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Steady-State and Transient Simulation of SuperTruck Waste
Heat Recovery System in GT-Suite
Milan VisariaCummins Inc.
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Outline
� Background
� System Architecture
� Model Development
� Steady-State Calibration
� Steady-State Performance Comparison of Different Working Fluids
� Transient Testing
� Transient FTP75 Cycle Performance Comparison of Different Working
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� Transient FTP75 Cycle Performance Comparison of Different WorkingFluids
� Real-Time WHR Model link to Simulink models
Background
� SuperTruck – DoE funded program
� Engine system demonstration of 50% or greater BTE in a test cell
� 50% improvement in Class 8 freight efficiency
� Waste Heat Recovery is one of the many technologies considered
� Organic Rankine Cycle
� Suitable for long-haul, high-load applications (trucks, inter-citybuses)
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buses)
� Sources of “waste” energy for recovery: Exhaust & EGR stream
� Mechanical power output to crankshaft through gearbox
Energy Balance and WHR Sources
Fuel Energ
y(1
00%
)
Bra
ke P
ower
(42%
)
Friction/Misc Losses
(8%)
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Fuel Energ
y
(8%)
Heat Transfer(24%)
Exhaust Energy(26%)
Waste
Heat Quality
Hig
hW
aste
Heat Quality
Hig
h
Cooled EGR
Tailpipe Exhaust
200-600o C200-600o C
200-750o C200-750o C
Charge Air CoolingCharge Air Cooling
Engine CoolingEngine Cooling
20-60o C20-60o C
80-100o C80-100o C
Waste
Heat Quality
Low
Waste
Heat Quality
Low
Inta
ke M
anifold
Radiator
CAC
WHR Condensor
Manifold
T
C
Heat Exchanger
Recuperator
Pum
p
2
Ram Airflow
CMI WHR System Overview
1
6
7
Working Fluid
EGR/Exhaust Gas
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Inta
ke M
anifold
Exhaust
Manifold
T
Aftertreatment
Exhaust
Heat Exchanger
EGR
Heat Exchanger
Expander
Turbine
Expander
Power Out
3
4
5
Tailpipe
Purpose of Model Development
� Compare steady-state and transient performances of differentworking fluids
� Optimize and predict the most efficient system operating point(Engine + WHR)
� Perform OBD and controls development
� Ability to replace component(s) and study its effect on thesystem
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� Ease of linking WHR model to GT-Power engine model andstudy the integrated system performance
Cold side in
Core depth
Core width
Hot side out
A-A
A
A
Hot side in Cold side out
Model Building Procedure
Combine all calibrated components and plumbing and
retune the model
GT-Suite WHR System
Model
Heat exchanger physical specs from supplier
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Calculate relevant parameters e.g. Hydraulic diameter, flow
area, heat transfer area, dimensions, etc.
Select heat transfer and pressure drop correlations
Calibrate each component against performance data
Compare model results against data/specs
Heat exchanger performance
specs/test data
GT-Suite WHR System ModelExhaust HeatExchanger
EGR Heat Exchanger
Recuperator
Actuated Parameter
Model Inputs:� Exhaust inlet
flow rate and temperature
� EGR inlet flow rate and temperature
� Condenser and
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Condenser
Subcooler Feed Pump
Turbine Expander
Receiver and Valve Block
Air C
ooled
� Condenser and subcooler sir flow rate and temperature
� Pump and turbine expander speed
� Target EGR gas outlet temperature
0.3
0.4
0.5
0.6
0.7
0.8
0.9
1.0
0.3 0.4 0.5 0.6 0.7 0.8 0.9 1.0
GT
-Po
we
r
Pump Flow (kg/s)
±5%
±10%
Experiment
Mo
de
lSystem Flow Rate
10.0
15.0
20.0
25.0
30.0
35.0
10.0 15.0 20.0 25.0 30.0 35.0
GT
-Po
we
r
Turbine Inlet Pressure (bar)
±5%
±10%
Experiment
Mo
de
l
Turbine Inlet Pressure
Steady-State Model CalibrationIn
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ExperimentExperiment
