A Computational Analysis of Multiphase Flow Through PEMFC Cathode Porous Media Using the Multifluid Approach

A three-dimensional multiphase model that describes the liquid water flux through the porous media and into the gas flow channel of a proton exchange membrane fuel cell (PEMFC) cathode is presented. The model is based on the multifluid approach, thus solving one complete set of transport equations for each phase. It is used to investigate the effect of different material parameters on the predicted liquid water saturation in various layers, i.e., catalyst layer (CL), microporous layer (MPL), and gas diffusion layer (GDL). Each layer can be characterized by its porosity, permeability, and contact angle, while the Leverett function was used to describe the capillary pressure vs saturation. The irreducible saturation can be specified for each layer independently. An expression for the channel/GDL interface condition was developed, which accounts for the number of droplets per unit area at the GDL interface. Describing the different porous media by Leverett equations leads to a jump condition in saturation across each interface. In accordance with previous studies it is found that the MPL remains at a low saturation level, while the CL might become flooded depending on the fraction of hydrophilic pores. Under-the-land compression leads to an increased level of flooding compared to the channel section. (C) 2009 The Electrochemical Society. [DOI: 10.1149/1.3206691] All rights reserved.