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 a high temperature by what process?
- A. Heating by the jacket-water system
- ✓ Heat of compressionCorrect
- C. Residual heat from the previous exhaust stroke
- D. Preheating by the fuel transfer pump
Why B is correct
Air alone is compressed to roughly 300–500 psi, raising its temperature to about 1000°F. Finely atomized 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