Abstract

There is a great need to predict liquid water saturation in porous layers such as gas diffusion layers (GDL) and micro porous layers (MPL) of polymer electrolyte membrane fuel cells (PEMFCs) as this is a key parameter in flooding occurrence which is a limiting factor of PEM fuel cell performance. Several models have been developed in order to study water distribution and migration in micro porous layers. These models require heavy computational efforts and doubt in their applicability to the gas diffusion layer (GDL). Recently Qin & Hassanizadeh [1] developed a new approach based on the reduced continua model for modeling multiphase flow through a stack of thin porous layers. Their approach requires much less computational efforts and predicts less water flooding in the GDL, but is using an empirical closure inaccurate model.

In this work, a volume averaging approach is developed and applied to the microscopic mass balance equations for transforming the threedimensional point wise equations to two dimensional averaged equations. An explicit closure model for the interlayer mass exchange of liquid will also be constructed. The resulting equations consist of macroscopic mass balance equations combined with a series of constitutive relationships. The obtained 2D model will enormously improve the computational speeds, allowing the users to obtain faster, reasonably accurate simulations at lower cost. A numerical algorithm will be developed and the effects of major material parameters of the macroscopic model on water flooding in the GDL and MPL layers will be investigated.