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Introduction to Thermodynamics for Gas Turbine Cycles & Cycle Simulation Tools
A Cycle Innova-ons Tutorial Session by
Pavlos K. Zachos -‐ Luis Sanchez de LeonDepartment of Power & Propulsion
Cranfield University, UK
ASME Turbo Expo 2013San Antonio, US
1
CRANFIELD UNIVERSITYDEPARTMENT OF POWER & PROPULSION
These slides have been prepared by Cranfield University for the personal use of tutorial attendees. Accordingly, they may not be communicated to a third party without the express permission of the author(s). The slides are intended to support the tutorial in which they are to be presented. However the content may be more comprehensive than the presentations they are supporting.
Some of the data contained in the notes/slides may have been obtained from public literature. However, in such cases, the corresponding manufacturers or originators are in no way responsible for the accuracy of such material.
All the information provided has been judged in good faith as appropriate for the course. However, Cranfield University accepts no liability resulting from the use of such information.
Disclaimer
2
Who we are...
Pavlos K. ZachosLecturer in Aerothermal Performance of TurbomachineryDepartment of Power & PropulsionCranfield University, [email protected]
Luis Sanchez de LeonDoctoral Researcher in Advanced Cycle Performance
Department of Power & PropulsionCranfield University, UK
Thermodynamics for Gas Turbine Cycles & Cycle Simulation ToolsASME Turbo Expo San Antonio, Texas, 6th June 2013
3
PART I - Thermodynamics in our every day life.
Thermodynamics for Gas Turbine Cycles & Cycle Simulation ToolsASME Turbo Expo San Antonio, Texas, 6th June 2013
4
PART II - A little bit of modelling.
Thermodynamics for Gas Turbine Cycles & Cycle Simulation ToolsASME Turbo Expo San Antonio, Texas, 6th June 2013
5
PART III - A whole lot of modelling.
Thermodynamics for Gas Turbine Cycles & Cycle Simulation ToolsASME Turbo Expo San Antonio, Texas, 6th June 2013
6
Why do you care ?
Thermodynamics for Gas Turbine Cycles & Cycle Simulation ToolsASME Turbo Expo San Antonio, Texas, 6th June 2013
7
The science.
The people.
The product.
Thermodynamics for Gas Turbine Cycles & Cycle Simulation ToolsASME Turbo Expo San Antonio, Texas, 6th June 2013
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Thermo dynamics
θέρμη (therme)
heat
δυναμική
power
=theory of relationship between heat and mechanical energy
Aeolipile (or Hero engine)Hero of Alexandria
1st century AD[source: Encyclopedia Britannica]
9
source: WikipediaThermodynamics for Gas Turbine Cycles & Cycle Simulation Tools
ASME Turbo Expo San Antonio, Texas, 6th June 2013
10
1650
Otto von Guericke invents the vacuum pump
1656
Boyle & Hookenotice a correlation betweenpressure, temperature and volume
18501750
1824
Carnotcorrelates heat , power, energy & engine efficiency
Rankine - Clausius - Lord Kelvin1st & 2nd Laws of Thermodynamics
1750
Saverybuilds the first steam piston engineto be later improved by Watt
Father of Thermodynamics
equation of state
Thermodynamics for Gas Turbine Cycles & Cycle Simulation ToolsASME Turbo Expo San Antonio, Texas, 6th June 2013
11
Entropy, s
Tem
pera
ture
, T
1 2
34Entropy, s
Tem
pera
ture
, T
1
2
3
4
Entropy, s
Tem
pera
ture
, T
1
23
4
v = co
nst.
v = const.
P = const.
v = co
nst.
Entropy, s
Tem
pera
ture
, T
1
2
3
4P =
const
.
P = const.
Carnot cycle Ideal Otto cycle
Ideal Diesel cycle Ideal Brayton cycleThermodynamics for Gas Turbine Cycles & Cycle Simulation ToolsASME Turbo Expo San Antonio, Texas, 6th June 2013
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13
Why do you care ?
EAT.
BREATH.
TRAVEL.
Thermodynamics for Gas Turbine Cycles & Cycle Simulation ToolsASME Turbo Expo San Antonio, Texas, 6th June 2013
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Case study:London to New York5,526 km
100 days in 1866 by sailing ship
15 days in 1910 by early steam ships
3 days in 1960 by the fastest steam ship
< 8 hrs today by plane !!
