How is fuel ignited in a diesel cycle engine?

How is fuel ignited in a diesel cycle engine?

• A. The diesel cycle depends on high compression pressures to provide for the ignition of the air-fuel charge in the cylinder.
• B. By spark plug.
• C. By electric coil.
• D. By external flame.

Answer: (A)

Diesel engines rely on compression ignition. The air in the cylinder is compressed to a very high pressure, which raises its temperature to a point where the injected fuel auto-ignites. There is no spark plug or external flame involved; ignition happens because the hot, compressed air triggers the fuel’s combustion as soon as it’s sprayed into the cylinder. The high compression ratio is essential to reaching that ignition temperature, and the timing is governed by when fuel is injected, not by a separate ignition event.

Diesel engines rely on compression ignition. The air in the cylinder is compressed to a very high pressure, which raises its temperature to a point where the injected fuel auto-ignites. There is no spark plug or external flame involved; ignition happens because the hot, compressed air triggers the fuel’s combustion as soon as it’s sprayed into the cylinder. The high compression ratio is essential to reaching that ignition temperature, and the timing is governed by when fuel is injected, not by a separate ignition event.