Effects of Irregular “Bump-Type” Gas Distribution Zones and Cooling Channels on Mass Transport in Proton Exchange Membrane Fuel Cells

Abstract

Proton exchange membrane fuel cells are often constrained by nonuniform reactant distribution, liquid–water accumulation, and localized heat build-up during full-scale single-cell operation. To clarify the coupled effects of mass transfer, water management, and thermal regulation, a three-dimensional multiphase numerical model incorporating an irregular bump-type gas distribution zone (GDZ) is developed for full-plate-scale flow-field analysis. Reactant-transport analysis indicates that anode-side hydrogen is progressively consumed along the flow direction, while concentration differences among adjacent channels remain relatively small. In contrast, cathode-side oxygen shows more pronounced lateral maldistribution because of its lower effective concentration, greater diffusion resistance, and product-water accumulation, with the concentration deviation increasing from 2.45% at 20 mm to 5.45% at 80 mm. Liquid water accumulates downstream and preferentially stagnates in low-velocity channels and the outlet GDZ, indicating weakened drainage and intensified oxygen starvation. Forced-convection cooling improves output performance, whereas a realistic cooling-water boundary reduces net power density by only about 0.5%. Moreover, coflow of coolant and oxygen better coordinates heat removal and outlet drainage, increasing the cell voltage to 0.6013 V, with a maximum improvement of 0.69%.