HALOCARBONS (“FREONS”) – REFRIGERANTS FOR COMMERCIAL AND SMALL INDUSTRIAL INSTALLATIONS
Synthetic cooling fluids, known as “freon”, were developed during the thirties of the last century with the idea of being stable, non-toxic and non-combustible compounds that mix well with compressor lubricants and are suitable for operating in commercial installations at pressures higher than atmospheric. In addition to the relatively high critical temperature, they are to be good electrical non-conductors and to have a low compressor discharge temperature. Based on the developed series of “freons”, R12 (CCl2F2), R11 (CCl3F) for centrifugal compressor air conditioners, R22 (CHClF2) and R502 (azeotropic mixture R22 and R115 (C2ClF5)), R13 (CClF3) for low temperature cooling, it seemed that “ideal” refrigerants for the commercial sector and some applications in the industry were eventually found.
However, at the beginning of the seventies, it was undoubtedly found that chlorine and bromine obtained by decomposition of freons in the atmosphere, critically cause the destruction of the ozone layer – the Earth’s protective barriers against cosmic radiation. As a result immediately a feverish need for “new” refrigerants began.
It started with “new” refrigerants, in fact with the mixtures of existing ones in order to obtain the desired features. One-component HFC (chlorine-free) and HFO fluids are produced. The attention was returned to some natural fluids, which in most cases were suppressed by the appearance of just halocarbon refrigerants (propane, butane, isobutane and carbon dioxide). However, since the beginning of its application (since 1873), ammonia has remained indispensable as a refrigerant for the industrial cooling sector.