What are the Classifications of Refrigerant?

Refrigerant:

The refrigerant is a heat carrying medium which during their cycles (i.e. compression, condensation, expansion, evaporation) in the refrigeration system absorbs heat from a low temperature system and discards the heat so absorbed to a higher temperature system.

Classification of Refrigerants:

The refrigerants are classified as follows:

        ➦ Primary refrigerants
        ➥ Secondary refrigerants

    ⬗ Primary refrigerants:

Primary refrigerants are those working mediums or heat carries which directly take part in the refrigeration system and cool the substance by the absorption of latent heat, e.g. Ammonia, Carbon dioxide, Sulphur dioxide, Methyl chloride, Methylene chloride, Ethyl chloride and Freon group etc.

The Primary refrigerants are grouped below:

            (i) Halo-carbon compounds:

In this group are included refrigerants which contains one or more of three halogens, chlorine and bromine and they are sold in the market under the names as Freon, Genetron, Isotron and Areton. Since the refrigerants belonging to this group have outstanding merits over the other group's refrigerants, therefore they find wide field of application in domestic, commercial and industrial purpose.

The list of the halo-carbon refrigerants commonly used is given below:

• R10 -- Carbon tetra chloride (CCl₄)   
• R11 -- Tri-chloro monofluoro methane (CCl₃F)  
• R12 -- Di-chloro difluoro methane (CCl₂F₂) 
• R13 -- Chlorotrifluoromethane (CClF₃) 
• R21 -- Di-chloro mono-fluoro methane (CHCl₂F) 
• R22 -- Mono chloro difluoro methane (CHClF₂) 
• R30 -- Methylene Chloride (CH₂Cl₂) 
• R40 -- Chloromethane (CH₃Cl) 
• R100 -- Ethyl chloride (C₂H₅Cl) 
• R113 -- Trichloro trifluoro ethane (C₂F₃Cl₃) 
• R114 -- Tetra- flouro dichloroethane (C₂F₄Cl₂) 
• R152 -- Di fluoro ethane (C₂H₄F₂) 

                (ii) Azeotropes:

The refrigerants belonging to this group consists of mixture of different substances. These substances cannot be separated into components by distillation. They possess fixed thermodynamic properties and do not undergo any separation with changes in temperature and pressure. An azetrope behaves like a simple substance.

Example: R-500. It contains 73.8% of R-12 & 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 installation. Most of them possess satisfactory thermodynamic properties but are highly inflammable. Some of the important refrigerants of this group are:

• R50 -- Methane (CH₄) 
• R170 -- Ethane (C₂H₆)
• R290 -- Propane (C₃H₈) 
• R600 -- Butane (C₄H₁₀) 
• R601 -- Pentane (C₅H₁₂₎

                (iv) Inorganic Compound:

 

Before the introduction of hydrocarbon group these refrigerants were most commonly used for all purposes. The important refrigerants of this group are:

• R717 -- Ammonia (NH₃)
• R718 -- Water (H₂O)
• R729 -- Air (Mixture of O₂, N₂, CO₂)
• R744 -- Carbon Di Oxide (CO₂)
• R764 -- Sulphur dioxide (SO₂)

                (v) Unsaturated Organic Compound:

The refrigerants belonged to this group possess ethylene or propylene as their constituents. They are

• R1120 -- Trichloroethylene (C₂HCl₃)
• R1130 -- Dichloroethylene (C₂H₂Cl₂)
• R1150 -- Ethylene (C₂H₄)
• R1270 -- Propylene (C₃H₆)

Secondary Refrigerants:

Secondary refrigerants are hose circulating substances which first cooled with the help of the primary refrigerants and are then employed for cooling purpose, e.g. ice, solid carbon dioxide etc. These refrigerants cool substances by absorption of their sensible heat.