Polymer electrolyte fuel cells (PEFCs) operate with a ternary mixture of fuel and reactants. The majority of numerical models in the literature, including the in-house Open-source Fuel Cell Simulation Toolbox (OpenFCST) software, use Fick’s law of diffusion which is only valid for binary mixtures. An accurate multi-component mass transport (MMT) model accounting for both convective and diffusive transport is necessary to improve PEFC performance predictions and assess the errors due to the use of Fick’s law. The focus of this research is the implementation of a novel isothermal compressible MMT model. The new model will allow OpenFCST to perform along the channel and possibly 3-dimensional PEFC simulations.

In the porous media of the fuel cell, the volume averaging method is applied to the equations resulting in an additional Darcy-Forchheimer term. Diffusion coefficients and dynamic viscosities of the species are calculated using Chapman-Enskog theory. The partial dynamic viscosity of the gas species are calculated using either Wilke’s or Kerkhof and Geboers’ model. The MMT model is validated by comparing results to several benchmark problems, including a Stefan tube problem. The Stefan tube solution showed a maximum molar fraction error of 0.007 (1.6%) compared to the analytical Maxwell-Stefan solution, which is considered to be within an acceptable range. Finally, the MMT model is coupled with electron and proton transport, and electrochemical reaction equations in order to develop a PEFC cathode model. Performance predictions of the multi-component and Fick’s cathode models are compared to show the effect of the improved model.