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What is R22 Refrigerant or Freon?
R22 refrigerant is one of the most commonly used refrigerants in the air conditioning systems. R22 is the short name for the halocarbon compound CHClF2 (monochlorodifluoromethane), which is used as the refrigerant. R stands for the refrigerant. In the number “22” second “2” denotes the number of the fluorine atoms in the compound.
The boiling point of R22 is -40.8 degree Celsius (-41.4 degree F). Due to its low boiling point this refrigerant was initial developed for the low temperature applications like domestic and farm freezers and in industrial refrigeration applications. Even at present R22 is extensively used in the industries for liquefaction of the gases like chlorine, for supplying chilled water to various processes, machines, chillers of central air conditioning systems, etc.
One of the most common uses of R22 is in the domestic air conditioners like window AC, split AC, packaged AC and also in number of central air conditioning systems. R22 is non-toxic and it is non-flammable that makes this refrigerant highly safe for the domestic and industrial purposes.
The discharge temperature of R22 is quite high, hence the degree of superheat in the systems using this refrigerant should be minimum. The compression ratio for the systems using this refrigerant should also be low, and if it is high intercooling between the two stages of the compression should be kept.
R22 refrigerant is easily miscible with the oil at condenser temperature, but at the evaporator temperature it tends to get separated from the oil, however, if the evaporator and the suction piping are designed properly, no such problem occurs. In case of the flooded evaporators the oil gets separated from R22 so there should be provision for separating the oil. It the system is being used for the developing low temperature, the oil separators should be installed to remove the oil from the evaporator. In the present days some good synthetic lubricants have been developed that don’t separate from R22.
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Advantages of R22 Refrigerant
1) Has less effect on ozone layer: Refrigerant R22 is a hydroclhorofluorohydrocarbon (HCFC). It has one hydrogen atom in its compound and not all the hydrogen atoms from it are replaced by the halocarbons as it happens in chlorofluorohydrocarbons (CFCs). The halocarbons have high detrimental effect to the ozone layer of environment. Since R22 is HCFC it has lesser ozone destruction capability. The ozone destruction potential of R22 is only 5% of refrigerant R11, which has the highest ozone destruction potential.
2) Low compressor displacement: For producing the same compression the displacement required by the compressor with refrigerant R22 is small compared to refrigerant R12. In fact the displacement required for R22 is 60% of that required for R12. This means that for the given displacement of the compressor the system using refrigerant R22 produces 65% more refrigeration capacity than the system using the refrigerant R12. This translates into higher refrigeration efficiency and lower power consumption, which is very crucial in the large industrial applications though it is important for the domestic applications as well.
3) Greater water absorbing capacity: Refrigerant R22 has greater water absorbing capacity than R12. This is very important in low temperature applications since the water in refrigerant R22 would have less troubling effects on the refrigeration system. Anyways, even minor amount of water in the refrigeration system is undesirable.
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Replacements for Refrigerant R22
In developed countries R22 is being replaced in the phase manner. No new equipment using Refrigerant R22 would be available from January 2010. Thereafter R22 would be available only for servicing the old systems. By the year 2021, complete production of refrigerant R22 would stop. Some of the available alternatives for R22 are: R-134a, R-507, and R-407c.
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1) Book: Principles of Refrigeration by Roy J Dossat, fourth edition, Prentice Hall.