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Transcript of Basics in the Thermodynamic Analyses of the Gas Turbine Power Plant Prof. R. Shanthini Dept. of C &...
![Page 1: Basics in the Thermodynamic Analyses of the Gas Turbine Power Plant Prof. R. Shanthini Dept. of C & P Engineering University of Peradeniya Sri Lanka.](https://reader034.fdocuments.net/reader034/viewer/2022042717/56649c505503460f948f89e7/html5/thumbnails/1.jpg)
Basics in the Thermodynamic Analyses
of theGas Turbine Power Plant
Prof. R. ShanthiniDept. of C&P EngineeringUniversity of PeradeniyaSri Lanka
![Page 2: Basics in the Thermodynamic Analyses of the Gas Turbine Power Plant Prof. R. Shanthini Dept. of C & P Engineering University of Peradeniya Sri Lanka.](https://reader034.fdocuments.net/reader034/viewer/2022042717/56649c505503460f948f89e7/html5/thumbnails/2.jpg)
Comp-ressor
atmosphericair
Combustionchamber
fuel
Gasturbine
gasesto the stack
Gen
compressed air
hot gases
Gen stands for Electricity Generator
Compressorshaft
Turbineshaft
![Page 3: Basics in the Thermodynamic Analyses of the Gas Turbine Power Plant Prof. R. Shanthini Dept. of C & P Engineering University of Peradeniya Sri Lanka.](https://reader034.fdocuments.net/reader034/viewer/2022042717/56649c505503460f948f89e7/html5/thumbnails/3.jpg)
atmospheric air
(WGT)out
fuel
Gen
compressed air
hot gases
Comp-ressor
Combustionchamber
Gasturbine
gasesto the stack
W stands for work flow rate and GT stands for Gas Turbine
![Page 4: Basics in the Thermodynamic Analyses of the Gas Turbine Power Plant Prof. R. Shanthini Dept. of C & P Engineering University of Peradeniya Sri Lanka.](https://reader034.fdocuments.net/reader034/viewer/2022042717/56649c505503460f948f89e7/html5/thumbnails/4.jpg)
atmospheric air
(WGT)out
Comp-ressor
(QCC)in
Gen
compressed air
hot gasesCombustion
chamber
Gasturbine
gasesto the stack
Q stands for heat flow rate and CC stands for Combustion Chamber
![Page 5: Basics in the Thermodynamic Analyses of the Gas Turbine Power Plant Prof. R. Shanthini Dept. of C & P Engineering University of Peradeniya Sri Lanka.](https://reader034.fdocuments.net/reader034/viewer/2022042717/56649c505503460f948f89e7/html5/thumbnails/5.jpg)
atmospheric air
(WGT)out
Comp-ressor
(WC)in
(QCC)in
1
2 3
4Gen
compressed air
hot gasesCombustion
chamber
Gasturbine
gasesto the stack
W stands for work flow rate and C stands for Compressor
![Page 6: Basics in the Thermodynamic Analyses of the Gas Turbine Power Plant Prof. R. Shanthini Dept. of C & P Engineering University of Peradeniya Sri Lanka.](https://reader034.fdocuments.net/reader034/viewer/2022042717/56649c505503460f948f89e7/html5/thumbnails/6.jpg)
atmospheric air
(WGT)out
Comp-ressor
(QCC)in
1
2
4Gen
hot gases
compressed air 3
Combustionchamber
Gasturbine
gasesto the stack
(WC)in
![Page 7: Basics in the Thermodynamic Analyses of the Gas Turbine Power Plant Prof. R. Shanthini Dept. of C & P Engineering University of Peradeniya Sri Lanka.](https://reader034.fdocuments.net/reader034/viewer/2022042717/56649c505503460f948f89e7/html5/thumbnails/7.jpg)
(WGT)out
3
4
+ (QGT)out
= m ( h – h )3 4g
+ m ( C – C ) / 23 42 2
g
hot gases
gasesto the stack
Gasturbine
m stands for mass flow rate of gas,
h stands for enthalpy,
C stands for speed of gas flow
g stands for gravitational acceleration, &
Z stands for height above reference level
