When we burn fuel, water vapour is produced because hydrogen is burnt as well. But since the vapour is in gaseous state already, it shouldn't steal any heat from fuel gases, should it?


1 Answer 1


Water vapor produced during the burning of hydrogen-containing fuels should not steal any heat from the fuel, unless they condense on solid surfaces. In such cases, it may require a small amount of heat to evaporate them again. However, in my experiences, there is a stage during burning that there is a lot of water vapor on the solid object, and as the object is warmed up, there is no more vapor condensed.

  • $\begingroup$ thanx shadow.I have another question.does the condensed water present in the fuel before combustion makes the heat difference between gross calorific value and the net calorific value then? $\endgroup$ Mar 25, 2016 at 4:14
  • $\begingroup$ See en.wikipedia.org/wiki/Heat_of_combustion. You should consider posting another question, rather than asking in the comments. $\endgroup$ Mar 25, 2016 at 6:06

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