Refrigerants, Antifreezes and Cooling Liquids

Refrigerants, antifreezes and cooling liquids include primary refrigerants, secondary refrigerants, and antifreeze additives. A primary refrigerant uses a thermodynamic or adiabatic process (evaporation-condensation cycles) to remove heat and cool a region. A secondary refrigerant, such as antifreeze liquids, provides cooling solely through heat transfer. Antifreeze additives also prevent water-based cooling systems from freezing. Refrigerants, antifreezes, and cooling liquids include refrigerants and refrigeration fluids that are based on halogenated (fluorinated and/or chlorinated) hydrocarbons fluids. They also include glycol-based antifreezes.

Refrigerants, antifreezes, and cooling liquids are used in a wide variety of applications, including automotive, marine, and aerospace applications to cool combustion engines or processing equipment such as gears and drives, pistons, and compressors. Refrigerants, antifreezes, and cooling liquids include compounds that use a thermodynamic process - changing phase between a liquid and a gas - such as anhydrous ammonia or sulfur dioxide. Sulfur dioxide is toxic, and has been rapidly replaced as a refrigerant by Freon. Antifreeze is a solution of glycol-based chemicals in water and can withstand temperatures below 0 degrees Celsius.

Other types of refrigerants, antifreezes, and cooling liquids include oils, such as mineral oil for used in mechanical gears, silicone oils, dielectric or transformer oils for electrical apparatus, and fluorocarbon (FC) oils for use in applications that have a wide operating temperature range. Fluorocarbon (FC) refrigerants include other haloalkane compounds such as chlorofluorocarbon (CFC), which is a chlorinated fluorocarbon; hydrofluorocarbon (HFC), a hydrogenated fluorocarbon; and hydrochlorofluorocarbon (HCFC), which is a CFC substitute that is more environmentally friendly, since not all of the hydrogen has been replaced by chlorine or fluorine atoms. Many refrigerants, antifreezes, and cooling liquids based on fluorocarbons are being phased out in many refrigeration applications because of their effect on the environment. CFCs are damaging to the ozone; HCFCs and HFCs are safer for the ozone, but also contribute to greenhouse gases.

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