GATE 2020 ME (ME1) – Question 65

Thermal Engineering Applications · I.C. Engines: Otto, Diesel and dual cycles · 2 marks · Numerical answer

Engine indicated power is calculated using an air-standard Otto cycle with compression ratio 8 and constant properties. Heat-addition rate is 10 kW, specific-heat ratio is 1.4 and mechanical efficiency is 80%. Find brake power output (kW), to one decimal.

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Correct answer: 4.4 to 4.6

Explanation

Air-standard thermal efficiency is $1-r^{1-\gamma}=1-8^{-0.4}=0.564725$. Indicated power is 10×0.564725=5.64725 kW. Brake power is 0.8×5.64725=4.51780 kW, rounded to **4.5 kW**.