“R-407C”的意思、由来-开放百科全书

R-407C is a mixture of hydrofluorocarbons used as a refrigerant. It is a zeotropic blend of difluoromethane (R-32), pentafluoroethane (R-125), and 1,1,1,2-tetrafluoroethane (R-134a). Difluoromethane serves to provide the heat capacity, pentafluoroethane decreases flammability, tetrafluoroethane reduces pressure.^[1] R-407C cylinders are colored burnt orange.

This refrigerant is intended as a replacement for R-22. R-22 production will be phased out by 2020 as per the Montreal protocol.^[2]

It is not recommended to drop R-407C into R-22 systems on top of the existing charge in cases of low refrigerant levels. A licensed professional should be contracted to completely remove the R-22 and as much of the mineral oil as possible. In the case of compressor change-outs, replacement compressors are already manufactured with POE (polyolester) oil and are therefore more compatible with R-407C than returning the recovered R-22. The recovered R-22 can be sent to a facility for disposal.

It is cost effective to replace R-22 with R-407C before there is an emergency. Preventive maintenance programs should include strong suggestions to replace ozone-depleting refrigerants such as R-22 with environmentally friendly refrigerants and it seems that R-407C has become the front runner. There are many millions of tons of R-22 in air conditioning and refrigeration equipment in use today and most of it is destined to end up in the atmosphere in spite of efforts to curtail this probability. These efforts have been in place since the late 1980s.

Physical properties

Physical properties of R407C refrigerant

Property

Value

Formula>

CH₂F₂	R32 (23%)
CF₃CHF₂	R125 (25%)
CF₃CH₂F	R134a (52%)

Molecular Weight (kg/kmol)

86.2

Boiling point (°C)

−43.8

Saturated liquid density (25°C), kg/m³

1138

Saturated vapour density (25°C), kg/m³

43.8

Critical temperature (°C)

86.4

Critical pressure, bar

46.3

Liquid heat capacity @ 25°C, (kJ/(kg·K))

1.533

Vapour heat capacity @ 1.013 bar (kJ/(kg·K))

1.107

References

1. ^A brief history of refrigerant {{webarchive|url=https://web.archive.org/web/20110718150305/http://home2.btconnect.com/grss/Web/R407C.htm |date=2011-07-18 }}
2. ^{{cite web|title=Unwrapping The Mystery Of R-407C|url=http://www.achrnews.com/articles/114247-unwrapping-the-mystery-of-R-407C|website=www.achrnews.com|accessdate=27 June 2016}}