Question Bank • QB_EXP_FP_CYC_035 MSQ • 2 Marks

Section 3: Farm Power

Sources of Power

Subtopic: Thermodynamic cycles of IC engines

Question Statement:

Which of the following factors will INCREASE the indicated thermal efficiency of the air-standard Diesel cycle shown in the diagram?

Options:

  • (A) Increasing the compression ratio r
  • (B) Decreasing the cut-off ratio rc towards 1
  • (C) Using a working fluid with higher specific heat ratio gamma
  • (D) Increasing the fuel injection duration at constant rpm

Answer Key:

A, B, C

Step-by-Step Solution & Explanation

$\eta = 1 - \frac{1}{r^{\gamma - 1}} \left[\frac{r_c^\gamma - 1}{\gamma(r_c - 1)}\right]$. Efficiency increases with higher $r$, lower $r_c$, and higher $\gamma$. Increasing injection duration increases $r_c$, which decreases efficiency.
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