吹扫条件对PEMFC阻抗弛豫现象和低温启动的影响

Effect of purging conditions on the impedance relaxation phenomenon and low temperature start-up of PEMFC

停机吹扫作为质子交换膜燃料电池(PEMFC)零下温度启动前的关键流程,能够有效降低冷启动前膜电极(MEA)的含水量,以提高电池启动的成功率。为了研究PEMFC在停机吹扫后出现的阻抗弛豫现象,以及吹扫条件如何直接作用于PEMFC低温启动性能,以25 cm2的单片电池作为对象,进行实验研究。实验条件下的结果表明,随着吹扫气体流量的增加以及吹扫温度的提高,阻抗弛豫表现更加明显;吹扫流量和吹扫时间对PEMFC冷启动性能存在显著影响。在实验条件下,以1500 ml/min的干燥N2吹扫15 min,测试电池在低温中的表现最佳。吹扫流量过大、过小以及吹扫时间过长、过短均不利于PEMFC的低温启动,存在最佳吹扫条件。

As a key process before starting at sub-zero temperature in a proton exchange membrane fuel cell(PEMFC),purging is effective in reducing the water content in the membrane electrode to improve the success rate of cold start.Shutdown purging,as a key process before sub-zero temperature start-up of proton exchange membrane fuel cell(PEMFC),can effectively reduce the water content of membrane electrode(MEA)before cold start,so as to improve the success rate of battery start-up.In order to investigate the impedance relaxation phenomenon of PEMFC after purging and how the purging conditions directly contribute to the low temperature start-up performance of PEMFC,an experimental study was conducted with a 25 cm2 single cell as the subject.The results under experimental conditions showed that the impedance relaxation became more obvious with the increase of gas flow rate and purging temperature;the purging flow rate and purging time had significant effects on the cold start performance of PEMFC.Under experimental conditions,the test cell performed best in low temperature by purging with dry N2 at 1500 ml/min for 15 min.The excessive or insufficient purge flow rate and purge time are not conducive to the low temperature start-up of PEMFC,and optimal purge conditions exist.