EXPERIMENTAL AND NUMERICAL STUDIES ON AN AUTOMOBILE AIR CONDITIONING SYSTEM WITH THE REFRIGERANTS R134a, R1234yf AND R1234ze(E)

Abstract The 2016 Kigali amendment suggested phase-out of the HFCs and this process will go on until 2036 in industrialized nations and until 2047 in non-industrial nations to accomplish a condition of 85% decrease of HFCs. The HFC134a refrigerant used in vehicle air conditioning has a Global Warming Potential (GWP) of 1300, which prompted researchers to look for new low-GWP refrigerants. Recent research has revealed that the HydroFluoroOlefin (HFO) refrigerants R1234yf and R1234ze(E) with a GWP of 4 or less, show promise for application in Automobile Air Conditioning (AAC) field. The AAC requires special attention due to frequent leakages of HFC caused by vibration-induced pipe failures. In this research, the low-GWP refrigerants R1234yf and R1234ze(E) are considered to explore the AAC system performance and comparisons are made with the currently used refrigerant HFC134a. The numerical simulations are performed by including and excluding liquid-to-suction heat exchanger/Internal Heat Exchanger (IHX). The results show that use of IHX is advantageous for both R1234yf and R1234ze(E). R1234yf with IHX is a better alternative in the current AAC system working with R134a without IHX, with only a slight compromise in the system's performance and also the performance of R1234yf is better than R1234ze(E). Finally, the numerical simulation results are validated against the experimental results for R134a and R1234yf and found that most of the results agree within 10% deviation for system without IHX and within 15% deviation for system with IHX.