Enhanced Pressure‐Driven Mass Transfer With Staggered Constrictions in Proton Exchange Membrane Fuel Cells

ABSTRACT A simple staggered constriction design is demonstrated to be effective to improve the substance distribution uniformity of bipolar plate of proton exchange membrane fuel cells (PEMFCs), yet the optimal design is limited by the geometry parameters such as the constriction width. In this study, the impacts of staggered constriction designs on PEMFCs performance were investigated using a 3D multiphysics numerical simulation model. The research focuses on the relationship between constriction geometry (width and number) and key performance metrics, including current density, pressure drop, and net power output. Results show that a constriction width of 0.4 mm optimally balances mass transfer enhancement and pressure loss, achieving an 8.4% increase in current density and a 9.3% improvement in net power output at 0.4 V compared to traditional straight channels. It is revealed that the constriction design induces pressure difference between adjacent channels and thereby enhances lateral mass transfer, positively correlating with oxygen content and current density while negatively correlating with water content, thereby achieving high output performance. Moreover, increasing the number of constrictions improves current density uniformity but leads to higher pressure drop losses, limiting net power output. The sub‐rib convection resistance ratio ( R c / R b ) with an optimal value of 0.1 is recommended as a scalable index to guide cathode‐side channel design across various fuel cell sizes, conditions, and materials.