Mathematical model of a PEM fuel cell incorporating CO poisoning and O>SUB align=right>>SMALL>2>/SMALL>>/SUB> (air) bleeding

A one-dimensional mathematical model has been developed for a fully hydrated and isothermal PEM fuel cell. Mass transport in the gas flow channels, electrode backing and catalyst layers is accounted for, along with the adsorption, desorption and electro-oxidation of hydrogen and carbon monoxide. Additionally, the heterogeneous catalysis of hydrogen and carbon monoxide with oxygen is included for the simulation of oxygen or air bleeding. The model prediction agrees well with published, experimental data at various temperatures, pressures and carbon monoxide concentrations. Simulations with oxygen and air bleeding indicate that a threshold amount of oxygen or air bleeding exists; any increase in the amount of bleeding above the threshold amount results in no further mitigation of CO poisoning. The threshold amount of oxygen or air bleeding is a function of cell current density, with a greater cell current density demanding a larger threshold amount of oxygen or air bleeding.