A nested convection-enhanced serpentine flow field for improving multi-physics distributions in large-scale proton exchange membrane electrolyzers

The flow field, serving as the primary region for water and gas management, directly affects the multi-physics distributions and electrolysis efficiency of proton exchange membrane (PEM) electrolyzers. In this work, a nested convection-enhanced serpentine flow field (NCESFF) is proposed for large-scale PEM electrolyzers. A three-dimensional, two-phase, non-isothermal model is employed to simulate the flow characteristics, multi-physics distributions, and electrolysis performance under different flow field configurations, thereby providing a comprehensive evaluation of the performance improvements achieved by NCESFF. The results reveal that the nested architecture enables efficient water supply and rapid gas bubble removal across all regions, while the convection-enhanced serpentine structure induces in-plane forced convection to strengthen mass transport within the electrolyzers. Compared with conventional multi-serpentine flow field (MSFF) and multi-parallel flow field (MPFF), NCESFF effectively suppresses gas accumulation beneath the ribs, reduces in-plane temperature variations, and improves the uniformity of liquid saturation by 5.02% and 10.51%, as well as temperature distribution uniformity by 17.76% and 19.91%, respectively. Moreover, the evolution of current density in large-scale PEM electrolyzers is revealed, showing that at low voltages the current density distribution is mainly governed by the liquid saturation distribution, while at higher voltages it is progressively dominated by the temperature distribution. Across different voltages, NCESFF consistently demonstrates superior current density uniformity and enhanced electrolysis efficiency.