Implications of non-uniform porosity distribution in gas diffusion layer on the performance of a high temperature PEM fuel cell

Abstract

The present study discusses a detailed investigation on the implications of non-uniform porosity distribution in the gas diffusion layer (GDL) on the performance of proton exchange membrane fuel cell (PEMFC). A three-dimensional, single-phase, isothermal model of high-temperature PEMFC is employed to study the effect of non-uniform porosity distribution in GDL. The different porosity configurations with stepwise, sinusoidal, and logarithmic variation in porosity along the streamwise direction of GDL are considered. The numerical experiments are performed, keeping average porosity as constant in the GDL. The electrochemical characteristics such as the oxygen molar concentration, power density, current density, total power dissipation density, average diffusion coefficient, vorticity magnitude, and overpotential are studied for a range of porosity distributions. Furthermore, the variations of oxygen concentration, average diffusion coefficient, and vorticity magnitude are also discussed to showcase the influence of non-uniform porosity distribution. Our study reveals that the PEM fuel cell performance is the best when the porosity of the GDL decreases logarithmically in the streamwise direction. On the contrary, the performance deteriorates when the GDL porosity decreases sinusoidally. Also, it has been observed that the effects of non-uniform porosity distribution are more pronounced, especially at higher current densities. The outcomes of present investigation have potential utility in GDL fabrication and membrane assembly's sintering process for manufacturing high valued PEMFC products.