Refrigerant
A refrigerant is a chemical substance that is found in an air conditioner, a refrigerator, and in other refrigeration equipment. [1][2] Air conditioners work by circulating refrigerant through coils, absorbing heat from the air and releasing it outside, cooling the space with chilling efficiency. [3]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 and carbon based refrigerants such as Freon 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. [4] [5] As a result, the Montreal Protocol has been adopted. The treaty bans the production of CFCs, halons and other ozone-depleting chemicals such as carbon tetrachloride and trichloroethane.
| Type | Meaning | Atoms in the Molecule |
|---|---|---|
| CFC | Chlorofluorocarbon | Cl, F, C |
| CFO | Chlorofluoroolefin | |
| HCFC | Hydrochlorofluorocarbon | H, Cl, F, C |
| HCFO | Hydrochlorofluoroolefin | |
| HFC | Hydrofluorocarbon | H, F, C |
| HFO | Hydrofluoroolefin | |
| HCC | Hydrochlorocarbon | H, Cl, C |
| HCO | Hydrochloroolefin | |
| HC | Hydrocarbon | H, C |
| HO | Hydroolefin (Alkene) | |
| PFC | Perfluorocarbon | F, C |
| PFO | Perfluoroolefin | |
| PCC | Perchlorocarbon | Cl, C |
| PCO | Perchloroolefin | |
| H | Halon/Haloalkane | Br, Cl (in some but not all), F, H (in some but not all), C |
Refrigerant Media
Ball and stick model of*diethyl ether, used in the earliest vapor-compression refrigeration systems. (In the drawing, white is a carbon atom, black is hydrogen, and red is oxygen.)
Dichlorodifluoromethane (CFC-12, R-12), introduced in 1931
Isobutane (R-600a), an A3-class refrigerant
The 1,1,1,2-Tetrafluoroethane molecule (HFC-134a or R-134a), which has an atmospheric lifetime of 13.5 years
The observed stabilization of HCFC concentrations (left graphs) and the growth of HFCs (right graphs) in Earth's atmosphere.
The 2,3,3,3-Tetrafluoropropene (HFO-1234yf) molecule, with an atmospheric lifetime of 12 days
Disposable refrigerant gas cylinders, using different colors for different refrigerants. (Current guidelines discourage color-coded cylinders.)
References
- ↑ All about Refrigerator. energyeducation.ca. Retrieved 2024-08-29.
- ↑ What is Refrigeration - Definition, Source, Application and FAQs (in en). BYJUS. Retrieved 2024-08-29.
- ↑ Air-conditioning | Types, Benefits & Maintenance | Britannica (in en). www.britannica.com (2024-08-16). Retrieved 2024-08-30.
- ↑ Part III. The Science of the Ozone Hole. Retrieved 2007-03-05.
- ↑ Andino, Jean M.. 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? (21 October 1999)Sci. Am..
- ↑ Refrigerant blends to challenge hydrocarbon efficiencies (22 December 2019).
Related pages
- Freon, an old class of refrigerants