| PEMFC (Proton Exchange Membrane Fuel Cell) is a multi-physics fields, multi-phase and multi-scale and complex dynamic system. Water management have effect on PEMFC. In which the water transport process in gas channel, gas diffusion layer and membrane is very important, it is difficult to observe water transport process in PEMFC in the lab, numerical simulation of water transport process in GDL and PEM by MATLAB is used and the effect of water transport inside the PEMFC on performance is revealed.A one-dimensional mathematical model is built to study the water transport process in GDL by using the law of Darcy and the law of Fick. This study adequately considers the influence of operating conditions and structure parameters on the water transport process in GDL. The results show that fuel cell needs to be humidified, but when humidification temperature is too high, it is easily to be flood in GDL. Higher operating temperature increase the reaction’s rate, and it can accelerate the rate of mass transport in GDL, but it also could lead to loss of water. Higher stoichiometry could provide more gas for the reaction in PEMFC, but more water is taken away from GDL. This study deeply analyzes the effect of porosity, contact angle, thickness and permeability of GDL on gas-liquid two-phase flow. The results show that by reducing the thickness of GDL or by increasing porosity, contact angle and permeability of GDL could make the saturation of liquid water lower, and more oxygen will reach to CL. Contrast to the results of experiment, it is found that when the PTFE content is about20%in GDL, PEMFC shows the best performance.A iterative procedure to predict the water content and distribution of membrane is built by using water transport process balance in this study. The results show that self-humidification is totally feasible on PEMFC. but it needs to strictly control the operating condition. Under atmospheric pressure, the thickness of PEM needs to be very low (lower than50μm), stoichiometry also needs to be very low (about1.2), low operating temperature(about60℃). with these conditions, it could ensure the wettablity and conductivity of PEM. Anode and cathode humidification is beneficial to PEMFC, but the effect of the anode humidification is more obvious than the cathode humidification.In summary,this study analyzes the water transport process in GDL and PEM, some results can be used to improve the optimization and design of PEMFC. |