Thermodynamics for Gas Turbine Cycles & Cycle Simulation ToolsASME Turbo Expo San Antonio, Texas, 6th June 2013
15
= £475 per kg[source: http://www.bullionbypost.co.uk on 21.5.2013]
=
Courtesy of Rolls-Royce
per kg
Thermodynamics for Gas Turbine Cycles & Cycle Simulation ToolsASME Turbo Expo San Antonio, Texas, 6th June 2013
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aerodynamics materials
fuels
emissions
fuels
mechanical integrity
market research&
logistics
system integration
cycle thermodynamics
controls
17
Entropy, s
Tem
pera
ture
, T
1
2
3
4P =
const
.
P = const.
George Brayton1830 - 1892
Sir Frank Whittle1907 - 1996
Dr Hans von Ohain1911 - 1998
Courtesy of Rolls-Royce
Thermodynamics for Gas Turbine Cycles & Cycle Simulation ToolsASME Turbo Expo San Antonio, Texas, 6th June 2013
18
Here’s to the crazy ones.The misfits.The rebels.The troublemakers.The ones who see things differently.They are not fond of rules.And they have no respect for the status quo.You can praise them, disagree with them, quote, disbelieve them, glorify or vilify them.
About the only thing you can’t do...
Apple advertising campaignSeptember 1997
19
...is ignore them...
20
...because they change things
21
...and also the way WE see things...22
Let’s talk about today...
Thermodynamics for Gas Turbine Cycles & Cycle Simulation ToolsASME Turbo Expo San Antonio, Texas, 6th June 2013
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6 Trillion kg CO2
source: ClimateCrisis.netThermodynamics for Gas Turbine Cycles & Cycle Simulation ToolsASME Turbo Expo San Antonio, Texas, 6th June 2013
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20,000 kg CO2 per year and person
4,500 kg CO2 per year and person
source: ClimateCrisis.netThermodynamics for Gas Turbine Cycles & Cycle Simulation ToolsASME Turbo Expo San Antonio, Texas, 6th June 2013
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26
27
28
450 ppm
source: ClimateCrisis.netThermodynamics for Gas Turbine Cycles & Cycle Simulation ToolsASME Turbo Expo San Antonio, Texas, 6th June 2013
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10% less rainfall
source: ClimateCrisis.netThermodynamics for Gas Turbine Cycles & Cycle Simulation ToolsASME Turbo Expo San Antonio, Texas, 6th June 2013
30
Dust storm approaching Stratford, TEXAS - April 1935source: http://www.weru.ksu.edu
31
aerodynamics materials
fuels
emissions
fuels
mechanical integrity
market research&
logistics
system integration
cycle thermodynamics
controls
32
Thermodynamics for Gas Turbine Cycles & Cycle Simulation ToolsASME Turbo Expo San Antonio, Texas, 6th June 2013
33
PART II
34
Families of thermodynamic cycles
Powercycles
Refrigerationcycles
Gascycles
Vaporcycles
Closedcycles
Opencycles
Thermodynamics for Gas Turbine Cycles & Cycle Simulation ToolsASME Turbo Expo San Antonio, Texas, 6th June 2013
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Families of thermodynamic cycles
Powercycles
Refrigerationcycles
Gascycles
Vaporcycles
Closedcycles
Opencycles
Thermodynamics for Gas Turbine Cycles & Cycle Simulation ToolsASME Turbo Expo San Antonio, Texas, 6th June 2013
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Basic considerations in the analysis of power cycles
1. Study the ideal cycle first
No frictionNo heat lossesQuasi-equilibrium compressions & expansions
2. Neglect kinetic and potential energies
3. Use P-v or T-s diagrams
Thermodynamics for Gas Turbine Cycles & Cycle Simulation ToolsASME Turbo Expo San Antonio, Texas, 6th June 2013
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• Air as working fluid
• Ideal gas
Air standard assumptions
Equation of State: PV = RT
Cp
Cv=γ R = Cp - Cv
• Semi-perfect gas
Cp / Cv
Constant Cp / Cv
functions of Temperature
γ= 1.33 - Turbinesγ= 1.40 - Compressors
Thermodynamics for Gas Turbine Cycles & Cycle Simulation ToolsASME Turbo Expo San Antonio, Texas, 6th June 2013
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Internal Energy=
The total energy contained by a thermodynamic system
Thermodynamics for Gas Turbine Cycles & Cycle Simulation ToolsASME Turbo Expo San Antonio, Texas, 6th June 2013
