Review and analysis of the effect of ejector geometry on the performance of two-phase CO₂ ejectors

The use of two-phase ejectors with CO₂as the working fluid has received significant attention in recent years due to the fluid's large potential for expansion work recovery. These two-phase ejector studies commonly focus on the performance of the ejector cycle, but less attention is generally given to the performance of the ejector itself. The geometry of the ejector has been found to have a significant impact on the performance of the ejector and the ejector cycle. This paper summarizes available literature on CO₂ ejector geometries that have been found to offer favorable ejector performance and draws conclusions about what relations between various dimensions may lead to more favorable ejector performance. In order to gain further insight into how fluid properties affect the optimum geometry of an ejector, comparison is also made between the geometry of CO₂ ejectors and the geometry of ejectorsdesigned to work with other refrigerants.