A Refrigerant is a fluid which presents initially in the tubes of the evaporator of any refrigeration system.
The whole refrigeration system is mainly depending upon the type of refrigerant which is used for cooling purposes.
However, some factors of the refrigeration system i.e. system design, initial cost, safety, reliability, operating cost, etc. are much dependent on the type of refrigerant which is used for cooling purpose.
Classification of Refrigerants
Selection criteria of Refrigerants
The selection of the refrigerant for a particular application is based on the followings:
- Thermodynamic and thermophysical properties
- Environmental and safety properties
- Economics
In the first point, we deal with the pressure and temperature of the refrigerant that must be required in a particular range, so that the refrigeration system can work smoothly.
For example: At a given evaporator pressure, a refrigerant should have a positive pressure, it means the operating pressure or evaporator pressure should be higher than atmospheric otherwise refrigerant may leaks out from the refrigeration system to the surrounding.
In the second point, we discussed those refrigerants that are environmentally friendly, and may not harm human lives.
For Example, the Ozone depletion Potential of the refrigerant should be zero. Many refrigerants have a positive ODP, which harms the ozone layer and increasing the Global warming.
That’s why now Govt. of India takes an initiative, the default lowest temperature of the new air conditioner must be set at 24°C, so that the temperature of the earth may not increase.
Because as we lowered down the desired room temperature, the heat rejection rate is high as a result it increases the surrounding temperature.
Now, most of the air conditioner manufacturers use R-32 refrigerant which is chlorine-free.
Because due to the presence of Chlorine atom, the free chlorine atom may react with the ozone layer and delete it. Hence to control the depletion of the ozone layer, the refrigerant nowadays used is chlorine atom free.
At last in the third point, we screening those refrigerants which does not too much costly and must be available easily.