ExperimentExperiment
400
420
440
460
480
500
520
540
400 420 440 460 480 500 520 540
GT
-Po
we
r
Experiment
Superheater Outlet Temperature (K)
±5%
±10%
Experiment
Mo
de
l
Turbine Inlet Temperature � Model calibrated using test data at 12different steady-state speed and loadpoints
� Figures compare the system flowrates, turbine inlet pressure andturbine inlet temperature
� The mean error in all quantitiesbetween model and test data was lessthan 3%
WF 1
WF 2
WF 3
Ne
t S
ys
tem
Po
we
rSteady-State Performance Comparison
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A25 A50 A75 A100 B25 B50 B75 B100 C25 C50 C75 C100
State Point
Ne
t S
ys
tem
Po
we
r
� Steady-state performance of three different working fluidscompared at 12 different operating points
Transient Model Test – InputsExhaust Gas Flo
w
� Transient profiles (using steady-state test data) of relevantparameters was input to the model
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0 1000 2000 3000 4000 5000
0 1000 2000 3000 4000 5000
Exhaust Gas Tem
pera
ture
Time (sec)
Time (sec)
� The idea behind the testing wasto test the model controls andensure that the model can handlereceiver draining and filling
Tem
pera
ture
0 1000 2000 3000 4000 5000
Target Turbine Inlet Temp Turbine Inlet Temp
Valve Command
0 1000 2000 3000 4000 5000
Receiver Liq
uid
Level
Transient Model Test – ResultsIn
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0 1000 2000 3000 4000 5000
12
Time (sec)0 1000 2000 3000 4000 5000
Net Syste
m P
ower
Time (sec)
0 1000 2000 3000 4000 5000
Time (sec)
Pum
p S
ubcool
Time (sec)
Ideal Max Limit
Ideal Min Limit
0 200 400 600 800 1000 1200 1400
Time (sec)
Engin
e S
peed
FTP75 Simulation
� Engine test data from FTP75cycle was input to the WHRmodel
� Transient profiles of feed pumpspeed (engine driven), EGR andexhaust gas flow rates, EGR andexhaust gas inlet temperatures,etc. are input to the model
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0 200 400 600 800 1000 1200 1400
Exhaust Gas
EGR
Time (sec)
Time (sec)
Mass Flo
w
� Performance of three differentworking fluids over FTP75 cycleis then compared
Syste
m M
ass Flo
w
WF 1
WF 2
WF 3
0 200 400 600 800 1000 1200 1400
FTP75 Simulation – ResultsIn
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Turb
ine P
ressure
Ratio
WF 1
WF 2
WF 3
Time (sec)0 200 400 600 800 1000 1200 1400
0 200 400 600 800 1000 1200 1400
WF 1
WF 2
WF 3
Net Syste
m P
ower
0 200 400 600 800 1000 1200 1400
FTP75 Simulation – ResultsIn
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WF 1
WF 2
WF 3
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Receiver Liq
uid
Level
Time (sec)0 200 400 600 800 1000 1200 1400
0 200 400 600 800 1000 1200 1400
GT-Suite and Controls Model Link
Feed Pump Speed
Turbine Speed
EGR Flow
Exhaust Air Flow
Drain / FillValves Position
Condenser /SubcoolerAir Flow
Actuators to GT-Suite Model
SimulinkEngine Model
Exhaust BypassValve Position
User-Defined
Engine Conditions
Engine Speed /Fueling
Exhaust HeatExchanger
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GT-Suite WHR System Model
EGR CoolingValve Position
Valves Position
System BypassValve Position
Turbine Superheat
Pump Subcool
System Pressures
System Temps
System Flows
Simulink WHR Controls Model
Sensors from GT-Suite Model
Note: Not all actuators and sensors are listed here
EGR Heat Exchanger
Condenser
Subcooler Feed Pump
Turbine Expander
Recuperator
Receiver and Valve Block
Air Coole
d
Questions?
WHRWHRRecuperatorRecuperator
WHRWHREGR Heat ExchangerEGR Heat Exchanger
WHRWHRCondensorCondensor
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WHR ExhaustWHR ExhaustHeat ExchangerHeat Exchanger Exhaust Exhaust
AftertreatmentAftertreatmentWHR ExpanderWHR ExpanderDrive ModuleDrive Module
Thank You!
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Thank You!
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