Performances investigation of Ejector affected by Secondary Flow Humidity in PEMFC

Ejector has been successfully used in proton exchange membrane fuel cell (PEMFC) hydrogen circulation system because of its small size and no parasitic power. Since the secondary flow of ejector contains water vapor generated by PEMFC, and the outlet humidity of ejector is affected by the secondary flow humidity, the relationship between the outlet humidity of ejector and the secondary flow humidity needs to be studied through modeling and simulation. In this paper, the prediction model of the outlet humidity of the ejector is established and validated by simulation. The two-dimensional numerical model of the ejector is simulated by fluent, and the influence of the secondary flow humidity of the ejector on the outlet humidity is studied. The simulation results show that: The maximum error is 8% compared with the calculated value. In the case of double shock wave, the power is inversely proportional to the humidity; when the power is 40 kW, the outlet water content is the largest which increases by 0.158 kg. The outlet pressure is inversely proportional to the humidity, and the back pressure is reduced by at least 0.16 bar at the same power.