A combined gas turbine–vapor power plant has a net poweroutput of 200 MW. Air enters the compressor of the gas turbine at300 kPa, 1200 K, and is compressed to 1000 kPa. The pressure ratioof the gas turbine cycle is 11. Steam leaving the turbine of thevapor power cycle are used to heat the steam at 6 MPa to 350C in aheat exchanger. The combustion gases leave the heat exchanger at420 K. An open feedwater heater incorporated with the steam cycleoperates at a pressure of 1 MPa. The condenser pressure is 10 kPa.Assuming isentropic efficiencies of 80 percent for the pump, 82percent for the compressor, and 80 percent for the gas and steamturbines, determine (a) the mass flow rate ratio of air tosteam, (b) the required rate of heat input in thecombustion chamber, and (c) the thermal efficiency of the combinedcycle.
