fuel efficiency and emissions optimization of … efficiency and emissions optimization of...

Fuel Efficiency and EmissionsOptimization of Heavy-Duty Diesel

Engines using Model-BasedTransient Calibration

Chris Atkinson Atkinson LLC

& Marc Allain, Houshun Zhang, Yury Kalish & Craig Savonen

Detroit Diesel Corporation

Atkinson LLC

Presentation Topics

Background – Diesel Engine Industry Trends Motivation – Increasing Control and Calibration Burden Solution – Model-Based Calibration and Rapid Transient Calibration Optimization Process Results – Validation of Fuel Efficiency Improvements and Emissions Compliance Next Steps – Further Improvements using Model-Based Control and Diagnostics Summary

Atkinson LLC DEER Conference August 2007

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Background – Industry Trends

Ever Decreasing Emissions Levels Increasing Demands for Fuel Efficiency Rapidly Increasing Complexity of Engine Control Close Integration of Aftertreatment Systems New Combustion Regimes under Investigation Emissions Regulations – FTP, In-Use, NTE HD OBD Requirements ⇒ All Of These Lead To A Significantly Increased

Calibration and Optimization Burden. Atkinson LLC

DEER Conference August 2007 3

Diesel Engine Control Complexity

Year Engine Technologies Number of Calibrateable Control Parameters

1998 Injection Timing Injection Pressure Smoke Control

3

2004 EGR 4 - 5 VGT

2007 2010+

DPF Regeneration Injection Timing (multiple) Injection Pressure or Rate Shaping EGR

6 - 7 11 - 15+

Full Air Path Management Active Aftertreatment Control


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Full Factorial Calibration Space

Year Engine Control Parameters Number of Discrete Test Setpoints

1998 Speed, Load, Injection Timing & Pressure 10,000 2002 Speed, Load, Injection Timing & Pressure, EGR 100,000 2004 Speed, Load, Injection Timing & Pressure,

EGR, Turbocharger Control 1,000,000

2007 Speed, Load, Injection Timing, Injection Pressure, EGR, Turbocharger Control, Particulate Filter Regeneration

10,000,000

2010 Speed, Load, Multiple Injection Timing, Injection Pressure, EGR, Turbocharger Control, Aftertreatment Controls

10,000,000,000


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The Challenge for Calibration

The Curse of Dimensionality – a 2007 specification diesel engine has 107 test points if tested in a full factorial experiment Calibration requirements will increase by 2-3 orders of magnitude by 2010-2014 due to new engine technologies Design of Experiments can reduce the overall engine steady-state mapping burden significantly (perhaps by a factor of 100), but this still results in huge experimental matrices Most importantly, steady state engine mapping not well suited to TRANSIENT emissions regulations, fuel consumption reduction, performance and aftertreatment regeneration.

Atkinson LLCDEER Conference August 2007

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Motivation – The Engine Development Dilemma

How can engine calibration be performed quicker, better and cheaper?

How do we improve real-world fuel efficiency while maintaining very low

regulated exhaust emissions?

How do we maximize the brake thermal efficiency of any given engine and

aftertreatment hardware set?

How can we further increase fuel efficiency through smart calibration and

control?

How can we do all of this without further overloading transient engine test

facilities and without incurring significant extra expense?


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Solution – Model-Based Calibration

The Problem:

How can engine calibration be performed quicker, better and

cheaper?

The Solution:

Transfer the majority of the calibration effort out of the

transient test cell and onto the engineer’s desktop, using a

systematic MODEL-BASED Rapid Transient Calibration

approach. Atkinson LLC DEER Conference August 2007

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The Model-Based Calibration Process

Design of Transient Experiments Transient cycles Control and calibration perturbations

Data Collection Dynamic Engine Modeling

Real-time transient engine performance, emissions and operating states – with full inertial, thermal, EGR and air path dynamics included

Optimization Off-line optimization of engine calibration Multiple simulations with varying optimization weights

Verification and Validation of Calibration Data Sets


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First Application of this Technology

Utilized a 2007-specification DDC Series 60 engine with EGR, VGT and DPF. 15 custom transient cycles developed and implemented (~10 dynamometer days). Dynamic engine models developed off-line. Calibration optimization performed off-line. Simulated engine performance performed off-line. Re-visited transient engine test cell for validation and verification (~10 dynamometer days).


