Question

There is no spark plug in diesel engine. Why?

Answer 1

Hint: In the diesel engine, the fuel is injected during the compression process inside the engine cylinder to combust the air-fuel mixture.

Complete step by step solution:
The spark plug is used to generate spark inside the engine cylinder during compression of the air-fuel mixture inside the engine cylinder. The spark plug is used in the petrol engine in which air and fuel come simultaneously inside the engine cylinder during the suction process.

There is no spark plug in diesel engines because, in the suction process, only air comes inside the engine cylinder during the suction process, and fuel is injected inside the engine cylinder during the compression process. A spark plug cannot inject fuel; it can only generate the spark. To inject fuel inside the engine cylinder fuel injector is used in place of spark plug and combustion in the diesel engine when the mixture of air-fuel is compressed at a high rate. This combustion converts the fuel's chemical energy into a massive amount of power used in mechanical energy from the vehicle's movement. The diesel engine is efficient than the petrol engine and has a high compression ratio. The diesel engine can produce more torque at low rpm, but its disadvantage is that they produce more noise. The diesel engines require more servicing than petrol engines and are more economical because diesel's cost is less than petrol costs. The diesel engine is used in heavy vehicles like trucks, buses, and in some commercial cars. The diesel engines operate on the diesel cycle, which consists of a four-stroke process. Both diesel and petrol engine vehicles are not eco-friendly because the fuel used in these engines produces pollution in the environment.

Note: In the diesel engine, the combustion of air-fuel mixture occurs due to the generation of high temperature inside the engine cylinder, not with spark generation.