Talk:Adiabatic flame temperature

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unclarity about listed flame temperatures[edit]

The table in the article is claimed to be for stoichiometric fuel-oxidizer mixtures, but also under atmospheric conditions. Does this mean the other gasses that make up air are taken into account in the calculation/measurement? Obviously, an air mixture that also contains a lot of Nitrogen Gas would result in a different Temperature than a pure Fuel-oxidizer mixture. — Preceding unsigned comment added by 131.155.221.211 (talk) 09:34, 5 October 2017 (UTC)[reply]

Original research[edit]

This page seems to contain many unpublished calculations by one author. Seems well written, but may be outside of wikipedia standards for original research. Vaudeville (talk) 18:57, 4 January 2008 (UTC)[reply]

    • The author Mig8tr added several figures on 15:56, 19 March 2006 that do not cite external sources and, based on following the external link at the bottom, are clearly the author's own calculations that were added to the page, using the author's own equilibrium code. Although the results seem reasonable, this would seem to qualify be original research. Here is a statement from this author's webpage http://www.depcik.com/eduprograms/aftp.htm :

"Adiabatic Flame Temperature at Wikipedia - I am currently updating the free encyclopedia Wikipedia with respect to this topic using my AFTP program. I hope that web users will find this content interesting and helpful."

Thus is seems clear that this author is doing original calculations specifically for this page. Is this original research? —Preceding unsigned comment added by 70.231.147.48 (talk) 18:16, 6 January 2008 (UTC)[reply]

Questions about flame temperature[edit]

We have a number of questions about flame energy and temperature on Talk:Oxyhydrogen#Enthalpy and Talk:Atomic hydrogen welding due to some dubious claims made about a certain welding process ("our flame is hot enough to vaporize tungsten!") We welcome any input from people who are familiar with the processes and calculations. — Omegatron 19:52, 27 January 2008 (UTC)[reply]

If you are cutting Tungsten or Steel, you have a ratio of pure Oxygen and actually burning not melting the Steel. The Hydrogen arc welders break the very strong (104 KCal/mole) Hydrogen molecule bond resulting in plasma like temperatures on recombination and after all, Tungsten melts at only 3500 degrees.

--Shjacks45 (talk) 06:39, 11 July 2011 (UTC)[reply]

Maximum possible temperature[edit]

The adiabatic flame temperature is *not* the maximum possible temperature of a combustible mixture. Since the assumption in the calculation is that the system is in chemical equilibrium, the calculation tells one nothing about possible non-equilibrium states. Indeed several very rich methane and acetylene flames have been shown to exceed their adiabatic flame temperatures by large amounts (see papers with "superadiabatic" in the title, especially the work of Lucht at UIUC, Capelli at Stanford, Glumac at Rutgers, and Kennedy at UIC). 20304A (talk) 20:34, 7 February 2008 (UTC)20304A[reply]

Unscientific. However definition "ADIABATIC: occurring without loss or gain of heat" doesn't help. But consider that "superadiabatic" makes even less sense? However in flame research the constant state flame at thermodynamic 'Standard Temperature and Pressure' allows areas of the flame that are expanding due to energy production etc. (e.g. Methanol flame: decomposition of CH3OH to 2H2 and CO, a 1:3 expansion, before combustion zone) to be larger than areas at surrounding pressure. If the flame is constrained, these areas will be under pressure causing some reactions to slow and others to speed up. The pressure wave of a detonation, for instance, increases the rate of burning therefore propagating the detonation wave. A "simple" example would be internal combustion engines (time limited burn): too low compression equals low burning rate with leftover fuel and carbon monoxide products; a high compression leads to higher nitrogen oxides and carbon particulate.
Hence the "Adiabatic" tag really refers to reactants burning freely in standard pressure air. Note that these are usually peak temperatures (usually in the oxidizing part of the flame), that there are lower temp areas of flame. Many flames are hotter when not at equilibrium, leaving excess of reactants if in an inert gas atmosphere. E.g. Carbon: 85% of the energy released is burning to Carbon Monoxide. E.g. Oxygen: Water produced by Hydrogen/Oxygen flame decomposes over 2000 degrees and (without compression) at flame temperature of 2500 degrees exists as Hydroxyl and Hydrogen.

Shjacks45 (talk) 20:45, 10 July 2011 (UTC)[reply]

"Diagram needed"[edit]

What kind of diagram is requested? A graph? A chart? Any similar examples of what you're after? pfctdayelise (talk) 15:40, 26 July 2008 (UTC)[reply]

I'm not seeing what it would be either. I'll remove the request. The addition was this diff by Omegatron. I'll ask him on his talk page. —Ben FrantzDale (talk) 18:05, 26 July 2008 (UTC)[reply]

"In the study of combustion, there are two types of adiabatic flame temperature depending on how the process is completed: constant volume and constant pressure."

