Experimentally Investigating of Friendly Alternative Refrigerant for R134a in Automotive Air Conditioning System

Automobile air conditioning systems (AACS) generally use R134a as a refrigerant; however, this has a negative impact on the environment because of its high global warming potential (GWP) value. National constraints have thus been applied to phase this out, which require refrigerants with zero ozone depletion potential ODP and low GWP to be used instead. In this work, blends of Liquid Petroleum Gas (LPG) and R134a were evaluated as alternatives to pure R134a in AACS, in order to decrease the flammability of the mixture and the effects of R134a. The properties of refrigerants were theoretically analysed in the authors’ previous work to determine compatibility with the proposed AACS, and the mixture that thus emerged as an alternative refrigerant, named Rmix, consisted of R600A/R290/R134a with mass ratios 43/35/22. Rmix and R134a were thus evaluated experimentally in an experimental test rig, with results that revealed that the cooling capacity and coefficient of performance (COP) values for Rmix were l7.5% and 10% lower than those of R134a, respectively, and that the evaporator loads for these refrigerants were 4KW to 5KW at a compressor speed of 1,000 RPM. The reduction was increased at 2,300 RPM, with evaporator loads reaching 10% and 20%, respectively. The required charge size of hydrocarbons (HCs) was reduced, with a reduction ratio of 22. Overall, Rmix was found to be usable in existing AACS without modification.