Experimental analysis on the effect of internal heat exchanger in transcritical CO2 refrigeration cycle with two-phase ejector

The performance of CO2 ejector refrigeration system needs further improvement to make CO2 more viable than traditional harmful refrigerants. In this research, the effect of internal heat exchanger (IHX) in the performance of ejector refrigeration system was analyzed experimentally and compared with conventional expansion refrigeration system. Experiments were performed at different operating pressure and temperature for the cases of without IHX, 30 cm IHX and 60 cm IHX. The results showed that IHX significantly increased the coefficient of performance (COP) of ejector system. At the conditions used in this research, the ejector system with 60 cm IHX provided the maximum COP improvement of up to 27% compared to similar conventional system. The motive nozzle’s inlet condition had significant effect on the performance of ejector system. The results also confirmed the presence of considerable amount of liquid refrigerant at separator’s gas outlet of ejector system which was deemed possible in our previous research.