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Internal Energy = u(T)
Thermodynamics for Gas Turbine Cycles & Cycle Simulation ToolsASME Turbo Expo San Antonio, Texas, 6th June 2013
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u(T) + pV = Enthalpy
Thermodynamics for Gas Turbine Cycles & Cycle Simulation ToolsASME Turbo Expo San Antonio, Texas, 6th June 2013
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u(T) + pV = Enthalpy
u(T) + RT = Enthalpy = h(T)
Thermodynamics for Gas Turbine Cycles & Cycle Simulation ToolsASME Turbo Expo San Antonio, Texas, 6th June 2013
42
Specific Heat Capacity at Constant Volume
Thermodynamics for Gas Turbine Cycles & Cycle Simulation ToolsASME Turbo Expo San Antonio, Texas, 6th June 2013
43
Specific Heat Capacity at Constant Volume
=Cv
Thermodynamics for Gas Turbine Cycles & Cycle Simulation ToolsASME Turbo Expo San Antonio, Texas, 6th June 2013
44
Specific Heat Capacity at Constant Volume
=Cv =
du
dT
Thermodynamics for Gas Turbine Cycles & Cycle Simulation ToolsASME Turbo Expo San Antonio, Texas, 6th June 2013
45
Specific Heat Capacity at Constant Pressure
Thermodynamics for Gas Turbine Cycles & Cycle Simulation ToolsASME Turbo Expo San Antonio, Texas, 6th June 2013
46
Specific Heat Capacity at Constant Pressure
=Cp
Thermodynamics for Gas Turbine Cycles & Cycle Simulation ToolsASME Turbo Expo San Antonio, Texas, 6th June 2013
47
Specific Heat Capacity at Constant Pressure
=Cp =
dh
dT
Thermodynamics for Gas Turbine Cycles & Cycle Simulation ToolsASME Turbo Expo San Antonio, Texas, 6th June 2013
48
Ideal Gas Model
PV = RT
Internal Energy = u(T) = Cv T
Enthalpy = u(T) + RT = h(T) = Cp T
Cp
Cv=γ
γ= 1.33 - Turbines
γ= 1.40 - Compressors
Thermodynamics for Gas Turbine Cycles & Cycle Simulation ToolsASME Turbo Expo San Antonio, Texas, 6th June 2013
49
Wilcock R. C., Young J. B., and Horlock J. H., 2002, “Gas properties as a limit to gas turbine performance.”
Kyprianidis K., Sethi V., Ogaji S. O., PILIDIS P., Singh R., and KALFAS A. I., 2009, “Thermo-Fluid Modelling for Gas Turbines-Part I: Theoretical Foundation and
Uncertainty Analysis.”
Kyprianidis K., Sethi V., Ogaji S. O., PILIDIS P., Singh R., and KALFAS A. I., 2009, “Thermo-Fluid Modelling for Gas Turbines-Part II: Impact on Performance
Calculations and Emissions Predictions at Aircraft System Level.”
Thermodynamics for Gas Turbine Cycles & Cycle Simulation ToolsASME Turbo Expo San Antonio, Texas, 6th June 2013
50
Entropy, s
Tem
pera
ture
, T
1
2
3
4
P2 = co
nst.
P1 = const.
heat in
heat out
work in
maximum cycle pressure
limited by compressor
technology
maximum cycle temperaturelimited by turbine technology
work out
Useful work(Net)
Thermodynamics for Gas Turbine Cycles & Cycle Simulation ToolsASME Turbo Expo San Antonio, Texas, 6th June 2013
51
Entropy, s
Tem
pera
ture
, T
1
2
3
4
P2 = co
nst.
P1 = const.
heat in
heat out
work in
work out
Compressor Turbine
Combustionchamber
Ideal Brayton cycle processes:
1-2: Isentropic compression2-3: Constant pressure heat addition3-4: Isentropic expansion4-1: Constant pressure heat rejection
Thermodynamics for Gas Turbine Cycles & Cycle Simulation ToolsASME Turbo Expo San Antonio, Texas, 6th June 2013
52
Thermodynamics for Gas Turbine Cycles & Cycle Simulation ToolsASME Turbo Expo San Antonio, Texas, 6th June 2013
53
win
Thermodynamics for Gas Turbine Cycles & Cycle Simulation ToolsASME Turbo Expo San Antonio, Texas, 6th June 2013
54
win
qin+
Thermodynamics for Gas Turbine Cycles & Cycle Simulation ToolsASME Turbo Expo San Antonio, Texas, 6th June 2013
55
win
qin+
wout-
Thermodynamics for Gas Turbine Cycles & Cycle Simulation ToolsASME Turbo Expo San Antonio, Texas, 6th June 2013
56
win
qin+
wout-
qout-
InletEnthalpy
OutletEnthalpy
(qin - qout) + (win - wout) = 0
= -wnet
wnet = qin - qout
Steady-flow process energy balance on a unit-mass basis:
-=
57
wnet = qin - qout
qin = h3 - h2 = cp (T3 - T2)
qout = h4 - h1 = cp (T4 - T1)
Thermodynamics for Gas Turbine Cycles & Cycle Simulation ToolsASME Turbo Expo San Antonio, Texas, 6th June 2013
58
Entropy, s
Tem
pera
ture
, T
1
2
3
4
P2 = co
nst.
