Information AboutLiquid Air |
| CATEGORIES ABOUT LIQUID AIR | |
| atmosphere | |
| coolants | |
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Liquid air is Air that has been Liquified by Compression and cooled to very low temperatures. It must be kept in a Dewar Flask , as at Room Temperature , liquid air can absorb heat rapidly and revert to its gaseous state. It is often used for freezing other substances, and as a source of Nitrogen , Oxygen , Argon , and other Inert Gas es. PROPERTIES Liquid has a density of approximately 870 kg/m^3, though the density may vary depending on the elemental composition of the air. Since gaseous air has 78% nitrogen and 21% oxygen, the density of liquid air at standard composition is calculated by the decimal percentage of the components by their respective liquid densities. See Liquid Nitrogen and Liquid Oxygen . Melting Point: -216.2°C Boiling Point: -194.35°C CREATION OF LIQUID AIR The most common process for distillation of liquid air is the two column Linde Cycle using the Joule-Thomson Effect . Air is fed at high pressure >60 Psig (520 kPa) into the lower column, in which it is separated into pure nitrogen and oxygen-rich Liquid . The rich liquid and some of the nitrogen are fed as reflux into the upper column, which operates at low pressure <10 psig (170 kPa), where the final separation into pure nitrogen and oxygen occurs. A raw argon product can be removed from the middle of the upper column for further purification. In more detail: When a liquid - think of hot water - flows through a nozzle, the pressure drops, bubbles form, the bubble-liquid mixtures expands, cools down and is accelerated. The kinetic energy could be extracted by means of a Turbine or a Whistle , but engineers prefer to use it to reheat the just cooled down water. For some reason the water still stays cooler than in front of the nozzle. The Joule-Thomson Effect states, that this cooling also works with water vapor just over the boiling point and with nitrogen vapor just over the boiling point (an air liquefier has a hard start). But it does not work with Helium . REFERENCES http://www.wessingtoncryogenics.co.uk/Liquid%20Air%20Data%20Sheet.pdf |
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