Permeability of a PEMFC Gas Diffusion Layer Based on Morphology

The transport of gases and water through the gas diffusion layer of a PEMFC was investigated with a focus on the morphological characteristics of the carbon paper GDL. The capillary pressure and permeability of the GDL, which play important roles in water transport, were derived as functions of liquid saturation using a pore size distribution (PSD) model. A GDL gas permeability model is proposed on the basis of empirical pressure drop functions for the laminar flow across banks of tubes. The calculated relationship between gas permeability and porosity was in good agreement with the experimental data. The observed permeability of GDLs of different thickness suggests that the permeability, or mean pore diameter at the surface, is larger than that of the core. Calculated results indicated that diffusion loss of reactant gases is mainly determined by the PSD of the surface layer of the GDL