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Andy

Mon Apr 06 2015, 05:02AM

Registered Member #4266 Joined: Fri Dec 16 2011, 03:15AM
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Posts: 874

Hi, ive changed my mind about platic and firbeglass sub, instead make the whole thing out off aluminum alloys tig welded.
As the whole thing will be one large heat sink, and a natural water tempture about 10 C, im looking at making a heat source that can raise oil of a certain amount upto 40 C.
It has to safe to some degree, preferable a slow reaction.

So far Ive got copper sulphate hydrated as the oxygen source, with a postive entropy of 769.9 kJ/mol
The fuel, aaluminum and magnesium making Al2SO4 with negtive entropy of -3440kJ/mol and MgSO4 with -1278kJ/mol.

What cemistrys will be easy to ignite, maybe pushing Nicochrome wire source, or a liquid igniton.

No pre/clorate,and only small nirtrate just as a ignite part, and no gases made.

Cheers all.

Sulaiman

Mon Apr 06 2015, 12:28PM

Registered Member #162 Joined: Mon Feb 13 2006, 10:25AM
Location: United Kingdom
Posts: 3140

The topic is well covered in sciencemadness, e.g.

a search there for "thermite" will keep you busy for a while

pyrotechnics forums will likely have most answers but I'm not familiar with any.

Andy

Mon Apr 06 2015, 05:35PM

Registered Member #4266 Joined: Fri Dec 16 2011, 03:15AM
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Thanks, used google abit more and it looks like CuO and Al with 10grams of CuO and 2.26 grams of Al, makes 120.19kJ, with a 150gram Al container which will reach 900 Degrees and melt, not sure on the solid ti liquard changing transtion.

Do you have a idea to ignite the mixture, with 1 sec for it to drop into a pipe?

Sulaiman

Mon Apr 06 2015, 06:45PM

Registered Member #162 Joined: Mon Feb 13 2006, 10:25AM
Location: United Kingdom
Posts: 3140

sorry, you're way ahead of me, not an interest of mine, no experience,
I can't help ..... maybe others?

DÃ©dÃ©!

Mon Apr 06 2015, 08:46PM

Registered Member #4932 Joined: Thu May 17 2012, 01:42PM
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Don't many people use potassium permanganate with glycerol?

Andy

Mon Apr 06 2015, 11:13PM

Registered Member #4266 Joined: Fri Dec 16 2011, 03:15AM
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I will be trying it, but would like to minmize gases if any. Just trying to get a whole range of ideas.

Enceladus

Thu Feb 09 2017, 06:22AM

Registered Member #61428 Joined: Sat Jan 14 2017, 12:39PM
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Why not just insulate it and make up the rest with electric heat? Seems like oxygen would kind of be at a premium in a sub. If you've got your heart set on using chemicals why don't you gradually hydrate some concentrated H2SO4 or NaOH? Or you could do both at once, then gradually combine them.

Enceladus

Sun Feb 19 2017, 03:50AM

Registered Member #61428 Joined: Sat Jan 14 2017, 12:39PM
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Oxygen candle's would be ideal. I can't believe I didn't think of that before.

From wiki:

Main article: Chemical oxygen generator

"A chlorate candle, or an oxygen candle, is a cylindrical chemical oxygen generator that contains a mix of sodium chlorate and iron powder, which when ignited smolders at about 600 Â°C (1,112 Â°F), producing sodium chloride, iron oxide, and at a fixed rate about 6.5 man-hours of oxygen per kilogram of the mixture. The mixture has an indefinite shelf life if stored properly: candles have been stored for 20 years without decreased oxygen output. Thermal decomposition releases the oxygen. The burning iron supplies the heat. The candle must be wrapped in thermal insulation to maintain the reaction temperature and to protect surrounding equipment."

They only mention using sodium chlorate in the above quote, but you can also use potassium chlorate or perchlorate. Potassium chlorate can be prepared very easily by electrolysis of potassium chloride solution. Due to its low solubility compared to KCl, the KClO3 simply precipitates out of solution as it's produced. Upon gentle heating, the KClO3 converts to KClO4 (perchlorate) and KCl. Further heating releases breathable oxygen and the KClO4 decomposes back to KCl, which can be recycled.

Hazmatt_(The Underdog)

Sun Feb 19 2017, 06:07PM

Registered Member #135 Joined: Sat Feb 11 2006, 12:06AM
Location: Anywhere is fine
Posts: 1735

The electrolysis reaction is with HOT NaClO, with Platinum electrodes, and takes a long time. Any Hypochlorite solution will work, Calcium is preferred because of its lower solubility, but actually getting a high yield takes practice, I never succeeded at it, but others have and do regularly.

Also, Perchlorate is more stable then Chlorate, but any contamination of your salt makes it unstable and a storage risk.

Magnesium filings in your mixture are still by far the easiest solution for ignition, for $2.50 you can buy a bar for camping at harbor freight,

Conundrum

Mon Feb 20 2017, 07:20AM

Registered Member #96 Joined: Thu Feb 09 2006, 05:37PM
Location: CI, Earth
Posts: 4062

Yeah, one thing to be very careful with is that any S in your mixture will form metal sulphides. Can you guess why this is bad?

Ironically the "Titanic" is believed to have sunk due to sulphide inclusions in the metal magnifying the damage from the iceberg impact.
That and not having any welding equipment on board, not enough lifeboats, no way to signal other ships because the radio equipment never got tested before sailing, etc.

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