Thursday, January 10, 2013

Calorific value and its types (Higher calorific value and lower calorific value)

Any fuel that is to be used in any combustion process first, be checked by its calorific values. Cost of fuel is also affected by calorific value of fuel. Here you can find the basic information about calorific value and its type. 

What is combustion?
Combustion is defined as sequence of exothermic reactions/operations which at the end gives off heat as energy and by products or combustion products.
e.g. combustion of methane with oxygen gives water and carbon dioxide with energy.


Calorific Value of fuel
Calorific Value (C.V) or Heating Value or Energy Value is defined as the amount of energy liberated by complete combustion of unit quantity of fuel. 
  • Unit of Calorific Value: Joule per kg (J/kg)
  • Calorific Value is a characteristics of a fuel, based on this number, a fuel is selected for particular application and price is also decided based on CV. 
Types of Calorific Value:

1. Higher or Gross Calorific Value (HCV)

If a fuel contains hydrogen as content in it and if it reacts with oxygen during the combustion process, the product of combustion also contain water vapor. If this water vapor if condensed at the temperature at which fuel and oxygen are supplied, vapor will be condensed in water form and gives off its latent energy. This is addition to the energy liberated by unit mass fuel. Thus this is called gross or higher calorific value. 

1. Lower or Net Calorific Value (LCV)

If water vapor as product of combustion is not condensed in water form, the net energy obtained by complete combustion of unit quantity of fuel is called lower calorific or net calorific value. 

In practical purpose, LCV is used in consideration. 

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