Steady flow energy equationapplied to the flow across turbine:
g
+ m g ( Z – Z ) 3 4g r
r
![Page 8: Basics in the Thermodynamic Analyses of the Gas Turbine Power Plant Prof. R. Shanthini Dept. of C & P Engineering University of Peradeniya Sri Lanka.](https://reader034.fdocuments.net/reader034/viewer/2022042717/56649c505503460f948f89e7/html5/thumbnails/8.jpg)
+ (QGT)out=
+ m ( C – C ) / 23 42 2
g
Assumptions: - Adiabatic condition prevails across the gas turbine- Kinetic energy changes are negligible compared to enthalpy changes
= m ( h – h )3 4g+
- (QGT)out 3
4
hot gases
gasesto the stack
Gasturbine
+ m g ( Z – Z ) 3 4g r
- Potential energy changes are ignored
(WGT)out
![Page 9: Basics in the Thermodynamic Analyses of the Gas Turbine Power Plant Prof. R. Shanthini Dept. of C & P Engineering University of Peradeniya Sri Lanka.](https://reader034.fdocuments.net/reader034/viewer/2022042717/56649c505503460f948f89e7/html5/thumbnails/9.jpg)
(WGT)out
= 3
4
hot gases
gasesto the stack
Gasturbine
Assumptions: - Adiabatic condition prevails across the gas turbine- Kinetic energy changes are negligible compared to enthalpy changes- Potential energy changes are ignored
= m ( h – h )3 4g+
![Page 10: Basics in the Thermodynamic Analyses of the Gas Turbine Power Plant Prof. R. Shanthini Dept. of C & P Engineering University of Peradeniya Sri Lanka.](https://reader034.fdocuments.net/reader034/viewer/2022042717/56649c505503460f948f89e7/html5/thumbnails/10.jpg)
(WGT)out
= m ( h – h )3 4g 3
4
hot gases
gasesto the stack
Gasturbine
Assumptions: - Adiabatic condition prevails across the gas turbine- Kinetic energy changes are negligible compared to enthalpy changes- Potential energy changes are ignored
![Page 11: Basics in the Thermodynamic Analyses of the Gas Turbine Power Plant Prof. R. Shanthini Dept. of C & P Engineering University of Peradeniya Sri Lanka.](https://reader034.fdocuments.net/reader034/viewer/2022042717/56649c505503460f948f89e7/html5/thumbnails/11.jpg)
(WGT)out
= m ( h – h )3 4g
Assumption: - Gases flowing through the turbine behave as ideal gases
(WGT)out
= m C ( T – T )3 4g pg
3
4
hot gases
gasesto the stack
Gasturbine
![Page 12: Basics in the Thermodynamic Analyses of the Gas Turbine Power Plant Prof. R. Shanthini Dept. of C & P Engineering University of Peradeniya Sri Lanka.](https://reader034.fdocuments.net/reader034/viewer/2022042717/56649c505503460f948f89e7/html5/thumbnails/12.jpg)
(WGT)out
3
= m C ( T – T )3 4g pg
T 4
T 3
Specific heat of gas at constant pressure
Mass flow rate of gas
4
Temperature at the outlet
Temperature at the inlet
Gasturbine
m ( h – h )3 4g=
![Page 13: Basics in the Thermodynamic Analyses of the Gas Turbine Power Plant Prof. R. Shanthini Dept. of C & P Engineering University of Peradeniya Sri Lanka.](https://reader034.fdocuments.net/reader034/viewer/2022042717/56649c505503460f948f89e7/html5/thumbnails/13.jpg)
3
T 4
T 3 =
4
fixed
changes
fixed
free to choose, but we fix it at some value
= ?
(WGT)out
= m C ( T – T )3 4g pg
Gasturbine
![Page 14: Basics in the Thermodynamic Analyses of the Gas Turbine Power Plant Prof. R. Shanthini Dept. of C & P Engineering University of Peradeniya Sri Lanka.](https://reader034.fdocuments.net/reader034/viewer/2022042717/56649c505503460f948f89e7/html5/thumbnails/14.jpg)
3
T 4
T 3 =
4
= ?
P 4 =
P 3 =
should be as small as possible
T 4
How small should T4 be ?
