Multiscale modeling of single-phase multicomponent transport in the cathode gas diffusion layer of a polymer electrolyte fuel cell

This research reports a feasibility study into multiscale polymer electrolyte fuel cell (PEFC) modeling through the simulation of macroscopic flow in the multilayered cell via one-dimensional (1D) electrochemical modeling, and the simulation of microscopic flow in the cathode gas diffusion layer (GDL) via three-dimensional (3D) single-phase multicomponent lattice Boltzmann (SPMC-LB) modeling. The heterogeneous porous geometry of the carbon-paper GDL is digitally reconstructed for the SPMC-LB model using X-ray computer microtomography. Boundary conditions at the channel and catalyst layer interfaces for the SPMC-LB simulations such as specie partial pressures and through-plane flowrates are determined using the validated 1D electrochemical model, which is based on the general transport equation (GTE) and volume-averaged structural properties of the GDL. The calculated pressure profiles from the two models are cross-validated to verify the SPMC-LB technique. The simulations reveal a maximum difference of 2.4% between the thickness-averaged pressures calculated by the two techniques, which is attributable to the actual heterogeneity of the porous GDL structure.