Talk:Heat of combustion

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Importance of LHV vs HHV Debate[edit]

I would like to include some discussion - doesn't need to be an epistle - on why LHV is used (specifically in Gas Turbines) and how that sometimes causes confusion when comparing efficiency with other thermal plant like coal-fired boilers with steam turbines. Any thoughts or suggestions?--Graham Proud (talk) 06:12, 13 August 2013 (UTC)


Can we obtain heat of combution of any product without experiment? is it same like following? A +o2 → Co2+ No2 then based on number of moles and standard heat of formation of Co2 and No2, can we take the obtained result as heat of combustion of substance A? if yes, then does heat of formation is exactly same (with opposite sign) that of heat of combustion? as if we reverse this equation, then heat of the reversed equation will be heat of formation. is this logic correct?

It would be nice if someone would make a sister page about heat of formation.

The reference to energy obtained from antimatter may be misleading as that is presumably the amount of energy contained in that weight of antimatter which would be released when combined with equal weight of matter. I won't vouch for the math in it, but the description is not sufficient, or in any case, might just be listed as the energy available in any mass, whether matter or antimatter, if that is the intent. —Preceding unsigned comment added by Uhpl508 (talkcontribs) 21:12, 21 June 2008 (UTC)

Improper Reference[edit]

The first reference is not specific enough to find the information that it references. —Preceding unsigned comment added by (talk) 23:28, 12 February 2008 (UTC)


Should the organic compounds be named according to the systematic nomenclature of IUPAC? I believe olefines should be alkenes, diolefines should be dienes, etc. i believe tthe use of trivial nomenclature is to be avoided in favor of systematic names. If the fuel has some water , is it true that the state of fuel's water is not important for LHV and HHV ? —Preceding unsigned comment added by (talk) 10:12, 13 December 2007 (UTC)

Three Proposed Merges[edit]

Merge of Heating value here[edit]

It is proposed that Heating value be merged here. The two article each had a simple merge tag, but I have changed these to mergeto and mergefrom as I believe merging Heating value here is the best solution. Please discuss it. --Bduke 00:47, 22 August 2007 (UTC)

  • Support "Heating value" is not a standard term and it really is just a heat of combustion. I suggest tidying it up and merging the content here. --Bduke 00:47, 22 August 2007 (UTC)
  • Oppose I have found sulfur's heat of combustion to be ~4000btu/# in other resources, vs. the 2000btu/# given here. Where can this number be confirmed? —Preceding unsigned comment added by (talk) 13:27, 11 September 2007 (UTC)

Higher Heating Value (HHV) is commonly used by the local air quality management authority in Southern California, perhaps by other air quality regulatory agencies as well. If this is combined with Heat of Combustion, "Higher Heating Value" should be such that it is searchable from a search engine such as Google, since many people, such as I, will search for HHV and not heat of combustion. —Preceding unsigned comment added by (talk) 22:49, 14 November 2008 (UTC)

  • Yes, merge - they seem to be exactly the same thing. — Omegatron 21:50, 27 January 2008 (UTC)
This MERGE appears to have been completed in Jan 2008. N2e (talk) 20:30, 8 August 2008 (UTC)

Merge of Higher heating value and Lower heating value here[edit]

It has been further proposed, in merge tags within each of the two Xxxxx heating value articles, that both are merged here. Both merge tags were added 2008-03-30 by User:Omegatron. One can thus assume that

  • Omegatron Supports the merge, as the proposer.
  • Support -- Rationale: both higher and lower heating values are physical characteristics for particular fuels and are thus part of the heat of combustion. N2e (talk) 20:30, 8 August 2008 (UTC)


All merges proposed here are now complete. D O N D E groovily Talk to me 03:41, 23 November 2010 (UTC)

H2S heat of combustion[edit]

This should be added. —Preceding unsigned comment added by (talk) 13:45, 11 September 2007 (UTC)

Inconsistency in first table[edit]

The heat of combustion values in the 1st table are inconsistent for coal. The conversion between Mcal/kg and BTU/lb is correct, but the conversion to MJ/kg seems wrong. Although I have only checked the conversion of the units, I propose that these values are changed into 18.6 - 32.6 MJ/kg. - It is possible that the conversion went wrong the other way (and that MJ/kg are correct, and Mcal/kg and BTU/lb are wrong). I cannot find the reference.

