Modeling of ion and water transport in the polymer electrolyte membrane of PEM fuel cells

Abstract

Ion and water transport phenomena in the polymer electrolyte membrane (PEM) play a significant role in the energy conversion process of a PEM fuel cell, as they provide the closure for the electric and mass transport in the PEM fuel cells. A mathematical model for the transport of ion and water in the PEM is formulated in this study, based on the non-equilibrium thermodynamics and the Generalized Stefan–Maxwell equations. The physical constants of the model, such as the binary diffusion coefficients in the Generalized Stefan–Maxwell equations, are determined from experimental data available in literature for membrane-water diffusion and conductivity. The electrolyte transport model is incorporated into a model for the entire PEM fuel cell; water transport in the electrolyte and in the other cell components are coupled and solved in a single computational domain. It is shown that the present generalized formulation is advantageous to other formulations for the macroscopic analysis of transport phenomena through the membrane electrolyte.