Experimental investigation of the COP improvement of a refrigeration cycle by use of an ejector

In the present study an experimental comparison between the standard CO2 expansion valve refrigeration cycle and the ejector refrigeration cycle is presented. High pressure variations for different evaporation pressures and gas cooler outlet temperatures were performed. Additionally, the ejector efficiency, the entrainment ratio, and the pressure recovery by the ejector were investigated at these conditions. Both investigated cycles where realized using the same test rig, thus minimizing comparison errors. Compared to the maximal COP of the expansion valve cycle, COP improvements of the ejector cycle of 17% were reached with ejector efficiencies of up to 22%. (C) 2012 Elsevier Ltd and IIR. All rights reserved.