Effect of gas purging on the performance of a proton exchange membrane fuel cell with dead‐ended anode and cathode
Jun Shen, Zhengkai Tu, Siew Hwa Chan
Abstract
Water management is an important issue to be addressed to maintain the stable and efficient operation of a proton exchange membrane fuel cell (PEMFC). Gas purging is commonly performed to remove accumulated water in a PEMFC, especially in a dead-ended fuel cell system. A 3D dynamic model with a user-defined inlet boundary condition is proposed to study the effect of gas purging with different purge durations in an H2/O2 PEMFC. The results show that the performance immediately deteriorates and then recovers to the original level during gas purging. Purging has a significant effect on the flow and mass transfer in the flow channel, and it leads to efficient removal of water from the PEMFC. The voltage variation tendency is consistent with the water content of the membrane. Membrane dehydration is the main reason for the performance degradation. Notable variations could be observed with increments in the purge duration. Water in a PEMFC is more sensitive and responsive to changes of operating conditions than the reactants. In addition, the performance is significantly deteriorated at a higher operating temperature. A large amount of water is removed during the gas purging, resulting in low water content in the membrane and low water saturation at the interface between the flow channel and the gas diffusion layer.