Performance enhancement of a vapor compression cycle with R32/R1234yf by using internal heat exchanger

The internal heat exchanger (IHX) has been widely employed in vapor compression cycle to improve performances, which is also called the subcooling vapor compression cycle (SVCC). In this paper, the influence of IHX on cycle performance using zeotropic blend R32/R1234yf is evaluated theoretically. The potential benefits of IHX due to the use of zeotropic mixture with temperature glide feature are analyzed for air conditioner applications. The performance of the SVCC using R32/R1234yf with a mass fraction of 0.2/0.8, which has a maximum temperature glide of 7.9 °C, is compared in detail with that of the basic vapor compression cycle (BVCC) using R32. The refrigerant temperature at the condenser outlet is set from 35 °C to 55 °C in cooling mode and from 25 °C to 35 °C in heating mode. The subcooling at the outlet of the condenser and the superheating at the inlet of the compressor are both 5 °C. The results confirm that the SVCC using R32/R1234yf is prior to the BVCC using R32. The cooling COP (COP_c) of the mixture is 1.0 %–4.7 % and the heating COP (COP_h) is 4.1 %–8.4 %, which are all higher than R32. The compressor pressure ratio, compressor power consumption and discharge temperature of the R32/R1234yf are lower compared to pure refrigerant R32. It is evident that the cooling and heating performance of SVCC are enhanced by using zeotropic blend R32/R1234yf.