R290-Hydrofluoroolefin based low global warming potential refrigerant mixtures for room air conditioner: An energy, exergy, and environmental (3E) analysis

Among the numerous residential appliances, window or split air conditioners are the most prevalent. The hydrochlorofluorocarbon and hydrofluorocarbon refrigerants used in those systems are causing a serious threat to the environment. In this study, R290-hydrofluoroolefin (HFO) mixtures are proposed as replacements for high-GWP substances (R410A and R22) in window air conditioning (WAC) units. Low-flammability alternatives like R290-R1234yf (50:50 and 60:40 by mass) and R290-R1234ze(E) (50:50 and 60:40 by mass) mixtures were considered promising refrigerants for this study. Using the REFPROP 10.0 refrigerant database and MATLAB-based mathematical modelling, the energy and exergy performance of a WAC unit with proposed and existing refrigerants was investigated. The results demonstrated that R290-HFO mixers performed well, with coefficients of performance that were 5.1–11.9% and 10.8–17.0% higher than those of R22 and R410A, respectively. In a similar fashion, the exergy efficiency of the WAC system increased by 3.1% to 6.2%, with reductions in total exergy degradation and power consumption of 7.1% to 12.2% and 5.1% to 10.1%, respectively. An assessment of the total equivalent warming impact revealed that the use of R290-HFO compounds results in CO₂ emissions that are between 7.1 and 12.2% less than those of R22. Mini or microchannel heat exchangers for conventional evaporators and condensers can further decrease the predicted refrigerant change quantity for these mixtures, keeping it well below the IEC 60335–2-89 limit for flammable refrigerants.