(WGT)out
= m C ( T – T )3 4g pg
Gasturbine
To get maximum work output from the turbine,
at the given P 3 P 4and
(P stands for pressure)
![Page 15: Basics in the Thermodynamic Analyses of the Gas Turbine Power Plant Prof. R. Shanthini Dept. of C & P Engineering University of Peradeniya Sri Lanka.](https://reader034.fdocuments.net/reader034/viewer/2022042717/56649c505503460f948f89e7/html5/thumbnails/15.jpg)
3
T 4
T 3
4
P 4
P 3
(WGT)out
= m C ( T – T )3 4g pg
T
Specific Entropy (s)
3
4s
P3
P4
4
real flow
ideal flow
Gasturbine
![Page 16: Basics in the Thermodynamic Analyses of the Gas Turbine Power Plant Prof. R. Shanthini Dept. of C & P Engineering University of Peradeniya Sri Lanka.](https://reader034.fdocuments.net/reader034/viewer/2022042717/56649c505503460f948f89e7/html5/thumbnails/16.jpg)
3
T 4s
P 3
4
T 4s 3
T = P ( 4
P 3 )
(-1)/
(WGT)out,ideal
= m C ( T – T ) 3 4sg pg
T 3
P 4
Gasturbine
(WGT)out
= m C ( T – T )3 4g pg
For the ideal flow (ideal gas at constant specific entropy):
Therefore,
where is the isentropic constant
![Page 17: Basics in the Thermodynamic Analyses of the Gas Turbine Power Plant Prof. R. Shanthini Dept. of C & P Engineering University of Peradeniya Sri Lanka.](https://reader034.fdocuments.net/reader034/viewer/2022042717/56649c505503460f948f89e7/html5/thumbnails/17.jpg)
3
4
T =
(WGT)out
(WGT)out,ideal
m C ( T – T )3 4g pg
m C ( T – T )3 4sg pg
=
Turbine Efficiency
-=
T 3
T 3
T 4
T 4s -
Gasturbine
![Page 18: Basics in the Thermodynamic Analyses of the Gas Turbine Power Plant Prof. R. Shanthini Dept. of C & P Engineering University of Peradeniya Sri Lanka.](https://reader034.fdocuments.net/reader034/viewer/2022042717/56649c505503460f948f89e7/html5/thumbnails/18.jpg)
3
4
TT4 = T3 ( T3 T4s– – )
T 4s 3 T = P ( 4 P 3 )
(-1)/
(WGT)out
(WGT)out,ideal
= T
= T m C ( T – T ) 3 4sg pg
Gasturbine
Governing equations:
![Page 19: Basics in the Thermodynamic Analyses of the Gas Turbine Power Plant Prof. R. Shanthini Dept. of C & P Engineering University of Peradeniya Sri Lanka.](https://reader034.fdocuments.net/reader034/viewer/2022042717/56649c505503460f948f89e7/html5/thumbnails/19.jpg)
Let‘s do some Excel sheet calculations across the turbine
3
4
Gasturbine= 350 kg/s m g
C pg = 1.1 kJ/kg.s T 4
Data:
T 3
= 1200 K
P 4= 1 bar
T = 88%
γ = 1.3
(WGT)out
Determine
for P3 varying in the range of 2 to 15 bar
![Page 20: Basics in the Thermodynamic Analyses of the Gas Turbine Power Plant Prof. R. Shanthini Dept. of C & P Engineering University of Peradeniya Sri Lanka.](https://reader034.fdocuments.net/reader034/viewer/2022042717/56649c505503460f948f89e7/html5/thumbnails/20.jpg)
300
400
500
600
700
800
900
1000
1100
1200
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15Turbine Inlet Pressure P3 (in bar)
Tu
rbin
e O
utl
et T
emp
erat
ure
T4
(in
K)
at the specified efficiency
under ideal conditions
Turbine outlet temperature increaseswith decreasing turbine efficiency
