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Air-standard Diesel cycle: effect of cut-off ratio on efficiency For a fixed compression ratio, how does the thermal efficiency of the Diesel cycle vary with the cut-off ratio? Choose the correct trend.

Q: Air-standard Diesel cycle: effect of cut-off ratio on efficiency For a fixed compression ratio, how does the thermal efficiency of the Diesel cycle vary with the cut-off ratio? Choose the correct trend.

Concept Diesel cycle efficiency (for fixed compression ratio) decreases as the cut-off ratio rc increases, because more heat is added at higher temperatures with less effectiveness. Thus, η increases as rc decreases. Final Answer decrease in cut-off

Difficulty: Medium

decrease in cut-off
increase in cut-off
constant cut-off
none of these

Correct Answer: decrease in cut-off

Explanation:

Concept
Diesel cycle efficiency (for fixed compression ratio) decreases as the cut-off ratio r_c increases, because more heat is added at higher temperatures with less effectiveness. Thus, η increases as r_c decreases.

Final Answer
decrease in cut-off

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