Liquid fuels are widely used for industrial and domestic purposes. Almost all internal combustion engines run on liquid fuels. Liquid fuels are also used in heat generation in ovens and furnaces. The largest source of liquid fuels is petroleum. It is also called mineral oil. Products are obtained from the refining of crude oil.
Petroleum or crude oil is a dark greenish brown or black viscous and inflammable oil found in earth's crust. It is formed from organic matters like animals, vegetable etc. buried by sand. These matters get decayed and decomposed under reducing conditions and due to increased pressure and temperature. The main constituents of petroleum are paraffins, cycloalkanes, aromatic hydrocarbons, and small amount of other compounds containing S, N and O. approximately C = 80 - 87%; H = 11 - 15%; N = 0.4 - 0.9%; S = 0.1 - 3.5%; O = 0.1 - 0.9%.
Advantage and disadvantages in using liquid fuels
1. Liquid fuels are free from ash is clean.
2. It requires less excess air for combustion.
3. Combustion can be controlled and can be used as an economic fuel.
4. Storage and handling of liquid fuels is easy. Oils can be stored in tanks and can be handled with plums (economic).
5. Storage space required is less compared to solid or gaseous fuel.
6. The thermal efficiency of liquid fuels is higher than that of solid fuels.
1. It is more costly than solid fuels.
2. Due to high volatility and inflammability, it causes fire hazards.
3. Greater care must be taken to store them in closed containers.
4. The liquid fuels which contain high carbon and aromatic content may produce smoke.