What is Calorific Value or Heating value?
- The calorific value is used to find the amount of heat energy produced after the complete combustion of one kg of fuel.
Gross Calorific Values (GCV/HHV)
- Gross calorific value (GCV) is also called as a higher Heating Value (HCV)
- It measures the amount of heat released by the complete combustion of a unit of fuel. GCV considers that all water vapor (H2O) produced during the combustion process is fully condensed
- The flue gas formed from combustion is condensed during waste heat recovery and water condensate is formed. In such cases as coal-fired boilers, the GCV value is used to find out the firing capacity.
Formula for GCV or HCV
Dulong’s formula is used to calculate the GCV (Kcal/kg) of coal
GCV = 1/100* (8080*C + 34500* (H – O/8)+ 2240*S) Kcal/kg
where C, H, O, and S are percentages of carbon, hydrogen, oxygen, and sulfur in coal
Net Calorific Value (NCV)
- It is called a lower heating value (LHV) or lower calorific value (LCV)
- Its value is calculated by subtracting the latent heat of vaporization of the water vapor from the higher heating value (HHV)
- It assumes water vapor leaves with the combustion products is the gas phase that it is not condensed
- For furnaces firing with gaseous fuel, a lower heating value is used to find the firing capacity. The flue gas formed from combustion is not further condensed.
Formula for LCV
LCV = GCV – 9/100*H*587 Kcal/kg
where H is the percentage of carbon, hydrogen, oxygen, and sulfur in coal
GCV and LCV Calculator