Theoretical Prediction of Optimal Operating Conditions for Polymer Electrolyte Fuel Cells

Abstract

Comprehensive analytical models focusing on the anode water loss, the cathode flooding, water equilibrium, and water management strategy are developed for polymer electrolyte fuel cells. Along-the-channel locations of membrane/electrode interfaces characterizing the anode water loss and the cathode flooding, and the water activity at the channel outlets based on the continuous stirred fuel cell reactor (CSFCR) model are theoretically predicted to gain more theoretical insight into water transport in a fuel cell power system. Analytical solutions presented in this study are compared with two-dimensional computational results and shows a good agreement in predicting those critical characteristics of water. General features of water concentration profile as a function of membrane thickness and current density are presented to illustrate the net effect of the back-diffusion of water from the cathode to anode and the water production by the cathode catalytic reaction on water transport over a fuel cell domain. As one of practical applications, the required humidity level of feed streams for full saturation at the channel outlets are investigated as a function of the physical operating condition with a gradual temperature increase in the coolant