Question Bank • QB_EXP_FP_CYC_017 MCQ • 1 Mark

Section 3: Farm Power

Sources of Power

Subtopic: Thermodynamic cycles of IC engines

Question Statement:

In the Diesel cycle P-v diagram, if the cut-off ratio $r_c$ is increased while maintaining a constant compression ratio $r$, the thermal efficiency of the cycle will:

Options:

  • (A) Monotonically decrease
  • (B) Monotonically increase
  • (C) Remain strictly constant
  • (D) First increase then decrease

Answer Key:

A

Step-by-Step Solution & Explanation

Since the bracket term $\frac{r_c^\gamma - 1}{\gamma(r_c - 1)} > 1$ increases monotonically with $r_c$, increasing the cut-off ratio decreases the thermal efficiency of the Diesel cycle.
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