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

15

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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