Exergy Analysis of a Vapor Injection Refrigeration System with Flash Tank using Refrigerant Mixture R290/R600a

Abstract

Refrigeration systems are major consumers of energy. To reduce this energy consumption, alternative cycles have been studied and one of the most important is the refrigerant injection system. In the last decades, the environmental restraints of refrigerants have increased and refrigerant mixtures have attracted attention. In this context, this work presents the energy and exergy analyses for a conventional vapor compression refrigeration cycle (VCC) and an alternative vapor injection cycle with flash tank (FTVI) using a mixture refrigerant of R290/R600a. The influences of refrigerant mixture composition and expansion ratio in the upperstage valve on energetic and exergetic performance parameters were evaluated. Free expansion and heat transfer were identified as the greatest irreversibilities in VCC and FTVI, respectively, accounting for 26.7% and 23.6% of total exergy inputs in these systems. Higher values of efficiency metrics were observed at around 40% wt of R290 for both cycles. Reasons for the observed behaviors and ways to improve the cycles from the thermodynamic perspective are identified and discussed.