5. Experimental results and discussion
5.1. Performance comparison between R410A and R32 without vapor injection
First, experimental tests were conducted without vapor injection. In such a case the heat pump system works as a conventional single-stage vapor compression cycle. Fig. 5 shows the comparison between R410A and R32 at different operating conditions without vapor injection. As seen from Fig. 5a, the dotted line divides the ambient temperatures into heating mode and cooling mode results on the left and right, respectively. Comparing R32 to R410A without vapor injection, the capacity and COP improvements were observed to be 3e10% and 2e9%, respectively. The maximum improvement was observed at the cooling condition of 46 #C. However, it is noticed that there was no improvement at the ambient temperature condition of "18 #C. The power consumption using R32 was observed to be 1e5% higher than that of R410A. Fig. 5b shows the refrigerant mass flow rate comparison between R410A and R32 at different ambient temperatures. R32 shows lower mass flow rate as compared to R410A. The mass flow rate difference was noticed at "18 #C. From the refrigerant property comparison it was noticed that R32 has higher latent heat than R410A,