Energy Efficiencies of Three Configurations of Two-Stage Vapor Compression Refrigeration Systems

摘要

A thermodynamic analysis is performed on three different configurations of R134a two-stage vapor compression refrigeration systems designed to equip cold store rooms. For economic and commercial reasons relating to agricultural activities in southern Tunisia, two seasonal food products, dates and poultry, are selected for storage at different temperatures. Performance optimization of the refrigeration systems is investigated under various operating conditions in order to choose the most efficient for a given situation. The threestage vapor compression refrigeration systems have the same main components, but they differ in the arrangement of the flash separator. For the first considered system, the flash separator is installed before the first evaporator. In the second system, the flash separator is introduced before the second evaporator. For the third refrigeration system, the flash separator is placed before the two evaporators. An analytic study is performed in order to analyze the influence of the condensing temperature, the inter-stage pressure, the subcooling, and the superheat on the system performances. For the same operating conditions, each cycle is optimized with regard to energy performance, refrigeration efficiency, total compressor power consumption, and specific cooling capacity. A comparison between the obtained results for the three considered cycles is established. Optimum values of evaporators' superheat and inter-stage pressure are determined.