2. What is the formula for calculating calorific value?
Answers
Answer:
Gross calorific value (GCV) and net calorific value (NCV) are the terms used in the formula to calculate calorific value of fuel. Latent heat escaped (in form of water vapor) is subtracted from the Gross calorific value to get the Net calorific value.
Answer:
Calorific Value
The calorific value of a fuel is the amount of heat it generates on its complete combustion. For solid and liquid fuels, we express it in unit kJ/kg.
Furthermore, for the gaseous fuels, we express it as kJ/m3. Here m3 is a normal cubic meter that we measure at NTP conditions. Also, we can express the calorific value of gaseous fuels as kJ per cubic meter which we express at STP conditions.
Fuel consists of one or more combustible elements or compounds like carbon, hydrogen, carbon monoxide, hydrocarbons, Sulphur, etc.
Moreover, these combustibles generate heat by their combustion. Naturally, we take this heat from the heat of combustion of the fuel.
But the total heat of combustion of the fuel is not available to do external work. in addition, the heats that combustion of the fuel produces neglect the heat that it requires to evaporate the water which we call the Higher Calorific Value of the fuel (HCV).
However, hcv is the maximum heat energy that the complete combustion releases on the burning of the fuel. We refer to it as the gcv of the fuel.
We can subtract from the hcv, an amount of heat required to evaporate the water formed, we can easily find Lower Calorific Value (LCV). Besides, we also know it as Net Calorific Value (LCV) i.e. Net Calorific Value of the fuel.
There is no definite agreement in the literature is available on fuel. Whether to lower calorific value can be found simply by subtracting latent heat of steam or both the latent heat and sensible heat in cooling from 100°C from the gcv.
Procedure to Calculate Calorific Value
It is the measurement of the heat value or amount of energy released and is either measured in gcv or ncv.
Gross calorific value (GCV) that is Higher Heating Value (HCV) is the amount of heat that complete combustion releases by burning a unit of fuel. It assumes all water vapour produced during the combustion process is fully condensed.
Net Calorific Value (NCV) means lower heating value (LHV) i.e. lower calorific value (LCV) is determined by the subtraction of heat of vaporization of the water vapour from the higher heating value.
In addition, It assumes that water vapour leaves with combustion products without full condensation. Furthermore, we shall purchase Fuel on the basis of NCV.
For the conversion of GCV to NCV, we can use the formula given as follows:-
GCV = NCV + 584 (9 x H2%+M%)/100)