Influence of flow field configurations on electrochemical performance and hydrogen crossover in zero-gap alkaline water electrolysis stacks

A multiphase flow-based 3D model was developed to evaluate six flow field configurations, metal foam, parallel, three-channel serpentine, five-channel serpentine, pin, and zigzag pin, in alkaline water electrolysis (AWE) cells. Key performance metrics, including pressure drop, hydrogen crossover, temperature distribution, gas fraction, and the uniformity of current density distribution, were systematically compared. The metal foam design achieved superior bubble removal, temperature uniformity, and the most uniform current density distribution, but at the cost of high flow resistance and elevated hydrogen crossover from the negative to the positive electrode. Pin and zigzag pin designs minimized pressure drop and hydrogen crossover but exhibited higher local gas fractions, elevated temperatures, and reduced current density uniformity, while delivering higher cell voltages at 2 A cm⁻² due to enhanced OH⁻ diffusivity in high-temperature regions. Serpentine configurations provided a balanced compromise between flow resistance, bubble removal, and thermal management. These results reveal a fundamental trade-off between hydraulic losses, gas removal efficiency, thermal management, and electrochemical performance, offering practical guidelines for optimizing AWE flow field design to enhance both efficiency and durability.