A review – Status of CO2 as a low temperature refrigerant: Fundamentals and R&D opportunities

Carbon dioxide (CO2) has emerged as one of the most promising and preferred refrigerants for low temperature refrigeration systems in the food and refrigeration industry and/or recreational activities. In recent times, the widespread use of CO2 refrigerant, particularly in supermarkets, has proved commercially attractive worldwide. Some of the designs that are most commonly used in industry include cascade, transcritical and transcritical booster, while many other interesting designs and variations are also being consistently used for specific situations. This paper presents the holistic view of the fundamentals and application of CO2 refrigerant in low temperature refrigeration systems, along with some discussion on its benign properties, thermodynamic analysis, the challenges, the need for fundamental research and design of novel systems for its continuing dominance in the refrigeration industry.