A refrigerant is a fluid (a liquid or a gas) that has a very low boiling point. Refrigerants are used in cooling units such as air conditioning units, refrigeration and freezing. A refrigerant evaporates into vapour and condenses back into liquid when in operation.
The heat in the air is absorbed by the refrigerant in an air conditioning unit and thereby cooling the air which in turn cools the space. The absorbed heat from the space is dissipated outside to the atmosphere. The refrigerant is later turned back into a liquid state by pressurizing the refrigerant with the aid of a compressor and the cycle is continuously repeated.
The most commonly used refrigerants for air conditioning over the years include R12, R22 (Freon), R410A (Puron) and R134A.
General Properties of Refrigerants
The following are the ideal properties of refrigerants:
- Low boiling point.
- High latent heat of vaporization.
- High critical temperature and pressure.
- Small compression ratio.
- Low toxicity.
- Easy leak detection.
- Low flammability.
- None corrosive properties.
- Low viscosity.
- High thermal conductivity.
- High dielectric strength.
- Low ozone depletion potential.
- Low global warming potential.
Types of Refrigerants
Chlorofluorocarbons (CFCs): These are the first generation refrigerants, they contain chlorine. The refrigerants categorized under CFCs are R11, R12 and R502. These refrigerants are known to contribute to the greenhouse gas effect. Production of new stocks ceased in 1994.
Hydrochlorofluorocarbons (HCFCs): These are the second generation refrigerants, they contain chlorine. The refrigerants categorized under HCFCs are R22, R401A and R123. These refrigerants are slightly less damaging to the ozone than R12, but the U.S. Environmental Protection Agency (EPA) has still mandated a phase out as a result of the Clean Air Act of 2010. R22 will phase out completely by 2020.
Hydrofluorocarbons (HFCs): These are the third generation refrigerants, they do not contain chlorine. The refrigerants categorized under HFCs are R134A, R410Aand R32. These refrigerants are contain no chlorine in the mix, they are safer for the environment and are now being used in place of the HCFCs. These refrigerants are more efficient, offer better air quality, increase comfort and improve reliability.
Boiling Points of Some Refrigerants
The boiling points of some commonly used refrigerants are given thus:
R22 has a boiling point of -40.80C.
R134A has a boiling point of -26.30C.
R410A has a boiling point of -48.50C.
Comparison of Refrigerants
R22
R22 is one of the commonly used refrigerants in air conditioning units. It has the following properties:
- Non toxic.
- Non flammable.
- Ozone layer depletion potential is high.
- Less energy efficient (because it absorbs and releases heat in lesser amount).
R410A
R410A is one of the commonly used refrigerants in air conditioning unit. It is a better substitutes for R22 refrigerant, it provides a better overall operations. It has the following properties:
- Non toxic.
- Non flammable.
- Ozone layer depletion potential is low.
- Greater cooling capacity.
- Energy efficient.
- Costlier.
R32
R32 is one of the commonly used refrigerants in air conditioning units. It has the following properties:
- Non toxic.
- Energy efficient.
- Higher cooling capacity than R22 and R410A.
- Mildly flammable but suitable for the atmosphere.
- Ozone layer depletion potential is low (lower than R410A).
- Recyclable.
When procuring new air conditioning units, ensure they are the types that run on R410A as this provide increased efficiency, better air quality, increased comfort and improved reliability. Since, R22 is an environmentally hazardous refrigerant, it is phasing out and its depleting supplies could make the repairs more expensive than it’s worth.
References
https://www.aireserv.com/about/blog/2016/june/what-is-refrigerant-and-how-does-it-help-your-ai/ Accessed on September 26, 2020
https://www.theengineeringmindset.com/refrigerant-types-future/ Accessed on September 26, 2020
Kazeem Olugbade, ProFM, is a facility management professional who has extensive knowledge and skills in the subject areas.
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