One-dimensional phenomenological model for liquid water flooding in cathode gas channel of a polymer electrolyte fuel cell

Abstract

The mathematical description of liquid water flooding in the gas channel (GC) of a polymer electrolyte fuel cell (PEFC) at the macro scale has remained a challenge up to now. The mist flow assumption in the GC has been commonly used in previous numerical studies. In this work, a one-dimensional (down-the-channel) macroscale phenomenological model for the liquid water flooding in the cathode GC is developed based on several reasonable assumptions. We focus on the operating conditions with fully humidified inlet air on the cathode side. Some simplifications are introduced to obtain a manageable numerical model. A series of case studies are conducted to investigate the effects of droplets and various operating parameters on the liquid water flooding in the GC. The results show that the gas drag force at the film-gas interface significantly enhances the film flow along the GC corners. Based on a proposed droplet model, we can capture key scenarios of liquid water flooding in the GC under different operating conditions like varying stoichiometry, current density and cell temperature. We find that droplets in the GC mainly contribute to the gas pressure loss and water flooding in the GC, which should be depressed for better water management. At last, a proper selection of the GC sidewall contact angle is found to be critical to a better water management in the GC