Consider a regenerative vapor power cycle with two feedwater heaters, a closed one and an open one. Steam enters the first turbine stage at 8 MPa, 480C, and expands to 2 MPa. Some steam is extracted at 2 MPa and fed to the closed feedwater heater. The remainder expands through the second- stage turbine to 0.3 MPa, where an additional amount is extracted and fed into the open feedwater heater, which operates at 0.3 MPa. The steam expanding through the third-stage turbine exits at the condenser pressure of 8 kPa. Feedwater leaves the closed heater at 205C, 8 MPa, and condensate exiting as saturated liquid at 2 MPa is trapped into the open heater. Saturated liquid at 0.3 MPa leaves the open feedwater heater. The net power output of the cycle is 100 MW. If the turbine stages and pumps are isentropic, determine (a) the thermal efficiency. (b) the mass flow rate of steam entering the first turbine, in kg/h.
Consider a regenerative vapor power cycle with two feedwater heaters, a closed one and an open
one. Steam enters the first turbine stage at 8 MPa, 480C, and expands to 2 MPa. Some steam is
extracted at 2 MPa and fed to the closed feedwater heater. The remainder expands through the second-
stage turbine to 0.3 MPa, where an additional amount is extracted and fed into the open feedwater
heater, which operates at 0.3 MPa. The steam expanding through the third-stage turbine exits at the
condenser pressure of 8 kPa. Feedwater leaves the closed heater at 205C, 8 MPa, and condensate
exiting as saturated liquid at 2 MPa is trapped into the open heater. Saturated liquid at 0.3 MPa leaves
the open feedwater heater. The net power output of the cycle is 100 MW. If the turbine stages and
pumps are isentropic, determine (a) the thermal efficiency. (b) the mass flow rate of steam entering the
first turbine, in kg/h.
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