Worldwide efforts to reduce the environmentally harmful effects of chlorofluorocarbons revived the study of the CO₂ refrigeration cycle. A laboratory prototype of the CO₂ refrigeration cycle was built to experimentally investigate the cycle's performance potential. The performance of CO₂ was compared with that of R-22 for water-chilling applications. Though the ideal cycle coefficient of performance (COP) of CO₂ is only 50% to 60% that of R-22, the actual CO₂ cycle performs similarly to the R-22 cycle. This large deviation between the ideal cycle and the actual cycle is due to the beneficial thermophysical properties of CO₂ 

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