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:
- 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
- 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 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
- 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