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Thermodynamic analysis of transcritical CO2 refrigeration cycle integrated with thermoelectric subcooler and ejector

Liu, Xi, Fu, Ruansong, Wang, Zhiqiang, Lin, Li, Sun, Zhixin, Li, Xuelai
Energy conversion and management 2019 v.188 pp. 354-365
carbon dioxide, evaporation, exergy, refrigeration, temperature
In this paper, the new configuration of transcritical CO2 refrigeration cycle combined with a thermoelectric subcooler and an ejector (TES + EJE) is proposed. The thermoelectric subcooler is installed after the gas cooler in the transcritical CO2 refrigeration cycle with an ejector. Comparisons are carried out with the conventional transcritical CO2 refrigeration cycle (BASE), CO2 cycle with a thermoelectric subcooler (TES) and CO2 cycle with an ejector (EJE). Maximum cooling coefficient of performance (COPc) is obtained for the new TES + EJE cycle with a simultaneous optimization of subcooling temperature and discharge pressure. The improved new cycle exhibits higher COPc and lower discharge pressure compared with the other three cycles. Compared with the BASE cycle, the maximum COPc of the TES + EJE cycle is increased by 39.34% and the corresponding optimum discharge pressure is reduced by 8.01% under given operation conditions of 5 °C evaporation temperature and 40 °C gas cooler outlet temperature. The effects of the subcooling temperature, discharge pressure, gas cooler outlet temperature and evaporation temperature on the TES + EJE system performance are also discussed by energy and exergy analysis and results present here.