Combining HFO refrigerants with different system architectures to reduce energy use and CO₂ emissions in supermarket refrigeration

Commercial refrigeration systems worldwide predominantly use high global warming potential (GWP) refrigerants such as R404A. However, these refrigerants are under an agressive phase out process in several countries through strict CO2 regulations. One widely implemented strategy to reduce CO2 emissions is to retrofit existing systems to lower GWP refrigerants such as R448A, while improving the system efficiency at same time. For new installations, there is opportunity to further reduce CO2 emissions by designing system architectures that enable the use of very low-GWP refrigerants. In this paper, two new concepts of distributed system architectures using ultra-low GWP fluids are proposed. In the first concept system, refrigeration at both low and medium temperature levels is provided using R1234yf based hermetic self-contained units while a two phase heat transfer fluid based secondary loop in combination with R1234ze(E) based chiller removes the heat from self-contained units to ambient. In the second concept, a low-GWP refrigerant is used in both medium temperature cases and to provide cooling to low-temperature self-contained cases through cascade heat exchangers. We will show that both new systems can signifanctly reduce emissions and energy consumption.