A generalized multiphase mixture (M2) model for PEFC flow field design

A lot of effort has gone into designing an optimum flow field for PEFC (Polymer Electrolyte Fuel Cell) that can both efficiently distribute reactants to the reactions sites and remove products through the outlet. Presence of liquid water in the products has been one of the main concerns. Unfortunately, single phase flow solutions have been considered for most of the design optimization studies due to the unavailability of a fast and accurate two-phase flow model. Recently a Multiphase-Mixture (M2) based model has been developed for two-phase flow computations in the cathode channels of a PEFC. This model has now been extended to the anode side. A drawback of implementing this mvodel is that it requires an orthogonal hexahedral mesh which in a real PEFC stack geometry is very difficult to achieve. In this study the model has been extended to non-orthogonal hexahedral and tetrahedral meshes, which can be used to mesh any three-dimensional geometry. Also, in order to reduce the meshing effort, an immersed body approach has been tested successfully on this model. The resulting two-phase flow model valid for arbitrary flow field geometries is fast and accurate and a possible direction to reduce the meshing effort is presented.