Refrigerant

Refrigeration cycle

A can of R407c refrigerant.

A basic diagram of a HVAC system

A refrigerant is a chemical substance that is found in an air conditioner, a refrigerator, and in other refrigeration equipment. Refrigerants are chosen for the ease of converting them from liquid to vapor or vice versa, depending on their temperature and pressure. Most refrigerants in their liquid state will evaporate very fast if at atmospheric pressure. They can be classed as CFC, HCFC, HFC, HC, or HFO along with less common types.

In refrigeration equipment, a refrigerant vapor is compressed by a compressor. Compression makes it hot. It enters a condenser, where it condenses into a liquid. The refrigerant then passes through a part called a metering device, or an expansion device (there are several types of this part) where the pressure is reduced to a point where the liquid begins to boil. At this point, the refrigerant is very cold and it enters an evaporator, where it absorbs heat from the air passing over it. By the time the refrigerant leaves the evaporator, it is all a vapor again, and it goes back to the compressor where the cycle begins again. This is called the refrigeration cycle. This is one example of the use of a refrigerant, in a residential air conditioning system.

Phase out of chlorine-based refrigerants

Older chlorine based refrigerants such as R22 have been phased out due to ozone depletion. The chlorine molecule in them was found to be depleting the ozone molecules in the atmosphere. ^[1] ^[2] As a result, the Montreal Protocol has been adopted. The treaty bans the production of CFCs, halons as and other ozone-depleting chemicals such as carbon tetrachloride and trichloroethane.

Types of Refrigerants ^[3]
Type	Meaning	Atoms in the Molecule
CFC	Chlorofluorocarbon	Cl, F, C
CFO	Chlorofluoroolefin	Cl, F, C
HCFC	Hydrochlorofluorocarbon	H, Cl, F, C
HCFO	Hydrochlorofluoroolefin	H, Cl, F, C
HFC	Hydrofluorocarbon	H, F, C
HFO	Hydrofluoroolefin	H, F, C
HCC	Hydrochlorocarbon	H, Cl, C
HCO	Hydrochloroolefin	H, Cl, C
HC	Hydrocarbon	H, C
HO	Hydroolefin (Alkene)	H, C
PFC	Perfluorocarbon	F, C
PFO	Perfluoroolefin	F, C
PCC	Perchlorocarbon	Cl, C
PCO	Perchloroolefin	Cl, C
H	Halon/Haloalkane	Br, Cl (in some but not all), F, H (in some but not all), C

Refrigerant Media

DuPont R-134a (1,1,1,2-Tetrafluoroethane) refrigerant in a 12 ounce can. Picture by Phroziac
The observed stabilization of HCFC concentrations (left graphs) and the growth of HFCs (right graphs) in earth's atmosphere.
R407C pressure-enthalpy diagram, isotherms between the two saturation lines

References

↑ "Part III. The Science of the Ozone Hole". Retrieved 2007-03-05.
↑ Andino, Jean M. (21 October 1999). "Chlorofluorocarbons (CFCs) are heavier than air, so how do scientists suppose that these chemicals reach the altitude of the ozone layer to adversely affect it?". Sci. Am.
↑ "Refrigerant blends to challenge hydrocarbon efficiencies". 22 December 2019.

Related pages

Freon, an old class of refrigerants

[1] "Part III. The Science of the Ozone Hole". Retrieved 2007-03-05.

[2] Andino, Jean M. (21 October 1999). "Chlorofluorocarbons (CFCs) are heavier than air, so how do scientists suppose that these chemicals reach the altitude of the ozone layer to adversely affect it?". Sci. Am.

[3] "Refrigerant blends to challenge hydrocarbon efficiencies". 22 December 2019.

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