heat driven ejector refrigeration system, refrigerant comparison, HFO refrigerant, natural refrigerant, efficiency analysis
In this study, a numerical efficiency analysis for ejector refrigeration systems driven by low grade waste heat (65-85 °C) is performed. A 1-D numerical ejector model which was validated is applied to estimate the characteristics of the ejector. Investigation is focused on various refrigerants such as HFC (R134a, R245fa, R365mfc), HFO (R1234yf, R1234ze(E), R1233zd(E), R1336mzz(Z)), and natural refrigerants (NH3, R600, R600a), and their COPs (Coefficient of Performance) are compared. Main operating conditions (e.g. generation temperature, evaporation temperature, condensation temperature) are also considered to compare the system characteristics for each refrigerant. Simulations are performed for different operating conditions and their effects on system performance is analyzed. The results show that high NBP (Normal Boiling Point) refrigerants tend to show higher theoretical performance because of their high latent heat. In addition, it is found that sensitivity of generation temperature is less than evaporation temperature and condensation temperature.