Numerical study of carbon monoxide poisoning effect on high temperature PEMFCs based on an elementary reaction kinetics coupled electrochemical reaction model

Abstract

High-temperature proton exchange membrane fuel cells have received lots of attention due to their high tolerance of impurities in the fuel gas. Many researchers have conducted experimental and numerical investigations to study the influence of carbon monoxide on performance of the high-temperature proton exchange membrane fuel cell. However, most numerical models use an empirical formula to consider the effect of adsorption and desorption of hydrogen and carbon monoxide. To more accurately study the influence mechanism of carbon monoxide as an impurity, a novel three-dimensional non-isothermal model considering elementary reactions of hydrogen and carbon monoxide for high-temperature proton exchange membrane fuel cells is developed in this study. The elementary reaction kinetics of the anodic catalytic layer adopts a six-step global reaction, and the adsorption processes, desorption processes, as well as electrochemical reactions are taken into account. This model is able to accurately predict the steady polarization curve of a high-temperature proton exchange membrane fuel cell fed by hydrogen containing different amounts of carbon monoxide. The sensitivities of elementary reaction rates in the voltage range of 0.4–0.9 V for the fuel cell fed by pure hydrogen or a mixture of hydrogen and carbon monoxide are analyzed. The rate-determination step is studied at different voltages. In addition, the distributions of gaseous species, surface species and reaction rates of all elementary reactions along different directions of the anode catalytic layer are presented. Finally, the influences of carbon monoxide content in the fuel gas and the operating temperature of a high-temperature proton exchange membrane fuel cell fed by a mixture of hydrogen and carbon monoxide are numerically studied.