Effect of hygrothermal cycles on physicochemical behavior of a PEM (Proton Exchange Membrane) [L'effet des cycles hygrothermiques sur le comportement physicochimique d'une PEM (Proton Exchange Membrane)]

The objective of this study is to analyze the coupled heat and mass transport in a pem fuel cell and to better understand the physicochemical behavior occurring in the membrane using numerical simulations developed under cfd software and confirmed by experimental results. the results show that the membrane proton conductivity increases and the membrane specific resistance decreases with increasing temperature and water content. indeed,particularly at high current densities the water-back-diffusion diffusion may be insufficient to counteract the anode drying effect due to the electro-osmotic drag and the risk of cathode flooding particularly occurs. furthermore hygrothermal cycles and the membrane drying create the risk of cracking of the membrane and subsequently promote the permeability of gases. the results have shown us also the influence of the thickness on water management.