Prediction of hygro—thermal stress distribution in proton exchange membranes using a three-dimensional multi-phase computational fluid dynamics model

Abstract

A three-dimensional, multi-phase, non-isothermal computational fluid dynamics model of a proton exchange membrane fuel cell has been developed to simulate the hygro and thermal stresses in polymer membrane, which developed during the cell operation. The behaviour of the membrane during the operation of a unit cell has been studied and investigated. The model accounts for both gas and liquid phase in the same computational domain, and thus allows for the implementation of phase change inside the gas diffusion layers. The model includes the transport of gaseous species, liquid water, protons, energy, and water dissolved in the ion-conducting polymer. The new feature of the present model is to incorporate the effect of hygro and thermal stresses into actual three-dimensional, multi-phase, non-isothermal fuel cell model. In addition to hygro—thermal stresses, the model features an algorithm that allows for a more realistic representation of the local activation overpotentials, which leads to improved prediction of the local current density distribution in high accuracy, and therefore, high accuracy prediction of temperature distribution in the cell and then thermal stresses. This model also takes into account convection and diffusion of different species in the channels as well as in the porous gas diffusion layer, heat transfer in the solids as well as in the gases, and electrochemical reactions.