Two-phase flow equations in porous media for PEMFC (Proton Exchange Membrane Fuel Cells)

In Proton Exchange Membrane Fuel Cells (PEMFC) for electrical mobility, the water management and transport is very important. Water vapour is produced and liquid water can be formed since the gases can become saturated by water vapour production during the electrochemical reactions. In addition, significant water transport mechanisms occur between the anode and the cathode. Therefore a two-phase flow must be considered in both sides, the two phases being the liquid water and the gas mixture (the different gas components are essentially hydrogen, oxygen, nitrogen and water vapour). The core of a PEMFC is constituted of several porous media called GDL (Gas Diffusion Layer), MPL (Micro Porous Layer) and CL (Catalytic Layer). Therefore, we have a two-phase multicomponent gas-liquid flow in porous media. The objective of this paper is to present a complete derivation of the balance equations governing this kind of flows and to compare these equations to the equations used in PEMFC calculations in order to put in evidence the simplifying assumptions made by the PEMFC community.