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Practical Laboratory Data
Published in W. M. Haynes, David R. Lide, Thomas J. Bruno, CRC Handbook of Chemistry and Physics, 2016
W. M. Haynes, David R. Lide, Thomas J. Bruno
Material Trichlorofluoromethane, CCl3F Trichloromethane, CHCl3 Methylamine, CH3NH2 Difluoromethane, CH2F2 Trifluoromethane, CHF3 Bromochlorodifluoromethane, CF2ClBr Chlorodifluoromethane, CHClF2 Dichlorofluoromethane, CHCl2F Chlorofluoromethane, CH2ClF Hexafluoroethane, C2F6 Ethyne (Acetylene), C2H2 Chloropentafluoroethane, C2ClF5 Dichlorotetrafluoroethane, C2Cl2F4 Chlorotrifluoroethylene, C2ClF3 1,1,1-Trichloro-2,2,2-trifluoroethane 1,1,2-Trichloro-1,2,2-trifluoroethane Chloroethane, C2H5Cl 1,1-Dichloroethane Trifluoroacetonitrile, CF3CN Acetonitrile, CH3CN Dimethylamine, (CH3)2NH Ethylamine, C2H5NH2 Ethylene oxide (oxirane), CH3CHO Perfluoropropene, C3F6 Octafluoropropane, C3F8 3,3,3-Trifluoro-1-propene, CH2CHCF3 Pentafluoroisocyanoethane, C2F5NC 1,1,1,4,4,4-Hexafluoro-2-butyne, CF3CCCF3 Octafluorocyclobutane, C4F8 1,1,1,2,3,4,4,4-Octafluoro-2-butene Decafluorobutane, C4F10 Perfluorobutanenitrile, C3F7CN Perfluoro-2-methyl-1,3-butadiene, C5F8 Hexafluorobenzene, C6F6 Perfluorocyclohexane, C6F12, (saturated vapor)
Refrigeration and Freezing of Foods
Published in C. Anandharamakrishnan, S. Padma Ishwarya, Essentials and Applications of Food Engineering, 2019
C. Anandharamakrishnan, S. Padma Ishwarya
Refrigerants absorb heat from the food product to be cooled and transfer it to the surroundings. Since the 19th century, a variety of refrigerants have been introduced for different applications (Table 11.1). Usually, refrigerants are designated as R followed by a two- or three-digit number and, in some cases, one or two letters. The designation Rxyz is determined by the criteria described in Table 11.2. Earlier, ammonia was considered to be more advantageous among the several refrigerants due to its lower energy cost, higher heat transfer coefficients, greater detectability in the event of a leak, and no effect on the ozone layer. Ammonia has been predominantly used for the cooling of fresh fruits, vegetables, meat, and fish and refrigeration of beverages such as beer and wine and dairy products such as milk and cheese. However, the major drawback of ammonia is its toxicity, which renders it inappropriate for domestic use. Similar to ammonia, owing to toxicity, many of the refrigerants used earlier are not in use today. In the 1920s, instances of accidental leaks and fatal consequences necessitated the development of safe refrigerants for the domestic and commercial use. As a result, “dichlorofluoromethane,” the first member of the chlorofluorocarbon (CFC) family of refrigerants was introduced. Later, among the various CFCs developed, “dichlorodifluoromethane” was ascertained the most suitable refrigerant for commercial use. This marked the beginning of identifying the CFC family of refrigerants with the trade name, “Freon.” Accordingly, dichlorodifluoromethane is popularly known under the brand name, “Freon-12.” Soon after their introduction, CFCs were appreciated for their versatility and low cost. A mixture of R115 (chloropentafluoroethane) and R22 (chlorodifluoromethane) known as R502 is the dominant refrigerant used in commercial refrigeration system installed in supermarkets. Nevertheless, in the 1970s, it was established that CFCs deplete the ozone layer which protects the earth from harmful ultraviolet radiation and thereby enhance the greenhouse effect and prevent infrared radiation from escaping the earth. The greenhouse effect of CFCs turned out to be a major scientific and public concern. Hence, various national and international legislative actions imposed a ban on the use of some CFCs. Consequently, the research focus was shifted towards refrigerants with zero ozone depletion potential (ODP) and low global warming potential (GWP). An example of such refrigerant is the chlorine-free R134a (1, 1, 1, 2-tetrafluoroethane) which was developed to replace R12 (dichlorodifluoromethane) (Papadopoulos and Koroneos, 2004).
Electron ionisation cross sections of CF3Cl and CF2Cl2 molecules
Published in Molecular Physics, 2022
Pawan Kumar Sharma, Rajeev Kumar
Chlorotrifluoromethane (CF3Cl) also named chlorofluorocarbon-13 (CFC-13), R-13 or Freon 13, is a non-flammable, non-corrosive, one of the mixed halomethanes which are man-made substances used primarily as a refrigerant but now banned by the Montreal Protocol and when released in the environment, deplete the ozone layer highly, produce global warming and has a very long atmospheric lifetime (640 years) [4]. Dichlorofluoromethane (CF2Cl2) also named chlorofluoro-halomethane-12 (CFC-12), R-12 or Freon-12, is a colourless gas that depletes the ozone layer highly and also has enough long atmospheric lifetime (100 years). High symmetry and high electronegativity of molecule CF2Cl2 (X1 A1) provide it with several important technological applications like cleaner of the chemical vapour deposition chamber, as a solvent, as an etching gas with applications in plasma processing and semiconductor industry, as a refrigerant, a foam blowing agent, an aerosol propellant and as an additive in gaseous dielectric mixtures [4,5].