systems that use renewable energy sources, under particular observance of technological and financial development of relevant system components and operating material. It gives an overview of the prospective trends and the best type of energy supply for one specific kind of building.
Editor: Monika Wicke
Tutor: Prof. Dr.-Ing. Clemens Felsmann

Development of New Features for the Integration of Intraday Trading in an Energy-Economical Optimisation Software Meeting the Requirements of Load and Usability

By reason of increasing trade flexibility on the European power- and commodity exchange power supply industry with own production capacities have a lot of different marketing respectively purchasing possibilities. An optimal use of the market potential requires the application of mathematical optimization software like MipOpt. On the basis of absolutely amounts they calculate an activity schedule, which is characterised by its maximum economical success. However, therefore it is necessary to implement the transformation of real technical and economical parameters and determining factors in the mathematical model as accurately as possible. This interface between mathematical modelling and physical respectively contractual implementation is the topic of the associated diploma thesis.		Incipient with the research and assessment of elementary important load forecasts for power and heat and continued with the evaluation of detected demand fulfilment including corresponding cause study the spectrum of first part tasks extends into the analysis of operation management concepts. Following up these results the integration of the intraday trading is the subsequent central subject matter. Until now there exists no feature for mathematical optimization of intraday trading within the utility company “eins energie in sachsen” in Chemnitz. Development of useful assimilation recommendations and extension concepts for all mentioned theme aspects including theoretical and empirical verifications represent the result of the diploma thesis.
Editor: Tobias Widder
Tutor: Dr.-Ing. Thomas Sander

Development of contracting models for micro-CHP and heat pump systems

IAs part of the climate and energy policy objectives of the German government, the efficient energy production in decentralized systems is promoted. The technologies used particularly include small combined heat and power plants. These shall increasingly be used for building supply in future. Especially in case of single-family house owners, there are often barriers to use technologies which are new and less established so far. The main barriers, which include the lack of technical know-how, the lack of confidence in the economic efficiency of the system as well as higher financial burden in the phase of acquisition, can be overcome by contracting models.		Therefore in this paper, contracting models for the energy supply of single-family houses with micro-CHP plants are developed. In the analysis the heat-controlled and current optimized operation is focused. A conventional supply option serves as a basis for comparison of economic efficiency analyses. Besides the contractual relations, the risk potential for both contracting partners is analyzed. In an outlook, opportunities are identified to realize more economic efficient strategies for energy production with heat pumps and CHP plants through participation in the network operation in a virtual power plant.
Editor: Nicole Graich
Tutor: Dr.-Ing. habil. Joachim Seifert, Dipl.-Ing. Andrea Meinzenbach

The German Renewable Energies Heat Act (REHA/EEWärmeG) – Analysis and comparison of different heating technologies for their technical and economical practicability in single-family houses, including a validation of the result-transferability to public buildings

According to the German Renewable Energies Heat Act (REHA/EEWärmeG) the use of renewable energies is compulsory in new buildings since 2009. For that reason this bachelor thesis analyzed different kinds of heat production systems for single-family houses that match the statutory provisions and compared their long-term cost efficiency. Furthermore, it considered aspects for public buildings, which are affected by this law as well since 2011. In the main part, for each technology, costs expected to occur during a period of 20 years were estimated and evaluated by using investment appraisal methods. The results revealed the heat pump to be the most economical alternative that fulfills the targets defined by the REHA/EEWärmeG.		More detailed analyses showed that system and consumption related costs have the biggest influences on the total costs. The significance of factors influencing these costs was illustrated as well. The second part of this thesis demonstrated the limited possibilities of transferring insights between these two types of buildings by comparing the attributes and requirements of single-family houses and public buildings. That way it also stated the need of individual considerations. In conclusion a qualitative evaluation of advantages and disadvantages compared both self-financing and contracting-based financing, which proved contracting to be an effective financial instrument with high potential.
Editor: Marcel Steppuhn
Tutor: Prof. Dr.-Ing. Clemens Felsmann

Investigation of long term stability of CIGS thin film modules

CIGS thin-film solar modules have a special feature compared to traditional silicon solar modules: their power increases under irradiation with light. This effect is called positive light soaking effect. For the thin film modules Q.SMART by Q.CELLS SE this effect in the laboratory was investigated under standard test conditions and determined with an increase of typically 2.5%. It was first a method developed to filter out and make visible the increase of the performance under all environmental conditions (spectrum of sunlight, temperature, irradiance, module temperature, sunshine duration, ...).		By using various PV installations should this power increase also be detected on existing facilities. During the work it was found that this evidence is only possible if various conditions, such as Start of monitoring, connection of the measuring technique, etc., are observed during the installation of PV systems. Only then is it possible to investigate the light soaking effect to the smallest detail. The investigation has shown that the CIGS thin-film solar modules can actually benefit under real conditions in the field from the laboratory already shown positive light soaking effect.
Editor: Christoph Thiel
Tutor: Dr.-Ing. Karin Rühling

