Performance Characteristics of the R404A Indirect Refrigeration System Using CO2 as a Secondary Refrigeran

In this study, to investigate the performance characteristics of the R404A indirect refrigeration system using CO2 as a secondary refrigerant, the R404A refrigeration system was analyzed experimentally. Under given experimental conditions, the lower the difference between the R404A condensing temperature and the CO2 cooling temperature was, the greater the coefficient of performance (COP) of the total indirect refrigeration system was, including the R404A refrigeration and CO2 refrigerant circulation systems. These findings indicate that the COP of the R404A indirect refrigeration system using CO2 as a secondary refrigerant and the COP of the total refrigeration system are influenced by such variables as the R404A condensation temperature, the efficiency of the R404A internal heat exchanger, and the difference in CO2 cooling temperature, CO2 evaporation temperature, and CO2 mass flow. Therefore, the optimum R404A indirect refrigeration system using CO2 as a secondary refrigerant could be designed by considering these variables