Transient Phase Change in the Cathode Side of a PEM Fuel Cell

Abstract

We numerically investigated the temporal variation and spatial distribution of interfacial mass-transfer phase-change rate in the cathode side gas diffusion layer of a proton exchange membrane (PEM) fuel cell during startup. For this purpose, a three-dimensional transient two-phase nonisothermal model was used. A nonequilibrium evaporation–condensation interfacial mass-transfer rate is incorporated in the model, which enables us to take supersaturation and subsaturation into consideration. This helps us to investigate the most significant contribution of the phase-change rate to the transient response and thermal behavior of the cell. The effects of the operating temperature and channel inlet humidity on the phase-change rate are also investigated. It is observed that when condensation is dominant, the transient time decreases. It is also observed that the maximum temperature decreases with time due to vapor-phase diffusion and phase change.