Gas cooler heat driven sub-cooling system for CO2 chillers

Abstract

The use of carbon dioxide (CO2) as a refrigerant can help in reducing the use of synthetic refrigerants. However, the use of CO2 is penalized at high ambient temperatures as those require operating in supercritical conditions. In this situation, the losses at the gas cooler represents up to 30% of the total entropy losses of the cycle. This paper presents a low GWP refrigerant ejector based sub-cooling system driven by the heat of the gas cooler. The paper presents the cycles modeling including the ejector mathematical model and the cycle optimization method. The refrigeration cycle architecture, the choice of the ejection cycle fluid, and the performance gain are discussed as well