Energy and exergy analysis of transcritical CO 2 two-stage compression cycle

Based on theoretical analysis and experimental testing, the performances of transcritical CO2 two-stage compression cycle with two gas coolers were analysed. The maximum experimental refrigeration COPc and heat COPh are 2.24 and 3.25, the maximum theoretical COPc and COPh are 2.85 and 3.85. The COP both of COPc and COPh decrease gradually with increasing of the outlet temperature of gas cooler, and the average value of experimental COPc and COPh are 2.02 and 3.13, the average value of theoretical COPc and COPh are 2.54 and 3.54. Range of the evaporating temperature from −5°C to 17°C, the average value of experimental COPc and COPh are 1.99 and 3.17. The exergy loss both of theoretical value and experimental value are all increase gradually with increasing of differential pressure of throttling valve. The error of exergy loss percentage on theoretical calculation and experimental testing are almost all within +20% and −20%.