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Jet fuel is a type of aviation fuel designed for use in aircraft powered by gas-turbine engines. It is clear to straw-colored in appearance. The most commonly used fuels for commercial aviation are Jet A and Jet A-1 which are produced to a standardised international specification. The only other jet fuel commonly used in civilian turbine-engine powered aviation is Jet B which is used for its enhanced cold-weather performance.

Jet fuel is a mixture of a large number of different hydrocarbons. The range of their sizes (molecular weights or carbon numbers) is restricted by the requirements for the product, for example, freezing point or smoke point. Kerosene-type jet fuel (including Jet A and Jet A-1) has a carbon number distribution between about 8 and 16 carbon numbers; wide-cut or naphtha-type jet fuel (including Jet B), between about 5 and 15 carbon numbers.[1]

Contents

History of jet fuel

Fuel for a piston-engine powered aircraft (usually a high-octane gasoline known as Avgas) has a low flash point to improve its ignition characteristics. Turbine engines can operate with a wide range of fuels, and jet-aircraft engines typically use fuels with higher flash points, which are less flammable and therefore safer to transport and handle. The first jet fuels were based on kerosene or a gasoline-kerosene mix, and most jet fuels are still kerosene-based.

Types

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Differences Between Jet A and Jet A-1

Shell Jet A-1 refueller truck on the ramp at Vancouver International Airport (notice the signs indicating 1863 hazardous material and JET A-1)

Jet A specification Fuel has been used in the USA since the 1950s and is only available in the USA, whereas Jet A-1 is the standard specification fuel used in the rest of the world. Both Jet A and Jet A-1 have a relatively high flash point of 38 °C (100 °F), with an autoignition temperature of 210 °C (410 °F). This means that the fuel is safer to handle than traditional aviation gasoline Avgas.

The primary differences between Jet A and Jet A-1 are the higher freezing point of Jet A (−40 °C vs −47 °C for Jet A-1), and the mandatory requirement for the addition of an antistatic additive to Jet A-1.

Like Jet A-1, Jet A can be identified in trucks and storage facilities by the UN number 1863 Hazardous Material placards.[2] Jet A trucks, storage tanks, and pipes that carry Jet A are marked with a black sticker with a white "Jet A" written over it, next to another black stripe.

The annual U.S. usage of jet fuel was 21 billion gallons (80 billion litres) in 2006.[3]

Typical Physical Properties for Jet A and Jet A-1

Jet A-1 Fuel must meet the specification for DEF STAN 91-91 (Jet A-1), ASTM specification D1655 (Jet A-1) and IATA Guidance Material (Kerosine Type), NATO Code F-35.

Jet A Fuel must reach ASTM specification D1655 (Jet A) [4]

Jet A-1 Jet A
Flash point: > 38 °C (100.4 °F)
Autoignition temperature: 210 °C (410 °F)
Freezing point: > −47 °C (−52.6 °F) > −40 °C (−40 °F)
Open air burning temperatures: 287.5 °C (549.5 °F)
Density at 15 °C (59 °F): 0.775 kg/L - 0.840 kg/L
Specific energy >42.80 MJ/kg

Jet B

Jet B is a fuel in the naphtha-kerosene region that is used for its enhanced cold-weather performance. However, Jet B's lighter composition makes it more dangerous to handle. [5] For this reason it is rarely used except in very cold climates.

Additives

The DEF STAN 91-91 and ASTM D1655 specifications allow for certain additives to be added to jet fuel: [6]

Water in Jet fuel

It is very important that Jet fuel is free from water contamination. During a flight the temperature of the fuel in the tanks will decrease due to the low temperatures in the upper atmosphere. This will cause dissolved water in the fuel to precipitate out and since the water is more dense than fuel it will drop to the bottom of the tank. Since it is no longer in solution this water can freeze, blocking fuel inlet pipes. Since it is impractical to remove all water from fuel, fuel heaters are usually used on commercial aircraft to prevent water in the fuel from freezing.

