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Old 12-05-2007, 09:35 AM   #16
kevinthenerd
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Re: Acetylene as a fuel

I think I found my error. While acetylene has a positive enthalpy of formation, it produces less CO2 and H2O, resulting in less heat on the product side of the reaction.

(By the way, it's been a couple of years since I took chemistry. I just got to thinking how hot welding gas gets. I think it has to do with the fact that the output heat doesn't have a whole lot of mass to heat up, resulting in a high temperature.)
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Old 12-05-2007, 06:27 PM   #17
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Re: Acetylene as a fuel

Quote:
Originally Posted by kevinthenerd
I think I found my error. While acetylene has a positive enthalpy of formation, it produces less CO2 and H2O, resulting in less heat on the product side of the reaction.

(By the way, it's been a couple of years since I took chemistry. I just got to thinking how hot welding gas gets. I think it has to do with the fact that the output heat doesn't have a whole lot of mass to heat up, resulting in a high temperature.)
Oxy-Acetylene produces high temps because of the pure oxygen you feed it. It means the 80% nitrogen that's usually along for the ride and taking home heat isn't involved.
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Old 12-09-2007, 07:18 PM   #18
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Re: Acetylene as a fuel

Quote:
Originally Posted by KiwiBacon
Oxy-Acetylene produces high temps because of the pure oxygen you feed it. It means the 80% nitrogen that's usually along for the ride and taking home heat isn't involved.
Quote:
Originally Posted by kevinthenerd
think it has to do with the fact that the output heat doesn't have a whole lot of mass to heat up, resulting in a high temperature.)
I didn't spell it out, but that's it... less product mass per unit of heat

dH=m*Cp*dT
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Old 12-09-2007, 11:28 PM   #19
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Re: Acetylene as a fuel

Quote:
Originally Posted by kevinthenerd
I didn't spell it out, but that's it... less product mass per unit of heat

dH=m*Cp*dT
I thought you were referring to an open flame not having to heat the mass of an internal combustion engine, thus producing a hotter flame than engine exhaust.

Which was of course correct, even if that wasn't your intent.
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Old 03-24-2011, 09:38 PM   #20
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Re: Acetylene as a fuel

Given the extremely unstable and explosive nature of acetylene, I cannot think of any way one could safely use it. It's explosive at pressure over 26psi, it's violently explosive at virtually any mixture with oxygen or air. It can only be transported dissolved in acetone. Scary to think of someone trying to introduce it into an engine.
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