= 88%T
![Page 21: Basics in the Thermodynamic Analyses of the Gas Turbine Power Plant Prof. R. Shanthini Dept. of C & P Engineering University of Peradeniya Sri Lanka.](https://reader034.fdocuments.net/reader034/viewer/2022042717/56649c505503460f948f89e7/html5/thumbnails/21.jpg)
0
50
100
150
200
250
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15Turbine Inlet Pressure P3 (in bar)
Tu
rbin
e W
ork
Ou
tpu
t
(WG
T )o
ut (
in M
W)
under ideal conditions
at the specified efficiency
= 88%T
Turbine work output decreaseswith decreasing turbine efficiency
![Page 22: Basics in the Thermodynamic Analyses of the Gas Turbine Power Plant Prof. R. Shanthini Dept. of C & P Engineering University of Peradeniya Sri Lanka.](https://reader034.fdocuments.net/reader034/viewer/2022042717/56649c505503460f948f89e7/html5/thumbnails/22.jpg)
atmospheric air
gasesto the stack
(WGT)out
fuel
Gen
compressed air
hot gases
Comp-ressor
Combustionchamber
Gasturbine
![Page 23: Basics in the Thermodynamic Analyses of the Gas Turbine Power Plant Prof. R. Shanthini Dept. of C & P Engineering University of Peradeniya Sri Lanka.](https://reader034.fdocuments.net/reader034/viewer/2022042717/56649c505503460f948f89e7/html5/thumbnails/23.jpg)
atmospheric air
gasesto the stack
(WGT)out
Comp-ressor
(WC)in
(QCC)in
1
23
4Gen
compressed air
hot gasesCombustion
chamber
Gasturbine
![Page 24: Basics in the Thermodynamic Analyses of the Gas Turbine Power Plant Prof. R. Shanthini Dept. of C & P Engineering University of Peradeniya Sri Lanka.](https://reader034.fdocuments.net/reader034/viewer/2022042717/56649c505503460f948f89e7/html5/thumbnails/24.jpg)
atmospheric air
gasesto the stack
(WGT)out
Comp-ressor
(WC)in
(QCC)in
1
2
4Gen
3compressed air
hot gasesCombustion
chamber
Gasturbine
![Page 25: Basics in the Thermodynamic Analyses of the Gas Turbine Power Plant Prof. R. Shanthini Dept. of C & P Engineering University of Peradeniya Sri Lanka.](https://reader034.fdocuments.net/reader034/viewer/2022042717/56649c505503460f948f89e7/html5/thumbnails/25.jpg)
atmosphericair
Comp-ressor
(WC)in
1
= (QC)out
+ m ( h – h )2 1a
+ m ( C – C ) / 22 12 2
a
2
compressed air
Subscript a stands for air
+ m g ( Z – Z ) 3 4a r
Steady flow energy equationapplied to the flow across compressor:
![Page 26: Basics in the Thermodynamic Analyses of the Gas Turbine Power Plant Prof. R. Shanthini Dept. of C & P Engineering University of Peradeniya Sri Lanka.](https://reader034.fdocuments.net/reader034/viewer/2022042717/56649c505503460f948f89e7/html5/thumbnails/26.jpg)
atmosphericair
Comp-ressor
(WC)in
1
= (QC)out
+ m ( h – h )2 1a
+ m ( C – C ) / 22 12 2
a
2
compressed air
+ m g ( Z – Z ) 3 4a r
Assumptions: - Adiabatic condition prevails across the compressor- Kinetic energy changes are negligible compared to enthalpy changes- Potential energy changes are ignored
