Detecting and modeling oxygen bubble evolution and detachment in proton exchange membrane water electrolyzers

In this work, we discuss the effect of multiphase flow dynamics on the performance of a PEM electrolyzer. We obtained images of a flow system consisting of O2 and water at two stages of gas production: gas evolution via bubbles and gas exiting through the channels of a flow field. We processed the obtained images of bubble evolution with a MATLAB-based bubble detection and counting algorithm, and we found that the bubble detachment sizes remained invariant within a water flow range between 0.07 and 4.65 l h−1. We measured an average bubble detachment radius of 22.47 μm. We applied a bubble force balance developed by van Helden et al. [1] to model the observed effect of water flow on bubble evolution, and we found that the bubble detachment radius is a weak function of water flow when the water flow is below 60 l h−1. We found that the variables that affect the bubble detachment radius the strongest were the electrode's hydrophobicity and pore size.