Numerical modeling of two-phase flow considering multiple bubble sizes in an alkaline water electrolyzer

Precise bubble flow description is crucial for predicting water electrolysis performance. This study employs the Euler-Euler model to simulate bubble flow in an alkaline water electrolysis cell, categorizing the dispersed gas bubble phase into three size classes: 30 (small), 90 (medium), and 270 (large). The volume fraction and velocity fields for each size class were simulated across three current densities, revealing distinct flow patterns: large bubbles exited directly through the outlet, while smaller bubbles were carried along by the circulating liquid. The simulated flow fields were compared with experimentally visualized flow fields, validating the model. Finally, the proposed model demonstrated its advantages over existing models, such as the monodispersed model and the population balance model (PBM), particularly in terms of upward flow velocity near the electrode and bubble descending height in the downward flow. • Bubble transport simulation in an alkaline water electrolyzer was developed. • Multiple bubble size classes were considered within the framework of the Euler model. • Each size class has its own distinct velocity and volume fraction fields. • Simulated bubble flow fields were compared to experimentally visualized images. • The importance of considering multiple size classes was demonstrated.