Study on the effect of pulsed gas flow on the entrainment performance of hydrogen ejector

Abstract

The ejector is a crucial component of the hydrogen circulation system of proton exchange membrane fuel cell (PEMFC), which is widely used because of its simple structure, reliable operation, and no additional power consumption. However, the current research on pulsed ejectors is still lacking and in-depth. In this study, CFD modeling is conducted on the ejector, and the pulsed gas flow is simulated by user define function (UDF), and the influence of the pulsed gas flow on the entrainment performance of the ejector is analyzed. The results show that, compared with the steady-state condition, the entrainment performance of the ejector using pulsed gas flow under different primary flow pressures is improved, and the maximum entrainment ratio is 3.195 under steady-state conditions and 3.507 under transient conditions, which is increased by 9.8%. The effect is especially pronounced at low pressure, where the entrainment ratio increases by 16.6%. And by comparing the gas flow of different pulse frequencies, it is found that when the pulse frequency is 1Hz, the ejector has the best entrainment performance.