Freon is widely used as refrigerant, foaming agent [6] and cleaning agent, and is widely used in household appliances, foam plastics, daily chemicals, automobiles, fire-fighting equipment and other fields.
Freon is a trademark of refrigerant registered by Dupont Company of the United States. In China, there are differences in the definition of freon, which is generally defined as the general name of halogenated compounds of saturated hydrocarbons (mainly methane, ethane and propane). According to this definition, freon can be divided into four categories: CFC, HCFC and HFC. Some scholars define freon as CFC refrigerant; Freon only refers to dichlorodifluoromethane (CCl? F? R12, a kind of CFC).
the thermal properties of freon refrigerants with different chemical compositions and structures are quite different, and they can be used in high-temperature, medium-temperature and low-temperature refrigerators to meet the requirements of different refrigeration temperatures. Freon refrigeration system includes high pressure system, low pressure system, oil circuit system and defrosting system. The equipment selection calculation of Freon refrigeration system is basically the same as that of ammonia refrigeration system. The selection of refrigeration compressor should be based on the refrigerator load of the refrigeration unit, and the selection and calculation should be carried out according to the determined freon refrigerant type, refrigeration working condition and compressor type.
Freon is colorless gas or volatile liquid at room temperature, tasteless or slightly odorous, non-toxic or low-toxic, and its chemical properties are stable.
CFC refrigerants, such as dichlorodifluoromethane, have been restricted in use because they destroy the atmospheric ozone layer. There have been many holes in the ozone layer on the earth, and some holes have exceeded the area of Africa, which is largely due to the chemical properties of CFCs. Another harm of freon is the greenhouse effect.