Congratulations on the defense of Guanghao Jiao's diploma thesis

On December 13, 2023, Guanghao Jiao successfully defended his diploma thesis at our chair with the topic "Experimental Study on Bubble Flows through Open-Porous Foams by Radiographic Imaging".

Proton exchange membrane water electrolyzer (PEMWE) is a highly potential and future-oriented equipment for hydrogen production. During its operation, gas hydrogen, oxygen and liquid water are all transported through the porous transport layer, and the gas-liquid two-phase flow transportation is a key factor for the performance of a PEMWE. However, the gas-liquid two-phase flow with a liquid fraction of up to 50% through the porous transport layer is not well-researched yet. This thesis aimed to study this flow through the open-porous foam in a model measurement cell. The non-invasion techniques of X-ray and neutron radiographic imaging were employed to visualize the flow condition. An algorithm was developed and tracks the moving bubbles and provides information on bubble velocities and bubble trajectories. The bubbles were found to have preferred paths through the foam. The bubble terminal velocity in the foam is generally lowest, compared with the theoretical solution of a single freely rising bubble and the terminal velocity of rising bubbles in bubble chains. The bubble velocities and trajectories were characterized by several experimental parameters. The relationship between the bubble diameter and the pore size was found to be significant for bubble behaviors through the foam. The impact of the air flow rate and nozzle size on the bubble behaviors is less significant. Further investigation on the effect of the material of the foam on the flow behavior was suggested.