Cooling of Li-Ionen battery systems

Within the framework of the growing utilisation of renewable energy sources and the development of electric mobility, lithium-ion batteries are increasingly applied to store electrical energy. In order to ensure safe use of this cell type limitations to the operating conditions arise. The operating temperature has a great impact in that from a certain value the life of a battery cell is reduced with increasing temperature and there is a risk of an uncontrolled release of energy, a so-called "thermal runaway". A remedy is provided by the dissipation of the thermal energy by means of a cooling system. Thereby a cooling element, flown through by a fluid and attached to the cells, is often used.		The objective of the project work is to create individual concepts for the design of a cooling element, adapted to the cell format of the company Li-Tec Battery GmbH, and constructively design one variant. First of all, the fundamentals of the application of a cooling system are briefly described and a patent research on battery cooling is performed. Subsequently, the thermal energy released in the cell, due to the electric current flowing during the processes of charging/discharging, is calculated. Using the guideline VDI 2222, principle solutions for the cooling of the present cell are created and assessed with regard to determined criteria. Based on the assessment a preferred alternative is selected and designed. Further, the calculation of heat transfer and pressure drop under specified operating conditions are made for the constructed cooling element.
Editor: Torsten Klemm
Tutor: Prof. Dr.-Ing. Clemens Felsmann

Comparative evaluation of building energy performance

The Gerhard-Grafe gymnasium in Dresden Weixdorf is a passive house gymnasium, which is managed by the association Sportgemeinschaft Weixdorf e.V. It was planned with the help of the Passive House Planning Package (PHPP), so that the primary energy demand would undercut the standard requirements of a passive house by 50%. Actually, deviations from the planning parameters are existent, whereby a potential for optimization in the system operation is present. This diploma thesis was realized as part of a research project for the overall optimization of the building and system operation of the gymnasium.		The aim is to calculate a total balance sheet using EnEV calculation programs, which are based on DIN V 18599. The required data is collected from planning documents and is expanded or corrected by local visits. In the calculation program, the energy-efficient building cannot be mapped accurately because the limits of the standard are exceeded and some engineering systems can only be modeled insufficiently. Compared to real consumption data, these aspects are shown in the increased gas and electricity demand. For buildings with very low energy consumption, the calculation of demand should be resorted to other calculation methods such as PHPP, which produces reliable and accurate results.
Editor: Markus Leibelt
Tutor: Dipl.-Ing. Juliane Schmidt

Numerical study of a novel heat exchanger concept for use in solar thermal power plants

The “Cell-Flux“ project at the institute of technical thermodynamics of the DLR has the goal of developing a sensible thermal storage for use in solar thermal power plants. The interface between the heat transfer medium of the solar thermal process and the storage structure is realised by a heat exchanger. This heat exchanger is the object of the current paper. Using the CFD-software Ansys		CFX the feasibility of a hybrid heat exchanger, where the heat exchanging surface is also a storage medium, is examined. Thereto three different types are considered and numerically modelled. The models will be validated empirically and experimentally and their usage is being evaluated. In conclusion, the different types are compared regarding their heat transfer- and flow characteristics and the possibility of their usage is under discussion.
Editor: Marcus Rohne
Tutor: Dipl.-Ing. Lars Schinke

Decentralized district heating substations with feed-in function

The following thesis is an investigation into decentralized district heating substations with feedin function for the integration of volatile regenerative energy into district heating networks. The basic design of those stations is developed and compared to district heating stations existing in solar supported heating systems. This led to the design of a hydraulic circuit that allows a consumer (load) to be supported by either the district heating network and a solar collector circuit and also to feed in the solar generated		surplus heat into the district heating network. In order to realize stable states of feed-in and supply and the related changeover processes a control concept is laid out. The circuit was then implemented in a simulation model with existing types in the software TRNSYS-TUD. A simple control algorithm is implemented to simulate the designed station in different scenarios. The results show the functionality of the designed hydraulic circuit.
Editor: Andreas Jurack
Turor: Dr.-Ing. Karin Rühling

Development of a concept for the determination of requirements for control reserve at short notice

