Moisture dehumidification and its application to a 3 kW proton exchange membrane fuel cell stack

Abstract

Humidification is one of the most important factors for the state-of-the-art Proton Exchange Membrane Fuel Cell (PEMFC) to maintain high water content in the electrolyte and to ensure reasonable ionic conductivity. However, liquid water may generate when the partial pressure of the water vapor reaches to its saturated point during operation, which can cause water flooding to the electrode and lead to poor performance of the PEMFC, especially at high current density. Moisture dehumidification is introduced to help remove the excessive water inside a 3 kW PEMFC stack in this paper. A radiator is set at the outlet of the stack to cool the moisture of the cathode. Thus, liquid water is condensed from the moisture due to the variation of the saturated pressure of water vapor, which can accelerate the evaporating of the liquid water inside the stack and mitigate the probability of flooding in the membrane electrode assembly (MEA). The stack with a radiator at the outlet of the cathode is fabricated to systematically investigate the effects of the stack temperature, air relative humidity, and operating pressure on the stack performance. The results show that with the help of moisture condensation, water removal ability is improved inside the stack. With the introduction of moisture dehumidification, 13% of increase in stack performance at 1.0 A cm−2 is observed compared with the stack performance without moisture dehumidification.