Refrigerants for the 21st Century
6. Early Fluorinated Refrigerants
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After successful introduction of CFC-12 for mechanical
refrigeration, other fluorocarbons were prepared and found to have commercial
utility. We list some of these below. You can see how the availability of these
chlorofluorocarbons led to a wide range of specialized refrigeration, aerosol and other
commercial uses. |
| Chemical Composition | Designation | Boiling Point @760 torr |
Applications |
| CF2Cl2 | CFC-12 | -29.8oC | Refrigeration, auto air conditioning, aerosols, polymer foam blowing |
| CFCl3 | CFC-11 | 23.8oC | Air conditioning, water chillers, aerosols, foam blowing, solvent |
| CHF2Cl | HCFC-22 | -40.8oC | Low temperature refrigeration, central and window air conditioners, "Teflon" raw material |
| CF2ClCFCl2 | CFC-113 | 47.6oC | Foam blowing, solvent |
| CF2ClCF2Cl | CFC-114 | 3.8oC | Refrigeration, aerosols |
| CF3CF2Cl | CFC-115 | -38.7oC | Supermarket open-case refrigeration |
If we review these applications for the CFC's, it's not hard to see that many CFC's would be emitted to the atmosphere during use - aerosol, foam blowing, solvent. While mechanical refrigerators are designed not to leak refrigerant (though they are not hermetically sealed), eventually they will release their contents. Auto air conditioners have long been subject to leakage owing to vibration and the need to use rubber hoses for connections. The practice of "topping off" the auto refrigerant has become common, even by the car owners.
Therefore, it should not have come as a surprise when British philosopher and chemist Prof. James Lovelock reported in 1973 that he detected a build-up of CFC-11 and CFC-12 in the atmosphere. His results stemmed from his invention of extraordinarily sensitive electron capture devices (ECD) that enabled him to detect the presence of compounds like the chlorofluorocarbons at the parts per billion level in gases. Prof. Lovelock's findings might at first raise only limited concern until we recall the chemical stability of the chlorofluorocarbons.
| You can keep abreast of chlorofluorocarbon developments by searching one or more of the search engines. From AltaVista you will find these references. |
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Concept Map for this ChemCase
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Or move on to
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Principal Investigator Laurence Peterson; Project Director Matthew Hermes;
Author of this module William Gumprecht.
Fluorocarbon Alternatives