Estimation of oxygen transport properties in proton exchange membrane fuel cells under dry and wet operating conditions

Quantifying the mass transport in the proton exchange membrane fuel cells at different working conditions are important to further improve their performances. A transport model is established and the oxygen total transport resistance ( R tot ) at different working current densities in the membrane electrode assembly is measured by the limiting current densities. The R tot is almost fixed at the dry region at low current density. However, the R tot significantly increases at the wet region at high current density due to the flooding. It is found that the flooding mainly influences the gas diffusion layer, and hinders molecular diffusion. An empirical relationship between the R tot and current density is proposed. Based on the calculated R tot at certain current density, the cell voltages are estimated, which are reasonably close to the measured cell voltages. These results provide a simple method to determine the mass transport resistance in wet region in fuel cells.