Diesel cycle efficiency responds to a decrease in cut-off by_________________?
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Answer: A. increases
Explanation
In a Diesel cycle, reducing the cut-off ratio increases the expansion ratio, improving efficiency. Shorter cut-off means heat addition terminates earlier in the power stroke expansion phase. Extended expansion extracts more work from the working fluid before exhaust release. The Diesel cycle models compression-ignition engines where fuel is injected into hot air. Cut-off ratio is the fraction of stroke during which heat addition occurs at constant pressure. Higher expansion ratios correlate directly with improved thermodynamic cycle efficiency.
Modern diesel engine management systems optimize fuel injection timing to maximize fuel economy. Agricultural and heavy-duty transport vehicles rely on efficient diesel combustion cycles. Engine designers balance cut-off ratios with peak cylinder pressure limits for durability. Option B incorrectly suggests efficiency drops when expansion ratios are increased. Option C ignores thermodynamic principles linking cut-off ratios to thermal efficiency. Option D incorrectly describes non-monotonic behavior not supported by cycle analysis.
- Subject
- Engineering
- Category
- Mechanical Engineering
- Topic
- —
- Difficulty
- medium
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