Two-phase flow modeling for the cathode side of a Polymer electrolyte fuel cell

Abstract

Liquid water flooding in micro gas channels is an important issue in the water management of polymer electrolyte fuel cells (PEFCs). However, in most previous numerical studies liquid water transport in the gas channels (GC) has been simplified by the mist flow assumption. In this work, we present a two-phase flow model for the cathode side of a PEFC. The GC is assumed to be a structured porous medium with the porosity of 1.0. The two-phase Darcy’s law is applied to both diffusion layers and GC. Based on the developed model, the liquid water flooding in the GC and its impact on the liquid water distribution in the diffusion layers are explored in detail. Furthermore, we study the effect of the immobile saturation on the predicted liquid water distribution in the diffusion layers. The results show that neglecting the GC flooding leads to an incorrect prediction of liquid water distribution in the diffusion layers and an overestimation of the cell performance. The gas flow rate in the GC can be optimized to achieve the best cell performance. Finally, when considering the immobile saturation in the model, more liquid water is predicted in the diffusion layers.