![Page 27: Basics in the Thermodynamic Analyses of the Gas Turbine Power Plant Prof. R. Shanthini Dept. of C & P Engineering University of Peradeniya Sri Lanka.](https://reader034.fdocuments.net/reader034/viewer/2022042717/56649c505503460f948f89e7/html5/thumbnails/27.jpg)
atmosphericair
Comp-ressor
(WC)in
1
= + m ( h – h )2 1a
2
compressed air
Assumptions: - Adiabatic condition prevails across the compressor- Kinetic energy changes are negligible compared to enthalpy changes- Potential energy changes are ignored
![Page 28: Basics in the Thermodynamic Analyses of the Gas Turbine Power Plant Prof. R. Shanthini Dept. of C & P Engineering University of Peradeniya Sri Lanka.](https://reader034.fdocuments.net/reader034/viewer/2022042717/56649c505503460f948f89e7/html5/thumbnails/28.jpg)
atmosphericair
Comp-ressor
(WC)in
1
= m ( h – h )2 1a
= m C ( T – T )2 1a pa
2
compressed air
Assumption: - Air flowing through the compressor behaves as an ideal gas
![Page 29: Basics in the Thermodynamic Analyses of the Gas Turbine Power Plant Prof. R. Shanthini Dept. of C & P Engineering University of Peradeniya Sri Lanka.](https://reader034.fdocuments.net/reader034/viewer/2022042717/56649c505503460f948f89e7/html5/thumbnails/29.jpg)
1
2
T 1
T 2
(WC)in
= m C ( T – T )2 1a pa
T at the inlet
T at the outlet
Specific heat of air at constant pressure
Mass flow rate of air
Comp-ressor
![Page 30: Basics in the Thermodynamic Analyses of the Gas Turbine Power Plant Prof. R. Shanthini Dept. of C & P Engineering University of Peradeniya Sri Lanka.](https://reader034.fdocuments.net/reader034/viewer/2022042717/56649c505503460f948f89e7/html5/thumbnails/30.jpg)
1
2
T 1
T 2
(WC)in
= m C ( T – T )2 1a pa
fixed
changes
fixed
free to choose, but we fix it at some value
=
= ?
Comp-ressor
![Page 31: Basics in the Thermodynamic Analyses of the Gas Turbine Power Plant Prof. R. Shanthini Dept. of C & P Engineering University of Peradeniya Sri Lanka.](https://reader034.fdocuments.net/reader034/viewer/2022042717/56649c505503460f948f89e7/html5/thumbnails/31.jpg)
1
T 1
=
P 1
=
T 2 = ?
(WC)in
= m C ( T – T )2 1a pa
; P 2 = 2
should be as small as possible
T 2
How small should T2 be ?
at the given P 1 P 2and
Comp-ressor
To give minimum work input to the compressor,
![Page 32: Basics in the Thermodynamic Analyses of the Gas Turbine Power Plant Prof. R. Shanthini Dept. of C & P Engineering University of Peradeniya Sri Lanka.](https://reader034.fdocuments.net/reader034/viewer/2022042717/56649c505503460f948f89e7/html5/thumbnails/32.jpg)
T
3
4s
P3=P2
4real flow
idealflow
(WC)in
= m C ( T – T )2 1a pa
1
T 1
P 1
T 2
P 2
2
1
2s2
P4=P1
Comp-ressor
Specific Entropy (s)
![Page 33: Basics in the Thermodynamic Analyses of the Gas Turbine Power Plant Prof. R. Shanthini Dept. of C & P Engineering University of Peradeniya Sri Lanka.](https://reader034.fdocuments.net/reader034/viewer/2022042717/56649c505503460f948f89e7/html5/thumbnails/33.jpg)
1
T 2s 1
T = P ( 2
P 1 )
(-1)/
T 1
=
P 1
=
T 2s = ?
