Volume 11: Sustainable Energy Solutions for Changing the World: Part III

Thermodynamic evaluation of the effect of internal heat exchanger and expander on the CO2 trans-critical cycle cascade refrigeration system QIfanwang Dandan Su

Abstract

In order to study the influence of expander
and internal heat exchanger on the performance of the CO2 trans-critical cycle cascade refrigeration system, the effects of evaporation temperature (Te) on discharge temperature of the compressor, recovery power of expander, input power of compressor, COP, exergy efficiency and exergy destruction of the system, and exergy destruction ratio of each component were carried out by thermodynamic analysis. The results show that expander can effectively decrease the optimum condensation temperature of low-temperature cycle (LTC) and optimum high pressure, while high-temperature internal heat exchanger can slightly reduce the optimum condensation temperature and optimum high pressure of LTC and significantly reduce COP and recovery work of the expander. The COP of CE, when R14 is used as refrigerant, is 89.7% ~ 91.4% of that of R23 / R22CT. The biggest exergy destruction component is the gas cooler. The results provide a solution to improve the efficiency of the CO2 trans-critical cascade
refrigeration system.

Keywords C O 2 system; internal heat exchanger; expander; refrigerant; thermodynamic analysis