Study of the anisotropic permeability of proton exchange membrane fuel cell gas diffusion layer by lattice Boltzmann method

Abstract

In proton exchange membrane fuel cells (PEMFCs), the gas diffusion layers (GDLs) are located between the flow channel and the catalytic layer, which not only provides a transport channel for the reaction gas and the output water, but also its fibrous skeleton is the key structure for the electron load transfer, and its transport performance is an important factor that affects the performance of the cell. In this paper, GDLs are stochastically reconstructed and the Lattice Boltzmann method (LBM) is adopted to study permeability. The changes of through-plane permeability and in-plane permeability are studied by varying the porosity, fiber diameter, and pressure drop. It is found that the porosity plays a dominant role in the variation of permeability, and the through-plane permeability at a porosity of 0.85 is 24.78 times greater than that at 0.5. The influence of fiber diameter can not be ignored. When the diameter is larger than 8 μm, the influence on permeability is more obvious, and the permeability is no longer sensitive to changes in diameter after a certain degree of porosity has been reached. The pressure drop only changes the magnitude of the average cross-sectional velocity of the gas diffusion layer, and the effect on the permeability is negligible. The in-plane permeability is larger than the through-plane permeability. In the scope of the paper research, the ratio of the two values ranges from 1.3 to 1.7.