Numerical study on bubbly flow in alkaline water electrolysis

Green hydrogen is considered a promising energy carrier for storing renewable energy such as solar and wind energy. Alkaline water electrolysis (AWE), one of the methods for producing green hydrogen, has been widely studied due to its characteristics of simple structure and low-cost electrode materials. In AWE, hydrogen bubbles generated at cathode increase electrical resistance, reducing the efficiency of water electrolysis and causing irregular hydrogen production. Despite several studies of hydrogen bubble formation in AWE, a comprehensive predictive model for electrolysis efficiency of AWE involving the interaction between potential field and bubble flow is lacking in the literature. In this work, we develop a numerical model to investigate the hydrogen bubble flow in alkaline water electrolysis using OpenFOAM. The two-fluid model for the continuous KOH electrolyte phase and the disperse hydrogen bubble phase is combined with a charge conservation equation for the electric potential. The numerical model is validated with the experimental results from the literature. We analyze the interaction between current and bubble distribution and investigate its effect on water electrolysis efficiency.