Water transport characteristics in cathode gas diffusion layer of proton exchange membrane fuel cell under dynamic loading

Abstract

During the applications of proton exchange membrane fuel cells (PEMFCs) on vehicles, dynamic loads occupy a large proportion of total operating conditions. Additionally, the water-gas transmission under dynamic conditions significantly affects the lifetime. However, most existing simulations of water transport characteristics in the cathode gas diffusion layer (GDL) focus on steady-state conditions. There is a lack of accurate understanding regarding the mechanisms of dynamic water transmission processes within the GDL. Therefore, a dynamic simulation of water transfer characteristics with variable loads was conducted in this study using a one-dimensional fuel cell model and a three-dimensional lattice Boltzmann method (LBM) GDL model. The simulation results showed that current density significantly affects the transport paths in the GDL. The water saturation rises under higher current densities, under both stable and dynamic loads. Under dynamic conditions, higher water pressure and saturation occur in the GDL with higher load changes. Additionally, less time is taken for water to develop in the GDL with higher load changes. This study provides a reference for optimizing control methods of PEMFCs and offers insights for future research on mass transfer under dynamic conditions.