Abstract:An analytical multiphase model for cold start simulation of proton exchange membrane (PEM) fuel cell has been employed to elucidate the cold startup behavior, mainly focusing on the inherent coupled mass and heat transport at subfreezing temperature. A comprehensive phase change mechanism is proposed by accounting the recent reported super-cooled water. The results indicate that the water sustained by the membrane is of great benefits for preventing water freezing. Liquid water and ice is found to easily accumulate at the interface of micro-porous layer (MPL) and catalyst layer (CL). Increasing the phase change rates between membrane water and super-cooled water, and super-cooled water and ice deteriorates the startup capability of PEM fuel cell. Phase change rate has no prominent influence on the cell temperature evolution due to the weak latent heat generation. Furthermore, the super-cooled water maintained in CL follows increasing-decreasing-zero trends with the PEM fuel cell starting up. The amount of super-cooled water is found relatively low which matches the trend in the practical PEM fuel cell due to the highly erratic super-cooled state.