GATE 2020 ME (ME1) – Question 34
An ideal intercooled Brayton-cycle gas-turbine compressor achieves overall pressure ratio 6 in two stages. Intercooling cools first-stage outlet air to the first-stage inlet temperature before entry to the second stage. Inlet air is at 300 K and 100 kPa. With constant gas properties, find the intercompressor pressure for minimum compressor work (kPa), to two decimals.
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Correct answer: MTA
Explanation
Perfect intercooling to the original temperature and identical stage properties make minimum total work occur at equal stage pressure ratios. Thus $p_i=\sqrt{p_1p_3}=\sqrt{100(600)}=\mathbf{244.95}$ kPa. The appended official key labels this question MTA (marks to all), which must be retained for scored use.