High and Low Heat Values
The gross (high) and net (low) heating values.
The heat value is
- the amount of heat produced by combustion 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
In thermodynamics, the term standard heat of combustion corresponds to Gross heating value. See Heat of combustion for examples of calculation of gross heating values from standard heat of formation of substances.
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 for heating value:
- 1 Btu/lb = 2326.1 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 = 4187 J/kg
Related Topics
-
Combustion
Combustion processes and their efficiency. Boiler house and chimney topics. Properties of fuels like oil, gas, coal and wood and more. Safety valves and tanks. -
Thermodynamics
Work, heat and energy systems.
Related Documents
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Alternative Fuels - Properties
Properties of alternative fuels like biodiesel, E85, CNG and more. -
Biogas - Energy Content
Energy content in biogas produced from municipal and industrial waste. -
Combustion Heat
Heat of combustion (energy content) for som common substances - with examples how to calculate heat of combustion. -
Energy Content in common Energy Sources
Heating fuels and their energy content. -
Food - Calorific Combustion Values
Combustion heat values of some foods. -
Fuel Gases - Heating Values
Combustion heat values for gases like acetylene, blast furnace gas, ethane, biogas and more - Gross and Net values. -
Fuels - Higher and Lower Calorific Values
Higher and lower calorific values (heating values) for fuels like coke, oil, wood, hydrogen and others. -
Gases - Gross and Net Heat Values
Gross heat and net heat values for gases like hydrogen, methane and more. -
Paraffins and Alkanes - Combustion Properties
Properties like heat values, air/fuel ratios, flame speed, flame temperatures, ignition temperatures, flash points and flammability limits. -
Standard Grade Coal - Heat Values
Standard grades coal heat values. -
Waste Fuel - Heat Values
Fuel from waste products and their heat values. -
Wood - Combustion Heat Values
Combustion of wood and firewood heat values for species like Pine, Elm, Hickory and more.
