In diesel engine, what is used to ignite the fuel?

In diesel engine, what is used to ignite the fuel?

Option:

a. spark plug
b. ignitor
c. heat generated by compressing air which is supplied for combustion
d. injected fuel

Correct Answer : c. heat generated by compressing air which is supplied for combustion

Explanation:

Diesel engine is a four-stroke engine which is also known as compression ignition engine. The diesel engine is similar like petrol engine except that in the diesel engine the fuel injection pump is used instead of spark plug. In the diesel engine the fuel and air are introduced separately instead of fuel-air mixture like in petrol engine.

The four strokes of the diesel engine are explained as follows



(1) Intake: In the intake stroke only air is drawn in cylinder through the inlet port by opening inlet valve. The piston of the cylinder travels from top dead centre to the bottom dead centre.

(2) Compression: In this stroke the inlet valve closes and piston moves from the bottom dead centre to top dead centre. As the piston moves up, it compresses the air mixture, heating it up. In this process fuel is injected into the hot gas through the central fuel injector and it ignites spontaneously. Unlike with a petrol engine, a spark plug is not needed to make this happen.

(3) Power: As the air-fuel mixture ignites spontaneously, it pushes the piston downward. This power is transmitted through the crank shaft to the wheels of vehicle.

(4) Exhaust: In this stroke the exhaust valve opens up and the exhaust gases are taken out as piston moves from bottom dead centre to top dead centre.