Fuel is defined as any combustible material, obtained in bulk, containing carbon as a major constituent and when burnt in presence of oxidant evolves heat which can be economically used for domestic and industrial heating or power generation.
The calorific value of fuel
The Calorific value or heating value of a fuel is the amount of heat released during the complete combustion of a unit mass of fuel. it is a characteristic property of a fuel. It is measured in the unit of heat per mass of fuel, such as cal /g, kcal /kg etc.
Various units of heat are as follows:
Calorie(cal) or gram calorie(g cal)
Calorie or gram calorie is defined as the amount of heat required to raise the temperature of 1 g water through 1 0C (from 15 000C to 16 0C)
Thus, 1 cal = 4.185 Joules =4.185 ×107 ergs.
Kilocalorie (kcal) or kilogram calorie (kg cal)
Kilocalorie or kilogram calorie is defined as the amounts of heat required to raise the temperature of 1 kg of water through 1 0C (from 150C to 16 0C).
Thus, 1 kcal = 1000 cal
British thermal unit(B.T.U)
British thermal unit is defined as the amount of heat required to raise the temperature of 1lb of water through 10F (from 60 0F to 61 0F)
Thus, 1 B.T.U = 1054.6 Joules = 1054.6 × 107ergs.
Centigrade heat unit (C.H.U)
Centigrade heat unit is defined as the amount of heat required to raise the temperature of 1lb of water through 10.
The various unit of heat can be inter-converted as follows-
1 kcal =1000 cal = 3.968 B.T.U = 2.2 C.H.U