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 raised to ignition temperature by which process?
- A. Friction between the piston rings and cylinder liner
- B. Heat transferred from the jacket-water cooling system
- ✓ Compression of the air charge to roughly 300-500 psiCorrect
- D. Preheating of the intake air by the turbocharger aftercooler
Why C is correct
A diesel compresses air alone to approximately 300-500 psi, raising its temperature to about 1000 degrees F. Fuel injected near the end of compression ignites spontaneously from this heat of compression, requiring no spark plug or carburetor. (DOE-HDBK-1018 Vol.1 §1-1)
Cited:DOE-HDBK-1018 Vol.1 §1-1