GATE 2018 ME (ME1) – Question 56
An air-standard Otto engine receives air at 0.1 MPa and 35°C. Compression ratio is 8; heat input is 500 kJ/kg. Air cp = 1.005, cv = 0.718 and R = 0.287 kJ/kg K. Maximum cycle temperature, to one decimal, is ______ K.
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Correct answer: 1402.0 to 1406.0
Explanation
Isentropic compression gives $T_2=T_1r^{\gamma-1}$, where $\gamma=1.005/0.718$. Constant-volume heating then gives $T_3=T_2+500/0.718$. Using the conventional rounded T₁ = 308 K gives 1403.6 K. Using 308.15 K gives a nearby value within the official interval.