TITLE.PM5

REFRIGERATION CYCLES 765

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group have outstanding merits over the other group’s refrigerants, therefore they find wide field of
application in domestic, commercial and industrial purposes.
The list of the halocarbon-refrigerants commonly used is given below :
R-10 — Carbon tetrachloride (CCl 4 )
R-11 — Trichloro-monofluoro methane (CCl 3 F)
R-12 — Dichloro-difluoro methane (CCl 2 F 2 )
R-13 — Mono-bromotrifluoro methane (CBrF 3 )
R-21 — Dichloro monofluoro methane (CHCl 2 F)
R-22 — Mono chloro difluoro methane (CHClF 2 )
R-30 — Methylene-chloride (CH 2 Cl 2 )
R-40 — Methyle chloride (CH 3 Cl)
R-41 — Methyle fluoride (CH 3 F)
R-100 — Ethyl chloride (C 2 H 5 Cl)
R-113 — Trichloro trifluoroethane (C 2 F 3 Cl 3 )
R-114 — Tetra-fluoro dichloroethane (Cl 2 F 4 Cl 2 )
R-152 — Difluoro-ethane (C 2 H 6 F 2 )
(ii)Azeotropes. The refrigerants belonging to this group consists of mixtures of different
substances. These substances cannot be separated into components by distillations. They possess
fixed thermodynamic properties and do not undergo any separation with changes in temperature
and pressure. An azeotrope behaves like a simple substance.

Example. R-500. It contains 73.8% of (R-12) and 26.2% of (R-152).
(iii)Hydrocarbons. Most of the refrigerants of this group are organic compounds. Several
hydrocarbons are used successfully in commercial and industrial installations. Most of them pos-
sess satisfactory thermodynamic properties but are highly inflammable. Some of the important
refrigerants of this group are :
R-50 — Methane (CH 4 )
R-170 — Ethane (C 2 H 6 )
R-290 — Propane (C 2 H 8 )
R-600 — Butane (C 4 H 10 )
R-601 — Isobentane [CH(CH 3 ) 3 ]
(iv)Inorganic compounds. Before the introduction of hydrocarbon group these refriger-
ants were most commonly used for all purposes.
The important refrigerants of this group are :
R-717 — Ammonia (NH 3 )
R-718 — Water (H 2 O)
R-729 — Air (mixture of O 2 , N 2 , CO 2 etc.)
R-744 — Carbon dioxide (CO 2 )
R-764 — Sulphur dioxide (SO 2 )
(v)Unsaturated organic compound. The refrigerants belonging to this group possess
ethylene or propylene as their constituents. They are :
R-1120 — Trichloroethylene (C 3 H 4 Cl 3 )