Model of Two-Phase Flow and Flooding Dynamics in Polymer Electrolyte Fuel Cells

A mathematical model for two-phase flow and flooding dynamics in polymer electrolyte fuel cells (PEFCs) has been developed based on recent experimental observations. This three-dimensional PEFC model consists of four submodels to account for two-phase phenomena, including a catalyst coverage model in the catalyst layer, a two-phase transport model in the gas diffusion layer (GDL), a liquid coverage model at the GDL-channel interface, and a two-phase flow model in the gas channel (GC). The multiphase mixture model is employed to describe liquid water transport in the GDL while a mist flow model is used in the gas channel. An interfacial coverage model by liquid water at the GDL/GC interface is developed, for the first time, to account for water droplet emergence on the GDL surface. The inclusion of this interfacial model not only gives the present two-phase model a capability to predict the cathode flooding effect on cell performance, but also ultimately removes the inability of prior two-phase models to correctly capture effects of the gas velocity (or stoichiometry) on cell performance.