Self-humidifying effect of air self-circulation system for proton exchange membrane fuel cell engines

A dynamic mechanism model of a control-oriented hydrogen fuel cell system based on the cathode exhaust gas cycle is established, and the effects of operating parameters on the two-phase water transfer and dynamic output performance of a fuel cell are analyzed, the transport process of material and the spatial distribution of water content in the membrane electrode were obtained. The study found that too low humidity at the cathode inlet of the stack will cause corrosion of the catalyst layer and the carbon black carrier, resulting in agglomeration and sintering of the catalyst particles. The membrane is also severely damaged by mechanical properties, and black impurities and broken fibers are found on the membrane surface. Under the passive operation of the cathode self-circulation system, the maximum humidity of the mixed gas can reach 60%. The new system is advantageous to the evaporation of water vapor at higher operating temperature and can inhibit the flooding of membrane electrode assembly. It takes about 20s for the current to reach the steady state of the set value, and about 30s for the voltage to reach the steady state. The voltage fluctuation is small and the output power is stable, indicating high reliability. (c) 2020 Elsevier Ltd. All rights reserved.