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Engine Control Unit(ECU)

DEER Conference August 2007

Atkinson LLC

Data Collection

Engine Dynamic test

cycle speed and

load requirements

Engine Control Unit

Calibration Maps and Lookup Tables

TRANSIENT DATA Emissions

Performance Fuel Economy

Map and Lookup Table Perturbations using Rapid Prototyping

Engine Control System

1

Transient Engine Data Coverage


1

Air-EGR Perturbations (all cycles)


1

EGR-Injection Timing Perturbations


1

Injection Pressure-Timing Perturbations


1

Dynamic Engine Modeling Approach

Dynamic (transient) models use a combination of Physical Modeling

First principles Equation-based Phenomenological

Heuristic ModelingData-driven Learning Data from actual engine operation (real time emissions, performance, fuel consumption and operating states).


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Atkinson LLC

Diesel Engine Modeling

Equation-Based and

Data-Driven Engine Model

INPUTS

Engine Speed Fuel Quantity

Injection Timing Injection Pressure

Exhaust Gas Recirculation Variable Geometry Turbocharger Setting

OUTPUTS Torque

Emissions •HC •CO •NOx •CO2 •PM

Exhaust Temperature Exhaust Backpressure

Turbo Speed Combustion Pressure

DDC S60 Diesel Engine Model

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1DEER Conference August 2007

Atkinson LLC

Transient Engine Modeling Results -Torque

Transient Engine Modeling Results -NOx


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Transient Engine Modeling Results -PM


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Atkinson LLC

Rapid Transient Calibration Optimization

Equation-Based and Data-Driven

Engine Model

PREDICTED OUTPUTS Emissions

Performance Fuel Economy

Calibration Optimizer (variable weights)

COMMANDS Engine cycle

dynamic requirements

Engine Control Unit (ECU)

Calibration Maps and Lookup Tables

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Calibration Optimization Functions

Cost function – minimize fuel consumption, Subject to the constraint of meeting NOx and PM emissions integrated across a transient cycle, While not exceeding certain engine operating state parameter levels, such as turbocharger speed, peak cylinder pressure, exhaust temperature and peak injection pressure, While also meeting NTE and steady-state exhaust emissions levels.


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Typical Calibration Optimization Progress – cell by cell


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Atkinson LLC

Simulated Emissions Results – I (~100 FTPs with different calibration optimization weights)

CALIBRATION SIMULATION RESULTS

0

0.25

0.5

0.75

1

1.25

0 0.25 0.5 0.75 1 1.25

N Ox [ nor m a l i z e d]

S88 S88

S88

S88

S87

S87 S87

S87

S86S86

S86 S86

S8S85

S85S85

S84

S84

S84 S84

S83

S83

S83

S83 S8S82

S82 S82

S81 S81

S81S81S80

S80

S80

S80

S79S79 S79

S79 S7S78

S78S78

S02-7

S02-7

S02-S02-7

S02-6S02-6

S02-6S02-6

S02-5

S02-5

S02-5S02-5

S74 S74

S74S74

S03 S03

S03

S03

S02S02

S02S02

S03

S03

S02 S02

S01

S01 S01

S01

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Simulated Emissions Results – II

1.200

1.150

1.100

1.050

1.000

0.950

0.900

0.850

0.800 0.000 0.250 0.500 0.750 1.000 1.250

N O x E M IS S IO N S [ n orma lize d ]


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Validation and Verification – Actual FTP Emissions Results - I

PM

[nor

mal

ized

] 1.25

0.00 0.25 0.50 0.75 1.00

NOx [normalized]

Baseline S01M S02M 1.00

S03M S04M S02N

S02O S02P S02Q 0.75

S05 S06 S07

S02R S02S S02T 0.50

S01-R S07-R S03N

S04N S08N S09N

0.25 S10N S08N S11

S12 S13 S14

0.00 S15


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Validation and Verification – Actual FTP Emissions Results - II

HC

[nor

mal

ized

] 1.20

1.00

0.00 0.25 0.50 0.75 1.00

NOx [normalized]

Baseline S01M S02M

S03M S04M S02N

0.80 S02O S02P S02Q

S05 S06 S07 0.60

S02R S02S S02T

S01-R S07-R S03N 0.40

S04N S08N S09N

0.20 S10N S08N S11

S12 S13 S14

0.00 S15


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Validation and Verification – Actual FTP Emissions Results - III

