Analysis of Rankine Cycle: Techno- economically Feasible Thermodynamic Model n appropriate selection of operational parameters & Processes P M V Subbarao Professor Mechanical Engineering Department
Jan 31, 2016
Analysis of Rankine Cycle: Techno-economically Feasible Thermodynamic Model
n appropriate selection of operational parameters & Processes
P M V Subbarao
Professor
Mechanical Engineering Department
Optimal Design of Vapour Power Plant
Effect of Maximum Temperature
0.370.380.390.40.410.420.430.440.45
300 400 500 600 700 800
Maximum Temperature C
Effic
ienc
y
pmax=10MPa
Effect of Maximum Temperature
100
110
120
130140
150
160
170
300 400 500 600 700 800
Tmax, C
MEP
, kPa
pmax=10MPa
050010001500200025003000350040004500
7 7.5 8 8.5 9 9.5 10 10.5
Enth
alpy
Max. Entropy
Max. Entroy Vs Enthalpy
hturb,in
hturb,out
smin smax
If Carnot Studies The Rankine Cycle !
Carnotization of Rankine Cycle
• Equivalent Carnot cycle of Rankine Cycle
23
3
2
3
2
3
2
hhdhdss
hTdsq
pin
23
233
2
3
2, ss
hh
ds
Tds
T inm
• Heat Addition in Steam Generator, qin
• Mean Effective Temperature of heat addition for equivalent isothermal process or entropy averaged temperature
Equivalent Carnot Model of Rankine Model
• Heat rejection in Steam Condenser, qin
41
1
4
1
4
1
4
hhdhdss
hTdsq
pout
cond
condoutm T
ss
ssT
ss
hh
ds
Tds
T
41
41
41
411
4
1
4,
• Mean Effective Temperature of heat rejection for equivalent isothermal process.
Equivalent Carnot Model of Rankine Model
smin smax
Tm,out
Tm,in
Analysis of Equivalent Carnot Model
• Net work out put =
• Heat Input =
TdSWnet
max
min
S
S
in TdSQ
outminmnet TTSSw ,,minmax
inmin TSSQ ,minmax
Efficiency, inm
outm
inm
outminm
in
netRankine T
T
T
TT
Q
W
,
,
,
,, 1
Parametric Study of Rankine Cycle
Tmax
D.S.S.
1MPa
3MPa
6MPa10MPa18MPa
22MPa
23.5MPa
Ideal Rankine Cycle : P-h Diagram
1
23
4
1
23
4
Tmax=5500C
pmax=5Mpaequi=246.30C
pmax=17Mpaequi=284.40C
0.35
0.36
0.37
0.38
0.39
0.40
0.41
0 5 10 15 20 25
Selection of Optimum Boiler Pressure
Pressure, MPa
h
Tmax = 450 oC
Selection of Optimum Boiler Pressure
0.6
0.65
0.7
0.75
0.8
0.85
0.9
0 5 10 15 20 25
Pressure, MPa
x
Tmax = 450 oC
0.2820.2840.2860.2880.2900.2920.2940.2960.2980.3000.3020.304
0 2 4 6 8 10 12 14 16 18 20 22 24
Selection of Optimum Boiler Pressure
Pressure, MPa
xh
Tmax = 450 oC
Progress in Rankine Cycle
Year 1907 1919 1938 1950 1958 1959 1966 1973 1975
MW 5 20 30 60 120 200 500 660 1300
p,MPa 1.3 1.4 4.1 6.2 10.3 16.2 15.9 15.9 24.1
Th oC 260 316 454 482 538 566 566 565 538
Tr oC -- -- -- -- 538 538 566 565 538
FHW -- 2 3 4 6 6 7 8 8
Pc,kPa 13.5 5.1 4.5 3.4 3.7 3.7 4.4 5.4 5.1
,% -- ~17 27.6 30.5 35.6 37.5 39.8 39.5 40
Pressure Vs Entroy
5
5.5
6
6.5
7
7.5
8
0 5 10 15 20 25
Pressure, MPa
Entro
py, k
J/kg
K
Pressure Vs Q & W
500
1000
1500
2000
2500
3000
3500
0 5 10 15 20 25
Pressure, MPa
wnet
qin
0
500
1000
1500
2000
2500
3000
3500
5 5.5 6 6.5 7 7.5 8
Q o
r W
Max. Entropy
Max. Entropy Vs Q & W
qin
wnet
051015202530354045
5 5.5 6 6.5 7 7.5 8
Max. Entropy
Max. Entropy Vs Efficiency
Pressure Vs Enthalpy
0
500
1000
1500
2000
2500
3000
3500
0 5 10 15 20 25
Pressure (MPa)
htur.,in
htur.,out
15001700190021002300250027002900310033003500
5 5.5 6 6.5 7 7.5 8
h, KJ/k
g
Max. Entropy, kJ/kg K
Max. Entropy Vs Enthalpy
htur.,in
htur.,out
Optimaization of Boiler Pressure
1500
2000
2500
3000
3500
5 5.5 6 6.5 7 7.5 8
Entropy, kJ/kg K
h3 &
h4
0.2820.2840.2860.2880.2900.2920.2940.2960.2980.3000.3020.304
0 2 4 6 8 10 12 14 16 18 20 22 24
Selection of Optimum Boiler Pressure
Pressure, MPa
xh
Tmax = 450 oC
Parametric Study of Rankine Cycle
Tmax, 0C
wkJ/kg
D.S.S. 1MPa3MPa
6MPa
10MPa
18MPa
22MPa
23.5MPa