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GATE 2016 ME (ME3) – Question 56

Thermal Engineering Applications Β· Power Engineering: vapour and gas power cycles, regeneration and reheat Β· 2 marks Β· Numerical answer

In a 3-stage air compressor, the inlet pressure is 𝑝1, discharge pressure is 𝑝4 and the intermediate pressures are 𝑝2 and 𝑝3 ( 𝑝2 < 𝑝3). The total pressure ratio of the compressor is 10 and the pressure ratios of the stages are equal. If 𝑝1 = 100 kPa, the value of the pressure 𝑝3 (in kPa) is __________

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Correct answer: 460 to 470

Explanation

Three equal stage pressure ratios satisfy rΒ³=10, so r=10^(1/3). The pressure p₃ is after two stages: p₃=p₁rΒ²=100Γ—10^(2/3)=**464.159kPa**. The final pressure is1000kPa; pβ‚‚ would instead be215.443kPa.