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Errrrm, there is a reason airplanes run on kerosene and not diesel oil. Can biofuels be made of kerosene's grade?

*Lunatic*, n.
One whose delusions are out of fashion.
by DoDo on Wed Sep 27th, 2006 at 08:32:49 AM EST
Kerosene is obtained from the fractional distillation of petroleum at 150°C and 275°C (carbon chains from the C12 to C15 range).

Any chemists in the room? Can ethanol be polymerised? Can cellulose be broken down to alkanes in this range?

What is the reason kerosene and not longer-chain alkanes are used for aviation fuel?

Those whom the Gods wish to destroy They first make mad. -- Euripides

by Carrie (migeru at eurotrib dot com) on Wed Sep 27th, 2006 at 08:37:42 AM EST
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Energy density, I think.
by Colman (colman at eurotrib.com) on Wed Sep 27th, 2006 at 08:38:26 AM EST
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Kerosene releases heat when burned, making it useful as a fuel. Its heating value, or heat of combustion, is around 18,500 Btu/lb, or 43.1 MJ/kg, making it similar to that of diesel.

Those whom the Gods wish to destroy They first make mad. -- Euripides
by Carrie (migeru at eurotrib dot com) on Wed Sep 27th, 2006 at 08:41:10 AM EST
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In that case I'm very confused. It can't be the temperature issue.
by Colman (colman at eurotrib.com) on Wed Sep 27th, 2006 at 08:43:15 AM EST
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And it's sure as hell not safety!
by Colman (colman at eurotrib.com) on Wed Sep 27th, 2006 at 08:43:34 AM EST
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by asdf on Wed Sep 27th, 2006 at 08:53:22 AM EST
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I was talking about kerosene vs diesel, not kerosene vs gasoline. As far as I know diesel is even less volatile than kerosene. Though I'm not sure why  I think that.
by Colman (colman at eurotrib.com) on Wed Sep 27th, 2006 at 08:56:22 AM EST
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That's exactly the problem: diesel has longer carbon chains and so it is less volatile and more viscous, so it 'clouds' earlier that kerosene as it cools.

Those whom the Gods wish to destroy They first make mad. -- Euripides
by Carrie (migeru at eurotrib dot com) on Wed Sep 27th, 2006 at 09:22:46 AM EST
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Why not? Kerosene consists of medium-length linear-chain alkanes, and diesel consists of long alkanes (paraffins) and polycyclic hydrocarbons
Petroleum derived diesel is composed of about 75% saturated hydrocarbons (primarily paraffins including n, iso, and cycloparaffins), and 25% aromatic hydrocarbons (including naphthalenes and alkylbenzenes).[2] The average chemical formula for common diesel fuel is C12H26, ranging from approx. C10H22 to C15H32.


Those whom the Gods wish to destroy They first make mad. -- Euripides
by Carrie (migeru at eurotrib dot com) on Wed Sep 27th, 2006 at 08:48:56 AM EST
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I mean it in the sense that the temp issue is one of engineering, not physics.
by Colman (colman at eurotrib.com) on Wed Sep 27th, 2006 at 08:49:56 AM EST
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It's evaporation and ignition temperature. Kerosene used for aircraft fuel also needs to be of a very high purity.

*Lunatic*, n.
One whose delusions are out of fashion.
by DoDo on Wed Sep 27th, 2006 at 08:58:31 AM EST
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What are the constraints?
by Colman (colman at eurotrib.com) on Wed Sep 27th, 2006 at 09:01:25 AM EST
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There is an interplay between engine design and fuel design. Doesn't manon know about aircraft engines? Where is she when we need her?

Those whom the Gods wish to destroy They first make mad. -- Euripides
by Carrie (migeru at eurotrib dot com) on Wed Sep 27th, 2006 at 09:26:09 AM EST
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it would be an enormous amount of fuel to keep warmer than the external temperature at 30,000 ft.

one could heat it at the intake, but it still seems dodgy. i bet kerosene withstands much colder temps before freezing.

anyone confirm or deny this supposition?

next: natgas and its possible use as jetfuel...

'The history of public debt is full of irony. It rarely follows our ideas of order and justice.' Thomas Piketty

by melo (melometa4(at)gmail.com) on Wed Sep 27th, 2006 at 09:07:03 AM EST
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Why? It starts off warm, so the problem is mainly insulation - which I guess is a problem if you're keeping fuel in thin wings.
by Colman (colman at eurotrib.com) on Wed Sep 27th, 2006 at 09:08:59 AM EST
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