(WC)in,ideal
= m C ( T – T )2s 1a pa
P 2 = 2
(WC)in
= m C ( T – T )2 1a pa
Comp-ressor
For the ideal flow (ideal gas at constant specific entropy):
Therefore,
![Page 34: Basics in the Thermodynamic Analyses of the Gas Turbine Power Plant Prof. R. Shanthini Dept. of C & P Engineering University of Peradeniya Sri Lanka.](https://reader034.fdocuments.net/reader034/viewer/2022042717/56649c505503460f948f89e7/html5/thumbnails/34.jpg)
1
C =
(WC)in,ideal
(WC)in
= T
2s
T 2
T 1
T 1
--
2 m C ( T – T )
2s 1a pa
m C ( T – T )2 1a pa
=
Compressorefficiency
Comp-ressor
![Page 35: Basics in the Thermodynamic Analyses of the Gas Turbine Power Plant Prof. R. Shanthini Dept. of C & P Engineering University of Peradeniya Sri Lanka.](https://reader034.fdocuments.net/reader034/viewer/2022042717/56649c505503460f948f89e7/html5/thumbnails/35.jpg)
T 2s 1 T = P ( 2 P 1 )
(-1)/
1
2
CT2 = T1 ( T2s T1+ – )/
= C m C ( T – T ) 2s 1a pa /
Comp-ressor
in(WC) (WC)
in,ideal= C/
Governing equations:
![Page 36: Basics in the Thermodynamic Analyses of the Gas Turbine Power Plant Prof. R. Shanthini Dept. of C & P Engineering University of Peradeniya Sri Lanka.](https://reader034.fdocuments.net/reader034/viewer/2022042717/56649c505503460f948f89e7/html5/thumbnails/36.jpg)
Let‘s do some Excel sheet calculations across the compressor
= 350 kg/s m a
T 2
Data:
T 1
= 300 K
P 1= 1 bar
C = 85%
γ = 1.4
Determine
for P2 varying in the range of 2 to 15 bar
1
2
Comp-ressor
(WC)in
C pa = 1.005 kJ/kg.s
![Page 37: Basics in the Thermodynamic Analyses of the Gas Turbine Power Plant Prof. R. Shanthini Dept. of C & P Engineering University of Peradeniya Sri Lanka.](https://reader034.fdocuments.net/reader034/viewer/2022042717/56649c505503460f948f89e7/html5/thumbnails/37.jpg)
300
400
500
600
700
800
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15Compressor Outlet Pressure P2 (in bar)
Co
mp
ress
or
Ou
tlet
Tem
per
atu
re T
2 (i
n K
)
at the specified efficiency
under ideal conditions
= 85%C
Compressor outlet temperature increaseswith decreasing compressor efficiency
![Page 38: Basics in the Thermodynamic Analyses of the Gas Turbine Power Plant Prof. R. Shanthini Dept. of C & P Engineering University of Peradeniya Sri Lanka.](https://reader034.fdocuments.net/reader034/viewer/2022042717/56649c505503460f948f89e7/html5/thumbnails/38.jpg)
0
20
40
60
80
100
120
140
160
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15Compressor Outlet Pressure P2 (in bar)
Co
mp
ress
or
Wo
rk I
np
ut
(WC)in
(in
MW
)
at the specified efficiency
under ideal conditions
= 85%C
Work input to the compressor increaseswith decreasing compressor efficiency
![Page 39: Basics in the Thermodynamic Analyses of the Gas Turbine Power Plant Prof. R. Shanthini Dept. of C & P Engineering University of Peradeniya Sri Lanka.](https://reader034.fdocuments.net/reader034/viewer/2022042717/56649c505503460f948f89e7/html5/thumbnails/39.jpg)
atmospheric air
gasesto the stack
(WGT)out
fuel
Gen
compressed air
Comp-ressor
hot gases
(WC)in
Wnet
Combustionchamber
Gasturbine
![Page 40: Basics in the Thermodynamic Analyses of the Gas Turbine Power Plant Prof. R. Shanthini Dept. of C & P Engineering University of Peradeniya Sri Lanka.](https://reader034.fdocuments.net/reader034/viewer/2022042717/56649c505503460f948f89e7/html5/thumbnails/40.jpg)
= (WC)in
(WGT)out
Wnet -
(WC)in,ideal
= (WGT)out,ideal-
Wnet,ideal
Net work output from the turbine is the power available for electricity generation
Net work output under ideal conditions is the maximum power available for electricity generation
![Page 41: Basics in the Thermodynamic Analyses of the Gas Turbine Power Plant Prof. R. Shanthini Dept. of C & P Engineering University of Peradeniya Sri Lanka.](https://reader034.fdocuments.net/reader034/viewer/2022042717/56649c505503460f948f89e7/html5/thumbnails/41.jpg)
