(345c) A Steady State Three-Dimensional Model for a Pemfc System to Simulate Water Transport and Performance Characteristics

The automotive industry is rapidly moving towards development and commercialization of PEM fuel cells. PEM fuel cells promise to be an attractive alternative for the internal combustion engine in automotive applications for they are cleaner and more fuel-efficient. More importantly, automotive fuel cells enable the goals of reduced-dependence-on-oil and transition to a hydrogen economy. In order to successfully design PEM fuel cell systems for these applications we need to develop a thorough understanding of various phenomena that occur during the operation of these systems. Mathematical modeling can be used to better understand these systems and help us design these systems.

In this work, we present a steady state three-dimensional model architecture that solves for the performance and water movement within a solid plate PEMFC stack. The model captures water movement through layers within the membrane-electrode assembly (MEA), pore-flooding within the unitized electrode assembly (UEA), two-phase flow in the flow channels, heat transport, gas transport, along with detailed electrochemistry. This model architecture allows the capability to simulate both single cell and stack systems and capture effects both within and outside active area. Through simulations of this model we studied the effect of different operating conditions – relative humidity, temperature, and pressure of the gases – and system parameters – membrane thickness, gas channel design, etc. – on water management and steady state performance of the fuel cell. A significant result from these simulations is the prediction of dry out under certain operating conditions, which can be alleviated by using a porous plate flowfield system. Other results from these simulations will also be presented and discussed.