Modeling and analysis of water vapor dynamics in high-temperature proton exchange membrane fuel cell coupling gas-crossover phenomena

A 3-D numerical model coupling gas-crossover phenomena for high-temperature proton exchange membrane fuel cell (HT-PEMFC) is developed to investigate the water vapor behavior. After model validation, sensitivity analysis of the water vapor diffusion coefficient is carried out, which does not further affect the water vapor behavior, when the order of magnitude of diffusion coefficient is higher than 10⁻⁵m²/s. It is also found that the water vapor transport flux decreases with increasing membrane thickness. However, the flux increases slightly with increasing the catalyst layer. In addition, Increasing the pressure and humidity on the anode side will cause water vapor to diffuse from the anode to the cathode, while increasing the current density or the pressure of cathode, the rate of water vapor transport from the cathode to the anode is enhanced. In the dead-end mode, the accumulation of water vapor at the anode outlet is the main cause for the reversible performance decline, which can be restored through reasonable purge strategies. This work contributes to improve the water management strategy of HT-PEMFC operating in dead-end mode.