Experimental assessment of alternative low global warming potential refrigerants for automotive air conditioners application

R134a, one of the most commonly used refrigerants especially for air conditioning (AC) systems, will be banned in automotive air conditioners after 2022 due to a high global warming potential (GWP). R152a and R1234yf are considered as two potential low GWP drop-in alternatives to R134a due to similar thermodynamic properties. In this paper, the performance of R152a, R1234yf, and R134a in an oil-free vapour compression refrigeration (VCR) system is investigated. The absence of oil lubricant enables a wide range of refrigerant selection and highly efficient refrigeration cycle. Experiments for R152a, R1234yf, and R134a were conducted over wide range of operating conditions. The results show that R1234yf is similar to R134a in terms of operating pressure and temperature, but R1234yf has an 11% and 16% deterioration in cooling capacity and coefficient of performance (COP) respectively. The higher volumetric efficiency, adiabatic efficiency and cooling capacity of R152a contributes to a 13% and a 6% higher cooling capacity and COP respectively than that of R134a. At an evaporator temperature of 0 degrees C, the COP of R152a, R1234yf, and R134a are 2.8, 1.8, and 2.3, respectively. Though flammability restricts the use of R152a in conventional automotive air conditioners, R152a can be considered as a more promising alternative to R134a for oil-free automotive air conditioning than R1234yf due to its high efficiency, low cost, and reasonable safety level benefiting from the absence of oil lubricants.