Types of refrigerants and their numerical coding system

The three main types of refrigerants:

  1. Halocarbons
  2. Hydrocarbons, R-290 = C3H8 (Propane)
  3. Inorganic fluids, R-717 = NH3 (Ammonia)

Ionic liquids vapour pressure is less than hydrocarbon types and as suitable as refrigerant that increases the efficiency of absorption refrigeration processes.

Further Classification of Halocarbons:

  • Fully halogenated chlorofluorocarbons, (CClF3)
  • Hydrochlorofluorocarbons, (CHClF2)
  • Hydrofluorocarbons, (CHF3)

The numerical coding system of refrigerants:

Refrigerants were represented as R-ABCD, it is developed based their molecular structure.

  • A: number of double bonds in the structure
  • B: number of C atoms – 1
  • C: number of H atoms + 1
  • D: number of F atoms

For dichlorodifluoromethane, the code used is R-12, which is understood as

  • R stands for the refrigerant
  • ClCl-C-FF we observe that as similar to Methane molecule, Carbon atom as single bonds with each molecule of chlorine and fluorine and have no double bounds so A=0.
  • The value of B is zero because of single carbon atom (i.e 1-1=0).
  • The value of C is plus one on H atom where we do not have so its value is 0+1=1.
  • Finally, the value of D is 2 due to two fluorine atoms.

Therefore, the code given for dichlorodifluoromethane is R-0012, commonly called as R-12.