0
50
100
150
200
250
300
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15Compressor outlet Pressure P2 (in bar) =
Turbine Inlet Pressure P3 (in bar)
Turbine work output (in MW)
Compressor work input (in MW)
Net work output from the Gas Turbine System (in MW)
= 85%C
T= 88%and
![Page 42: Basics in the Thermodynamic Analyses of the Gas Turbine Power Plant Prof. R. Shanthini Dept. of C & P Engineering University of Peradeniya Sri Lanka.](https://reader034.fdocuments.net/reader034/viewer/2022042717/56649c505503460f948f89e7/html5/thumbnails/42.jpg)
0
10
20
30
40
50
60
70
80
90
100
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15Compressor outlet Pressure P2 (in bar) =
Turbine Inlet Pressure P3 (in bar)
Net
Wo
rk O
utp
ut
fro
m t
he
Gas
Tu
rbin
e S
yste
m (
in M
W)
under ideal conditions
at the specified efficiencies
= 85%C
T= 88%and
![Page 43: Basics in the Thermodynamic Analyses of the Gas Turbine Power Plant Prof. R. Shanthini Dept. of C & P Engineering University of Peradeniya Sri Lanka.](https://reader034.fdocuments.net/reader034/viewer/2022042717/56649c505503460f948f89e7/html5/thumbnails/43.jpg)
atmospheric air
gasesto the stack
(QCC)in
1
23
4Gen
compressed air
hot gases
WnetComp-ressor
Combustionchamber
Gasturbine
![Page 44: Basics in the Thermodynamic Analyses of the Gas Turbine Power Plant Prof. R. Shanthini Dept. of C & P Engineering University of Peradeniya Sri Lanka.](https://reader034.fdocuments.net/reader034/viewer/2022042717/56649c505503460f948f89e7/html5/thumbnails/44.jpg)
atmospheric air
gasesto the stack
(QCC)in
1
23
4Gen
compressed air
hot gases
WnetComp-ressor
Combustionchamber
Gasturbine
![Page 45: Basics in the Thermodynamic Analyses of the Gas Turbine Power Plant Prof. R. Shanthini Dept. of C & P Engineering University of Peradeniya Sri Lanka.](https://reader034.fdocuments.net/reader034/viewer/2022042717/56649c505503460f948f89e7/html5/thumbnails/45.jpg)
(QCC)in,ideal
= m ( h – h ) 3 2a
Assumptions: - Kinetic energy changes are negligible
- Potential energy changes are ignored
- Fuel flow rate is negligible compared to the air flow rate
2 3compressed air
hot gasesCombustionchamber
fuel
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2 3compressed air
hot gasesCombustionchamber
fuel
= m C ( T – T )3 2a pa
Assumption: - Air flowing through the compressor behaves as an ideal gas
(QCC)in,ideal
= m ( h – h ) 3 2a
![Page 47: Basics in the Thermodynamic Analyses of the Gas Turbine Power Plant Prof. R. Shanthini Dept. of C & P Engineering University of Peradeniya Sri Lanka.](https://reader034.fdocuments.net/reader034/viewer/2022042717/56649c505503460f948f89e7/html5/thumbnails/47.jpg)
(QCC)in
2 3compressed air
hot gasesCombustionchamber
fuel
= m C ( T – T )3 2a pa
is the compressor efficiency
(QCC)in,ideal
= CC/
CC
CC/
![Page 48: Basics in the Thermodynamic Analyses of the Gas Turbine Power Plant Prof. R. Shanthini Dept. of C & P Engineering University of Peradeniya Sri Lanka.](https://reader034.fdocuments.net/reader034/viewer/2022042717/56649c505503460f948f89e7/html5/thumbnails/48.jpg)
Let‘s do some Excel sheet calculations across the combustion chamber
2 3compressed air
hot gasesCombustionchamber
fuel
= 350 kg/s m a
CC = 80%
C pa = 1.005 kJ/kg.s
P 2
P 3
=
Determine
(QCC)in
![Page 49: Basics in the Thermodynamic Analyses of the Gas Turbine Power Plant Prof. R. Shanthini Dept. of C & P Engineering University of Peradeniya Sri Lanka.](https://reader034.fdocuments.net/reader034/viewer/2022042717/56649c505503460f948f89e7/html5/thumbnails/49.jpg)
= 80%CC
0
50
100
150
200
250
300
350
400
450