P1 = const.
heat in
heat out
work in
work out
Compressor Turbine
Combustionchamber
Fresh air
Fuel
Exhaust gases
work out
wnet = qin - qout
qin = h3 - h2 = cp (T3 - T2)qout = h4 - h1 = cp (T4 - T1)
ηthermal =wnet
qin= 1-
qout
qin
using...
T2
T1=
P2
P1
( )γ-1/γ
=P3
P4
( )γ-1/γ
=T3
T4
ηthermal = 1- 1
P2
P1
γ-1/γ
Thermodynamics for Gas Turbine Cycles & Cycle Simulation ToolsASME Turbo Expo San Antonio, Texas, 6th June 2013
59
Entropy, s
Tem
pera
ture
, T
1
2
3
4
P2 = co
nst.
P1 = const.
heat in
heat out
work in
work out
Compressor Turbine
Combustionchamber
Fresh air
Fuel
Exhaust gases
work out
ηthermal = 1- 1
P2
P1
γ-1/γ
ηth
erm
alPressure ratio
Is this right ?
Thermodynamics for Gas Turbine Cycles & Cycle Simulation ToolsASME Turbo Expo San Antonio, Texas, 6th June 2013
60
Entropy, s
Tem
pera
ture
, T
1
2s4s2a
in reality...- no compression/expansion is isentropic &- some pressure loss is inevitable
4a
3
ηcompr
ηturb
=
=
h2s - h1
h2a - h1
h3 - h4a
h3 - h4s
Component isentropic efficiencies:
note
for preliminary cycle modelling component
efficiencies can be guessed or estimated
Thermodynamics for Gas Turbine Cycles & Cycle Simulation ToolsASME Turbo Expo San Antonio, Texas, 6th June 2013
61
Case study #1:Effect of compressor efficiency on cycle performance
Compressor Turbine
Combustionchamber
- Standard air assumptions- Standard ISA conditions: 288.15K @ 1 bar- Constant ηt,is
- T3 = 1600K - Combustion efficiency=0.98- Account for cooling flows
isentropic
Isentropic
0.90.85
0.8
Thermodynamics for Gas Turbine Cycles & Cycle Simulation ToolsASME Turbo Expo San Antonio, Texas, 6th June 2013
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0.65
0.7
0.75
0.8
0.85
0.9
0.95
1
1 3 5 7 9 11 13 15OVERALL PRESSURE RATIO
ISEN
TRO
PIC
EFF
ICIE
NC
Y
POLYTROPIC EFFICIENCY = 0.90
0.85
0.8
Thermodynamics for Gas Turbine Cycles & Cycle Simulation ToolsASME Turbo Expo San Antonio, Texas, 6th June 2013
63
Case study #2:Effect of Turbine Entry Temperature on cycle performance
Compressor Turbine
Combustionchamber
- Standard air assumptions- Standard ISA conditions: 288.15K @ 1 bar- Constant ηt,is
- Combustion efficiency=0.98- Account for cooling flows
Assuming a value for the polytropic efficiency of our compressor a new isentropic efficiency is calculated for every pressure ratio based on:
TET = 1000 K
1200 K1400 K
1600 K 1800 K
Thermodynamics for Gas Turbine Cycles & Cycle Simulation ToolsASME Turbo Expo San Antonio, Texas, 6th June 2013
64
Cycle design in a gas turbine performance solverUse of “BRICKS”
Compressor Turbine
Combustionchamber
Thrust per unit flow
IntakeFreshair
ALTITUDE
MACH No.
Rel. Humidity
PRESSURE RECOVERYFACTOR
PRESSURE RATIO
POLYTROPICEFFICIENCY
BLEED FLOWS
COMBUSTION EFFICIENCY
PRESSURE LOSS
TURBINE ENTRY TEMPERATURE
(TET)
ISENTROPICEFFICIENCY
COOLINGFLOWS
Nozzle
Thermodynamics for Gas Turbine Cycles & Cycle Simulation ToolsASME Turbo Expo San Antonio, Texas, 6th June 2013
65
Cycle design in a gas turbine performance solverUse of “BRICKS”
Compressor Turbine
Combustionchamber
IntakeFreshair
ALTITUDE
MACH No.