1.20

1.15

0.00 0.25 0.50 0.75 1.00

NOx [normalized]

Baseline S01M S02M

1.10 S03M S04M S02N

S02O S02P S02Q 1.05

S05 S06 S07 1.00

S02R S02S S02T

0.95 S01-R S07-R S03N

S04N S08N S09N 0.90

S10N S08N S11 0.85

S12 S13 S14

0.80 S15


Bra

ke T

herm

al E

ffici

ency

[nor

mal

ized

]

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Project Results

Rapid Transient Calibration process requires two periods ofabout 10 dynamometer days each in the transient test cell

Data collection – 15 custom transient cycles Verification and validation

4 calendar months beginning to end Improved real-world fuel efficiency (~5%) across the FTPwhile meeting the same regulated emissions levels, with thesame levels of engine performance and protection. Shifted a significant portion of the calibration burden out ofthe high cost, high demand transient test cell.Process is scalable – adding an extra control or calibration variable (such as urea dosing for SCR) will add effort, butnot in a geometric fashion.


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Future Applications

Control Strategy Development Using Point-by-Point calibration optimization (determining the optimum set of control parameters on a time-based basis, rather than on a table-based basis) gives insight into transient control strategies.

Model-Based Control System Development Utilize dynamic engine modeling techniques for real-time on-line, on-engine application, rather than off-line use.

Model-Based Diagnostics Dynamic modeling for real-time Virtual Sensing.


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Summary

Model-Based Rapid Transient Calibration is able to Meet prevailing low emissions standards With improved fuel economy With significant reductions in the time and effort required to calibrate.

The key enabling technologies are dynamic engine modelingand off-line optimization.Reductions in engineering time, cost and effort have beenshown with this beginning-to-end model-based calibrationoptimization process.Process is scalable – encouraging for even more complex future engine and aftertreatment systems.Further gains in on-line engine control, calibration,optimization and diagnostics are possible using the samemodel-based methods. Atkinson LLC

DEER Conference August 2007 3

Acknowledgements

• U.S. Department of Energy • Gurpreet Singh • Roland Gravel

• National Energy Technology Laboratory• Carl Maronde • Jeffrey Kooser

• Atkinson LLC •Gregory Mott


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Atkinson LLC

Design of Transient Experiments

BTRQ NOx HC CO PM

RPM Fresh air setpoint EGR setpoint Injection parameters (timing & pressure)

Offline Equation and Data-based Transient Engine

Model

Transient Engine Model

BTRQ NOx HC CO PM BSFC

Optimization scheme

RPM Fueling rate Fresh air setpoint EGR setpoint Injection parameters (timing & pressure)

Air

EGR

Inj.

3

Transient Engine Test CycleEn

gine

Spe

ed (r

pm) a

nd T

orqu

e (N

m)

2250

1750

1250

750

250

-250

0 200 400 600 800 1000

Transient Engine Test Cycle

Time (s)


3

3000

Typical Table-Based Output EGR Table

10

5

0

EGR

[kg/

min

] EG

R [k

g/m

in]

30002000

200 300 400

Speed [rpm] EGR Table Original

Fuel [mg/stroke]

10

5

0

1000 0 0 100

2000 1000

0 0 100 200 300 400

Speed [rpm] Fuel [mg/stroke]


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Simulated Emissions Results – III (Integrated FTP emissions as a function of optimization weights)

NOx_Weight CO_Weight PM_Weight CO2_Weight NOx CO PM CO2 EMISSIONS NOx -0.62 0.31 0.26 -0.06 1 CO 0.43 -0.61 -0.36 -0.05 -0.67 1 PM 0.36 -0.36 -0.58 0.19 -0.51 0.81 1 CO2 -0.05 0.09 0.07 -0.37 0.05 0.00 0.07 1

Increasing NOx, CO, PM or CO2 weights in the optimization function results in a reduction in those emissions NOx and PM emissions are anti-correlated, as expected, while CO and PM are co-correlated.


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Background – Industry Trends

Ever Decreasing Emissions Requirements Ever Increasing Fuel Economy and Brake Thermal Efficiency Demands Increasing Mechanical and Electronic Complexity of Engines and Aftertreatment Systems Cost Reduction Demands for Engine Development Reduced Product Engineering Development Cycles Increasing Demands on Transient Engine and Emissions Test Facilities


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