Exergetic Investigations of a Multistage Multi-evaporator Vapour Compression Refrigeration System

Energy is the ability to cause a change in a system. It is usually available as exergy and anergy. Exergy is a useful part of energy, also known as available energy. Anergy is the counterpart of exergy, also known as unavailable energy. Thermodynamics is the science associated with energy and exergy, thereby ensuring both laws of thermodynamics—the first and the second by incorporating energy and exergy efficiencies. Refrigeration is a technology to preserve commodities at lower temperatures than their surroundings. One of the most widely used refrigeration systems is a vapour compression refrigeration system whose basic objective is to produce a refrigerating effect at the desired location. Commercial large capacity plants consist of the preservation of a different variety of food items requiring different preservation temperatures. It needs to maintain the evaporators correspondingly at different required temperatures. It requires multi-staging in compressors to save the compressor energy consumption. Exergy efficiency governs the actual performance of the system by knowing its deviation from the ideal one, and thus, is a true measure of any system performance. In this paper, an exergetic investigation of a multistage multi-evaporator vapour compression refrigeration system with individual expansion valves using R22 refrigerant is carried out. A shell and helical type heat exchanger is inbuilt as an intercooler between two compression stages comprises of refrigerant on both—shell and tube side. The two evaporators are maintained at −10 °C and 10 °C. Various parameters like exergy destruction and exergy efficiency are computed. Compressor consumes the maximum exergy destruction among all the components. Variation of exergy efficiency with different parameters is represented in graphical forms. Exergy analysis is a well-known technique and proved to be an alone tool for evaluating and comparing systems more meaningfully. It also helps to improve and optimize the design and analysis of a system.