Furthermore, all the values are inconsistent with another wikipedia page: (see the 1st table). —Preceding unsigned comment added by (talk) 13:12, 11 August 2008 (UTC)

The table at Heating values of some fuels is still inconsistent and poorly referenced. The HHV for coal is listed at 8000-14000 BTU/lb which converts to 18.6-32.6 MJ/kg, not 15-27 MJ/kg as stated in the table. Searching the reference yielded no easy source of information. --LRG (talk) —Preceding undated comment was added at 09:42, 30 September 2008 (UTC).

"Fuel needed to run a 100 W lightbulb for a year (876 kWh, or 3153.6 MJ)"section has to be changed/deleted[edit]

This section has no thermodynamical sense, which is outlighted by the text into parenthesis. Actually, it would be better to change it or to delete it. The deletion seems to me definitely required because it would have no sense to replace "to run a 100 W lightbulb for a year" by "to provide to 100 W of heat for a year". If someone finds usefull to keep relevant data from this section, he can revert or modify this deletion. (talk) 14:20, 25 October 2009 (UTC)

"Lower heating values for some organic compounds at 15.4C"[edit]

A BIG citation needed here - What is the significance of 15.4C anyway? One source I found is here: "" but I don't know how reputable that site is. Also, there's no reason to keep half of the table empty, since it only differs by a conversion factor. I added the value for carbon monoxide, since I used that value on my homework. Traversc (talk) 09:33, 28 October 2010 (UTC)

Is it kJ/L or MJ/L? — Preceding unsigned comment added by (talk) 16:11, 25 August 2011 (UTC)

Table of Higher Heating Values[edit]

I just merged in Higher Heating Value to this article, with the exception of this table, which is difficult for me to go thru. Here it is:

Heating values for selected fuels[1]
Name HHV
Coal [note 1] 34.1 33.3 1.024 0.977
CO 10.9 10.9 1.000 1.000
Methane 55.5 50.1 1.108 0.903
Natural gas [note 2] 42.5 38.1 1.115 0.896
Propane 50.3 46.3 1.086 0.920
Gasoline [note 3] 46.7 42.5 1.099 0.910
Diesel[note 3] 45.9 43.0 1.067 0.937
Hydrogen 141.9 120.1 1.182 0.846
  1. ^ Anthracite, average
  2. ^ Groningen, Netherlands
  3. ^ a b Average gas station fuels

And here is a slightly different one taken from Lower heating value:

Heating values for selected fuels[2],[3]
Name HHV
Coal [note 1] 34.1 33.3 1.024 0.977
CO 10.9 10.9 1.000 1.000
Methane 55.5 50.1 1.108 0.903
Natural gas [note 2] 52.2 47.1 1.108 0.903
Propane 48.9 45.8 1.068 0.937
Gasoline [note 3] 46.7 42.5 1.099 0.910
Diesel [note 3] 45.9 43.0 1.067 0.937
Hydrogen 141.9 120.1 1.182 0.846
  1. ^ Anthracite, average
  2. ^ Groningen, Netherlands
  3. ^ a b Average gas station fuels

If there's anything new here, feel free to toss it in. D O N D E groovily Talk to me 03:34, 23 November 2010 (UTC)

  1. ^ Ulf Bossel: Well-to-Wheel Studies, Heating Values, and the Energy Conservation Principle, Proceedings of Fuel Cell Forum 2003
  2. ^ Ulf Bossel: Well-to-Wheel Studies, Heating Values, and the Energy Conservation Principle, Proceedings of Fuel Cell Forum 2003
  3. ^ GREET Transportation Fuel Cycle Analysis Model, GREET 1.8b, developed by Argonne National Laboratory, Argonne, IL, released September 5, 2008.

