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EGR Layout

Oct 06, 2015

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EGR Layout

  • Control Strategy for a Dual Loop EGR System to Meet Euro 6 and Beyond

    John Shutty and Robert Czarnowski

    2009 Directions in Engine-Efficiency and Emissions Reduction Research (DEER) ConferenceAugust 3-6, 2009, Dearborn, Michigan.

  • 2DEER Conference 2009

    Contents

    Background System Description Thermodynamic Analysis

    Control System Overview Structure Features Control Optimization

    NEDC Results On Engine Application

    Conclusions

  • 3DEER Conference 2009

    Motivation

    Reduce the cost and lower emissions of diesel engines in an ever tightening regulatory world Focus on EGR and

    Boost Systems

    NOx Emissions Regulation (g/km)

    KoreaEuro III 2005

    Euro IV 2010

    China

    Euro 3

    2007

    Euro 4

    2010

    EuropeEuro 3 2000

    Euro 4 2005Euro 5 2009

    United

    States

    Tier II

    Bin 5 2

    007

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  • 4DEER Conference 2009

    Exhaust Throttle

    Charge Air Cooler

    LP-EGR Valve

    DPFHP-EGR Valve

    Intake throttle

    LP-

    EGR Cooler

    EGR Mixer

    HP-

    EGR Cooler

    VTGI4 diesel engine, common rail

    EGR & Turbo Charging System Architecture Base Dual Loop EGR system Layout

    Base engine HW: 2L Inline 4 EURO4

    Adjusted Parameters: EGR-rate, Boost pressure

    Combustion system: standard Diesel (diffusive)

    EGR-system: cooled HP-EGR, cooled LP- EGR

    Boosting system:1-stage VTG

  • 5DEER Conference 2009

    Last year conclusions

    A Dual Loop EGR System offers significant advantages to reduce emissions and fuel consumption and can meet future emission requirements Mostly due to improved turbocharger operating efficiency Charge Air Temperature Reduced Up to 4% improvement in BSFC in steady state More EGR can be driven without performance sacrifice

    Dynamic engine performance can be improved with a dual loop EGR system Transient controls need to be developed and improved

    (focus of today's presentation)

  • 6DEER Conference 2009

    n = 2500 1/minBMEP = 12 barEGR = 30%

    38%

    75%

    55%

    n = 2500 1/minBMEP = 12 barEGR = 30%

    38%

    75%

    55%

    Specific fuel consumption at different HP/LP-EGR-splits

    Thermodynamic Analysis HP&LP Loop

    Low fuel consumptionBetter use of the exhaust energy and higher efficiencies of the compressor and turbine

    100% HP

    VTG Open

    VTG Closed

    100% LP

  • 7DEER Conference 2009

    Development Process

    Modeling of Production Baseline Full GT-Power Model Real time capable mean value model (MVM)

    Development of controller in Simulink Controller Verification and calibration

    with GT-Power MVM in Simulink Dynamometer testing and final

    calibration using same Simulink code Verification on Dyno simulating NEDC

    Cycle

  • 8DEER Conference 2009

    Previous Controller Options

    Separate EGR and Boost Controllers Stability achieved by maintaining open loop or slow

    dynamic controls

    Decoupled EGR and Boost Controllers Loop interference reduced but slow response and

    overshoots still an issue

    In both cases, NOx and PM control compromised during transients

  • 9DEER Conference 2009

    Load

    Speed HP EGR set point

    LP EGR set point

    EGR-Boost optimization

    HP EGR Control

    Map

    LP EGR Control

    Map

    HPLSplit

    LPLSplit

    Total EGR frac

    estimator

    Feedback Controller

    EGR TOTAL set-point

    Sensor(s)

    HP EGR Valve

    Intake Throttle

    LP EGR & Exhaust Throttle Module

    Temperature

    Boost Pressure Set Point Boost Controller

    Turbo VTGSensor(s)

    Engine State

    Engine State

    Air Controller System ArchitectureHigh Pressure Loop Controls

    Turbo Controls

    Low Pressure Loop Controls

    Feed Forward Loops

  • 10

    DEER Conference 2009

    BW Coordinated Controller Features Negative coupling is eliminated and positive coordination is added

    to improve response and control Dual Loops and VTG help each other to achieve higher

    efficiency Static EGR Estimation Improvement Achieves requested EGR rate more accurately

    EGR Boost Optimization Block Determines EGR loop split Calculated dynamically for best efficiency

    Utilization of EGR path which is most capable and efficient of achieving the set-point statically (actuator saturation (virtual or actual)) dynamically (slower loop dynamics)

    Improved Dynamic Control Coordinated EGR and boost system to adjust on the fly with

    closed loop control

  • 11

    DEER Conference 2009

    Coordinated Controller Results Static EGR Estimation Improvement Better fuel economy achieved at same NOx level

    EGR Boost Optimization Block Fuel economy improved by higher Turbo Efficiency and lower

    NOx achieved by increasing EGR

    Dynamic feedback control of EGR mass flow, both EGR loops and VTG

    Improved Dynamic Control Decoupling of VTG and EGR allows control of each during

    transients Less NOx and PM spikes

    Easy to implement in production ECU Low memory and CPU usage No extra I/O

  • 12

    DEER Conference 2009

    HPL/LPL Split Strategy

    Maximize Efficiency of Turbocharger Minimize pumping losses Improve dynamic Performance Control Charge air temperature Minimize Condensation in LPL

