Two-phase transport of water in porous medium of proton exchange membrane fuel cells

A new two-dimensional, two-phase flow model based on the mixture flow model was developed to investigate the water transport and distribution in the proton exchange membrane (PEM) fuel cell. The model couples the flows, species, electrical potential, and current density distributions in the cathode and anode fluid channels, gas diffusers, catalyst layers, and membrane, respectively. The catalyst layers are now included in the respective unified domains for the cathode and anode. Furthermore, the two-phase flow model was also used in the anode side, and the momentum transfer between the liquid and gas phases due to phase change was taken into consideration. The model was used to study water transport and its distribution in the cathode, the anode, and the membrane of PEM fuel cell simulation results show that the increase of humidification temperature and current density, or the decrease of fuel cell temperature makes the increase of water content in membrane, leading to the increase of ionic conductivity and overpotential of concentration difference in cathode attributed to flooding.