Needs a diagram of the two processes. How is the flame temperature physically measured? — Omegatron (talk) 22:45, 24 August 2008 (UTC)[reply]

Ummm...[edit]

I'm rather shocked at how much is said in this article, most of it POV and smacking of research, yet even after reading it twice over I have little idea of what the flame temperature actually is. The only help here is the vague statement that it is the temperature produced by the total combustion of a substance etc. etc. etc. To be fair, this is a clear explanation, but it leaves many questions unanswered- how much exactly is burned to produce a given flame temperature, explanation of why it doesn't matter how much, and so on. I know it's lame of me to criticize without trying to sort it out but I have a hard time understanding and reading this type of material, much less writing it. But this page, to me at least, is nigh-unreadable. Mr0t1633 (talk) 01:37, 11 April 2009 (UTC)[reply]

Put a bead thermocouple in the hottest part of the flame, or use a splinter of refractory material and see it it fuses. The tip of the oxidizing flame is usually the hottest. If you have done any welding or glassblowing you get a feel for where the hot spot is. Helps if you think of flame layers as successive decomposition of fuel/oxidizer, the outer cone where the final combustion takes place. The inner cone(s) are components that decompose at lower temperatures, e.g. methanol to formaldehyde and hydrogen then carbon monoxide and hydrogen, the 1:3 pressure increase forcing out the outer cone.
Burning a fuel in Air, e.g. Bunsen Burner using Methane (Natural Gas), has only the fuel component creating flame zones. A typical AA Instrument uses concentric gas feeds: inner is fuel like Acetylene, outer ring Air (from compressed Air), Oxygen, or Nitrous Oxide, the surrounding Air being irrelevant. In some cases the gases are premixed before going to the burner (like Bunsen Burner), leading to a hotter more condensed flame (earlier oxidation of some fuel components) but will still have a cone structure. The atmosphere in flame research can be an inert gas. It is amusing to see a flame coming from an Oxygen jet into an atmosphere of hydrogen or Chlorine gas burning in Ammonia.
Remember that combustion zone of a "flame" is a chain reaction that proceeds at a certain velocity or rate, dependent on temperature, pressure, and concentration of reactants. Hydrogen/Oxygen burns at 4% to 97% mixtures. Therefore large outer cone (reaction zone). Octane flammability range is 8% - 10% Octane/Air. Candle wax (around C30 limits around .5%, hence the narrow reaction zone. The inner cone exerts pressure from chemical decomp and thermal expansion of fuel. Thermal cracking of hydrocarbons yields carbon/soot.

--Shjacks45 (talk) 06:30, 11 July 2011 (UTC)[reply]

missing flame temps[edit]

Atomic Absorption Spectroscopy instrument manuals list common gas mixtures. Also there are some Rocketry references re flame temps also. This list is all gases. Probably could list solid fuels and liquids as well, e.g. Magnesium metal in air is 2800 degrees C. (Bank robbers open vaults with Magnesium tubes with oxygen flowing through for even higher temperature.) AA fave for refractory metals was Cyanogen and Nitrous Oxide (decomp of N2O generates energy also). Ammonia and Oxygen (can burn as gases) was rocket fuel in X-15 plane. Ammonia also burns in Freon. I worked at Rocket Research (before Aerojet takeover) and catalytic (Iridium) decomposition of Hydrazine (vapor in space vacuum) to N2 and H2 was around 2000 degrees requiring refractory nozzles. One welding technique is dissociation of H2 to H + H. the subsequent recombination generates plasma scale temperatures (104 KCal/mole). At least add the Cyanogen/Nitrous Oxide and Ammonia/Oxygen flame temps, Hydrogen/Flourine, and Ammonia/Freon would be nice too. Shjacks45 (talk) 21:34, 10 July 2011 (UTC)[reply]

AFT for Wood seems high[edit]

OK, I know that this is a theoretical value with the listed temperature occurring rarely if at all. Having said that, the AFT for wood is listed at 1980°C. It is relatively well known (I can cite piles of papers if needed) that Iron (Fe) cannot be melted directly by wood (or charcoal) burning in air. People tried for about 12 centuries. That's why pre-industrial iron production involved liquefying everything BUT the iron in the iron ore, and manipulating the red hot spongy mass of iron that remained.

Given that the listed melting point for Fe is 1535°C, I'm thinking that if the real AFT for wood was 1980&degC, there would have been a lot more melted iron ore in the ancient era.

Or maybe it's just a really good example of theory and practice differing. — Preceding unsigned comment added by Riventree (talk • contribs) 04:14, 9 April 2012 (UTC)[reply]

External links modified[edit]

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AFT for methane / oxygen[edit]

Value for methane + oxygen looks like nonsense (9kK?!), completely out of line for hydrocarbons, and the supporting ref is not reputable. Not a domain expert here, but seriously... — Preceding unsigned comment added by 75.142.76.114 (talk) 22:48, 8 March 2017 (UTC) (I went ahead and reverted it since it was added just a week ago. Real Wikipedians, I now leave it in your hands.) — Preceding unsigned comment added by 75.142.76.114 (talk) 22:53, 8 March 2017 (UTC)[reply]

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