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GATE 2019 ME (ME1) – Question 59

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

The regenerative steam cycle shown uses one open feedwater heater. Turbine expansion is isentropic; bleed enters the heater from state 2. Process 3–4 is condensation; neglect pump work; boiler inlet is state 5. Enthalpies at states 1–6 are respectively 3350, 2800, 2300, 175, 700 and 1000 kJ/kg. Find turbine bleed mass flow as a percentage of state-1 turbine inlet flow.

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Correct answer: 19 to 21

Explanation

Let bleed fraction be $y$. Open-heater mixing balance gives $2800y+175(1-y)=700$. Therefore $y=(700-175)/(2800-175)=0.20$, or **20%**.