Combining HFO Refrigerants with different System Architectures to Reduce Energy Use and CO_2 Emissions in Supermarket Refrigeration

摘要

Commercial refrigeration systems worldwide predominantly use high global warming potential(GWP) refrigerants such as R404A. However, these refrigerants are under an agressive phase outprocess in several countries through strict CO_2 regulations. One widely implemented strategy toreduce CO_2 emissions is to retrofit existing systems to lower GWP refrigerants such as R448A, whileimproving the system efficiency at same time. For new installations, there is opportunity to furtherreduce CO_2 emissions by designing system architectures that enable the use of very low-GWPrefrigerants. In this paper, two new concepts of distributed system architectures using ultra-low GWPfluids are proposed. In the first concept system, refrigeration at both low and medium temperaturelevels is provided using R1234yf based hermetic self-contained units while a two phase heat transferfluid based secondary loop in combination with R1234ze(E) based chiller removes the heat fromself-contained units to ambient. In the second concept, a low-GWP refrigerant is used in bothmedium temperature cases and to provide cooling to low-temperature self-contained cases throughcascade heat exchangers. We will show that both new systems can signifanctly reduce emissionsand energy consumption.