|Written by C. L. Easey|
Net heating value is the actual amount of heat, which is available after all gases are released during the combustion process. This is known as the lower heating value. Calculating the lower heating value or net value of heat will require a known reference. This will be the higher heating value amount, for the combustible. The higher heating value is the amount of energy that is released when 1 kilogram of fuel is burned.
Step 1 - Determine the amount of hydrogen that is contained in a specific fuel, such as coal. If the amount is 10 percent then multiply .10 by 9, which will equals .9.
Step 2 - Multiply the result by latent heat evaporation of the combustion reaction. If the partial pressure of the steam being released is 5 kilopascals, the latent heat evaporation is 2,424 kilojules per kilogram. This will be .9 x 2,424, which will equal 2,181.
Step 3 - Subtract the result from the higher heating value, such as 40,120 kilojoules. This equation will look like (40,120-2,181), which results in 37,939 kj/kg.
If you do not want to calculate the values by hand go to the online calculator at the Hydrogen Analysis Resource Center.
A kilopascal is a unit of measurement.
A kilojule is a unit of energy.