MODELLING AND ANALYSIS OF CO2 GAS COOLERS FOR COMMERCIAL REFRIGERATION APPLICATIONS

CO2 is an environmentally benign refrigerant which is increasingly being used in commercial refrigeration applications. CO2 refrigeration systems can operate subcritically during periods of low ambient temperature or transcritically when the ambient temperature is above 25 oC or so, depending on the design of the heat rejection heat exchanger. Optimisation of the heat transfer performance of the heat rejection heat exchanger can extent the temperature range in which the CO2 refrigeration system can operate in the subcritical region and this will improve the seasonal efficiency of the system. This paper presents a model which has been developed to simulate the performance of CO2 heat rejection heat exchangers. The model has been validated against both sub-critical and transcritical data with the view to establishing its suitability for use as a design and selection tool for CO2 heat rejection heat exchangers over a wide range of conditions