Question

Consider a combined gas-steam power cycle. The topping cycle is a simple Brayton cycle that has a pressure ratio of 7. Air enters the compressor at 15 ºC at a rate of 10 kg/s and the gas turbine at 950 ºC. The bottoming cycle is a reheat Rankine cycle between the pressure limits of 6 MPa and 10 kPa. Steam is heated in a heat exchanger at a rate of 1.15 kg/s by the exhaust gases leaving the gas turbine, and the exhaust gases leave the same exchanger at 200 ºC. Steam leaves the high-pressure turbine at 1 MPa and is reheated to 400 ºC in the heat exchanger before it expands in the low-pressure turbine. Assuming 80 percent isentropic efficiency for all pumps and turbines,

1) determine the enthalpy of air at the compressor outlet .

2)determine the enthalpy of air at the Turbine outlet

3)determine the enthalpy of steam-water mixture at the low pressure turbine outlet

4)determine the moisture content at the exist of the low-pressure turbine.

5) determine the steam temperature at the inlet of the high-pressure. (hint: trial and error)

6)determine the net power output of the combined plant

7) determine the thermal efficiency of the combined plant.

Answer 1

Note -I have solved first four Parts of this question

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