Lattice Boltzmann simulation of liquid water transport properties in gas diffusion layers using an orthogonal design method

Optimizing the microstructure of the gas diffusion layer (GDL) can enhance transport behavior and cell performance. In this work, an orthogonal design method is employed to investigate three factors - porosity, carbon fiber diameter, and anisotropy ratio - across four levels. Stochastic numerical reconstruction is performed to generate 16 distinct GDL microstructure cases for comparative orthogonal analysis. The Lattice Boltzmann Method (LBM) is subsequently applied to compute anisotropic effective transport properties, including tortuosity and liquid water permeability, in the in-plane (IP) and through-plane (TP) directions. Finally, combinations of the three factors leading to maximum and minimum liquid water permeability are selected to optimize liquid transport behavior. The results reveal that porosity, carbon fiber diameter, and anisotropy ratio all affect the anisotropic tortuosity and permeability in GDL. Porosity has the greatest impact on liquid water transport, with impact degrees of 18.5 in the IP direction and 14.3 in the TP direction. The carbon fiber diameter exerts a nearly equal effect in both directions, with an impact degree of approximately 10. The anisotropy ratio exhibits the smallest effect, with impact degrees of 3.8 in the IP direction and 7.88 in the TP direction. Notably, although the anisotropy ratio has the least effect on liquid water transport, it is the factor that increases the difference in liquid water transport between the IP and TP directions among the three factors. As the anisotropy ratio increases, it makes the difference in liquid water transport between the IP and TP directions in the GDL significantly larger.