Chemistry of Fuel and Lubricants

       

  Fuel And Lubricants

                        Fuel:      

 A Fuel is a substance that can be made to combine with oxygen with evolution of light and thermal energy that can be utilized for domestic as well as industrial heating.

      Classification of Fuels:

According to the physical state in which they exist in nature - solid, liquid and gaseous.

According to the mode of their procurement- natural and manufactured.

   Fuel------- (a) Natural Fuels

                            (B) Manufactured Fuels

  

Natural Fuels: (1) solid( wood,coal)

(2) Liquid (petroleum). (3) Gas (Natural gas).

Manufactured Fuels: (1) solid (coke, charcoal).   (2) Liquid ( coal tar, kerosene).     (3) Gas ( coal gas, producer gas)

          Calorific value:

The calorific value of a fuel is the number of units of heat evolved during complete combustion of unit weight of the fuel. For liquids and solids it is usually expressed in btu/In or Cal/hm.

   The calorific value may be expressed in two types - (1) Gross calorific value (Gcv). (2) Net calorific value (Ncv)

 Gross calorific value

The quantity of heat evolved by the combustion of unit quantity of fuel is it's gross calorific value.

       Gross or higher calorific value is the quantity of heat liberated by combusti-ng unit mass of fuel in oxygen, The orig-inal  material and the final product of    Combustion being at a reference tempe-rature of 25°c and the water obtained is in the liquid state.

  Net calorific value

Net calorific value (Ncv) is the quantity of heat evolved when a unit quantity of fuel is burnt in oxygen, the original material and the final products of Combustion being at a reference tempe-rature of 25°c and the water obtained from the fuel is in the vapour state.