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heat of combustion

noun

  1. chem the heat evolved when one mole of a substance is burnt in oxygen at constant volume
“Collins English Dictionary — Complete & Unabridged” 2012 Digital Edition © William Collins Sons & Co. Ltd. 1979, 1986 © HarperCollins Publishers 1998, 2000, 2003, 2005, 2006, 2007, 2009, 2012


heat of combustion

  1. The amount of heat released when one mole of a substance is completely oxidized.


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Example Sentences

Availability of Heat of Combustion.—Taking the value 1.13 kilogrammetres per kilo-calorie for 1� C. fall of temperature at 100� C., Carnot attempted to estimate the possible performance of a steam-engine receiving heat at 160� C. and rejecting it at 40� C. Assuming the performance to be simply proportional to the temperature fall, the work done for 120� fall would be 134 kilogrammetres per kilo-calorie.

In reality the fraction of the heat of combustion available, even in an ideal engine and apart from practical limitations, is much less than might be inferred from the efficiency formula of the Carnot cycle.

Taking θ′ − θ0 = 2300� C., and θ0 = 313� Abs. as before, we find θ″ = 903� Abs. or 630� C. The heat supplied to the boiler is then 74.4% of the heat of combustion, and of this 65.3% is converted into work, giving a maximum possible efficiency of 49% in place of 89%.

The gain by increased temperature range has been comparatively small owing to limitations of pressure, and the best modern steam-engines do not utilize more than 20% of the heat of combustion.

It is easy, however, to see that the general effect of dissociation must be to diminish the available temperature of combustion, and all experiments go to show that in ordinary combustible mixtures the rise of temperature actually attained is much less than that calculated as in � 22, on the assumption that the whole heat of combustion is developed and communicated to products of constant specific heat.

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