Refrigerent AND ITS NOMENCLATURE RAC

2. Meaning of Refrigerant:
A refrigerant is a working substance which is used in refrigerating machine.
It is a working fluid through which heat is transferred from the cold body to the hot body.
Formerly the number of useful refrigerants was very limited. Air, ammonia (NH3), carbon dioxide
(CO2), sulphur dioxide (SO2) were the only four refrigerants which has survived the adolescent
stage.
Somewhat later methyl chloride (CH3Cl) came in general use for domestic and commercial units
but since the development of the fluorinated hydrocarbons, a great variety of refrigerants has been
put at the disposal of the refrigerating engineer. They are largely used in modern plants.
The most common Freon refrigerants in use are:
Freon-11 (CHCl3), Freon-12 (CF2Cl2)
Freon-13 (CF3Cl), Freon-21 (CHFCl2)
Freon-22 (CHF2Cl), Freon-113 (C2F3Cl3)
and Freon-114 (C2F4Cl2)
Curiously enough the use of air as a refrigerant is both older and more recent than the other vapour
refrigerants.

3. Desirable Properties of Refrigerant:
Desirable refrigerant possess such chemical, physical and thermodynamic properties which permit their practical application in
refrigerating machines in an efficient way. No refrigerant may be ideal for all jobs.
The refrigerator selected for service should possess-as many qualities as practicable out of the following:
1. The condensing pressure should not be excessive.
2. The boiling temperature should be low.
3. The critical temperature should be high.
4. The latent beat of vaporisation should be high.
5. The specific heat of liquid should be low.
6. The specific volume of vapour should be low.
7. It should be non-corrosive to metals and inert to oils.
8. The refrigerant should be chemically stable.
9. The refrigerant should be non-inflammable and non-explosive.
10. It should be non-toxic and harmless to human beings or living cells.
11. It should be easily detectable for leaks.
12. It should be easily available and have low cost.
13. It should have satisfactory heat transfer and viscosity coefficient.

4. DESIGNATION OF REFREGERANTS

5. NUMERICAL PROBLEMS

7. AFTER COMPARING