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Swede
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[*] posted on 16-6-2012 at 07:06
Oxygen balance


I love (and collect) old books on chemistry, energetics, and history, especially late 19th century texts back when nitrocellulose was still a bit untameable.

One chemist maintained that mixtures that promote better oxygen balance may not, in fact, produce more propulsive force than those that deflagrate to a mixture of CO and CO2. In other words, a deflagration that produces CO as in

(deflagration) --> 2CO

is better than one that looks more like this:

(deflagration) --> CO2

2 moles of a gas produce more pressure at a given temperature than 1.

I'm not balancing anything here... the point is that when producing gas, producing more molecules of gas will create a higher pressure, and CO gas propels just as good as CO2.

Now the caveat is, having the constituents fully oxidized to CO2 will release MORE energy, more heat, and more heat equates to higher gas pressure.

Nutshell time - all else being equal, is it possible to gain more propulsive force with an oxygen poor reaction, or does the increased energy output of the production of CO2 outweigh the former?




[Edited on 16-6-2012 by Swede]
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Ral123
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[*] posted on 16-6-2012 at 10:54


PETN have quite more energy even on volume basis then RDX, but it's not too different. Supposedly the small amounts of carbon reduce the velocity of some explosives. On the other hand the guys who make CL-20 go trough quite inconvenient synthesis just to get better density and get rid of few hydrogens witch lead to more CO2... Supposedly the sprengel explosives are best stoichiometric. May be the best performance is with stoichiometric, but most of the times there are other practical concerns-the temperature in a rocket engine, the smoke and the flash of a gun, the corrosive effects of the products, I red that with F2 based propellants they don't bother to oxidize the carbon to CO2, but only to CO.
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AndersHoveland
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[*] posted on 17-6-2012 at 02:22


For a given weight, the formation of CO will produce slightly more propelling force than formation of CO2.

However, for several reasons I do not care to make the effort of explaining, in the case of nitrocellulose an excess of oxygen is more beneficial, even in excess of the stoichiometric proportion needed to fully oxidize itself.

[Edited on 17-6-2012 by AndersHoveland]
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hissingnoise
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[*] posted on 17-6-2012 at 02:38


Quote:
For a given weight, the formation of CO will produce slightly more propelling force than formation of CO2.

During WW1 propellants in heavy artillery produced enough CO to produce muzzle-flashes that could be up to 150 ft in length so that at night they could be seen at great distances, giving their position to the enemy.

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franklyn
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[*] posted on 17-6-2012 at 16:33


At high temperatures CO2 can't be formed under low pressure. CO is formed instead.
The reason why rocket propellants are balanced to produce CO.

.
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quicksilver
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[*] posted on 18-6-2012 at 06:52


Quote: Originally posted by Swede  
I love (and collect) old books on chemistry, energetics, and history, especially late 19th century texts back when nitrocellulose was still a bit untameable.

]



Let me know (via U2U) what you're looking for. I collect also.....I'd be happy to help.




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[*] posted on 18-6-2012 at 07:06


TY, much appreciated. I tend to accumulate based upon the interest of the day, and I use them both for actual study and research, and also simply for fun reading.

eBooks and PDF's abound, but there is something about the original text that makes it a bit special.
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