The previous article mentioned principles of refrigeration which can be seen that the refrigerant is an important substance to cooling and can distribute the cool to all areas through equipment such as an evaporator, a pressure relief valve and a condensing unit to reduce the temperature down.
The importance of the refrigeration depends on selection in accordance to sizes of the cooling system as there are several sizes and come in different functions.
Refrigerant is a substance that create cool because the substance will spread to all relevant parts in the refrigeration system as aforementioned. The ability of convection by evaporation and vice versa into a refrigeration system without losing its function.
Once the refrigerant is at low temperature, the substance need stability and durability to heat and to conversion. It should not contain corrosive that is sensitive to metal of the refrigeration system in order to prevent from deterioration. Lastly, the refrigerant must be non-flammable and non-blast.
Journey of Refrigerants in Refrigeration System
Refrigerants circulate in refrigeration system and change its form, temperature, and pressure constantly in order to remove the heat from the specified area that need to replace with the cool.
Journey of the refrigerants start when expansion valve sprays refrigerants to an evaporator, that suck out heat from the inside area being cooled, making the refrigerants in liquid form absorb the heat until boiling and evaporate at low pressure.
At the same time, the refrigerants in gas can absorb the heat from area being cooled near the evaporator by using air and water as a medium. After the that, the refrigerants move to a compressor to compress at high pressure before proceeding to a condenser in order to remove the heat from the refrigerants and to condense back into liquid at high pressure.
Next, the refrigerants transfer back to the expansion valve to reduce the pressure and prepare for reuse as a cycle.
Qualities of good refrigerants in Thermodynamic should contain the followings:
- High rate of evaporation
- Low boiling point
- Sensitive to heat absorption
- Pressure of evaporation is higher than atmospheric pressure
- Average in condensation
- Specific volume to gas is rather low
Types of Common Refrigerants
Chlorodifluoromethane (ClCF2H) such as R22 is one of the most common substance in refrigeration system. R22 is an abbreviation of Halocarbon ClCF2H when using R is for refrigerant and 2 refers to atom of fluorine in the compound.
R22 can reduce the temperature up to -40.80 ºC and has lower boiling point than atmospheric pressure. The refrigerant is developed for general refrigeration system such as in residences, in manufacturers and operations to store raw material and products. It is safe and non-toxic, inflammable, no colour, and no odour, making an effective refrigeration.
Although R22 can be mixed up with lubricant easily at in high temperature and high pressure in the condenser, once the refrigerants transfer to the evaporator, the lubricant in the refrigerant will be separated. Nowadays, the lubricant has been reformulated and will not be mixed with the R22 during refrigeration process which make it convenient for cooling.
Tetrafluoroethane (CH2FCF3) such as R134a has a chemical composition of Carbon 2 atoms, Hydrogen 2 atoms, and Fluorine 4 atoms. The boiling point is -26.11 ºC at atmospheric pressure.
R134a is Hydrofluorocarbon (HFC) that slightly affects the atmosphere and is very similar to R-22. Its qualities are non-erode, inflammable, and non-toxic. In general, it is used in a cooling system that need average temperature such as an air-conditioning in buildings, cars, or refrigerators.
Mixed substance can be categorised into 3 types
1. R404A (R125/ R143a/ R134a)
The refrigeration has a compound of R404a. The boiling point is -46.4 ºC at atmospheric pressure. This is one of the purest types of refrigerant and has no effects to the atmosphere. The qualities are no colours, no odours, and non-toxic. Because its boiling point is rather low, therefore, it is perfect for a refrigeration system and suitable for freezers, refrigerators, and can be used in ice-cream makers as well.
2. R407C (R32/ R125/ R134a)
The refrigeration has a compound of R407C. The boiling point is -43.6 ºC at atmospheric pressure. This is one of the purest types of refrigerant and it is widely used lately. The new generation for air conditioning is manufactured to work well with this type of refrigerant. It is suitable for medium refrigeration systems such as in buildings, residences, factories, and refrigerators.
3. R410A (R125/ R32)
The refrigeration has a compound of R410a. The boiling point is -51.6 ºC at atmospheric pressure. It is suitable for general refrigeration and freezing for buildings, residences, factories, refrigerators, and walk-in refrigerators.
Change of Refrigerants in Refrigeration System
It is not recommended to change types of refrigeration from one to another because the refrigeration system was designed to each specific type of refrigerants. Some compressor or model were designed for specified refrigerants only. However, if it is necessary to change the type of refrigerant, meaning that other tools must be changed accordingly such as an Expansion Valve for example.
Another caution before replacing new refrigerants is that the whole cooling system need to be clean deeply by using Nitrogen gas to drive out dirt and residues as well as new lubricant should be replaced and a dehumidifier. All process will extend lifetime of the refrigeration system and make it functional.
In choosing refrigerants, the refrigeration system should be the most concern because each types of refrigerants have different qualities at different boiling point and vary in prices. Therefore, it should be chosen based on effectiveness of the refrigerants to refrigeration system. Moreover, the refrigeration should be environmentally friendly and non-harmful to human.
For further information on how to choose refrigerants and refrigeration solutions, please kindly comment below or contact us here. We look forward to service you.
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