The present work is concerned with the development of a concept for the determination of requirements for control reserve at short notice. Control reserve is used to level out feed-in and extraction within a power supply system. The objective of the concept is to design the process of providing control reserves in consideration of renewable energy sources in a dynamic way. This will adjust the amount of power provided better to actual hourly demand, which becomes more important with a view to an increasingly fluctuating power production. The development of the new concept encompasses two versions with regard to the required lead time: a day-ahead version and an intraday version. For each version, a program flow chart illustrating the process for the determination of error distributions was created.		The calculation of the hourly control reserve requires a total of six error distributions; among others distributions of the photovoltaic and wind forecast error. Using correlation analysis, it was calculated that the forecast errors of photovoltaic and wind power are statistically independent from each other. In a model calculation, the requirement of wind-induced control reserve under the current and the new, dynamic concept was determined by means of kernel density estimation. The results show that the new concept reduces the demand for control reserve and allows for a dimensioning of wind-induced control reserve that is better in line with demand than the current concept. It has to be tested in subsequent works whether the positive results of the model calculation are also valid when applied to the overall concept and whether the technical challenges in terms of the implementation of the new concept can be overcome.
Editor: Julia Jäger
Tutor: Dr.-Ing. Thomas Sander

Definition of an application profile for a lithium-ion power cell in consideration of the electrical and thermal cell behavior

Lithium-ion high-performance batteries in hybrid vehicles are subject to cyclic current loads during operation, which leads to aging. It is necessary to replicate this aging behavior via load profiles in order to carry out life considerations. The operating limits of the battery must not be violated. The aim of this work is the computational definition of such a profile based on an existing current drive cycle and the construction of a thermal an electrical model in Matlab/Simulink to describe the cell behavior. The cell temperature was calculated by the power loss taking into account the processes of heat dissipation.		To simulate the cell voltage an equivalent circuit model was used, consisting of a serial resistance and two RC-elements, which was parameterized using pulse tests for various charge conditions and temperature levels. Thermal and electrical model were coupled due to the temperature dependence of the cell parameters. The cell model was validated using load profiles, and showed good agreement with the measured values. The definition of the cycling profile was carried out for a new and an aged cell using a BMS. In addition, an application profile was generated based on the EoL criterias by extrapolation of the aging characteristics.
Editor: David Günther
Tutor: Dipl.-Ing. Lars Schinke

Energetic and economic evaluation of greenhouses with the aim of identifying energy savings opportunities

The production of plants in greenhouses requires a lot of energy, which is mainly consumed by heat and electricity. Due to higher energy prices the heating and electricity costs increase and therefore increase the cost of production. If no measures to reduce the energy consume are implemented, the profitability from greenhouses is in danger. This work delves into the topic of saving energy in greenhouses. Through a systematic literature review the current state of research concerning energy saving measures in glasshouses is shown. Furthermore the viability of the measures in one greenhouse is evaluated.		In order to evaluate the measures critically and transparent in regard to their potential of energy conservation an energetic balance model of a greenhouse is developed. By only small variations this model can be used for different types of glasshouses. The balance model is modeling the heat flows in a greenhouse and shows the influence of parameters on the direction of the heat flows. By the applications of the balance model for four days with different parameters the problems discussed in the literature were detected. With the assistance of the identified scaled of the heat flows possible starting points for energy saving measures can be identified.
Editor: Maria Löther
Tutor: Dipl.-Ing. Lars Schinke, Dipl.-Ing. Konrad Treppe, Dipl.-Kfm. Stefan Münch

Generation of a physical drying process in a washer-dryer

An appliance that is able to wash and dry the laundry is a washer-dryer. For optimization a system of physical equations was generated. The system provides information about the drying efficiency and velocity.		To solve the equations the numerical program ‘EES’ was used. To find the ideal heat and material transition coefficients was the achieved goal.
Editor: Annelie Stoye
Tutor: Dipl.-Ing. Lars Schinke

Evaluation of upgrading measures to improve the efficiency of a CHP plant

The municipal utility of a medium-sized city operates a district heating grid, which is predominantly fed by a combined heat and power plant (CHP plant) consisting of a gasturbine with a heat recovery boiler and a peak load boiler. Because of the low heat demand in summer the gasturbine is in a non-operating state during this time, which results in a low CHP rate. Furthermore it is known that the heat recovery boiler shows relatively high exhaust gas temperatures of approx. 150 °C, which leads to a rather low overall efficiency.		To prevent these negative consequences of the current plant operation two modernization measures are examined within the project thesis. These measures are analyzed regarding the energetic and the economic effects on the plant operation. Installation of a new heat recovery boiler. Installation of a new heat recovery boiler in combination with the reconstruction of an almost unused fuel oil tank to a heat storage.
Editor: Jessica Hebing
Tutor: Dipl.-Ing. (FH) Dominik Haas

