Thermodynamic Analysis of CO2 Transcritical Supermarket Refrigeration Systems

Refrigeration systems using carbon dioxide (CO2) as a refrigerant, either in subcritical or transcritical cycles, or as secondary coolant systems, have recently received considerable attention due to carbon dioxide's low Global Warming Potential (GWP). This paper presents a comparative analysis of various CO2 transcritical refrigeration systems to optimize the operating parameters of these systems. In addition, the performance of selected CO2-based refrigeration systems is compared to the baseline R-404A multiplex direct expansion system using bin analyses in sixteen cities from eight climate zones of the United States. The operating parameters considered in this study include ambient temperature, suction line heat exchanger (SLHX) effectiveness and evaporator superheat.