Consider a regenerative vapor power cycle with two feed water heaters, a closed one and an open one, as shown in the figure. Steam enters the first turbine stage at 12 MPa, 480°C, and expands to 2 MPa. Some steam is extracted at 2 MPa and fed to the closed feed water heater. The remainder expands through the second-stage turbine to 0.3 MPa, where an additional amount is extracted and fed into the open feed water operating at 0.3 MPa. The steam expanding through the third-stage turbine exits at the condenser pressure of 6 kPa.
The condensate drains from the closed feed water as saturated liquid at the higher extraction pressure. The feed water leaves the heater at 12 MPa and a temperature equal to the saturation temperature at the extraction pressure. Saturated liquid at 0.3 MPa leaves the open feed water heater. Assume the pump and each turbine stage has an isentropic efficiency of 80%. Determine for the cycle
1. The rate of heat transfer to the working fluid passing through the steam generator, in kJ per kg of steam entering the first-stage turbine, (2) The thermal efficiency, and (3) The rate of heat transfer from the working fluid passing through the condenser to the cooling water, in kJ per kg of steam entering the first-stage turbine.