Energy and exergy performance comparison of different configurations of an absorption-two-stage compression cascade refrigeration system with carbon dioxide refrigerant

This paper presents a comparative study of six configurations of an absorption-compression cascade refrigeration system. The cascade system is composed of a single-effect or a double-effect LiBr/H2O absorption chiller in cascade with a two-stage CO2 compression chiller. The cooling capacity of the absorption chiller is used to enhance the efficiency of the compression chiller. The system runs by a micro-turbine which provides the supplied energy to both chillers. System components are modeled and analyzed through the energy and exergy approaches. The performance parameters of the systems and the second law efficiency are calculated in different operating conditions. The results show that a proper choice of discharge and inter-cooling pressure along with a well calculated generator temperature can upgrade the energy utilization factor of the system considerably. It is also concluded that at a specific discharge pressure, a system with inter-cooler, after-cooler and double-effect absorption chiller would result in the highest improvement of the system. (C) 2016 Elsevier Ltd. All rights reserved.