Experimental study of a two-phase ejector for CO2 transcritical refrigeration system

The geometry and operating parameters have an important influence on the performance of ejectors. The improvement of the refrigeration cycle performance and the design of the ejectors for the compression energy recovery requires a detailed analysis of the internal ejector working characteristics and geometry. To this aim, an experimental investigation of an ejector refrigeration system is conducted to determine the effect of the most important ejector dimensions on ejector working characteristics and system performance. Different dimensions of ejector components are tested. The influence of the ejector’s geometrical parameters on the system performance was analysed. The experiments with respect to the variation of ejector geometry such as the motive nozzle throat diameter, the mixing chamber diameter and the distance between the motive nozzle and diffuser were carried out. There exist optimum design parameters in each test. The experimental results show that the performance (entrainment ratio and a compression ratio of the ejector) increases significantly with the position between the primary nozzle and the mixing chamber. A maximum entrainment ratio of 57.3% and a compression ratio of 1.26 were recorded for the different parameters studied. The results obtained are consistent with experimental results found in the literature.

---

This work has been supported by the Centre for Energy and Thermal Sciences of the INSA of Lyon. All the gratitude and the recognition to the Centre for Energy and Thermal Sciences of the INSA of Lyon, who made available all the equipment necessary to carry out this experimental work.