There are several methods for detection of water in Jet fuel. A visual check may detect high concentrations of suspended water as this will cause the fuel to become hazy in appearance. An industry standard chemical test for the detection of free water in Jet Fuel is the Shell Water Detector which has a water sensitive filter pad which turns blue if the fuel exceeds the specification limit of 30ppm free water. [7]

Military jet fuels

Military organisations around the world use a different classification system of JP numbers. Some are almost identical to their civilian counterparts and differ only by the amounts of a few additives; Jet A-1 is similar to JP-8, Jet B is similar to JP-4. Other military fuels are highly specialized products and are developed for very specific applications. JP-5 fuel is fairly common, and was introduced to reduce the risk of fire on aircraft carriers (has a higher flash point - a minimum of 60 °C). Other fuels were specific to one type of aircraft. JP-6 was developed specifically for the XB-70 Valkyrie and JP-7 for the SR-71 Blackbird. Both these fuels were engineered to have a high flash point to better cope with the heat and stresses of high speed supersonic flight. One aircraft-specific jet fuel still in use by the United States Air Force is JPTS, which was developed in 1956 for the Lockheed U-2 spy plane.

Jet fuels are sometimes classified as kerosene or naphtha-type.[citation needed] Kerosene-type fuels include Jet A, Jet A-1, JP-5 and JP-8. Naphtha-type jet fuels, sometimes referred to as "wide-cut" jet fuel, include Jet B and JP-4.[citation needed]

Piston engine use

Jet fuel is very similar to diesel fuel, and in some cases, may be burned in diesel engines. The possibility of environmental legislation banning the use of leaded avgas, and the lack of a replacement fuel with similar performance, has left aircraft designers and pilot's organizations searching for alternative engines for use in small aircraft.[8] As a result, a few aircraft engine manufacturers, most notably Thielert, have begun offering diesel aircraft engines which run on jet fuel. This technology has potential to simplify airport logistics by reducing the number of fuel types required. Jet fuel is available in most places in the world, whereas avgas is only widely available in a few countries which have a large number of general aviation aircraft. A diesel engine may also potentially be more environmentally friendly and fuel-efficient than an avgas engine. However, very few diesel aircraft engines have been certified by aviation authorities, and widespread use of diesel aircraft engines is still years in the future.

Jet fuel is often used in ground support vehicles at airports, instead of diesel. The United States military makes heavy use of JP-8, for instance. However, jet fuel tends to have poor lubricating ability in comparison to diesel, thereby increasing wear on fuel pumps and other related engine parts.[citation needed] Civilian vehicles tend to disallow its use, or require that an additive be mixed with the jet fuel to restore its lubricity. Since jet fuel is also significantly more expensive than diesel, some critics consider using jet fuel in ground vehicles as wasteful.

Synthetic Jet fuel

A significant effort is under way to certify Fischer–Tropsch (FT) synthetic fuels for use in US and international aviation fleets. In this effort is being led by an industry coalition known as the Commercial Aviation Alternative Fuels Initiative (CAAFI)[9], also supported by a parallel initiative under way in the US Air Force [10], to certify FT fuel for use in all aviation platforms. The US Air Force has a stated goal of certifying its entire fleet for use with FT Synthetic Fuel blends by 2011.[11] The CAAFI initiative aims to certify the civilian aviation fleet for FT synthetic fuels blends by 2010, and has programs under way to certify HRJ hydrogenated biofuels as early as 2013.[12]

Synthetic jet fuels show a reduction in pollutants such as SOx, NOx, Particulate Matter, and Hydrocarbon emissions.[13].

