Global warming impact and performance enhancement of propane/isobutane mixtures as alternative in air conditioning systems

Abstract

In this paper, the energy enactment calculation of air conditioning systems has been theoretically assessed with R22 (Chlorodifluoromethane) and the mixtures of R290(Propane) and 600a(Isobutane) as alternative refrigerant. The energy performance assessment of the air conditioner was made for three different condensing temperatures such as 35, 45, 55 and 65°C with evaporator temperatures between −10 and 10°C. The calculations was made in terms of standard energy performance parameters such as coefficient of performance (COP), compressor work, power per ton of refrigeration and volumetric refrigerating capacity (VRC). Total equivalent global warming impact (TEGWI) of the air conditioner was assessed for fifteen years life time. The results obtained showed that the VRC of new refrigerant mixture composed of R290/R600a (in the ratio of 0.4:0.6by mass) is closer to R22. Hence, new refrigerant mixture can be used as drop in substitute in existing R22 systems. The compressor work of the new refrigerant mixture was observed to be 7–11°C lower than that of R22, which confirms that improved compressor life can be expected with new refrigerant mixture. TEGWI of new refrigerant mixture was found to be higher than that of R22 by about 24% due to its higher power per ton of refrigeration. The results confirmed that the new refrigerant mixture is an ozone-friendly alternative to phase out R22 in the existing air conditioning systems to extend its life without modifications. Additionally, the suggestions to improve performance of the system are discussed.