Modelling of the proton exchange membrane fuel cell in steady state

With an aim of optimizing the operation points of the proton exchange membrane fuel cell (PEMFC), it is better to understand the working procedure with the physical effects and to seek a prediction of its behaviour according to its operating conditions. By applying the diffusion equations of Maxwell-Stefan and the phenomenological model (developed by Springer), this approach presents a steady state ID model of the PEMFC. The fuel cell performances are also conditioned by the hydration of the membrane. In this work, we use an iterative procedure to compute the coupled diffusion equations of the reactants and the water transport in the membrane. That way, the membrane resistance behavior can be predicted for various relative humidity of the inlet gas. The water transport is always a balance between at least two competing diffusion mechanisms One is due to the proton displacement from anode to cathode that drag some water molecules with them, this phenomenon is called electro-osmotic drag. The other mechanism is back diffusion of water from cathode to anode. This water flux results from the water concentration gradient created in the membrane by the electro-osmotic drag and the water produced by the redox reaction at the cathode. In the literature, the electro-osmotic drag coefficient is mostly depending on the water content. We will study if this governing equation can be used for any membrane. The numerical results are then compared to the experimental ones. The experiments are led on a 500 W PEMFC test bench fed by dry hydrogen and humidified air, the type membrane of the stack is Gorereg.