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15
Compressor outlet Pressure P2 (in bar) = Turbine Inlet
Pressure P3 (in bar)
Heat input at the specified efficiency (in MW)
Heat input inder ideal conditions (in MW)
= 80%CC
![Page 50: Basics in the Thermodynamic Analyses of the Gas Turbine Power Plant Prof. R. Shanthini Dept. of C & P Engineering University of Peradeniya Sri Lanka.](https://reader034.fdocuments.net/reader034/viewer/2022042717/56649c505503460f948f89e7/html5/thumbnails/50.jpg)
atmospheric air
(QCC)in
1
2
compressed air
Comp-ressor
Combustionchamber
gasesto the stack
3
4Gen
hot gases
WnetGas
turbine
= th
Wnet
(QCC) in
Thermal efficiency
![Page 51: Basics in the Thermodynamic Analyses of the Gas Turbine Power Plant Prof. R. Shanthini Dept. of C & P Engineering University of Peradeniya Sri Lanka.](https://reader034.fdocuments.net/reader034/viewer/2022042717/56649c505503460f948f89e7/html5/thumbnails/51.jpg)
= 80%CC
0
50
100150
200
250
300
350400
450
500
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15
Compressor outlet Pressure P2 (in bar) = Turbine Inlet
Pressure P3 (in bar)
Heat input at the specifiedefficiency (in MW)
Net work output from the GasTurbine System (in MW)
![Page 52: Basics in the Thermodynamic Analyses of the Gas Turbine Power Plant Prof. R. Shanthini Dept. of C & P Engineering University of Peradeniya Sri Lanka.](https://reader034.fdocuments.net/reader034/viewer/2022042717/56649c505503460f948f89e7/html5/thumbnails/52.jpg)
0%
10%
20%
30%
40%
50%
60%
70%
80%
90%
100%
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15
Compressor outlet Pressure P2 (in bar) = Turbine Inlet
Pressure P3 (in bar)
Overall Thermal Efficiency underideal conditions
Overall Thermal Efficiency at thespecified unit efficiencies
C
CC = 80%
= 85%
T= 88%
![Page 53: Basics in the Thermodynamic Analyses of the Gas Turbine Power Plant Prof. R. Shanthini Dept. of C & P Engineering University of Peradeniya Sri Lanka.](https://reader034.fdocuments.net/reader034/viewer/2022042717/56649c505503460f948f89e7/html5/thumbnails/53.jpg)
atmospheric air
gasesto the stack
(QCC)in
1
23
4Gen
compressed air
hot gases
Wnet
Heat Loss?
Comp-ressor
Combustionchamber
Gasturbine
= -(QCC)in Wnet
![Page 54: Basics in the Thermodynamic Analyses of the Gas Turbine Power Plant Prof. R. Shanthini Dept. of C & P Engineering University of Peradeniya Sri Lanka.](https://reader034.fdocuments.net/reader034/viewer/2022042717/56649c505503460f948f89e7/html5/thumbnails/54.jpg)
0
50
100
150
200
250
300
350
400
450
500
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15
Compressor outlet Pressure P2 (in bar) = Turbine Inlet Pressure P3 (in bar)
Heat input at the specified efficiency (in MW)
Heat loss at the specified unit efficiencies (in MW)
Net work output from the Gas Turbine System (in MW)
![Page 55: Basics in the Thermodynamic Analyses of the Gas Turbine Power Plant Prof. R. Shanthini Dept. of C & P Engineering University of Peradeniya Sri Lanka.](https://reader034.fdocuments.net/reader034/viewer/2022042717/56649c505503460f948f89e7/html5/thumbnails/55.jpg)
atmospheric air
gasesto the atmospherethrough the stack
(QCC)in
1
23
4Gen
compressed air
hot gases
Wnet
Heat Loss
Comp-ressor
Combustionchamber
Gasturbine
![Page 56: Basics in the Thermodynamic Analyses of the Gas Turbine Power Plant Prof. R. Shanthini Dept. of C & P Engineering University of Peradeniya Sri Lanka.](https://reader034.fdocuments.net/reader034/viewer/2022042717/56649c505503460f948f89e7/html5/thumbnails/56.jpg)
Heat is lost with the turbine exhaust gases to the atmosphere through the stack
Should not we make good use of all that heat
that is not only getting wasted
but also pollute the environment in many ways?