In-plane gas permeability of proton exchange membrane fuel cell gas diffusion layers

A new analytical approach is proposed for evaluating the in-plane permeability of gas diffusion layers (GDLs) of proton exchange membrane fuel cells. In this approach, the microstructure of carbon papers is modeled as a combination of equally-sized, equally-spaced fibers parallel and perpendicular to the flow direction. The permeability of the carbon paper is then estimated by a blend of the permeability of the two groups. Several blending techniques are investigated to find an optimum blend through comparisons with experimental data for GDLs. The proposed model captures the trends of experimental data over the entire range of GDL porosity. In addition, a compact relationship is reported that predicts the in-plane permeability of GDL as a function of porosity and the fiber diameter. A blending technique is also successfully adopted to report a closed-form relationship for in-plane permeability of three-directional fibrous materials.

Research highlights▶ An analytical model for the in-plane permeability of gas diffusion layers is provided. ▶ Normal and parallel permeability of the unidirectionally aligned fibers provides bounds for the permeability GDLs. ▶ GDLs can be treated as a combination of fibers with different orientations. Therefore, the proposed approach may be used for predicting other transport properties. ▶ Permeability of GDLs is directly proportional to its porosity and the fibers diameter squared.