A Multiscale Decomposition Method for Pore-Scale Simulation of Multiphase Transport and Reactions in Cathode Catalyst Layers of Proton Exchange Membrane Fuel Cells

Abstract

An approach to simulate multiphysics phenomena in the cathode catalyst layer of the proton exchange membrane fuel cell (PEMFC) at the resolution of pore scale is presented. Within the framework of pore-scale simulation, a method to couple water generation by oxygen reduction reactions with liquid water transport and mass transport loss in pores and the ionomer is proposed. The multiscale decomposition method that reduces the computational cost of pore-scale simulation is applied to the proposed multiphase pore-scale model. The proposed computational framework is applied to several test cases. Cases with simple and idealized pore structures are used to demonstrate and validate the coupling of water generation, emergence and transport. The computational efficiency of the multiscale method is investigated. The results show that an estimation of the effective diffusivity considering water blockage effects is of importance to the reduction of the computational cost in the multiscale method. At low saturation levels, the effective diffusivity evaluated using global saturation is found to be sufficient. It is found that, as the saturation level increases, a more accurate estimation using a local saturation level leads to better performance. The application to an experimental case is presented to demonstrate the potential of the proposed framework.