Design and Characteristic Analysis of Ejector Used in High-Voltage Proton Exchange Membrane Fuel Cell System

According to the operating parameters of the 80kw fuel cell stack, the design of structure and CFD simulation analysis of the hydrogen circulation ejector are carried out based on COKOJIOB’ theoretical method. Firstly, the comprehensive influence of the diameter of the nozzle throat, the angle of the nozzle opening, the distance from the nozzle opening to the inlet of the hybrid chamber and the diameter of the hybrid chamber on the ejection equivalent ratio is analyzed by the orthogonal simulation. The single factor comparison method is also used to further clarify the influence of a single factor on the performance of the ejector. The result of simulation shows that the ejection equivalent ratio will decrease with the increase of the diameter of the nozzle throat and the maximum flow rate of the mainstream fluid. Meanwhile, the angle of the nozzle opening is preferably 5-10 degrees and the ejection effect will be enhanced by shortening the distance from the nozzle opening to the inlet of the hybrid chamber and increasing the diameter of the hybrid chamber. In addition, the influence of ejector exit mode on the ejection volume is studied through simulation. The result demonstrates that the flange connection of ejector has more ejection flow than the screw connection and the combination of flange connection and C1 chamfer will achieve higher ejection flow.