Volume 50

Modeling and Analysis of the Hydrogen Circulation Structure of PEMFC System Tiancai Ma, Beiming Huang, Chongjiu Li, Ziheng Gu

Abstract

Hydrogen supply system needs to provide sufficient mass flow and pressure of hydrogen to meet the requirement of fuel cell stack in PEMFC system. Ejector and hydrogen circulating pump (HRP) are commonly used to recycle unreacted hydrogen to improve energy utilization and system efficiency. However, ejector can not achieve active control and has narrow efficient working range, while HRP leads to extra parasitic power. This paper establishs an accurate hydrogen supply system model and proposes single recycle component scheme and combination of ejector and HRP scheme, discussing the working performance of different circulation structure scheme. The simulation results indicate that single ejector can not recycle enough flow rate and even counterflow occurs with fuel cell system output power less than 60kW. Single HRP controls the hydrogen recycle flow rate accurately but an average of 280.1W parasitic power is consumped. In ejector and HRP parallel scheme, matching control strategy is proposed and an average of parasitic power can be reduced 190W than single HRP scheme in whole fuel cell stack working operation. In ejector and HRP serial scheme, matching strategy controls HRP establish high pressure difference to help overcome flow resistance from ejector with maximun 0.45kPa in low current loading condition. When system output power exceeds 60kW, HRP is shut off and ejector overcomes a maximun flow resistance of 22.25kPa from HRP. An average of parasitic power is reduced 200.8W than single HRP scheme.

Keywords PEMFC, hydrogen supply system, ejector and HRP parallel scheme, ejector and HRP serial scheme