Numerical study of high performance ejectors with R134a as working fluid

In this paper, 5 key geometrical factors: the area ratio between the nozzle and constant-area section, nozzle exit position, diverging angle of nozzle, converging angle of mixing section and the length of constant-area section and different back pressures are considered to investigate the ejector performance under 209 working conditions with CFD model which is calibrated by experimental data. It is found that the maximum influence on both entrainment ratio and critical back pressure is area ratio among 5 key geometry parameters. There are maximum deviations for entrainment ratio of 181.1% and critical back pressure of 35.4% when area ratio varies from 5.92 to 12.96. It is also found that entrainment ratio increases with area ratio while critical back pressure decreases with area ratio. Optimum Geometry parameters are provided to meet high performance ejectors which work under evaporating temperature of 10°C, generating temperature of 80°C as well as condensing temperature of 31-35°C when R134a works as working fluid.