Performance and suitability comparisons of some R22 possible substitute refrigerants

All the R22 substitutes from the US EPA list together with some popular alternative refrigerants were studied. From the ODP and GWP criteria, only seven substitute refrigerants (R134a, R407C, R437A, R744, R1234yf and R290) were accepted. The environmental impact, compatibility with existing R22 systems and system performance of each refrigerant were compared. The system performances were studied in systems without and with internal heat exchangers. It was found that R744 is the most environmentally friendly refrigerant. R290 and R407C are the most suitable to retrofit existing systems. R290 and R134a have superior system performances as compared to other alternative refrigerants.