Effect of operating conditions and geometric structure on the gas crossover in PEM fuel cell

Abstract

Gas crossover is an unavoidable phenomenon in proton exchange membrane fuel cells. Gas crossover leads to heat and water generations without conducting any useful works, hence increasing fuel consumption. Particularly, Gas crossover can result in the degradation and formation of pinholes inside the membrane. Therefore, the gas crossover is a critical factor significantly affecting the durability of a fuel cell and quality of the membrane. Herein, we numerically investigate the effects of gas crossover across the membrane in a proton exchange membrane fuel cell. A two-dimensional, two-phase, steady state model of the gas crossover using the partial differential equation solver FreeFem++, was built to investigate the crossover characteristics of hydrogen and oxygen across the membrane versus changes in operating conditions and various geometric structure of components in the proton exchange membrane fuel cell. Results indicated that higher equivalent weight of Nafion® is required to significantly decrease gas crossover phenomenon while the cell performance was reduced negligibly. In addition, as the increase in the stoichiometric flow ratio and channel length, the gas crossover decreased and the cell performance improved.