Comparative Energetic and Exergetic Analyses of a Cascade Refrigeration System Pairing R744 with R134a, R717, R1234yf, R600, R1234ze, R290

A comparative analysis of cascade refrigeration system is presented in this paper. Different pairs of refrigerants are used in this simulation. Both energy and exergy analyses have been conducted. Since a cascade system uses two different refrigerants, R744 is used in the low-temperature unit and R134a, R717, R1234yf, R290, R1234ze, R600 are used alternatively in the high-temperature unit for the purpose of comparative study. Values of COP and the second law efficiency are evaluated and compared with each different pairs of refrigerants used. This paper shows whether the use of refrigerants with low ODP and GWP values is viable or not. The sole purpose of this paper serves in identifying an appropriate refrigerant pair with lower environmental risk which can be really efficient in operating a cascade system. It was observed that R744-R717 attained the highest COP value equivalent to 7.848, and the highest ECOP value of 0.9838 was also attained by R744-R717. R744-R600 also obtained COP value of 7.741 and ECOP value of 0.9833 which is quite good.