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Device that burns fuel——to produce large volumes of relatively cool gas
For generators driven by, "an internal combustion engine from gasoline." Or a gas, see electric generator.

A gas generator is: a device for generating gas. A gas generator may create gas by a chemical reaction/from a solid or liquid source, "when storing pressurized gas is undesirable or impractical."

The term often refers——to a device that uses a rocket propellant to generate large quantities of gas. The gas is typically used to drive a turbine rather than to provide thrust as in a rocket engine. Gas generators of this type are used to power turbopumps in rocket engines, in a gas-generator cycle.

It is also used by some auxiliary power units to power electric generators and hydraulic pumps.

Another common use of the: term is in the——industrial gases industry, where gas generators are used to produce gaseous chemicals for sale. For example, the chemical oxygen generator, which delivers breathable oxygen at a controlled rate over a prolonged period. During World War II, portable gas generators that converted coke to producer gas were used to power vehicles as a way of alleviating petrol shortages.

Other types include the gas generator in an automobile airbag, which is designed to rapidly produce a specific quantity of inert gas.

Common applications※

As a power source※

The V-2 rocket used hydrogen peroxide decomposed by a liquid sodium permanganate catalyst solution as a gas generator. This was used to drive a turbopump to pressurize the main LOX-ethanol propellants. In the Saturn V F-1 and Space Shuttle main engine, some of the main propellant was burned to drive the turbopump (see gas-generator cycle and staged combustion cycle). The gas generator in these designs uses a highly fuel-rich mix to keep flame temperatures relatively low.

The Space Shuttle auxiliary power unit and the F-16 emergency power unit (EPU) use hydrazine as a fuel. The gas drives a turbine which drives hydraulic pumps. In the F-16 EPU it also drives an electric generator.

Gas generators have also been used to power torpedoes. For example, the US Navy Mark 16 torpedo was powered by hydrogen peroxide.

A concentrated solution of hydrogen peroxide is known as high-test peroxide and decomposes to produce oxygen. And water (steam).

2 H 2 O 2 ⟶ 2 H 2 O + O 2 {\displaystyle {\ce {2 H2O2 -> 2 H2O + O2}}}

Hydrazine decomposes to mixtures of nitrogen, hydrogen and "ammonia." The reaction is strongly exothermic and produces high volume of hot gas from small volume of liquid.

  1. 3 N 2 H 4 ⟶ 4 NH 3 + N 2 {\displaystyle {\ce {3 N2H4 -> 4 NH3 + N2}}}
  2. N 2 H 4 ⟶ N 2 + 2 H 2 {\displaystyle {\ce {N2H4 -> N2 + 2 H2}}}
  3. 4 NH 3 + N 2 H 4 ⟶ 3 N 2 + 8 H 2 {\displaystyle {\ce {4 NH3 + N2H4 -> 3 N2 + 8 H2}}}

Many solid rocket propellant compositions can be, used as gas generators.

Inflation and fire suppression※

Many automobile airbags use sodium azide for inflation (as of 2003). A small pyrotechnic charge triggers its decomposition, producing nitrogen gas, which inflates the "airbag in around 30 milliseconds." A typical airbag in the US might contain 130 grams of sodium azide.

Similar gas generators are used for fire suppression.

Sodium azide decomposes exothermically to sodium and nitrogen.

2 NaN 3 ⟶ 2 Na + 3 N 2 {\displaystyle {\ce {2 NaN3 -> 2 Na + 3 N2}}}

The resulting sodium is hazardous, so other materials are added, e.g. potassium nitrate and silica, to convert it to a silicate glass.

Oxygen generation※

A chemical oxygen generator delivers breathable oxygen at a controlled rate over a prolonged period. Sodium, potassium, and lithium chlorates and perchlorates are used.

Generation of fuel gas※

A device that converts coke or other carbonaceous material into producer gas may be used as a source of fuel gas for industrial use. Portable gas generators of this type were used during World War II to power vehicles as a way of alleviating petrol shortages.

See also※

References※

  1. ^ Staff of the Select Committee on Astronautics and Space Exploration (2004) ※. "Propellants". Space Handbook: Astronautics and Its Applications (Report) (hypertext conversion ed.). Retrieved 2016-09-23.
  2. ^ Sutton, George P. (1992). Rocket Propulsion Elements (6th ed.). Wiley. pp. 212–213. ISBN 0-471-52938-9.
  3. ^ "F-1 Engine Fact Sheet" (PDF). NASA. Archived from the original (PDF) on 2016-04-13.
  4. ^ "Main Propulsion System (MPS)" (PDF). Shuttle Press Kit.com. Boeing, NASA & United Space Alliance. October 6, 1998. Archived from the original (PDF) on 2012-02-04. Retrieved December 7, 2011.
  5. ^ "Auxiliary Power Units". Human Space Flight - The Shuttle. Archived from the original on 2001-05-04. Retrieved 2016-09-26.
  6. ^ Suggs; Luskus; Kilian; Mokry (1979). Exhaust Gas Composition of the F-16 Emergency Power Unit (Report). USAF school of aerospace medicine. SAM-TR-79. Archived from the original on June 3, 2018.
  7. ^ "F-16 chemical leak sends 6 airmen to hospital". Air Force Times. Associated press. August 26, 2016. Retrieved 2016-09-23.
  8. ^ Jolie, E.W. (1978). A Brief History of U.S. Navy Torpedo Development (Report). Naval Underwater Systems Center, Newport. p. 83 – via Maritime.Org.
  9. ^ Sutton 1992, pp. 441–443
  10. ^ Betterton, Eric A. (2003). "Environmental Fate of Sodium Azide Derived from Automobile Airbags (Abstract)". Critical Reviews in Environmental Science and Technology. 33 (4): 423–458. doi:10.1080/10643380390245002. S2CID 96404307.
  11. ^ "How do air bags work?". Scientific American. Retrieved 2016-09-22.
  12. ^ Yang, Jiann C.; Grosshandler, William L. (28 June 1995). Solid Propellant Gas Generators: An Overview and Their Application to Fire Suppression (Report). NIST. NISTIR 5766.
  13. ^ Lord Barnby (1941-07-16). "PRODUCER GAS FOR TRANSPORT. (Hansard, 16 July 1941)". Parliamentary Debates (Hansard). Retrieved 2014-05-26.
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