Refrigerants

How do refrigerants deplete the Ozone layer?

Refrigerant 22 (R-22 or MonoChloroDiFlouroMethane, CHClF2) is one of the most common refrigerants and is used in a wide variety of applications such as refrigeration, aerosol propellants, cleaning solvents, and foaming agents for plastics. This refrigerant is believed to be partially responsible for damaging the earth’s ozone layer and it’s use is being phased out over the next two decades. The ozone layer is a result of sunlight reacting with oxygen to produce a layer in the stratosphere more than 10 km above the earth’s surface. As R-22 refrigerant escapes from an AC system through leaks or is released into the atmosphere by other means, the R-22 molecule containing the chlorine atom (“monochloro”) rises in the atmosphere. Sunlight breaks down the R-22 molecule to yield a free chlorine radical (Cl-). The free chlorine radical combines with ozone (O3), decomposing it into normal oxygen (O2).

AC refrigerants come in many varieties. R-22 is the most common, however, due to interactions with the ozone layer R-22 is being phased out. Refrigerants manufactured as replacements for R-22 are HFC-134a, R-410a, R-410b to name a few. The new refrigerants do not contain the chlorine atom and are not harmful to the earth’s ozone layer.

Refrigerants in HVAC

Refrigeration is the process in which work is done to move heat from one location to another.

A refrigerant is a substance or mixture, usually a fluid, used in a heat pump and refrigeration cycle. In most cycles it undergoes phase transitions from a liquid to a gas and back again.

Properties of Refrigerants

•Non- corrosive, non-flammable, non-explosive & non-toxic

•High heat of vaporization

•Moderate density

•High critical temperature

•Low boiling point and low freezing point.

• low specific volume to reduce the size of the compressor

Important Refrigerants: 

• Properties at -15oC

(1)  Ammonia (NH3)(R-717)

                   Latent heat = 1312.75 kJ/Kg

                   Specific volume = 0.509 m3/kg

(2) Dichloro–Difluoro methane (Freon–12) (R-12) [C Cl2F2]

                            Latent heat = 162 kJ/Kg

                            Specific volume = 0.093 m3/kg

(3) Difluoro monochloro methane – or Freon-22 (R-22) [CH Cl F2]

                     Latent heat = 131 kJ/Kg

                     Specific Volume = 0.15 m3/kg.

(4) Chloro Fluro Carbom (CFC)





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