Water Transport in Porous Media of PEM fuel cells

摘要

A two-phase flow model based on the mixture flow model for a proton exchange membrane (PHM) fuel cell is developed. 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 unified approach is used, and the catalyst layers are now included in the respective unified domains for the cathode and anode, thus continuity boundary conditions at the interface between the catalyst layer (CL) and the gas diffuser layer (GDL) are no longer needed. Furthermore, the two-phase flow model is also used in the anode side, and the momentum transfer between the liquid and gas phases due to phase change is taken into consideration. Experiments have been conducted to study the performances of a PEM fuel cell and the results are used to improve and validate our model. The modeling results of polarization curves compared well with the experimental data. The model is used to study the influences of fuel cell humidification temperature, operating temperature and average current density on the vapor and liquid water transports, as well as effective porosity, oxygen transport, overpotential in the cathode catalyst layer and ionic conductivity in the membrane.