Two-dimensional pseudo-phase-equilibrium approach on the cathode gas diffusion layer of proton exchange membrane fuel cell under varying degrees of humidiflcation

摘要

We propose a novel 2D water management for cathodes of proton exchange membrane fuel cells (PEMFCs). A pseudo-phase-equilibrium function is incorporated to the model to relate the vapor fraction to the liquid water within the cathode gas diffusion layer, so that explicit tracking of the liquid water front between the single phase and two-phase domains becomes completely unnecessary. In the proposed model, liquid water transport in the porous medium is governed by the capillary pressure gradient, whereas the multi-component gas transports of oxygen, nitrogen, and water vapor are described using the Stefan-Maxwell equations. The effects of the gas diffusion layer thickness, porosity, temperature, pressure, and varying degrees of feed humidification are investigated. In addition to the steady-state performance, the dynamic response is computed for a detailed exploration of both the oxygen diffusion and the transient water imbibition and drainage. It concludes that the proposed method can be successfully applied to the two-phase fuel cell models in 2D geometry for both the steady-state and dynamic analyses.