Options for use of waste energy from renewable energy sources

Due to network congestion or the coincidence of high renewable energy with low load in the power grid, it is increasingly becoming a temporary oversupply of electricity and thus the need to cut off renewable energy generation facilities. This mainly affects wind turbines. With the further development of renewable energies it is expectable that this problem will get worse in the future. The present work shows an estimation of the expected future loss energy, what reveals the more or less urgent need to act – especially against the background that this energy, which is not fed into the power grid is paid anyway, regulated by the current EEG control.		Based on this the potentials and chances for implementation of various forms of using the surplus energy are presented. Special attention is given to the option of using the energy for heat supply. For this purpose, different systems of converting electrical energy into thermal are considered and their applicability and economic efficiency for the problem are analyzed, showing that an economic incentive to use the excess work with the eligible options, especially the supply of heating energy is clearly stated. Furthermore the additional energetic benefit of using the as yet lost energy as thermal energy in district heating networks is pointed out.
Editor: Monika Wicke
Tutor: Prof. Dr.-Ing. Clemens Felsmann

Literature review and analysis of mini-and micro-CHP systems

As part of the great document, a market analysis of mini-and micro-CHP has been carried out. A distinction is made between four different technologies. These are the internal combustion engine, the Stirling engine, the steam expansion engine and the fuel cell technology. Furthermore, hydraulic integration variants of micro-CHP systems are analyzed. Here, the buffer used and the type of water heating, are discussed.		A third section deals with the topic "Virtual Power Plant". Here it is investigated whether there is a possibility to connect on the market, CHP systems to a virtual power plant. In a final chapter test data from three micro-CHP units are evaluated. The data come from field testers Leipziger Verbundnetz Gas AG.
Editor: Benjamin Gleichner
Tutor: Dr.-Ing. habil. Joachim Seifert

Analysis of a Vitotwin – micro CHP system from Viessmann

Between October 2011 and March 2012 an analysis of the Vitotwin 300-W took place in the innovation lab of the Professorship of Building Energy Systems and Heat Supply at Dresden University of Technology in cooperation with Viessmann. The thermal value device runs with domestic gas and is featured with a Stirling engine and an auxiliary burner and is based upon the micro-CHPtechnology (combined heat and power). Tests showed that the maximum over-all efficiency is similar to the one of condensing boilers (max. 105,59% relating to the heat value). The electrical net rated power is somewhere between 920 W and 958 W and causes the electrical efficiency to be between 14 and 15%.		Using the auxiliary burner meets the demand for heat of an apartment building (max. 20 kW). Besides the electrical connection by an electrician, the Vitotwin does not need more set up effort than a condensing boiler. On the part of the producer, for a cost-effective functioning, it is only recommended, if the household has a gas consumption of more than 20.000 kWh and a consumption of electricity of over 3.000 kWh. Furthermore the Vitotwin can only be purchased together with a hot water tank.
Editor: Philipp Oehmgen
Tutor: Dipl.-Ing. Paul Seidel

Investigations on a Double-Quattro-MED-Plant

The paper „Investigations on a Double-Quattro-MED-Plant“ is regarding a prototype of a seawater desalination plant of small output. The prototype was developed at the “Institut für Luft- und Kältetechnik gGmbH“ and is using the method of Multi-Effect-Distillation while aiming for an application on a local level. The paper covers the impact of different parameter settings on the prototypes operational behaviour. A series of measurements were taken and analysed.		The main operating parameters are: the temperature of the heating and cooling water, the extraction of non-condensable gases, the trickling density in the heat exchangers, the seawater-feeding and the preheating of the seawater. The interrelations between these parameters and the efficiency of the plant are demonstrated. Based on the measurements the preheaters are evaluated and the plant is compared to the previous Single-Quattro-MED-Plant.
Editor: Jakob Sablowski
Tutor: Dr.-Ing. Karin Rühling

Waste heat recovery in residential buildings

Saving energy is desirable out of many reasons. A significant proportion of energy consumption in Germany and other industrial countries arise in the home. In spite of efforts to save energy, waste heat from households is being emitted unused into the environment in most cases. That is why the present study will show different ways to reuse this energy practically within the building. The focus is on recovery in conjunction with a ventilation system.		For this example the actual energy savings will be shown by a model building and by using a simulation programme. Possible developments in house building will be considered due to the influence of various insulation measures. Furthermore, an assessment of the possible use of thermoelectric heating and cooling systems is made. The present study will show that heat recovery offers a great potential for energy savings. Heat recovery in conjunction with a ventilation system makes the use of alternative heating and cooling systems such as Peltier elements possible in the future.
Editor: Katharina Huck
Tutor: Dr.-Ing. Ralf Gritzki

