Experimental performances of a two-phase R134a ejector

This paper presents an experimental study of a liquid-vapour ejector operated under various conditions encountered in refrigeration and other cooling processes with R134a as the working fluid. Ejector performance in terms of entrainment ratio and pressure lift were investigated by imposing the pressure at the inlets and outlet of the ejector over ranges corresponding to intended applications. The primary stream subcooling level varied over a range of values in order to evaluate its impact on overall ejector operation. This range was sufficiently wide to include application cases such as found in some industrial processes with moderate to relatively high subcooling levels in comparison to those found in conventional refrigeration. Pressure sensors inside the mixing chamber allowed monitoring the pressure variation inside the ejector. Two-phase ejector entrainment ratio was found to strongly depend on the primary subcooling, especially below 20 °C values. The resulting performance curves show that the tested ejector works in off-design mode. Suction strength at the secondary inlet depended very much on the expansion of the secondary stream in the mixing chamber. The largest expansion recorded in the secondary flow hardly exceeded 25 kPa.