Center for Advanced Energy Systems
Michael R. Muller, Director
640 Bartholomew Road, Piscataway
NJ 08854
(908) 644-8469
•
FAX: (732) 445-0730
[email protected]
http://caes.rutgers.edu
Problem Set: Rankine Cycles
Problem 1
:
Calculate the thermal efficiency of a simple Rankine cycle for which steam leaves
the boiler as saturated vapor at 3 x 10
6
N/m
2
and is condensed to saturated liquid at 7000 N/m
2
.
The pump and turbine have isentropic efficiencies of 0.6 and 0.8, respectively.
The pump inlet is
saturated liquid.
Solution
:
( )
(
)
73
.
0
7167
.
7
559
.
0
1878
.
6
1878
.
6
s
J/g
2636
168
04
28
h
h
Q
Pa
M
[email protected]
2804
J/g
168
3
6
.
0
007
.
1
163
;
J/g
163
3
,
4
3
2
3
in
3
2
1
2
1
=
−
=
+
=
=
−
=
=
−
=
−
=
=
=
+
=
Δ
+
=
=
χ
fg
f
s
s
x
s
h
h
W
h
h
P
v
h
h
h
so
(
)(
)
(
)(
)
(
)
(
)
(
)
(
)
%
5
.
26
2636
/
5
704
704
8
.
0
880
1924
2804
8
.
0
J/g
1924
2572
73
.
0
163
27
.
0
4
3
4
=
−
=
=
=
−
=
−
=
=
+
=
η
η
h
h
W
h
Problem 2
:
A Rankine-cycle power plant has one stage of reheat.
The turbine inlet is 3 x 10
6
N/m
2
at 500
°
C.
After expansion to 0.5 x 10
6
N/m
2
the steam is reheated to 500
°
C and expanded
in a second turbine to a condenser pressure of 0.007 x 10
6
N/m
2
.
The steam leaves the condenser
as saturated liquid.
Calculate the cycle efficiency, using a pump efficiency of 0.6 and turbine
efficiencies of 0.8.
Solution
:
1)

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