USCG Exam PracticeDiesel engine principles (motor propulsion)
A diesel engine ignites its fuel charge without a spark plug because the fuel is injected into air that has been heated by which process?
- A. Combustion of a pilot charge of gas
- B. Heat transferred from the jacket-water system
- ✓ Heat of compression of the air chargeCorrect
- D. Electrical resistance heating of the cylinder head
Why C is correct
A diesel compresses air alone to roughly 300–500 psi, raising its temperature to about 1000°F. Fuel injected into this hot compressed air ignites spontaneously — no spark plug or carburetor is required. DOE-HDBK-1018 Vol.1 §1-1.
Cited:DOE-HDBK-1018 Vol.1 §1-1