A two-dimensional two-phase model of a PEM fuel cell

A two-dimensional, two-phase, steady-state, isothermal model was developed for a fuel cell region consisting of the catalyst and gas diffusion layers bonded to a proton exchange membrane (PEM). This model extends the previously published one-dimensional model of the gas diffusion and catalyst layers to two dimensions in order to account for the effects of the shoulder of the gas distributor and the electronic conductivity of the solid phase. The new model was validated with experimental results and then used to investigate the effect of the relative dimensions of the shoulders and channels on the cell performance. The effects of the in-plane liquid water permeability and electronic conductivity of the gas diffusion layer on cell performance were also examined. It was found that more channels, smaller shoulder widths on the gas distributor, and higher in-plane water permeability of the gas diffusion layer can enhance the transport of liquid water and oxygen, leading to better cell performance. The in-plane electronic conductivity of the gas diffusion layer was found to have minimal effect on the cell performance. However, a highly nonuniform distribution of electronic current was formed within the gas diffusion and catalyst layers when the in-plane electronic conductivity was low. (c) 2006 The Electrochemical Society.