GHV definition is incorrect[edit]

I have just had a discussion with my partner who works on the thermodynamic analysis of complex plant as part of her PhD in energy engineering. She tells me "I think its wrong on the wikipedia page. GHV should be HHV, not LHV."

I will refrain from making the necessary edits as I do not intend to maintain any kind of follow up on this page. Regards Robbiemorrison (talk) 11:28, 16 March 2011 (UTC)

I second this statment... The Gross Heating Value is HHV. The article is totally incorrect. —Preceding unsigned comment added by (talk) 16:04, 11 May 2011 (UTC)

Are the figures in the column headed kJ/L in the later LHV tables actually MJ/L? — Preceding unsigned comment added by (talk) 18:49, 31 August 2011 (UTC)

The heating values in the tables appear to be molar heating values not mass heating values. The reported units of BTU/lb, etc should be BTU/lb-mole etc — Preceding unsigned comment added by (talk) 03:30, 10 February 2012 (UTC)

Incorrect unit conversion factors[edit]

Section "heating value" lists some conversions. Last one (Btu/lb = kcals * 1.8) is dimensionally incorrect: Btu/lb does not correspond to kcals . It should be kcals/[some unit for mass], and when this unit is chosen, the constant can be adjusted. DarkoS (talk) 18:09, 25 October 2012 (UTC)

Usage of terms[edit]

In my opinion Wiki should refrain from making subjective statements such as: "... and if they are not already then they should be doing so..." or "...based on the simple fact that it is correct..." (talk) 10:21, 22 January 2013 (UTC)

Very poor quality article[edit]

This article appears to need considerable work. The most glaring issue that I see is that there appears to be no explanation of this property of a chemical. All we get is a few sentences, and then it's off to the races talking about higher/lower heating values. Essentially all of the textbook chemistry discussion is reduced to an introductory sentence and a few bullet points.

I came here hoping to remember which sign indicated an exothermic reaction. Guess what? There is no mention of a chemical which has a negative heat of combustion. It's not mentioned in this article.

Additionally, the writing is deplorable in the section "Usage of terms." Here is a gem:

  • The difference between HHV and LHV definitions causes endless confusion when quoters do not bother to state the convention being used. -- How lovely? This sentence broaches the topic of eternity, so we might as well link to it?

Why I picked on that sentence is anyone's guess. There are so many to choose from in other sections:

  • Most applications that burn fuel produce water vapor, which is unused and thus wastes its heat content. (Chemistry + Grammar = Wasted Energy?)
  • Using LHV in other energy calculations brings similar errors, especially when pulled (incorrectly) into electrolysis calculations etc. (Pulling + My Leg = Electrolysis of my Sides Splitting from Errors?)
  • Btu/lb = kcals * 1.8 (Was this error in unit conversion garbage what someone was really hoping to find here??)

Please, if anyone rates this article.... give it the lowest mark possible. IT'S A MESS! It is not fixable. I think it should be scrapped and started over. I like to saw logs! (talk) 05:51, 5 March 2014 (UTC)

150°C is NOT an arbitrary temperature[edit]

It is based upon the acid gas dew point for sulfuric acid (+ margin). Other acids (sulfurous, nitric, nitrous, carbonic) have an even lower dew point, so it is assumed that at 150°C. effectively no acids will condense. Hippocrocopig (talk) 22:22, 27 March 2016 (UTC)

Poor/dubious merge ? what units ?[edit]

We seem to have an article about heating values that doesn't define its current title of Heat of combustion. Is heat of combustion (a term used by chemists?) always/usually per mole ? Heating values seem to be engineering terms, usually per mass or per volume ? - Rod57 (talk) 11:57, 22 March 2017 (UTC)