Full Cost Analysis of Micro-CHP Systems

The use of CHP systems currently represents an attractive technology for heating and power generation, which enjoys great popularity even in private residences. While it is currently common practice to use a micro-CHP in smaller residences in conjunction with a boiler, this study investigates the economy of monovalent operating systems. The key point is a developed Excel-tool which makes it possible to calculate the profitability of different micro-CHP systems under varying conditions. After an overview of the technological fundamentals,		the economic impacts of individual components will be shown under various conditions at a range of CHP systems. Researched charges and technical datas of micro-CHP systems available in Germany will serve as a basis. Afterwards, the environmental aspects of monovalent operating CHP systems operation will be regarded. Finally, a manual enables the user to determine the economics of available CHP systems under individual conditions. This study shows that the monovalent operation of a micro-CHP can be ecologically as well as economically profitable under certain conditions.
Editor: Andreas Meurer
Tutor: Dr.-Ing. habil. Joachim Seifert

Cost effective energy supply for Inno-Park Kitzingen including renewable energy generation structures

During the renovation of a multipurpose building in the Innovation-Park Kitzingen, its energy supply is to be changed. The building has a current demand of around 290.000 kWh and about 2.270.000 kWh of heat requirement per year. It is scheduled to build a "double-hybrid-system" for base load supply: This includes a combination of photovoltaic, a combined heat and power plant, electrochemical and thermal storages. For peak load supply there is a conventional connection to the local power grid and a gas fired condensing boiler. In this work, a MATLAB ® program was developed that simulates and optimizes the operation of all interacting components. The intention is to get an optimal designed system, in which both, the economy and the share of renewable energy, are decisive. The necessary boundary conditions for the simulation were researched and calculated in advance. The heat demand is estimated by a simplified method according to DIN EN 12831 and determines an annual course in hourly intervals, by a static calculation with the data of the test reference year of the german weather service.		The current requirement results from standard load profiles of the “Bundesverband der Energie- und Wasserwirtschaft“. In addition, a photovoltaic profile was created by using radiation data from the NASA and the efficiency of the proposed photovoltaic module. Based on these data, the operation can be simulated and thus the costs per year can be calculated. These costs consist of: costs for natural gas costs for purchased electricity depreciation costs for PV, battery, cogeneration unit and condensing boiler potential feed-in compensation The bottom line is that a tool was created, which allows to easily compare different system configurations to optimize the design of the system.
Editor: Martin Arndt
Tutor: Prof. Dr.-Ing. Clemens Felsmann

Basics and possible applications of DEC air conditioning systems – a preparation for teaching

The subject of the thesis is the study of DEC air conditioners (Desiccant and Evaporative Cooling) also known as sorption-supported air conditioning. The special feature of this type of system is that no compression or adsorption chillers are needed for air-cooling. Supply air temperatures from 18 to 20 °C are reached using the thermodynamic process of air drying and air humidification (evaporative cooling) in combination with heat recovery depending on system design. A very important component is the sorption rotor. The drying of the intake air takes place by absorption or adsorption through the structural design. The lower the moisture content of the intake air, the more optimally and economically a DEC air conditioner works. Generally this type of technology is more dependent on the atmospheric weather than conventional air conditioners.		At absolute outside air moisture values greater than 12 - 13 g/kg, a typical relative ambient air humidity of 50 % is no longer feasible. Because the regeneration temperatures of the sorption rotor are higher than in the "normal" air conditioner heater battery and the amount of heat energy in DEC air conditioners is greater than in conventional air conditions, the regeneration determines the economic efficiency to a large extent. Energy cost savings from 20 to 40 % can, however, be obtained. Due to the increased amounts of heat energy for the regeneration, fuels low in CO2, waste heat or regenerative heat sources are favoured for environmental reasons. As a rule, low ambient air humidity levels of up to approx. 2 - 3 g/kg positively impact the use of DEC air conditioners. The higher the ambient air humidity levels or the greater the regeneration is, the more critical the use of DEC air conditioners is.
Editor: Boris Talarczak
Tutor: Dr.-Ing. habil. Joachim Seifert, Dr.-Ing. Markus Rösler

upgrading of testing devices for simulation of loads of solar-thermal collectors

The interdisciplinary project work (kleiner Beleg) 'upgrading of testing devices for simulation of loads of solar-thermal collectors' considers the revision of two pneumatically operated testing devices for the simulation of mechanical loads of solar thermals collectors and components in the laboratory of Bosch Solarthermie GmbH in Wettringen. It is one testing device for internal validation of the quality of transparent collector covers (Glasbruchteststand) and one test		station for simulation of snow and wind loads on solar thermal collectors and their fixing elements according to DIN 1055 and DIN EN 1991 (Belastungsteststand). Both testing devices were revised with regard to digital control and digital data measurement using the existing control and measuremental software of Delphin Technology Corp., as well as improving the security and individual mechanical components with accomplishing the requirements.
Editor: Max Bachmann
Tutor: Dr.-Ing. Karin Rühling

