In the paper, a two-phase, one-dimensional steady model of a proton exchange membrane fuel cell is developed for the porous cathode electrode. The interacted phenomena of cathode flooding and mass-transport limiting are investigated. In the model, the catalyst layer is treated as a separate computational domain with finite thickness and structure. Furthermore, through the Tafel kinetics, the mass transport processes of oxygen and liquid water are coupled. The transport of liquid water across the porous electrode is driven by the capillary force based on the Darcy’s law. However, the transport of gas is driven by the concentration gradient based on the Fick’s law. From the simulated results, it is found that the thin catalyst layer is very detriment for better understanding of the concurrent phenomena inside the electrode of a fuel cell, particularly, the flooding phenomena. More importantly, the saturation-level jump at the gas diffusion layer and catalyst layer interface is attained in order to satisfy the continuity of the capillary pressure on both sides of the GDL and CL interface. Meanwhile, the results show that the flooding phenomenon within the CL is more serious than that in the GDL, which has a significant influence on the mass transport of oxygen. Finally, the effect of some important parameters, such as the boundary value of saturation, absolute permeability, the cathode surface overpotential, on the saturation distribution inside the electrode is also obtained.

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