Mass transfer evaluation criteria and mechanisms in full-scale PEMFCs with collaborative flow distribution

The distribution region and flow field design of full-scale proton exchange membrane fuel cells (PEMFCs) are extremely important. This study systematically investigates the coupled effects of cathode distribution zone and flow field configurations on PEMFC performance through orthogonal simulations combining three distinct distribution zones, with four representative flow fields. A comprehensive suite of evaluation metrics was employed to evaluate mass transfer characteristics. Results demonstrate that flow field structure predominantly controls the oxygen transfer characteristics, liquid water and temperature distribution, whereas the distribution zone primarily dictates global pressure drop and parasitic power. Optimal performance is highly flow field dependent: the None configuration, which eliminates the inlet manifold entirely, achieves the highest net power density in weak convection structures such as parallel flow fields by maximizing velocity and minimizing pumping losses. In contrast, the Branch configuration maximizes the benefits of a flow field with strong ribs by enforcing flow direction. Additionally, sensitivity analysis reveals that the flow field with weak convection is significantly more dependent on the distribution zone configuration than the one with strong convection. These findings offer critical insights for the matching design of flow field and distribution zones, while providing guidelines for the synergistic design of bipolar plates in high-performance full-scale PEMFCs.