A Thermodynamic analysis of R-404A, R-449A, R-454C and R-744 in low and medium temperature refrigeration applications

As global regulations phase down the use of high global warming potential (GWP) HFCs such as R-404A in commercial refrigeration applications, there is an increased interest in quantifying performance differences between lower GWP fluorinated refrigerant solutions and refrigerant grade carbon dioxide (R-744). This study presents a thermodynamic energy efficiency and system performance model for a refrigeration system designed to represent two different USA supermarket sizes in every ASHRAE climate zone found in the United States. For fluorinated refrigerants, the architecture utilizes the standard vapor compression cycle with the inclusion of a liquid line – suction line heat exchanger to maximize the refrigerant performance. For the R-744 architecture, a transcritical booster layout is defined and utilized, including parallel compression to optimize performance with currently available technologies. Overall, this paper focuses on the fundamentals of refrigerant performance modeling and how to properly benchmark refrigerant performance for the next generation of refrigerants in commercial refrigeration.