Analysis of transient fluid behaviour in the triple duct district heating system of the Vattenfall Wärme AG utilizing the computer program DRUCKSTOSS

This thesis focuses on the transient hydraulic behaviour of district heating systems. Hydraulic shock waves, also known as water hammers, are characterised, concerning the circumstances of their emergence, their propagation in pipe systems, as well as a mathematical description of the phenomenon. Solutions for water hammer related problems are displayed.		The fundamental theories on this topic are used to validate the software DRUCKSTOSS. Different examples give an introduction to the modelling of pipe networks. On the basis of that, different pump malfunctions in the triple duct district heating system in Berlin are analysed. As a result, measures to ensure the functionality of the system are recommended.
Editor: Kristian Sieber
Tutor: Dr.-Ing. Stefan Gnüchtel

Operating behaviour of hydraulic integrated networks

In this diploma thesis, a methodology is developed in order to measure, illustrate and describe the static hydraulic operating behaviour of district heating networks with multiple feeds (integrated district heating network). The models created with this method permit the efficient analysis of modified operating regimes of integrated district heating networks. The reader is introduced to the fundamentals of how to operate district heating networks, focussing on the hydraulics of integrated networks. The operating behaviour of district heating networks is simulated on the network calculation software sisHYD using models of existing 2- and 3-pipe-systems. A macro for Microsoft Excel was developed in order to automate sisHYD. The operating behaviour is illustrated by heating network diagrams.		The methodology reveals the limitations on operating hydraulic components within an integrated network. This is used to derive at which operating state the utilisation of additional pumping stations and power plants becomes necessary due to the hydraulic restrictions. Analysing the results makes it possible to evaluate the influence of both adjusted flow temperature and decreased return temperature on the annual auxiliary energy demand which is necessary to transport the district heating water. Furthermore, the possibility to balance broken-down pumping stations through a raise of flow temperature is discussed.
Editor: Jens Unterseher
Tutor: Dr.-Ing. Stefan Gnüchtel

Compilation of a measurement concept for the investigation of the energy saving in buildings

The German government is currently pushing to save energy in buildings. Within the scope of this thesis a measurement concept is developed which makes it possible to identify potential energy savings in buildings. For this purpose the heat balance of a room is investigated and the most important parameters of the heat flows are summarized. In order to do this, the data logging system must meet many requirements, which are defined and are assigned to the different criteria of significance of the result, user friendliness, mistake behavior and robustness.		Current research about data logging systems reveals that different measurement systems exist. However, their requirements and scope of parameters differs immensely. A system which can measure all parameters and meet all defined requirements is currently not available on the market. This thesis shows with two tests of data logging systems and their respective measurements that energy savings, the operation of the heating system and user behavior are detectable with such systems.
Editor: Markus Leibelt
Tutor: Dipl.-Ing. Jens Haupt, Dr.-Ing. habil. Joachim Seifert, Dr.-Ing. J. Ohl (Techem Energy Services)

Development of a low-noise high-performance CPU cooling unit

The Central Processing Unit (CPU) of a computer is a thermally highly strained component assembly. During the last decade the heat flux was tripled and has reached a value of 100 W/cm² by today. Because of an increasing integration level a rise of the heat flux is expected for the near future, too. Besides the difficulty to conduct such a high heat flux another problem is the annoying or even inadmissible noise emission. Aim of the ILK Dresden is the development of a new low-noise high-efficiency CPU cooling unit based on a new patent in collaboration with the German Federal Ministry of Economic and Technology.		Based on previous research results a fan unit consisting of an axial and radial fan is constructed. Additionally different options of heat sinks with integrated heat pipe systems are developed and manufactured. By the help of PIV and volume flow measurements as well as through numerical simulations all single components are adapted to each other. Finally the developed prototypes are measured thermally and fluid dynamically. Furthermore the new cooling units are evaluated and suggestions for further optimizations are found.
Editor: Sebastian John
Tutor: Dipl.-Ing. Jens Haupt

