Книга: Refrigerant: Heat Engine, Phase Transition, Gas, Liquid, Organofluorine Chemistry, Chlorofluorocarbon, Ozone depletion, Ammonia, Sulfur Dioxide, Carbon Dioxide, Hydrocarbon

High Quality Content by WIKIPEDIA articles! A refrigerant is a compound used in a heat cycle that reversibly undergoes a phase change from a gas to a liquid. Traditionally, fluorocarbons, especially chlorofluorocarbons were used as refrigerants, but they are being phased out because of their ozone depletion effects. Other refrigerants are ammonia, sulfur dioxide, carbon dioxide, and non-halogenated hydrocarbons such as methane. The ideal refrigerant has good thermodynamic properties, is unreactive chemically, and safe. The desired thermodynamic properties are a boiling point somewhat below the target temperature, a high heat of vaporization, a moderate density in liquid form, a relatively high density in gaseous form, and a high critical temperature. Since boiling point and gas density are affected by pressure, refrigerants may be made more suitable for a particular application by choice of operating pressure. These properties are ideally met by the chlorofluorocarbons.