Energy, conventional and advanced exergy analysis for the organic Rankine cycle-vapor compression refrigeration combined system driven by low-grade waste heat

Abstract

Global issues such as energy crisis and environmental pollution have driven the development of waste heat recovery technology. The organic Rankine cycle (ORC)-vapor compression refrigeration (VCR) combined system is a promising solution to achieve refrigeration requirements by recycling waste heat. How to determine the irreversible losses of the system and the improvement priority of the components is of great significance to enhance the system performance. Firstly, the energy and conventional exergy analysis of the ORC-VCR combined system is carried out to obtain thermodynamic performance of the system. Then, the advanced exergy analysis of the system is conducted and the exergy destruction distribution characteristics and improvement potential of the components are obtained. In addition, the interactions between the components are investigated in detail to achieve the improvement priority of the components. Finally, the improvement strategies for each component are proposed based on the influence of the components on the system. The results show that the coefficient of performance (COP) and exergy efficiency of the system are 0.44 and 14.97 %, respectively. The condenser contributes the most (44148 W) to the exergy destruction of the system. The largest endogenous (32935 W), avoidable (28530 W) and endogenous-avoidable (21577 W) exergy destruction also belong to the condenser. The condenser is determined as the most important component to promote system performance. The turbine and compressor have dominant influence on the system and the improvement depends on themselves. While the generator, condenser and evaporator only affect themselves and the improvement depends on all the components of the system. The results can provide theoretical guidance for further improving system performance.