  • 13

    DEER Conference 2009

    0/100

    LP / HP EGR Split Strategy Steady State Map

    T

    o

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    Engine speed

    %HP EGR / %LP EGR

    100/0 Combustion temperature

    20/80

    40/60

    High pumping loss with LP EGR

    Increase oxygen content

    75/2540/60 Optimizing

    VTG position

    40/60

    Fast reaction time

    75/25

  • 14

    DEER Conference 2009

    E

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    a

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    (

    %

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    0

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    200 230 260 290 320 350 380 410 440 470 500

    EGR rate setpoint EGR rate actual

    E

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    a

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    (

    %

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    200 230 260 290 320 350 380 410 440 470 500

    EGR rate setpoint EGR rate actual

    Production ECU Control

    BorgWarner Control

    Static and Dynamic Improvements Relative to Baseline

    EGR valve shut-

    off to decouple

    EGR Rate above requested rate

    Maintains requested rate during cycle

  • 15

    DEER Conference 2009

    EUD Cycle - On Engine NOx Control

    V

    e

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    Cycle time [s]780 880 980 1080 1180

    Base HP EGR calibration / Daimler ECU controller HP+LP EGR V0 calibration / BWES controller HP+LP EGR V5 calibration / BWES controller

    HP EGR V0 / ECU Control HP/LP EGR V0 / BW Controller HP/LP EGR V5 / BW Controller

    BW Dual Loop 35%

    BW Dual Loop 20%

    Production ECU HPL 25%

    NOx Peaks reduced

    Significant NOx reduction

  • 16

    DEER Conference 2009

    25% Prod ECU HP EGR

    35% Dual Loop EGR

    25% Dual Loop EGR

    Km/hr

    Charge temperatures reduced with dual Loop EGR

    Temp reduced over 30C

    HPL & LPL have same size coolers

  • 17

    DEER Conference 2009

    Cumulative NOx and CO2 on NEDC Test

    24% Reduction in NOx

    Constant PM

    6% less fuel consumption

    Production ECU Control HPL vs. BW Control Dual Loop EGR

    BWDualLoopEGR20%

    ProdECUHPEGR25%

  • 18

    DEER Conference 2009

    N

    O

    x

    m

    g

    /

    k

    m

    Seconds

    K

    m

    /

    h

    r

    Increased EGR rate to Maximize NOx ReductionProduction ECU vs

    BorgWarner Coordinated Controls

    BWDualLoopEGR35%

    ProdECUHPEGR25%

    -72%

    72% Reduction in NOx

    Increased EGR to Obtain Equivalent Fuel Consumption & PM

  • 19

    DEER Conference 2009

    System SummarySystem EGR System Fuel

    Consumption reduction (%)

    NOxReduction (%)

    Baseline High Pressure loop w/ cooler25%

    NA NA

    BorgWarner coordinated controls

    High Pressure loop w/ cooler20%

    8 0

    BorgWarner coordinated controls

    Dual Loop EGR w/ coolers20%

    6 24

    BorgWarner coordinated controls w/ increased EGR

    Dual Loop EGR w/ coolers35%

    0 72

  • 20

    DEER Conference 2009

    Summary Map: CO2 vs

    NOx Relative Contributions to Emissions Reduction

    NOx Reduction Contributions

    155

    160

    165

    170

    175

    180

    0 0.05 0.1 0.15 0.2 0.25 0.3 0.35 0.4 0.45

    NOx g/km

    C

    O

    2

    g

    /

    k

    m

    + BW Controls

    + 15 EGR

    + 15% EGR

    ECU ControlHP EGR

    + LP EGR

    +BorgWarner Air Path Controls

    Theoretical Line +15% EGR

    +15% EGR Actual

    +15% EGR Actual

  • 21

    DEER Conference 2009

    Conclusions Dual Loop EGR offers significant advantages to

    reduce emissions and fuel consumption to meet future emission requirements

    A coordinated control system has been developed to optimize the EGR and air boost system

    Significantly reduces fuel consumption and / or NOx Improves dynamic performance of turbocharger

    Potential for NOx aftertreatment system cost reduction Future work includes two stage boosting systems

    together with dual loop EGR allows further enhanced performance while utilizing down speeding to achieve CO2 targets.

  • 22

    DEER Conference 2009

    Thank You For Your Attention

    For Further Information Contact:

    Bob Czarnowski

    rczarnowski@borgwarner.com

    Slide Number 1ContentsMotivationSlide Number 4Slide Number 5Slide Number 6Development Process Previous Controller OptionsAir Controller System Architecture BW Coordinated Controller FeaturesCoordinated Controller ResultsHPL/LPL Split StrategyLP / HP EGR Split Strategy Steady State MapStatic and Dynamic Improvements Relative to Baseline EUD Cycle - On Engine NOx ControlSlide Number 16Cumulative NOx and CO2 on NEDC TestSlide Number 18System SummarySummary Map: CO2 vs NOx Relative Contributions to Emissions ReductionSlide Number 21Slide Number 22

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