Comparison of a R744 cascade refrigeration system with R404A and R22 conventional systems for supermarkets

The present article focuses on the energy efficiency and climate performance of three different systems used in supermarket applications. The refrigeration systems consist of a cascade cycle (CO2/HFC-404A) – provide nominal refrigerating capacity – with carbon dioxide for subcritical operation and HFC-404A in the high stage temperature stage (pump circuit for normal refrigeration and direct expansion for deep-freezing), and also HFC-404A and HCFC-22 with direct expansion systems. The cascade system presented a lower refrigerant charge, 47 kg of both fluids, which represents less than a half of the refrigerant charge of the other systems. An important factor is the total GWP in case of leakage, where the impact in the atmosphere of the cascade system operating with CO2 was much less than the two direct expansion systems.