reheat Rankine cycle. Steam enters the high-pressure turbine at 12.5 MPa and 550°C at a rate of 7.7 kg/s and leaves at 2 MPa. Steam is then reheated at constant pressure to 450°C before it expands in the low-pressure turbine. The isentropic efficiencies of the turbine and the pump are 85 percent and 90 percent, respec[1]tively. Steam leaves the condenser as a saturated liquid. If the moisture content of the steam at the exit of the turbine is not to exceed 5 percent, determine (a) the condenser pressure, (b) the net power output, and (c) the thermal efficiency.
Answers
Answer:
The temperature entropy diagram of the thermodynamic cycle T-s Diagram is as follows.
T
2s
6s 6
S
State-3:
From the Superheated water vapor
At F T. =550°C:
k =3476.5 kJ
g
Id
s3 = 6_6317
kg -K
State-4:
Since 3-4s is an isentropic process
From the superheated water tables at pressure and entropy of
P4= 2000 kPa and s, =5, —6_6317
kg K
h, = 2945_557—
kg
The equation for the Efficiency tfr of the turbine is as follows_
rir =
lz —h4
4 —h4s h4 = h3 —7h 3 —h45)
Substitute the corresponding values in the above equation_
kJ
h,=3476.5 --0.85 (3476.5 —2945.557) kJ
kg kg
kJ
=3025.198
kg
State-5:
From the superheated water tables at pressure and temperature. of P, =2000 kPa and T, =450°C
kJ
=3358.35
kg ss =7 282
State-6:
kJ
kg -K Consider Dryness fraction x, =...A steam power plant operates on the reheat Rankine cycle. Steam enters the high-pressure turbine at 12.5 MPa and 550°C at a rate of 7.7 kg/s and leaves at 2 MPa. Steam is then reheated at constant pressure to 450°C before it expands in the low-pressure turbine. The isentropic efficiencies of the turbine and the pump are 85 percent and 90 percent, respectively. Steam leaves the condenser as a saturated liquid. If the moisture content of the steam at the exit of the turbine is not to exceed 5 percent, determine (a) the condenser pressure, (b) the net power output, and (c) the thermal efficiency.