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# Tutorial questions reheat rankine cycle

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• solution for exercise 2

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### Tutorial questions reheat rankine cycle

1. 1. Reheat & Regenerative Rankine cycle Tutorial problems MET 401 POWER PLANT ENGINEERING DR. TAIB ISKANDAR MOHAMAD
2. 2. Exercise 1Consider a steam power plant operating on the ideal Rankine cycle.Steam enters the turbine at 3 MPa and 350°C and is condensed in thecondenser at a pressure of 10 kPa. Determine(a) The thermal efficiency of this power plant(b) The thermal efficiency if steam is superheated to 600°C instead of 350°C(c) The thermal efficiency if the boiler pressure is raised to 15 MPa while the turbine inlet temperature is maintained at 600°C. 334 373 430
3. 3. Exercise 2Consider a steam power plant operating on the ideal reheat Rankinecycle. Steam enters the high-pressure turbine at 15 MPa and 600°Cand is condensed in the condenser at a pressure of 10 kPa. If themoisture content of the steam at the exit of the low-pressure turbineis not to exceed 10.4 percent, determine(a) the pressure at which the steam should be reheated(b) the thermal efficiency of the cycle.Assume the steam is reheated to the inlet temperature of the high-pressure turbine.
4. 4. Exercise 3
5. 5. Exercise 4A steam power plant operates on the reheatRankine cycle. Steam enters the high-pressure turbine at 12.5 Mpa and 550°C at arate of 7.7 kg/s and leaves at 2 MPa. Steamis then reheated at constant pressure to450°C before it expands in the low-pressureturbine. The isentropic efficiencies of theturbine and the pump are 85 percent and 90percent, respectively. Steam leaves thecondenser as a saturated liquid. If themoisture content of the steam at the exit ofthe turbine is not to exceed 5percent, determine(a) the condenser pressure(b) the net power output(c) the thermal efficiency Answers: (a) 9.73 kPa, (b) 10.2 MW, (c) 36.9 percent
6. 6. Exercise 5Consider a steam power plant operating on theideal regenerative Rankine cycle with one openfeedwater heater. Steam enters the turbine at15 MPa and 600°C and is condensed in thecondenser at a pressure of 10 kPa. Some steamleaves the turbine at a pressure of 1.2 MPa andenters the open feedwater heater. Determinethe fraction of steam extracted from the turbineand the thermal efficiency of the cycle.
7. 7. Exercise 6Consider a steam power plant that operates on an ideal reheat–regenerative Rankinecycle with one open feedwater heater, one closed feedwater heater, and one reheater.Steam enters the turbine at 15 MPa and 600°C and is condensed in the condenser at apressure of 10 kPa. Some steam is extracted from the turbine at 4 MPa for the closedfeedwater heater, and the remaining steam is reheated at the same pressure to 600°C.The extracted steam is completely condensed in the heater and is pumped to 15 MPabefore it mixes with the feedwater at the same pressure. Steam for the openfeedwater heater is extracted from the low-pressure turbine at a pressure of0.5 MPa.Determine, a) the fractions of steam extracted from the turbine b) the thermal efficiency of the cycle
8. 8. Solution for Exercise 6