- Primary refrigerants: They take part directly in refrigeration and cool the substance on absorption of their latent heat. Some of the primary refrigerants are NH3, CO2CH3, C12, CH2C12, SO2, C2H5C1 and Freon group.
- Secondary refrigerants: They are first cooled with the help of primary refrigerant and then used for cooling other substances by absorption of their sensible heat only e.g. ice, solid CO2.Primary refrigerants may be grouped as follows:
- Halo-Carbon compounds: They contain one or more of three halogens, fluorine, chlorine and bromine. Commercially they are sold under the names as Freon, Genetron, Irontron and Areton, They are used in domestic commercial and industrial refrigerating devices. Some of their important examples are:Carbon tetrachloride− R10: CC14Trichloromono-fluro methane− R11: CC13FDichloro-difluro methane− R12: CC12F2Monobromotri-fluro methane− R13: CBrF3
- Azeotropes: They are the mixtures of different refrigerants. They do not under go any separation with changes in temperature and pressure, e.g.R-500 (73.8% R12 + 26.2% R-152) : CC12F2 + CH3CH F2R-502 (48.8% R22 + 51.2% R-115) : CHC1F2 + CC1 F2 CF3
- Hydrocarbons: They are hydrocarbons, e.g.Methane− R50: CH4Ethane− R170: C2H6Propane− R200: C2H8
- Inorganic compounds:Ammonia− R717: NH3Water− R718: H20Air− R720: −Carbon dioxide− R744: CO2
- Unsaturated organic compounds: They contain ethylene or propylene as main constituents, e.g.Ethylene− R1150: C2H4Propylene− R1720: C3H6Trichloroethylene− R1120: C2H4Cl3
CLASSIFICATION OF REFRIGERANTS
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