Non-Equilibrium Phase Change in a Proton Exchange Membrane Fuel Cell

Abstract

A three-dimensional steady-state two-phase non-isothermal model which couples the water and thermal management has been developed in order to numerically investigate the spatial distribution of the interfacial mass transfer phase-change rate in the cathode side of a proton exchange membrane fuel cell (PEMFC). A non-equilibrium evaporation-condensation phase change rate is incorporated in the model which allows a supersaturation and undersaturation take place. The differences of non-equilibrium phase and equilibrium assumption inside the gas diffusion layer (GDL) has been addressed by comparing the corresponding liquid saturation and temperature distributions. Regarding water management, the assumption of isothermal model versus the non-isothermal model has been investigated. A parametric study has been also carried out to investigate the effects of operation conditions namely as the channel inlet humidity, cell operating temperature and inlet mass flow rate on the phase-change rate. Since the exact values of the phase change constants for the hydrophobic GDL has not been specified yet, the effects of the phase-change constant on the liquid saturation distribution are demonstrated.