Net Calorific Value Theory

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The net calorific value is determined by the following equation:

where,
NCV: net calorific value in MJ/kg fuel (wet basis)
GCV: gross calorific value in MJ/kg fuel (dry basis)
w: water content of fuel as percentage of weight
h: concentration of hydrogen as percentage of weight (dry basis).

The first term simply converts the gross calorific value to the wet basis. The second term is due to the latent heat of vaporization of the water contained in the wood. The specific latent heat of vaporization of water at 25 ^oC and constant pressure is 2.447 MJ/kg. The third term is due to the vaporization of the water produced when the hydrogen in the wood is combusted. The concentration of hydrogen in woody biomass is typically about 6% (dry basis).

References: Handbook of Biomass Combustion and Co-Firing, Sjaak van Loo and Jaap Koppejan (eds.) (Twente University Press 2002)

Last modified: Thu Dec 14 17:22:07 New Zealand Daylight Time 2006