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Encyclopedia > Liquid hydrogen

Liquid hydrogen is the liquid state of the element hydrogen. It is a common liquid rocket fuel for rocket applications. In the aerospace industry, its name is often abbreviated to LH2 or LH2. Hydrogen is found naturally in the molecular H2 form, thus the H2 part of the name. A liquid will assume the shape of its container. ... General Name, Symbol, Number hydrogen, H, 1 Chemical series nonmetals Group, Period, Block 1, 1, s Appearance colorless Atomic mass 1. ... Liquid fuels are those combustible or energy-generating molecules which can be harnessed to create mechanical energy, which in turn usually produces kinetic energy, and which also must take the shape of their container. ... Rocket fuel is a propellant that reacts with an oxidizing agent to produce thrust in a rocket. ... A remote camera captures a close-up view of a Space Shuttle Main Engine during a test firing at the John C. Stennis Space Center in Hancock County, Mississippi Spacecraft propulsion is any method used to change the velocity of spacecraft and artificial satellites. ... Look up aerospace in Wiktionary, the free dictionary. ... General Name, Symbol, Number hydrogen, H, 1 Chemical series nonmetals Group, Period, Block 1, 1, s Appearance colorless Atomic mass 1. ... 3D (left and center) and 2D (right) representations of the terpenoid molecule atisane. ...


To exist as a liquid, H2 must be pressurized and cooled to a very low temperature, 20.27 K (−423.17 °F/−252.87°C).[1] One common method of obtaining liquid hydrogen involves a compressor resembling a jet engine in both appearance and principle. Liquid hydrogen is typically used as a practical form of storing hydrogen. As in any gas, storing it as liquid takes less space than storing it as a gas at normal temperature and pressure. Once liquified it can be maintained as a liquid in pressurized and thermally insulated containers.


Uses

In rocket engines, liquid hydrogen is frequently used as a coolant to cool the engine nozzle (regenerative cooling) and other parts before being mixed with the oxidizer (often liquid oxygen (LOX)) and burned. In such a rocket, even with thermally insulated containers it is impossible to avoid the heating of such a cold liquid, and the hydrogen will gradually evaporate. The resulting exhaust of such LH2 - LOX engines is very clean water with traces of ozone and hydrogen peroxide. A cold (un-ignited) rocket engine test at NASA A rocket engine is a reaction engine that can be used for spacecraft propulsion as well as terrestrial uses, such as missiles. ... A coolant, or heat transfer fluid, is a fluid which flows through a device in order to prevent its overheating, transferring the heat produced by the device to other devices that utilize or dissipate it. ... Regenerative cooling in rockets is where the propellant is passed through tubes around the combustion chamber or nozzle as the fuel is a good conductor of heat. ... This article does not cite any references or sources. ... It has been suggested that Ozone generator be merged into this article or section. ... R-phrases , , , , S-phrases , , , ,, , , , Flash point Non-flammable Related Compounds Related compounds Water Ozone Hydrazine Except where noted otherwise, data are given for materials in their standard state (at 25 Â°C, 100 kPa) Infobox disclaimer and references Hydrogen peroxide (H2O2) is a very pale blue liquid which appears colourless in...


Liquified hydrogen can be used as a fuel in an internal combustion engine. Various concept hydrogen vehicles have been built using this form of hydrogen (see BMW H2R). The internal combustion engine is an engine in which the combustion of fuel and an oxidizer (typically air) occurs in a confined space called a combustion chamber. ... Sequel, a fuel cell-powered vehicle from General Motors A hydrogen vehicle is a personal transportation vehicle, such as an automobile, that uses hydrogen as its on-board fuel for motive power, or another vehicle, such as an aircraft, that use hydrogen in a similar fashion. ... The BMW H2R is a concept vehicle designed by BMW as an example of a high efficiency, environmentally friendly car. ...


Liquid hydrogen is sometimes used to keep certain types of ice cream cold.


Drawbacks

In terms of energy density, liquid hydrogen requires much more volume than other fuels to store the same amount of energy. Four litres of liquid hydrogen are needed to match the same energy content of one litre of gasoline. On the other hand it is also one of the lightest fuels available; 1 litre of hydrogen weighs only 0.07 kg. That is a density of 70.8 kg/m³ (at 20 K). Energy density is the amount of energy stored in a given system or region of space per unit volume or per unit mass, depending on the context. ... For other uses, see Kelvin (disambiguation). ...


References

  1. ^ Chemical elements data references

  Results from FactBites:
 
Universal Industrial Gases, Inc...Hydrogen H2 Properties, Uses, Applications (1117 words)
Hydrogen is mixed with inert gases to obtain a reducing atmosphere, which is required for many applications in the metallurgical industry, such as heat treating steel and welding.
Hydrogen is used in large quantities as a raw material in the chemical synthesis of ammonia, methanol, hydrogen peroxide, polymers, and solvents.
Hydrogen is used as a carrier gas for such active trace elements as arsine and phospine, in the manufacture of semi-conducting layers in integrated circuits.
Liquid Hydrogen (248 words)
Stable hydrogen is in the form of a diatomic molecule.
Liquid hydrogen is used extensively as a fuel in rocketry and more recently in commercial transportation.
Hydrogen is extremely flammable as with a small ignition energy it will combine with the oxygen is air with a strong exothermic reaction.
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