Question A2.11: Calculate the thermal efficiency of an engine working on the...

Given : D = 17 cm, L = 30 cm, V_C = 0.002025 m³ or 2025 cm³

Stroke volume, V_{\mathrm{s}}=V_1-V_2=\frac{\pi}{4} D^2 L=\frac{\pi}{4}(17)^2 \times 30=6809.4 \mathrm{~cm}^3

V_1=6809+2025=8834.4 \mathrm{~cm}^3

Compression ratio, r=\frac{V_1}{V_2}=\frac{8834.4}{2025}=4.36

Thermal efficiency of otto cycle,

\begin{aligned}\eta_{\mathrm{th}} &=1-\frac{1}{r^{r-1}} \\&=1-\frac{1}{(4.36)^{0.4}}=0.4452 \text { or } 44.52 \%\end{aligned}