How are refrigeration classified?
1 Answer

Classification of Refrigerants

1.On the basis of safety:

  • Toxic refrigerants (Ex: NH3, SO₂, ethylene, chloride, etc.)
  • Flammable refrigerants (Ex: Butane, Iso-propane, etc.)
  • Safe refrigerants (Ex:CO2, H₂O, R11, R12, etc)

2. On the basis of working principal:

Primary refrigerants:

  • Are those fluids, which are used directly as working fluids, for example in vapour compression and vapour absorption refrigeration systems.
  • The refrigerants undergoes compression, cooling, condensation and expansion with change in phase.
  • These fluids provide refrigeration by undergoing a phase change process in the evaporator.

Examples: R12, R22, CO₂, NH3

Secondary refrigerants:

  • This refrigerants does not undergo the cyclic process in refrigeration, but it used only as a medium for cooling.
  • which are used for transporting thermal energy from one location to other.

  • Secondary refrigerants are also known under the name brines or antifreezes.

Examples: H2O,Brine, Calcium chloride solution

3. On the basis of chemical composition :

Halocarbon Refrigerants

  • Halocarbon Refrigerant are all synthetically produced and were developed as the Freon family of refrigerants.
  • Essentially these refrigerants are compounds of chlorine, fluorine and carbon.


CFC's: R11, R12, R113, R114, R115

Trichloro monofluoro methane Freon-11, R-11, CFC-11 CCI3F
Dichloro difluoro methane Freon-12, R-12, CFC-12 CC1₂F2
MonoChloro trifluoro methane Freon-13, R-13, CFC-13 CCIF3
MonoChloro difluoro methane R-22 CHCIF2
Dichloro monofluoro methane R-21 CHCI₂F
Trichloro trifluoro ethane Freon 113a, R-113a, CFC-113a Cl3C₂F3
Dichloro tetrafluoro ethane Freon 114, R-114, CFC-114 C₂Cl₂F4


  • This group of refrigerants consist of mixture of different refrigerants which cannot be separated under pressure and temperature and they have fixed thermodynamic properties.
  • Azeotropic mixtures are designated by 500 series.
  • Azeotropic mixtures:

R 500: Mixture of R 12 (73.8 %) and R 152a (26.2%)

R 502: Mixture of R 22 (48.8 %) and R 115 (51.2%)


  • These refrigerants are nothing but compound of hydrogen and carbon.

  • Due to a ban on CFC, considerable interest has been generated in exploration of these refrigerant as alternatives.

  • These refrigerants have excellent thermodynamics properties, but are highly flammable and thus unsafe. some important hydrocarbons as refrigerant are:


Propane (C³HS): R 290

n-butane (C¹H¹0): R 600

Iso-butane (C4H¹0) : R 600a

Inorganic compounds:

  • These are non hydrocarbon group refrigerants, mostly naturally available.
  • They were used before the development of hydrocarbon group refrigerants and are still in use.
  • They being looked upon as environment friendly refrigerants for the future.


Ammonia: R 717

Water: R 718

Air : R 729

Carbon dioxide: R 744

Please log in to add an answer.