Consider a combined cycle power plant using helium and water as the working fluids. Helium enters the compressor of the gas turbine at 1.4 MPa, 350 K and is compressed to 5.5 MPa. The isentropic efficiency of the compressor is 80%. The conditions at the inlet to the turbine are 5.5 MPa and 760oC. Helium expands through the turbine to a pressure of 1.4 MPa. The turbine has an isentropic efficiency of 80%. The mass flow rate of the gas is 100 kg/s. Saturated vapor at 8 MPa exits the heat exchanger which is superheated to 425oC before it enters the turbine of the vapor power cycle, and expands to the condenser at a pressure of 7 kPa. The steam exits the turbine at a quality of 0.9. Water enters the pump as saturated liquid at 7 kPa. Determine
(a) The mass flow rate of steam and
(b) The net power developed.
(c) The thermal efficiency (ηth) of the combined cycle,