关键词: 燃料电池, 氢气再循环, 阳极吹扫, 工作特性, PEMFC

Abstract:

The anode system based on hydrogen recycling can improve the hydrogen utilization and output performance of Proton Exchange Membrane Fuel Cell （PEMFC） system. The effect of increasing nitrogen concentration and liquid water accumulation on the performance of the reactor can be alleviated by anode purge， but the working characteristics of the reactor will fluctuate periodically. In this paper， the operational？ characteristics of PEMFC anode system with ejector and circulating pump in parallel are studied. The results show that the ejector alone can guarantee the stable operation of the reactor under high working conditions， and the hydrogen circulating pump was required to intervene in the recirculation process to make up for the insufficient recirculation capacity of the ejector under low working conditions. When the working current was less than 180 A， the circulating pump and ejector work together. During the purge process， the inlet velocity of the anode in the ejector mode was increased by 2.4%， and after the purge， the flow rate was reduced by 71.5%. To ensure a high hydrogen recirculation ratio， the average nitrogen concentration in the exhaust pipe should be controlled below 6%. In this study， the orthogonal optimization of the purge strategy of the system was carried out based on the hydrogen utilization rate and nitrogen concentration. The results showed that the hydrogen utilization rate and the average nitrogen molar fraction of the exhaust pipe showed a mutually exclusive relationship， and the purge duration exceeded 1.5% of the purge cycle to meet the needs of the system. The optimized purge strategy can ensure that the hydrogen utilization rate reached 98%. The average nitrogen concentration in the exhaust manifold was about 4.0%.

Key words: fuel cell, hydrogen gas recirculation, anode purging, operational characteristic, PEMFC