Summary In proton exchange membrane fuel cells, baffled flow channels enhance the reactant transfer from flow channels to gas diffusion layers. However, the reactant transfer depends on both the diffusive transfer and convective transfer, and how the baffles in flow channels affect them is still unknown. Therefore, in this work, a two‐dimensional, two‐phase, nonisothermal, and steady‐state model of proton exchange membrane fuel cells is developed, and these two transfer processes from flow channels to gas diffusion layers are comparatively studied. Simulation results show that first of all, the reactant transfer from flow channels to gas diffusion layers mainly depends on the diffusive transfer. Therefore, if the desire is to enhance the mass transfer from flow channels to gas diffusion layers, the diffusive mass transfer should be enhanced firstly. Being guided by this goal, a porous‐blocked baffled flow channel is developed. This flow channel design can further enhance the reactant transfer from flow channels to gas diffusion layers, and the cell performance can be improved. Moreover, when the porosities of porous blocks at the front place of flow channels are lower, the cell power is also increased but the pumping power can be reduced a lot.

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Summary In proton exchange membrane fuel cells, baffled flow channels can enhance the reactant transfer and improve the cell performance. Many different baffled flow channels have been numerically studied in previous published papers. However, what kind of baffled flow channels can improve the cell performance most is still unknown. In this simulation work, a two‐dimensional, two‐phase, nonisothermal, and steady‐state model of proton exchange membrane fuel cells is developed. The mass transfer and cell performance of PEMFCs with different baffled flow channels have been numerically compared. Simulation results show that the rectangular baffle can enhance the reactant transfer most and improve the cell performance most; however, the power loss in rectangular baffled flow channel is also the highest. To inherit the advantages and overcome the shortages of the rectangular baffled flow channel, an optimized baffled flow channel is developed. In this newly developed baffled flow channel, the windward side is designed as the streamline shape and the leeward side is designed as the sloped shape. Results of the simulation also show that the optimized baffled flow channel can reduce the power loss accounted by the pumping power in reactant delivering process and the cell performance can be further improved.

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Summary The transfer processes of reactants and products affect each other in proton exchange membrane fuel cells (PEMFCs), because they have contrast transfer directions between flow channels and gas diffusion layers (GDLs). In this study, a two‐dimensional, two‐phase, non‐isothermal and steady state model is developed to analyze the species transportation behaviors through diffusion and convection in PEMFCs with orientated‐type flow channels. Five conventional shape baffles effects on mass transfers are compared, and the relationships between convection and diffusion of reactants and produced water vapor are discussed. Simulation results reveal that baffle shapes affect the mass transportation through the baffles leading angles and volumes, and larger leading angles enhance the reactants and the water vapor convective transferring into GDLs; meanwhile, larger baffle volumes enhance the reactant transferring into GDLs and water vapor transferring out from GDLs through diffusion processes. In addition, transportation processes of reactants and vapor affect each other, where more reactants convectively transferring into GDLs causes more water vapor entering GDLs; enhancing the reactants diffusively transferring into GDLs reduces water vapor diffusive transportation out from GDLs.