Refrigerants
The design of a VCRS is very much influenced by the properties of the refrigerant employed in the system. The most broadly employed refrigerants are the halocarbons of the FREON family. The chemical composition of each halocarbon in the family is specified by the number credited to it. For illustration, the generally used refrigerant in the domestic refrigerators is FREON-12 or R-12 that is nothing though ‘dichloro-difluoro methane (CCI2F2)’. Likewise, FREON-22 or R-22 that is generally employed in window– air-conditioners is ‘manochloro-difluoro methane (CHCIF2)’. The other refrigerants in the family are: R-11, R-13, R-14, R-22, R-113 & R-114. The choice of the refrigerant based upon the evaporator temperature required, the kind of compressor employed in the system and the capacity of the system.
It is not forever the halocarbons which are used as refrigerants. Most of the inorganic substances like NH3, H2O, Air, CO2 and SO2 are also employed as refrigerants in certain particular cases.The properties of refrigerants are available in the form of tables or charts in hand books on refrigeration and air-conditioning.