Calorific value of a fuel may be defined as the amount of heat produced on complete burning of 1 gm of fuel. S.I. unit of calorific value of fuels is kilojoule per gram (KJ/g). When fuels are burnt, heat is produced. The amount of heat produced by different types of fuels on burning is expressed in terms of calorific value. For example, when one gram of wood is burnt completely it produces 17 kilojoules heat. Therefore, the calorific value of wood is 17 KJ/g. in similar manner, when 1 gm of kerosene oil is burnt completely it produces 48 kilojoules heat. So, the calorific value of kerosene oil is 48 KJ/g. the calorific value of different types of fuels is given in following table.