1. Consider a reheat-regenerative vapor power cycle with two feedwater heaters.
ID: 1852274 • Letter: 1
Question
1. Consider a reheat-regenerative vapor power cycle with two feedwater heaters. Steam enters the first turbine at 8.0 Mpa, 480 ?C and expands to 0.7 Mpa. The steam is reheated to 450 ?C before entering the second turbine, where it expands to the condenser pressure 0.008 Mpa. Steam is extracted from the first turbine at 2 Mpa and fed to closed feed water heater. Feed water leaves the closed heater at 205 ??C and 8.0 Mpa, and condensate exits as saturated liquid at 2 Mpa. The condensate is trapped into the open feedwater heater. The steam extracted from the second turbine at 0.3 Mpa is also fed into the open feedwater heater, which operates at 0.3 Mpa. The steam exiting the open feedwater heater is saturated liquid at 0.3 Mpa. The net power output is 100 MW. If the isentropic efficiency of the turbines are 90%, please plot the T-S diagram and determine (a) thermal efficiency (b) mass flow rate of the steam entering the first turbine.Explanation / Answer
We start the solution with finding the enthalpies at the principal states of the cycle. State 1
is superheated steam ? h1 = 3384.4 kJ/kg and s1 = 6.6586 kJ/kg.K.
State 2 is fixed by P2 = 2.0 MPa and specific entropy s2 = s1. With interpolating, h2 =
2953.5 kJ/kg.
The state at the exit of the first turbine is fixed by P3 = 0.7 MPa and s3 = s1 ? h3 = 2741.8
kJ/kg.
State 4 is superheated vapor at 0.7 MPa, 440
Related Questions
Navigate
Integrity-first tutoring: explanations and feedback only — we do not complete graded work. Learn more.