Accuracy of forecast system yields from pv simulation programs

PV simulation programs are generally used for design purposes and yield prediction of photovoltaic systems. Especially the accuracy to forecast system yields has recently gained more attention because business operations in some international PV markets are characterized by providing performance guarantees. One of the findings in the examination of two reference systems with the three programs PV*SOL, PVsyst and Space is that the underlying weather data set and the input module		characteristics have the strongest influence on the yield prediction. If these input data are not set properly, the correct setting of the other loss factors in the simulation is secondary. The inherent uncertainties in system yield prediction allow only an approximation to the real yield. To get more confidence in the results of simulation programs and more competence in the field of simulation, more resources in the field of monitoring systems and the accompanying simulations have to be provided.
Editor: Hanno Fischer
Tutor: Dr.-Ing. Karin Rühling

Optimization of Multijunction Photovoltaic Cells by using new Concepts of Back Reflectors

Inventux Technologie is a provider of micromorph solar technology. Its aim is to become one of the world’s leading providers of solar systems by offering a future-proofed serial production. In pursuance of this aim new approaches have to be developed to increase efficiency. The optimization of the solar cells’ back reflector presents an area for potential development. In the context of this project, basic parameters characterizing the effects of various back reflector materials are examined.		Optical measurements are taken with different reflector configurations to obtain the reflective, absorptive and scattering properties in detail. Based on these results, a simple model is developed to simulate the electrical effects on the tandem solar cells. The validation of the data is made using selected electrical measurement series with mini-modules. The stable parameters after the light-induced degradation are then determined. This allows for the identification of cell- and back reflector combinations that are applicable for increasing efficiency.
Editor: Tina Pausch
Tutor: Dr.-Ing. Karin Rühling

Dimensioning and Design Concepts of a small sized Multi-Effect-Heat Exchanger for MED-plants

The aim of this paper is the development of the heat exchangers for a low-power desalination plant, which works according to the process of multiple effect distillation (MED). The first part of the paper analyses the current state of the art in the field of MED-plants. Then a calculation program is developed and verified on the basis of existing data of a small MED-plant. In the next part of this paper, two new design concepts will be presented		and calculated with the program. The two new design concepts have the aim to create heat exchangers, which are smaller, more compact and thus cheaper. In the last part a series consists of four effects and a series consists of eight effects is designed for both design concepts. The series is designed for a maximum heating capacity of 100 kW and a freshwater capacity of ten cubic meters per day or more.
Editor: Thomas Dick
Tutor: Dr.-Ing. Karin Rühling

Storage technologies for the compensation of local power peaks in the electricity grid

In recent years an increasing amount of electricity production from renewable energy sources could be noticed. By the year 2020 the share of renewable sources for the electricity production shall be increased to 35 %. Already today the intermittent loads of these power generation facilities put a strain on the electricity grid. Among others this stress can be reduced by using electric energy storage systems. In the present report most of the existing storage technologies are being assessed in terms of site dependency, scalability, status, cost, safety and limitations of storage capacity and power. Thereby an overview over the current state of the art is being provided.		In addition, ranges for characteristic values typical for each type of storage, as efficiency or lifetime, are being shown. Hence, the suitability of each technology for a specific application can be deduced. Furthermore, the systems engineering effort to build a storage, based on lithium-ion, sodium-sulphur or lead acid-batteries including the necessary peripherals, is being described. Finally, the three described systems are simulated for the application to compensate deviations between predicted and actual performance of a wind turbine. The analysis facilitates a comparison of the three storage technologies with regard to the operation results and the benefits of their application.
Editor: Torsten Klemm
Tutor: Prof. Dr.-Ing. Clemens Felsmann

Evaluation of long-term field testing and anaylysis of operational data of a heat pump

With this study is a pilot heat pump, based on literature research and on the current state of heat pumps technology evaluated. This pilot heat pump was developed before by the TU Dresden. Their concept is, to reach high temperatures of drinking water by getting a good efficiency. Two heating circuits are supplied with dierent temperature levels of heat. The heat pump was installed in 2003 in a single-family house.		Due to the long-term duration are many measurements available. As a result, statements about the operational and long-term performances and about the energetic evaluation with a detailed analysis of problems and weaknesses are taken. Furthermore, a comparison of economic and ecological perception is done with other heating systems.
Editor: Stefan Thiele
Tutor: Dipl.-Ing. Steffen Robbi

2011
Technology, Application and Economy of H Rotor Wind Energy Converters

The number of installed wind power plants increases every year in the whole world. The most common known type is the three bladed horizontal axis turbine but there is also a different concept for wind turbines with vertical axis which has been studied in the 70s and is getting more and more attention in the present days. This paper deals with the a special design of the vertical axis turbine, the H-rotor and its technical and

aerodynamic advantages and disadvantages compared to horizontal axis turbine. These advantages will be discussed and lead to certain areas like cities, urban areas, mountain and regions with a lack of infrastructure where the H-rotor will be suited for. Furthermore the chances of entering these markets will be evaluated and future perspectives will be given.

