Coordinated design of manifolds and branch channels for improving flow distribution and temperature uniformity in PEM water electrolyzers

Flow maldistribution in parallel flow fields can cause temperature nonuniformity in PEM water electrolyzers under high current density operation. A three-dimensional multiphysics model including inlet and outlet manifolds is developed to investigate the coupling between manifold induced flow maldistribution and anode membrane surface temperature distribution. A branch channel reconstruction method based on cubic splines is proposed to redistribute local hydraulic resistance. In the baseline flow field, increasing the manifold width from 1.0 to 3.0 mm reduces the coefficient of variation of branch channel mass flow rates from 0.83 to 0.25 and decreases the maximum membrane surface temperature from 367.36 to 363.53 K. After optimization, central channels are widened and side channels are narrowed to improve water supply to underfed regions. The largest improvement in temperature uniformity reaches 21.1%, and the lowest optimized temperature standard deviation is 1.51 K at 2.5 mm. The optimized design maintains comparable polarization performance.