Energy, Exergy, and Environment Performance Evaluation of Cascade Refrigeration System with Natural Refrigerants

Cascade refrigeration systems are preferred in applications where low temperature cooling is required, such as in some special industrial and laboratory applications. Since, in these systems, the energy consumed by the compressors is less and the compressor outlet temperature is lower. Due to environmental problems, the use of natural refrigerants in cascade refrigeration systems has become to be of great importance. In this study, two cascade systems consisting of R744/R290 (System 1) and R1270/R290 (System 2) natural refrigerant pairs were designed and thermodynamically examined. In the analyzes performed according to different evaporator temperatures, the highest COP value was 3.66 at -20℃ evaporating temperature was obtained in the cascade system consisting of the R1270/R290 refrigerant pair. Moreover, it was considered that there was a 17.95% enhancement in exergy efficiency with the use of R1270 refrigerant in the low temperature cycle. By the rise in the evaporator temperature, energy consumption decreases and as a result, the amount of carbon dioxide emissions reduced was attained.