Rel. Humidity
PRESSURE RECOVERYFACTOR
PRESSURE RATIO
POLYTROPICEFFICIENCY
BLEED FLOWS
COMBUSTION EFFICIENCY
PRESSURE LOSS
TURBINE ENTRY TEMPERATURE
(TET)
ISENTROPICEFFICIENCY
COOLINGFLOWS
Output Powerper unit flow
Thermodynamics for Gas Turbine Cycles & Cycle Simulation ToolsASME Turbo Expo San Antonio, Texas, 6th June 2013
66
Case study #3:Single spool gas generator design space exploraIon
Compressor Turbine
Combustionchamber
IntakeFreshair
ALTITUDE
MACH No.
Rel. Humidity
PRESSURE RECOVERYFACTOR
PRESSURE RATIO
POLYTROPICEFFICIENCY
BLEED FLOWS
COMBUSTION EFFICIENCY
PRESSURE LOSS
TURBINE ENTRY TEMPERATURE
(TET)
ISENTROPICEFFICIENCY
COOLINGFLOWS
Output Powerper unit flow
0.9
0.98
5% 0.91
SpecificFuel
Consumption=
Fuel flow [kg/s]def
initio
nsor SFC
SpecificPower =
Net Output [J/s]
Net Output [J/s]
Mass flow [kg/s]Thermodynamics for Gas Turbine Cycles & Cycle Simulation Tools
ASME Turbo Expo San Antonio, Texas, 6th June 2013
67
PR = 3
PR = 6
PR = 15 TET = 1000 K TET = 1200 K
TET = 1400 K TET = 1600 K Large sizeHigh weight
Small sizeLow weight
Lowtechnology
Hightechnology
Thermodynamics for Gas Turbine Cycles & Cycle Simulation ToolsASME Turbo Expo San Antonio, Texas, 6th June 2013
68
Compressor Turbine
Combustionchamber
IntakeFreshair
ALTITUDE
MACH No.
Rel. Humidity
PRESSURE RECOVERYFACTOR
PRESSURE RATIO
POLYTROPICEFFICIENCY
BLEED FLOWS
COMBUSTION EFFICIENCY
PRESSURE LOSS
TURBINE ENTRY TEMPERATURE
(TET)
ISENTROPICEFFICIENCY
COOLINGFLOWS
Thrust per unit flow
Nozzle
Thermodynamics for Gas Turbine Cycles & Cycle Simulation ToolsASME Turbo Expo San Antonio, Texas, 6th June 2013
69
High Pressure
Compressor
Combustionchamber
Low Pressure
Compressor
Low Pressure Turbine
High Pressure Turbine
COMING UP NEXT...
Thermodynamics for Gas Turbine Cycles & Cycle Simulation ToolsASME Turbo Expo San Antonio, Texas, 6th June 2013
70
High Pressure
Compressor
Combustionchamber
Low Pressure
Compressor
Low Pressure Turbine
High Pressure Turbine
COMING UP NEXT...
Thermodynamics for Gas Turbine Cycles & Cycle Simulation ToolsASME Turbo Expo San Antonio, Texas, 6th June 2013
71
High Pressure
Compressor
Combustionchamber
Low Pressure
Compressor
Low Pressure Turbine
High Pressure Turbine
COMING UP NEXT...
Thermodynamics for Gas Turbine Cycles & Cycle Simulation ToolsASME Turbo Expo San Antonio, Texas, 6th June 2013
72
High Pressure
Compressor
Combustionchamber
Low Pressure
Compressor
Low Pressure Turbine
High Pressure Turbine
Combustionchamber
COMING UP NEXT...
Thermodynamics for Gas Turbine Cycles & Cycle Simulation ToolsASME Turbo Expo San Antonio, Texas, 6th June 2013
73
High Pressure
Compressor
Combustionchamber
Low Pressure
Compressor
Low Pressure Turbine
High Pressure Turbine
Combustionchamber
COMING UP NEXT...
Thermodynamics for Gas Turbine Cycles & Cycle Simulation ToolsASME Turbo Expo San Antonio, Texas, 6th June 2013
74
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Thermodynamics for Gas Turbine Cycles & Cycle Simulation ToolsASME Turbo Expo San Antonio, Texas, 6th June 2013
75
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Thermodynamics for Gas Turbine Cycles & Cycle Simulation ToolsASME Turbo Expo San Antonio, Texas, 6th June 2013
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further info, compliments & complaints to be addressed to:
ASME Turbo Expo 2013San Antonio, US
77