Theoretical evaluation of carbon dioxide refrigeration cycle

Concerns of ozone depletion and global warming call for investigation of natural refrigerants. in this study the performance potential of the carbon dioxide refrigeration cycle is investigated theoretically. For this purpose, two cycle simulation models were developed. One is an Evans-Perkins cycle model for R-22, and the other is a transcritical cycle model for CO2. By using these models, the CO2 refrigeration cycle and heat exchangers for the CO2 refrigeration cycle were optimized. The water chilling and lap water heating performances of CO2 were compared to those of R-22. The thermophysical properties of CO2 and the proper heat exchanger design appropriate to CO2 offer the opportunity of reducing hear exchanger size and mass for tap water heating applications.