Classification, Types and Examples of Refrigerants
A refrigerant is defined as a heat carrying medium. According to the requirement of application, different types of refrigerants are used in indutries and domestic scale.
Refrigerants are classified on different basis. In this tutorial, we are going to learn about how refrigerants are classified
and what are the types of refrigerants are being used (were being used) in the world.
Classification of refrigerants
We can classify refrigerants considering several basis as below and examples of refrigerants are mentioned with each basis.
Basis: Safety of refrigerants
Basis: Working principle
Basis: Chemical composition
Basis: Nature of refrigerants
Basis: Safety of refrigerants
There are three sub-classifications considering safety of refrigerants.
Safe refrigerants: These refrigerants are not toxic and non flammable. Therefore using these refrigerants is safe for health of humans.
Carbon dioxide (CO2), water (H2O), R-11, R-12 are few examples to safe refrigerants.
Toxic refrigerants: These refrigerants can be harmful to health of people if people were exposed to such kind of refrigerants.
Ammonia (NH3),
sulfur dioxide (SO2),
ethylene chloride are several examples.
Flammable refrigerants: These refrigerants can catch fire if flammable conditions are met. Butane and isopropane are two examples for
flammable refrigerants.
Basis: Working Principle
There are two classifications considering working principle (refrigerant cycle).
Primary refrigerant: These kind of refrigerants are directly undergone through the refrigerant cycle
which has four stages; compression,cooling, condensation and expansion. In each phase, a phase change is occurred due to sensible heat transfer.
R12, R22, CO2 and NH3 are few examples for primary refrigerants.
Secondary refrigerant: These refrigerants do not undergone through the refrigeration cycle as
primary refrigerants. Secondary refrigerants are used only for cooling purposes and water, brine, calcium chloride solutions are few examples.
Basis: Chemical composition
Four groups can be identified when chemical composition of refrigerants are considered and discuss in detail in next section of this tutorial.
Halocarbon refrigerants
Azeotropes
Hydrocarbons
Inorganic
Basis: Nature of refrigerants
Natural refrigerants
Artificial / Synthetic refrigerants
Types of refrigerants
Here, we will look types of refrigerants in detail.
Halocarbon refrigerants
In these refrigerants, there are Chlorine, Fluorine and Carbon (sometimes Hydrogen too). Because these halocarbon refrigerants has the capability of damaging ozone layer and causing other environmental damages, they were globally banned. There are (were) several halocarbon refrigerants in the market and will provide you a detailed description for each of them.
These halocarbon refrigerants are commercially available as "Freons".
clear, colorless gas at room temperature, has a faint, sweet odor. Gas is noticeable only at levels that may be toxic to inhale. It is
heavier than air, and it is extremely flammable.
Applications: reciprocating and rotary compressors, to identify leakages
A colorless liquid with a sweet, ether-like odor and irritant.
Applications: In industrial refrigeration systems where centrifugal compressors are used.
Melting point: -36.220C
Boiling point: 47.70C
Azeotrope refrigerants
Stable mixture of refrigerants which have identical compositions in both liquid and vapor phases over a wide temperature rage is defined as
azeotrope refrigerants.