Experimental investigation of r1234yf with liquid line heat exchanger in automobile air-conditioning system used r134a

Nowadays, R134a (GWP = 1430) is widely used in automotive air conditioning (AAC) systems as refrigerant. Although R134a has no damage to the ozone layer, its effect on global warming is huge. Due to this reason, studies are being performed to restrict the use. According to Directive 2006/40/EC of the European Parliament (EP) and Council, the sale of cars using refrigerants those have higher GWP value than 150 was planned to be prohibited from 2017. This directive is in force within a plan. As the same, according to EP and Council's directive 517/2014 it was decided to forbid the use of R134a starting from 2022. The alternative refrigerant to R134a is R1234yf (GWP=4), which is being used in AAC systems. Thermo-physical properties of R1234yf are quite close to R134a. However performance of R1234yf is lower than R134a when R1234yf used without any modification in the AAC system. In this study, it was aimed to increase the performance of R1234yf using an internal heat exchanger (IHX) in AAC system designed for R134a. In this context, experimental AAC system, which is basically a vapour compression refrigeration cycle, was installed in Yalova University Air-Conditioning Laboratory and equipped with various measuring devices. R134a and R1234yf were tested in the experimental setup, respectively and then R1234yf with the double pipe heat exchanger was tested again under the same conditions. Experiments was carried out by increasing the condensation temperature at constant -10°C evaporation temperature, increasing the evaporation temperature at constant 40°C condensation temperature, finally increasing the compressor speed at the evaporator and condenser air flow inlet temperatures kept constant at 27°C and 35°C, respectively. Energy and exergy analyses were performed with the obtained experimental data and the performance parameters were reached. The results were given in comparative graphs. In experiments which heat exchanger was not used, it was calculated that the cooling capacity of R134a was 17.87%, COP value of it was 11.02% higher than R1234yf. With the heat exchanger the cooling capacity and COP value of the R1234yf increased by 9.2%, 5.47%, respectively. When R134a was used in the system, the compressor power reached maximum value. R134a was followed by R1234yf+ IHX and R1234yf. The most exergy destructed in the case of R1234yf+IHX. The effectiveness of the double pipe heat exchanger was calculated as 16% on average. As a result, it was observed that the performance of R1234yf was lower than R134a when without any modification in AAC system and was improved with the heat exchanger used to the liquid line but was not pass performance of R134a.