PERFORMANCE ENHANCEMENT OF CO_2 REFRIGERATION SYSTEMS BY THERMOELECTRIC SUBCOOLER

摘要

In this paper, the performance of the small capacity CO_2 refrigeration cycle was enhanced by the use of thermoelectric modules for subcooling. When compared to the basic CO_2 transcritical cycle, operating TE modules between the gas cooler outlet and the subcooler results in improved efficiency. As the TE modules subcool the CO_2 to below ambient temperature as it leaves the gas cooler, the enthalpy of the CO_2 entering the expansion valve is decreased, which enhances the system capacity and the coefficient of performance (COP). A prototype of the TE subcooler was designed and constructed. Experimental investigation reveals that the TE subcooler system capacity and COP at a TE current of 6A are 24.1% and 12.5% respectively higher than those of the baseline. When the current is increased to 12A, the TE subcooler system capacity and COP are 35.1% and 0.5% respectively higher than those of the baseline. This means that either the system capacity or the COP can be maximized through controlling the current of the TE supply.