Critical performance and carbon dioxide emission analysis of low GWP refrigerants R431A,R432A and R433A as replacements to R22 applicable in room air conditioners: An analytical study

The current investigation presents an extensive thermodynamic performance analysis and CO₂ emission analysis of R22 alternatives. Refrigerants such as R431A, R432A and R433A are considered as ozone friendly and low GWP R22 alternatives as per ASHRAE recommendations. Similarly, hydrofluorocarbon (HFC) refrigerant R407C is evaluated as a possible retrofit option for replacing R22. In this study, effect of various operating conditions like variation of superheating, subcooling, evaporation and condensing temperatures are considered in order to evaluate the performance of refrigerants. Moreover, comparative study of hydrocarbon (HC) blends (R431A, R432A and R433A) is made with HFC refrigerant R407C apart from hydrochlorofluorocarbon (HCFC) refrigerant R22. In this work, standard VCR cycle is taken for the thermodynamic analysis whereas CO₂ emissions are assessed by total equivalent warming index (TEWI). Results indicate that coefficient of performances (COPs) of R431A, R432A and R433A are higher in the range of 12.06%–15.98% when compared with R407C and they are relatively lower in the range of 2.73%–3.96% compared to R22. Compressor discharge temperatures of considered R22 alternatives are much lower than that of R407C and R22 by 1.62°C–17.05°C. The volumetric refrigeration capacities of R22 alternatives are higher in the range 0.11%–3.45% when compared with R407C and they are relatively lower in the range of 7.44%–10.82% compared to R22. TEWI of R407C is the highest among all the considered R22 alternatives and it is higher in the range of 13.28%–17.63%. Similarly, TEWIs of R22 alternatives are lower in the range of 2.48%–17.56% when compared to both R407C and R22. The study exhibited that overall performance of R22 alternatives (R431A, R432A and R433A) is better than R407C and R22.