NUMERICAL COMPUTATION OF MULTI-COMPONENT TWO-PHASE FLOW IN CATHODE OF PEM FUEL CELLS

Abstract

A two-dimensional, unsteady, isothermal and two-phase flow of reactant-product mixture in the air- side electrode of proton exchange membrane fuel cells (PEMFC) is studied numerically in the present study. The mixture is composed of oxygen, nitrogen, liquid water and water vapor. The governing equations are two species conservation, a single momentum equation for mobile mixture, liquid mass conservation, and the whole mixture mass conservation. In this study, liquid mass conservation is used to calculate the saturation, so, the effect of liquid phase velocity and also saturation at previous time step are accounted in calculating the next time step saturation. The capillary pressure was used to express the slip velocity between the phases. The strongly coupled equations are solved using the finite volume SIMPLER scheme of Patankar (1984). The computational domain consists of an open area (gas delivery channel), and a porous Gas Diffusion Layer (GDL). A single set of governing equations are solved for both sub domains with respect to each sub domain property. The comparison between the numerical current density and that of experimental (Ticianelli et al.(1988)) shows a good agreement.