Thermodynamic analysis of transcritical CO2 refrigeration cycle with an ejector

A comparative study on transcritical carbon dioxide refrigeration cycle with ejector and with throttling valve was performed by the first and second laws of thermodynamics in theory. The effects of the entrainment ratio of the ejector, heat rejection pressure, outlet temperature of gas cooler and evaporating temperature on the coefficient of performance (COP) and exergy loss were investigated in transcritical carbon dioxide refrigeration cycle with ejector and with throttling valve. It is found that ejector instead of throttling valve can reduce more 25% exergy loss and increase COP more 30%. In addition, critical entrainment ratio of the ejector, optimal heat rejection pressure and critical outlet temperature of gas cooler affects COP greatly for the transcritical carbon dioxide refrigerating cycle with ejector. (C) 2010 Elsevier Ltd. All rights reserved.