Study on the effect of purging time on the performance of PEMFC with dead-ended anode under gravity

In the working process of proton exchange membrane fuel cell (PEMFC) with dead-ended anode (DEA), the accumulation of water and nitrogen in the anode flow channel will cause its transient working performance to degrade. Generally, the transient working performance is recovered by periodically opening the anode outlet for gas purging. However, the purging time under gravity will change the distribution state of water and gas in the anode flow channel, thus seriously affecting the working performance of PEMFC with DEA. In this paper, the influence mechanism of purging time on the performance of PEMFC with DEA under gravity is investigated by theoretical analysis and experimental method. The results show that if the purging time under gravity is shorter, the faster the transient working performance of PEMFC with DEA decreases in the next working cycle, and the area with high current density distribution is always close to the gas inlet of the flow channel, as well as the area with low current density distribution is always close to the gas outlet of the flow channel. Moreover, the effect of different purging times on the local current density distribution will lasts for a long time, and also have significant effects on the accumulation and distribution status of water at the anode side under gravity. The results can provide an important guidance for optimizing the purging strategy of PEMFC with DEA.