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°C at a rate of 40 kg/s and the gas turbine at 9508C. 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 4.6 kg/s by the exhaust gases leaving the gas turbine, and the exhaust gases leave the heat exchanger at 200°C. Steam leaves the high-pressure turbine at 1.0 MPa and is reheated to 400°C in the heat exchanger before it expands in the low-pressure turbine. Assuming 80 percent isentropic efficiency for all pumps and turbines, determine
(a) The moisture content at the exit of the low-pressure turbine,
(b) The steam temperature at the inlet of the high-pressure turbine,
(c) The net power output and the thermal efficiency of the combined plant.

Combustion chamber Gas urbine Compressor Steam turbine Heat exchanger Condenser Pump FIGURE P10-84