Comparative energy and exergy analysis of a subcritical cascade refrigeration system using low global warming potential refrigerants

This study examines a variety of evaluation criteria such as various operating and design parameters for thermodynamic performance of a cascade refrigeration system (CRS). R41 is used in low-temperature circuit (LTC), whereas R1243zf, R423A, R601, R601A, R1233zd (E) and RE170 are used for the first time in this study and are adapted for a high-temperature circuit (HTC). This study with four aims are conducted: (1) to analyse refrigerant pairs with low global warming potential (GWP) to further contribute to the literature; (2) to investigate the impact of various operating parameters on system performance; (3) to suggest potential alternative refrigerant to R423A; (4) to also compare the performance of the refrigerant pairs used in this study with those analysed by researchers in the literature. The results demonstrate that condenser and evaporator temperature ranges have a significant effect on the performance parameters studied in the system designed for six refrigerant pairs. The greatest reduction in COP occurs in R41-R423A with about 43.85% in a change of 10 degrees C in the condenser temperature. A change of 10 degrees C in the evaporator temperature causes the COP of the CRS to rise by approximately 19% for all refrigerant pairs. For applications that desire low temperatures, R41-R423A exhibits the lowest COP and exergy efficiency with 1.105 and 33.93%, respectively, whereas R41-RE170 presents the highest COP and exergy efficiency with 1.210 and 37.18%, respectively. Furthermore, exergy destruction in HTC compressor is made up almost to one-third of total exergy destruction. RE170 is proposed as an alternative refrigerant for R423A by the reason of its low environmental detriment and superior performance. Furthermore, there is a maximum COP improvement of 13.05% compared to studies in the literature.

Automated summary

This study examines the thermodynamic performance of a cascade refrigeration system (CRS) with different refrigerant pairs and proposes potential alternatives to R423A, demonstrating the significant impact of various operating parameters on system performance. The results also show that RE170 is a promising alternative refrigerant with low environmental impact and superior performance, with a maximum COP improvement of 13.05% compared to existing literature studies.