Nov 20, 2025
Successful promotion of Johannes Manthey - congratulations!
Johannes Manthey (in the middle with hat), surrounded by colleagues, friends and family after successfully defending his dissertation.
On November 7, 2025, Dipl.-Ing. Johannes Manthey from the Chair of Energy Process Engineering defended his dissertation entitled "Bubble formation due to supersaturation in the cooling circuit of PEM electrolysis" with great success.
The thesis was supervised and reviewed by Prof. Dr.-Ing. Michael Beckmann (TU Dresden). Prof. Dr.-Ing. Michael Schlüter (TU Hamburg) acted as second reviewer; the examination committee was chaired by Prof. Dr. Cornelia Breitkopf (TU Dresden).
Mr. Manthey received his doctorate with the top grade of 1.0 - his thesis was also awarded summa cum laude. The examination committee particularly praised his excellent technical understanding, his in-depth theoretical and practical knowledge, his conscientious literature research and his clear and lively presentation style. With his calm and competent manner, he confidently answered all of the committee's questions and also impressed them with his comprehensive expertise in the field of electrolysis technology.
In his dissertation, Johannes Manthey investigated the formation of gas bubbles due to oxygen supersaturation in the cooling circuit of PEM electrolysis systems. As oxygen is present both in gaseous form and dissolved in the process water during hydrogen production at the anode, bubbles can form in the pipes - a phenomenon that has a significant impact on heat and mass transfer. The aim of the work was to quantitatively predict the time- and length-dependent decrease in supersaturation and thus the development of a two-phase flow between the stack and the gas separator.
Based on theoretical models and experimental investigations, Mr. Manthey developed a comprehensive cell model that describes all steps of bubble formation - from nucleation, growth and coalescence to detachment in the flow.
Measurements on a specially constructed modular test rig confirmed the model assumptions and provided valuable insights into desorption kinetics and flow characteristics. The results show that equilibrium assumptions without consideration of the kinetics of bubble formation can lead to incorrect dimensioning of technical systems - an important contribution to the optimized design of PEM electrolysis cooling circuits and other two-phase flow systems.
In addition to the examination board, numerous colleagues from the Chair of Energy Process Engineering, family members and friends were also present to witness and celebrate this important milestone together.
We would like to congratulate the future Dr.-Ing. Johannes Manthey on this outstanding scientific achievement and wish him all the best for his professional and personal future, much success and, of course, joy in the challenges ahead!