Selection of Efficient and Environmentally Friendly Working Fluids for Ground Source Heat Pumps

This paper presents an analysis of the technical and environmental properties of selected Freons, including critical point temperature and pressure, saturation temperature at atmospheric pressure, pressures, and heats of phase transitions at ground source heat pump operating temperatures, ozone-depleting potential, global warming potential, and a criterion to assess the presence and rightward slope angle of the saturated vapor line observed in several Freons. Thermal pump processes were developed for a range of intriguing Freons, considering a compressor efficiency of 60%. Calculations were performed for the temperature, pressure, enthalpy, and entropy of Freons at points between the heat pump components. It has been hypothesized and confirmed that the rightward slope of the saturated vapor line can significantly reduce the overheating of the Freon at the compressor output above the condensation temperature. Specific compressor and condenser performance, as well as the coefficient of heat transformation for these Freons, were computed. The advantages and disadvantages of R600a were outlined, highlighting its considerable benefits compared to other Freons for application in ground source heat pumps.