Experimental investigation of a two-phase ejector installed into the refrigeration system for performance enhancement

Abstract

In this paper, the performance enhancement of the two-phase ejector installed into the refrigeration system called an ejector-expansion refrigeration system (EERS) is investigated experimentally. A comparative performance of an ejector expansion refrigeration system (EERS) with a conventional vapour-compression refrigeration (VCRS) system is proposed. The main purpose is to demonstrate the ability to mitigate the throttling loss or to demonstrate the expansion work recovery in which the theoretical work is limited. The experimental test bench which can be operated with both VCRS and EERS is designed and built for investigations. It is designed to produce chilled water under various cooling loads which allows it to produce the desired cooling temperature for performance assessment. The condenser is cooled by the cooling water whose temperature can be controlled precisely. The test results indicate that the EERS gives better performance over the VCRS when the expansion pressure ratio must be large enough. Therefore, there is limitation of using the EERS for the expansion work recovery. The system COP can be increased by 5.3–12.7% when the cooling temperature is decreased from 12 to 2 °C. The pressure lift effect of the two-phase ejector causes a reduction in the compressor’s pressure ratio which results in a lower specific work and the refrigerant discharge temperature. This yields a longer life-time of the compressor and better lubrication. It is also found that the working condition has a significant impact on the ability to enhance the system performance of the two-phase ejector installed into the refrigeration system.