Optimal and Robust Design of the PEM Fuel Cell Cathode Gas Diffusion Layer

The cathode gas diffusion layer (GDL) is an important component of polymer electrolyte membrane (PEM) fuel cell. Its design parameters, including thickness, porosity and permeability, significantly affect the reactant transport and water management, thus impacting the fuel cell performance. This paper presents an optimization study of the GDL design parameters with the objective of maximizing the current density under a given voltage. A two-dimensional single-phase PEM fuel cell model is used. A multivariable optimization problem is formed to maximize the current density at the cathode under a given electrode voltage with respect to the GDL parameters. In order to reduce the computational effort and find the global optimum among the potential multiple optima, a global metamodel of the actual CFD-based fuel cell simulation, is adaptively generated using radial basis function approximations. For each level of the metamodel in the schematically reduced design space, a gradient-free, multi-island genetic algorithm is used to determine the optimum values of the cathode GDL design parameters for a global maximum current density on the cathode side. It is found that both the reactant and the current density tend to distribute more uniformly under the optimized conditions. Furthermore, as indicated by the polarization curve, the fuel cell with an optimized cathode GDL has a better performance.