GATE 2025 AE – Question 62
Air at temperature 300 K is compressed isentropically from a pressure of 1 bar to 10 bar in a compressor. Eighty percent of the compressed air is supplied to a combustor. In the combustor, 0.88 MJ of heat is added per kg of air. The specific heat at constant pressure is $C_p$ = 1005 J/kg/K and the specific heat ratio is $\gamma$ = 1.4. The temperature of the air leaving the combustor is ___ K (rounded off to one decimal place).
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Correct answer: 1447.53 to 1462.07
Explanation
The compressor outlet temperature is $T_2 = 300 \times 10^{0.4/1.4} = 579.2$ K. The heat is given per kg of the air in the combustor, so the share of air (80%) does not matter. $T_3 = T_2 + \frac{q}{C_p} = 579.2 + \frac{0.88 \times 10^6}{1005} = 579.2 + 875.6 = 1454.8$ K.