Question

Diesel engines do not require spark plugs. Why?

Answer 1

Hint: The diesel engine was named after the German inventor and mechanical engineer Rudolf Christian Karl Diesel. The diesel engines are also known as the compression-ignition engine. It is the heat engine which undergoes the off of the energy which was supplied by the combustion of the diesel fuel with the high pressure and the temperature.

Complete step by step answer:
Generally, the diesel engines are also called compression-ignition engines as the initial combustion depends on the air heated by the compression relatively than on an electric spark. Since, the diesel has very low volatility and as a result it cannot form the desired air-fuel mixture to be ignited by the spark plugs.
Diesel has the lower self-ignition temperature compared to other fuels such as petrol and gasoline. The compression of air during the compression strokes generates the temperature around is enough to ignite the diesel fuel which is sprayed into the hot-compressed air at the end of the compression two or four stroke engine. In Diesel engines, due to the higher compression ratio the compressed air gets heated high up to such a high temperature that the sprayed fuel catches fire on its own.
Hence, Diesel engines do not require the spark plug.

Note:Remember the difference between the engines and the motors. An engine is the device which converts the chemical energy into the required mechanical energy, whereas the motors are the devices which run on the electricity to produce motion. For example vehicles use an engine whereas in the house-hold appliance uses motors in it.