A study of thermal effects in a proton exchange membrane fuel cell with a two-fluid model

Abstract

Papers presented to the 11th International Conference on Heat Transfer, Fluid Mechanics and Thermodynamics, South Africa, 20-23 July 2015.Proton exchange membrane fuel cells (PEMFC) are considered a key future technology for both automotive and stationary applications. At high current densities the performance curve of a PEMFC deviates from the linear region where the cell losses are dominated by the ohmic resistance, and the cell performance deteriorates rapidly. This phenomenon has often been assigned to mass transport losses because conventional fuel cells rely on diffusion of the reactants to reach the catalyst layers. This study will investigate the role of thermal properties on expected cell performance in general and on the membrane hydration level in particular. The two key thermal properties that have been investigated in detail in this study are the thermal conductivity of the porous gas diffusion layers k, and the thermal contact resistance between the gas diffusion layer and the bipolar plates. At a high current density of 1.0 A/cm2 the difference in the average predicted membrane hydration level varies from  = 8.92 for the best case to a value down to  = 7.73 for the worst case. The difference in the predicted maximum temperature in the cell is more severe. The main conclusion is that it is highly recommended to use dense gas diffusion media with lower porosity but higher thermal conductivity when employing the interdigitated flow field.