On the modelling of two-phase flow in the cathode gas diffusion layer of a polymer electrolyte fuel cell

A front-tracking approach is derived for the numerical solution of the equations arising in the multi-fluid model for isothermal multiphase multicomponent flow in the gas diffusion layer of the cathode of a polymer electrolyte fuel cell under conditions of local thermodynamic equilibrium. The method is able to find the location of the one-phase/two-phase interface explicitly and without need for the artificial diffusion, smoothing and ad hoc source terms that are required in existing formulations. Also, the analysis indicates the presence of a previously unidentified integrable singularity, which can be removed provided that the dependent variables are chosen correctly. For quantitative comparison, a benchmark example is implemented using both approaches in the commercially available finite-element software Comsol Multiphysics.