Thermodynamic Analysis of Fluids for Transcritical Heat Pump Utilizing Low Grade Geothermal Source

Three working fluids R125, R143a and R32 were analyzed thermodynamically for the transcritical heat pump with low temperature geothermal source as its heat source. The system parameters investigated include coefficient of performance (COP), volumetric heat capacity (Q_v), compressor discharge temperature and the pressure ratio. The results show that Q_v, pressure ratio and compressor discharge temperature all increase with the increase of gas cooler pressures while COP values decrease. COP curve of R125 has a maximum value point. R32 presents better performances with higher COP and Q_v values and lower pressure ratio values, but it shows the highest compressor discharge temperature. R125 shows the lowest compressor discharge temperature values and also the lowest COP value.