Classification of fuel on the basis of availability
Coal and Petroleum of Class 8
CLASSIFICATION OF FUEL ON THE BASIS OF AVALABILITY
This type of classification is based on availability of the fuels. In this type fuels have been divided into two types.
The fuels which exist in nature itself and can be used directly to produce heat. For example, Wood, coal, petroleum, natural gas, animal dung and agricultural waste etc.
The fuels which are obtained from primary fuels by different physical and chemical methods are known as secondary fuels. For example, charcoal, coke, petrol, diesel, kerosene, coal gas, water gas, producer gas etc.
Some exhaustible natural resources like coal, petroleum and natural gas. These were formed from the dead remains of living organisms (fossils). So, these are all known as fossil fuels.
CALORIFIC VALUE OF A FUEL:
Calorific value is defined as the amount of heat energy produced on complete combustion of 1 kilogram of a fuel. It is expressed in a unit called kilojoule per kg. The higher the calorific value of a fuel, the more is its efficiency. Characterisation of fuel is done by its calorific value
- Higher mass % H greater calorific value.
- Higher mass % O lower calorific value.
- The greater the calorific value of fuel greater will be its efficiency
- Calorific value of fuel is also known as burning value of fuel or its heat of combustion
Each kilogram of LPG produces much more heat than one kilogram of wood or coal. The calorific value of LPG is the highest among wood, charcoal and LPG. In rural areas, cow dung and wood are still used as fuel because these are very cheap and easily available
However, burning wood produces a lot of smoke, which is very harmful to humans, since it causes respiratory problems.Cutting down trees for fuel also leads to deforestation, which harms the environment and also deprives us of all the other benefits of trees. Unburned carbon particles released when carbon fuels like wood, coal and petroleum burn, cause pollution and respiratory diseases such as asthma.To score More in your class 8 refer NCERT solutions for class 8 .