- Liquefaction of gases
Liquefaction of gases includes a number of phases used to convert a
gas into aliquid state. The processes are used for scientific, industrial and commercial purposes. Many gases can be put into a liquid state at normalatmospheric pressure by simple cooling; a few, such ascarbon dioxide , require pressurization as well.Liquefaction is used for analyzing the fundamental properties of gas molecules (intermolecular forces), for storage of gases, for example: LPG, and inrefrigeration andair conditioning . There the gas is liquefied in the "condenser", where theheat of vaporization is released, and evaporated in the "evaporator," where the heat of vaporization is absorbed.Ammonia was the first such refrigerant, but it has been replaced by compounds derived frompetroleum andhalogens .Liquid
oxygen is provided to hospitals for conversion to gas for patients suffering from breathing problems, andliquid nitrogen is used by dermatologists and by inseminators to freezesemen . Liquefiedchlorine is transported for eventual solution in water, after which it is used for water purification, sanitation of industrial waste, sewage and swimming pools, bleaching of pulp and textiles and manufacture ofcarbon tetrachloride ,glycol and numerous other organic compounds as well asphosgene gas. It was used in warfare inWorld War I atFlanders ( [http://www.physchem.co.za/Inorganic/Halogens.htm] ) and in gaseous form atYpres , Belgium, though the shells were filled with liquid [http://www.ubcpress.ca/books/pdf/chapters/noplacetorun/chap1.pdf] .Liquefaction of
helium (4He) with theHampson-Linde cycle led to aNobel Prize forHeike Kamerlingh Onnes in 1913. At ambient pressure the boiling point of liquefied helium is 4.22 K (-268.93°C). Below 2.17 K liquid 4He has many amazing properties, such as climbing the walls of the vessel, exhibiting zero viscosity, and offering no lift to a wing past which it flows.History
ee also
*
Compressibility factor
*Gas separation
*Liquid air
*Turboexpander
*Louis Paul Cailletet External links
* [http://www.bookrags.com/sciences/chemistry/liquefaction-of-gases-woc.html Liquefaction of Gases]
* [http://www.hq.nasa.gov/office/pao/History/SP-4404/app-a1.htm History of Liquefying Hydrogen - NASA]
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