A multi-fluid model to simulate heat and mass transfer in a PEM fuel cell

This article summarizes a multi-phase model of a polymer electrolyte membrane fuel cell based on the formerly commercial CFD code CFX-4. It is three-dimensional in nature and includes multiphase heat and mass transfer in porous media. An overview is given and some numerical issues are discussed in detail. We then present a three-dimensional study comparing two common flow field designs under normal operating conditions: the conventional straight channel design and the interdigitated design. While the interdigitated design leads to a higher pressure drop compared to the conventional design, its heat and mass transfer properties are superior. Another important aspect of this study is the wetting status of the electrolyte menbrane and the effective drag of water through the menbrane, which indicates what fraction of the product water created at the cathode side diffuses through the membrane and leaves at the anode side. Only a fundamental understanding of the various mechanisms involved can lead to proper water management and hence can prevent "flooding" of either anode or cathode side while keeping the membrane humidified, and consequently can optimize the fuel cell performance and durability while reducing cost.