Experimental Investigation of Gas Purge and Voltage Undershoot for an Air-Breathing PEMFC

The effect of anode gas purge on the air-breathing PEMFC performance is experimentally investigated by measuring and analyzing the recovery of output stack voltage in this paper. The amount of hydrogen exhaust during each gas purge is obtained by a drainage method. Secondly, the utilization efficiency of hydrogen which flows from the hydrogen tank to the anode side and then is drained away during purge events is verified according to the consumed hydrogen in the stack and hydrogen exhaust. This verification program can also be used for our next work on air-breathing PEMFC modeling and simulation. Different gas purge schedule on the anode side, such as the interval time and duration time under various loads, are investigated as well. The experimental results show that a slight reduction of stack voltage is observed under a low current. However, a large voltage recovery is found under a high current which may be due to the severe flooding effect. In addition, the degree of voltage undershoot under different load change is investigated as well, which can provide a guidance for the safety operation design of air-breathing PEMFC.