Incorporation of Evaporation and Vapor Transport in Pore Level Models of Fuel Cell Porous Media

摘要

Evaporation within fuel cell porous media is a complex, conjugate phenomenon that is highly dependent upon the local morphology and wetting conditions. The effect of phase change, vapor transport and temperature gradient on the liquid-vapor water movement inside the porous transport layer is being investigated through a series of numerical simulations using a network model. Viscous models are used for the flow of liquid water and for the air-vapor mixture. Thermal transport is included by performing an energy balance at each pore. Existing models for vapor transport and evaporation are adapted for incorporation into the network model. The focus of this paper is on the methodology for effectively incorporating evaporation into a local pore model. The uncertainty in these transport modes relative to the fuel cell operating conditions such as working temperature and relative humidity are highlighted.