Experimental assessment of the use of R515B as R1234ze(E) alternative in a small water-to-water heat pump

This paper presents the results of an experimental campaign carried out to assess the performance of a water-to-water heat pump working with R515B in a drop-in application. The heat pump is tested in a broad range of mass flow rates and temperatures of the secondary fluids at the heat exchangers outlets and the results are compared with those of R1234ze(E) since this refrigerant is the main component of the R515B mixture. In the range of the tested operating conditions, the use of R515B leads to capacity and COP variations that are within the ranges -4.70% to -0.92% and -1.86% to 3.74% respectively. From the compressor operation perspective, the use of R515B leads to slightly lower refrigerant temperature at the compressor discharge, with differences in the range -3.08 °C to -0.63 °C, whereas the volumetric efficiency is substantially the same.