Evaluation of Performance of Heat Pump using R32 and HFO-mixed Refrigerant by Refrigeration Cycle Simulation and Loss analysis

R32 was selected as the alternative for R410A for mini-split air conditioners/heat pumps in Japan and have already phased out R410A in residential market. Recently several new alternatives for R410A have been proposed in order to achieve more close capacity to R410A and mitigate high discharge temperature issue of R32 as well as to reduce energy consumption. We selected R32 from among the candidates a few years ago; however it is important to continue comparing it to new candidates in search for an even better choice. We carried out the drop-in tests of the new refrigerant R32/R125/R1234yf (67/7/26) by comparing its COP and especially pressure loss to those of R410A, R32/R1234ze(E)(70/30), and R32, using residential mini-split type air conditioner. We conducted the drop-in tests by two types of method, actual measuring and especially simulated calculation. Adjusting compressor suction superheat and the amount of refrigerant charged into the system. Moreover, we measured the performance of the system with changing compressor speed in the wide range by variable frequency drive. Furthermore, we compared electricity consumption at the constant capacities, and analyzed the results precisely by loss analysis. As a result, we found that the COP of R32/R125/R1234yf (67/7/26) is better than R410A in many conditions and it achieves very close capacity to R410A, but COP at the same capacity is not as high as R32. The reason is that pressure losses are increased by adding R125 and R1234yf to R32. It was clarified, comparing losses with R410A, R32/1234ze(70/30), and R32. From the above, we confirmed that R32 is still the best choice at present. However, we will continue searching for a better alternative.