Mass transport and distribution characteristics in proton exchange membrane fuel cells with innovative flow-guiding square-array gas distribution zones and multichannel straight-flow-fields bipolar plate for gases and coolant

Proton exchange membrane fuel cells are promising clean-energy devices, yet their performance and durability are limited by nonuniform reactant transport, water accumulation, and thermal imbalance, especially at high loads. To address these coupled issues, a three-dimensional multiphase multiphysics model is developed with a hierarchical bifurcating anode distribution zone, a cathode distribution zone containing square-array cooperative flow-guiding blocks, and bilateral cooling channels. Results show that reactant consumption and downstream water accumulation progressively worsen flow maldistribution and mass-transfer resistance, with cathode oxygen transport becoming the dominant limitation. Increasing pressure enhances catalyst-layer reactant availability and membrane hydration, but excessive pressurization intensifies downstream depletion, reaction nonuniformity, and pumping losses; thus, 2.0 atm offers a favorable performance-energy-consumption compromise. Under elevated pressure, increasing current density initially improves membrane hydration, whereas further loading causes severe reactant depletion, local dehydration, and heat accumulation, with net power density peaking at 1.5 A·cm −2 . Counter-flow operation only slightly changes average current density but creates complementary reactant-concentration gradients that improve electrochemical-reaction and membrane-hydration uniformity. With bilateral cooling, aligning coolant flow on both sides with the oxygen-flow direction better matches cathode thermal loading, promotes downstream water removal, suppresses local overheating, and preserves membrane hydration. Overall, coordinated regulation of reactant redistribution, water transport, pressure, load, and cooling strategy is essential for improving cell performance and spatial uniformity, providing a theoretical basis for integrated flow-field and thermal-management optimization.