Application of heat pumps in district heating systems with hydro geothermal supported supply

This project examines the application of heat pumps in district heating systems with hydro geothermal supported supply.
After an introduction in which the possible areas of application are described for geothermal energy and heat pumps, the current market situation is considered in the first section for the heat pumps which are developed for high temperatures and for high heat capacities. Some important and interesting examples are explained.

Afterwards the construction of an Excel tool which was developed to make possible the simulation of the heat supply of a district heating is explained and justified.
Furthermore several heat production possibilities are compared with the help of this program thanks to economic, energetic and ecological evaluations.
Finally fundamental recommendations for the application from heat pumps are summed up and different development perspectives are shown.

Development of an energy management system for climatisation of passenger space of a hybrid vehicle

As in all economic sectors, also the car industry is making an effort to reduce carbondioxid emission levels in order to fulfill government guidelines of pollution control. One of the means to reach this goal is the growing electrification of vehicles. The removal of the combustion engine leads to the loss of the heat source to warm up the cabin in winter. At the moment this loss is compensated by the installation of an electric auxiliary heater, which results in a dramatic decrease in range.
Within the scope of this thesis possibilities will be discussed to introduce a heat pump as the source of vehicle climate control on the basis of a luxury saloon car. Moreover, its potential will be evaluated.

The energy consumption for cabin climate control can be reduced significantly by using waste heat of aggregates and/or circulating heat.
A simulation will show a 70 percent reduction of energy requirement for cabin climate control by the reasonable use of the heat pump system. On the one hand, beneficial marginal conditions can be adjusted. On the other hand, pre-conditioning makes it possible to prepare the cabin for the travel commencement and therefore increase the passenger comfort before even starting the car.
Apart from developing the simulation model, the thesis will also draft the control system for further integration of the energy management system into a test vehicle.

Development of a Cleaning Technology for the Outer Face of Oil Coolers in Wind Energy Converters with Gear

Windpowerplants with gearbox require adapted cooling system for maintaining the
right oil temperature: special designed oil-air heat exchangers with air-fin are usually
employed for this. In order to reach the minimal required flow, a ventilator is placed
behind the exchanger and hoover the air. While the windturbine is working, the dirt
degree increases and the air-fin of the cooler get always dirtier. Besides the available
surface for the heat exchange diminisches, another potential risk is that the windpowerplant
could cut off the grid because of the too high oil temperatur that does not
allow the production of electricity anymore. Those cases are critical because they lead
to production losses, which are directly related to money troubles for the owner of the
windpark.

While the mid-year maintenance operation, a cleaning of the heat exchanger is
performed using tiny brushes, hooving and blowing under pressure air, removing big
piece of dirt. However a surface crusting is produced between the air-fin, particularly
at the bottom of the register, in wich area always new dirt settle. With the rise of this
deposit, the interval betwenn to cleaning maintenance operations get always shorter.
In order to make sure that the total surface of the heat exchanger is usable again,
the dismantling of the register is mandatory because of the current process with cleaning
baths, outside the windpowerplant. Besides the highlogistic costs (dismantiling,
transport), the standstiell of the windpowerplant is lenghtened.

Determination and evaluation of energy efficient operation modes of air conditioning systems in a computing center

Determination of the net storage power in district heating networks using linear regression

Assessment of Model Quality and Simulation of Selected Load Curves for a CHP Unit with Extraction Condensing Turbine

Technical-economical evaluation of μCHP units on the basis of fuel cells technology

System Conception and Process Design of a SOFC Unit with Reduced Operating Temperature

Exergy Analysis of a Trigeneration Unit Considering Different Temporal Resolution

The objective of this study is to assess a Combined Cooling, Heat and Power (CCHP) plant as to its exergy flows, in order to detect optimization measures as well as to analyse the use of various temporal resolutions (yearly, monthly, daily, etc.). This project shows that the major sources for exergy consumption (which combines exergy losses through e.g. emission of heat to the environment and exergy destruction through irreversible processes like friction or heat transfer) are the boilers and the cogeneration units. Taken together, they represent more than 90% of the source of exergy consumption, the rest being caused by the chillers, the heat dissipation to the environment, etc. Based on these findings, several optimisation measures are defined.

The various exergy assessments show that using different temporal resolution might be benefic for the results, as long as they are sufficiently representative for the normal working of the considered system. Exergy assessments should be conducted over a period of one year or at least over a representative period to detect and prioritise the adequate optimisation measures. Also, a detailed continuous analysis should be conducted, so that the variations in the system efficiency can be observed and additional conclusions drawn.

Economic optimization of a decentralized energy supply system initiating a virtual power plant

Collegiate Papers - Abstract

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