  • Qatar Airways became the first airline to operate a commercial flight on a 50:50 blend with synthetic GTL Jet Fuel. The natural gas derived synthetic kerosene for the six-hour flight from London to Doha came from Shell’s GTL plant in Bintulu, Malaysia. [14]

Jet biofuels

The air transport industry is responsible for 2 percent of man-made carbon dioxide emitted .[15] Boeing estimates that biofuels could reduce flight-related greenhouse-gas emissions by 60 to 80 percent. The solution would be blending algae fuels with existing jet fuel: [16]

Green Flight International became the first airline to fly jet aircraft on 100% biofuel. The flight from Stead airport in Reno, Nevada was in an Aero L-29 Delfín piloted by Carol Sugars and Douglas Rodante.[17]

Oil prices increased about fivefold from 2003 to 2008, raising fears that world petroleum production is becoming unable to keep up with demand. The fact that there are few alternatives to petroleum for aviation fuel adds urgency to the search for alternatives. Twenty-five airlines were bankrupted or stopped operations in the first six months of 2008, largely due to fuel costs. [21] .

See also

References

  1. ^ Chevron Products Corporation - This is a dead link, update me please -. "Aviation Turbine Fuel Composition". http://www.chevron.com/products/prodserv/fuels/bulletin/aviationfuel/4_at_fuel_comp.shtm. 
  2. ^ U.S. DOT. "U.S. Department of Transportation 2008 Emergency Response Guide (ERG)". http://wwwapps.tc.gc.ca/saf-sec-sur/3/erg-gmu/erg/idindex.aspx?page=15. 
  3. ^ Energy Information Administration. "U.S. Prime Supplier Sales Volumes of Petroleum Products". http://tonto.eia.doe.gov/dnav/pet/pet_cons_prim_dcu_nus_a.htm. 
  4. ^ http://www.csgnetwork.com/jetfuel.html
  5. ^ http://www.csgnetwork.com/jetfuel.html
  6. ^ http://www.dstan.mod.uk/data/91/091/00000600.pdf - Annex A, Page 8
  7. ^ http://www.shell.com/home/content/aviation/products_and_services/products/shell_water_detector/
  8. ^ Planemakers challenged to find unleaded fuel option - The Wichita Eagle
  9. ^ "Significant progress made towards adoption of semi-synthetic aviation fuel". http://www.caafi.org/information/pdf/CAAFI_factsheet_12dec2008.pdf. Retrieved 2009-06-24. 
  10. ^ "Synthetic Future, USAF Pushes Ahead With Fuel Production Despite Price Drop". http://www.defensenews.com/story.php?i=3969089&c=FEA&s=TEC. Retrieved 2009-06-24. 
  11. ^ "USAF drives biofuel bandwagon". http://www.flightglobal.com/articles/2009/02/09/322208/usaf-drives-biofuel-bandwagon.html. Retrieved 2009-06-24. 
  12. ^ "CAAFI pools aviation industry resources to certify synthetic jet fuel". http://www.flightglobal.com/articles/2008/02/25/221767/caafi-pools-aviation-industry-resources-to-certify-synthetic-jet-fuel.html. Retrieved 2009-06-24. 
  13. ^ Per the work of NREL http://www.nrel.gov/vehiclesandfuels/npbf/pdfs/36363.pdf, http://www.nrel.gov/vehiclesandfuels/npbf/pdfs/38195.pdf, and various other DOE/DOD studies
  14. ^ [1]
  15. ^ "Beginner’s Guide to Aviation Biofuels". Air Transport Action Group. May 2009. http://www-org.airbus.com/store/mm_repository/pdf/att00014178/media_object_file_BeginnersGuide_Biofuels.pdf. Retrieved 2009-09-20. 
  16. ^ A Promising Oil Alternative: Algae Energy - washingtonpost.com
  17. ^ http://www.greenflightinternational.com/index.htm
  18. ^ Tecbio,
  19. ^ Crop this: Virgin takes off with nut-fuel - 26 Feb 2008 - NZ Herald: New Zealand Business, Markets, Currency and Personal Finance News
  20. ^ http://www.boeing.com/aboutus/environment/environmental_report/alternative-energy-solutions.html
  21. ^ More airlines fold as fuel prices soar: IATA

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