Heating Value

The gross (high) and net (low) heating values

The heating value is

  • the amount of heat produced by combustion of a unit quantity of a fuel

We differentiate between gross and net heating values:

Gross (or high, upper) Heating Value

The gross or high heating value is the amount of heat produced by the complete combustion of a unit quantity of fuel.

The gross heating value is obtained when

  • all products of the combustion are cooled down to the temperature before the combustion
  • the water vapor formed during combustion is condensed

Net (or lower) Heating Value

The net or lower heating value is obtained by

  • subtracting the latent heat of vaporization of the water vapor formed by the combustion

from the gross or higher heating value.

Common Units

Common units used for heating value are

  • 1 Btu/lb = 2,326.1 J/kg = 0.55556 kcal/kg
  • 1 J/kg = 0.00043 Btu/lb = 2.39x10-4 kcal/kg
  • 1 kcal/kg = 1.80 Btu/lb = 4,187 J/kg

Related Topics

  • Combustion - Boiler house topics - fuels like oil, gas, coal, wood - chimneys, safety valves, tanks - combustion efficiency
  • Thermodynamics - The effects of work, heat and energy on a system

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