The mass transport characteristics and performance improvement with the nonuniform block flow channel in a proton exchange membrane fuel cell

The gas flow field significantly impacts the output power of proton exchange membrane fuel cells (PEMFCs). A nonuniform design is developed in this study to optimize the arrangement of blocks in the flow field, thereby enhancing PEMFC output power. Numerical simulations indicate nonuniform block arrangements significantly enhancing mass transfer performance compared to uniform arrangements. Under 0.4 V working voltage, the new design has increased power density by 4.84%. The flow field with three blocks positioned near the outlet effectively leverages the entrance effect and disrupts the thicker boundary layer. This improvement in mass transfer increases the reactant concentration in the catalyst layer, enhancing the reaction process. The efficiency of liquid water transport has also been enhanced by blocks near the flow field outlet, helping to mitigate water flooding. The impact of varying block arrangements and quantities on gas flow resistance is assessed through pumping power of cathode. Results indicate that for the same number of blocks, the pumping power remains identical in both uniform and nonuniform flow fields. With the same rear block arrangement, increasing the number of blocks significantly raises pumping power. As the block count increases from 3 to 7, the pumping power increases by as much as 64.7%. However, the change in current density is not significant. Therefore, adopting a nonuniform block arrangement in the flow field is a simple yet effective strategy to enhance PEMFC performance.