FORTY YEARS OF COURTING R32: PERSONAL RETROSPECTIVE ON ITS PROPERTIES AND DESIGN CONSIDERATIONS IN REFRIGERATION, AIR-CONDITIONING, AND HEAT PUMPING

摘要

The analysis of refrigerants for one-stage, low-temperature applications brought attention on R32 forty years ago. The analysis covered 20 refrigerants with normal boiling points ranging from that of R-12 to R13B1. A second consideration of R-32 was given in 1992 while analysing available alternatives to R-22 and R-502 in supermarket refrigeration in a range of evaporating temperatures from -45℃ to +7℃ at a condensing temperature 43℃. The current study explores design approaches that could broaden R32 application limits in low- and medium refrigeration, air conditioning, and heat pumping, mainly with hermetic and semi-hermetic compressors. Factors, such as controlled superheat at the compressor inlet and enhanced compressor isentropic and electric motor efficiencies are quantified to reflect opportunities for R32 application in secondary-coolant and distributed low- and medium-temperature supermarket refrigeration systems. New materials used in compressors could lead to allowing higher temperature level and broader application limits for R32 as well.