Numerical Study of Gas Purge in Proton Exchange Membrane Fuel Cell

A three-dimensional two-phase single-channel purge mode of proton exchange membrane fuel cell was established, and the steady-state and purge process were simulated. The water distribution in fuel cell after steady-state operation was studied. The changing trend of water content and water volume fraction under co-flow/counter-flow purge conditions was also studied. The results show that the membrane water content and water volume fraction under the ridge position of the fuel cell is more than the flow channel. The non-uniform distribution of membrane water along the direction of the flow channel is significant in co-flow, and the difference can be up to 6. In addition, the effects of different working conditions on purge were studied. It was found that in the purge condition, the water content of the inner membrane of 120s could be basically reduced to below 3. The purging efficiency can be improved by increasing the intake air flow and fuel cell temperature and reducing the relative humidity. Compared with other factors, the fuel cell temperature and relative inlet humidity had a greater impact on purge. Finally, the back-diffusion phenomenon during the purging process is studied. The water content on the anode side may increase slightly at the beginning of the purge due to the back-diffusion.