2005 Deer Flowers

8/2/2019 2005 Deer Flowers

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Modeling of HCCI and PCCICombustion Processes

Dan Flowers, Salvador AcevesLawrence Livermore National Laboratory

Robert DibbleUniversity of California, Berkeley

Randy Hessel

University of Wisconsin, Madison

Aristotelis BabajimopolousUniversity of Michigan

Work performed under the auspices of the U.S. Department of Energy by University of California,Lawrence Livermore National Laboratory under Contract W-7405-ENG-48.


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Project Overview: HCCI Engines have potential forHigh Efficiency and Low Emissions

Homogenous Charge Compression Ignition (HCCI)engines have many potential advantages:

Very Low NOx Emissions

Very Low Particulate Emissions

High Efficiency

Lower Cost

We apply chemical kinetic modeling and experiments

towards solving technical barriers of HCCI engines: Combustion timing measurement and control

Cylinder-by-cylinder combustion timing control

Startup Fuel air ratio measurement and control

Low Power Density

Hydrocarbon and CO emissions


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Approach: Fundamental and practical understanding ofHCCI by judicious use of modeling and experiments

Develop numerical tools that predict HCCI combustionwith complex fuels in reasonable computational time(hours and days, not weeks and months)

High Resolution CFD

H3C

C CH3

H2C

H3C

CH

CH2O

.O

H2C

C CH3

H2C

H3C

CHH3C

O

HOH3C

CH

H2C

H3C

CH

H2C

OO.

O

OH

Additive 1

Additive 2

Additive 3

Additive 4

H2C

C CH3

H2C

H3C

CH2

O

O.

O

HO

H2C

C CH3

H2C

H3C

C

H3C

O

HO

O

CH3 O.

Additive 5

H3C

CHC

H3C

CH2

Additive 122

O

O

OH

HC

O

O

HO

Additive 103

O

OHO

O.

H3C

C CH3

H2C

H3C

C

H3C

O

CH3 OH

Additive 204

Detailed Chemistry

Engine Experiments

Fundamental

Understanding+

DesignGuidance


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Objective: Modeling and experiments applied totechnical barriers towards practical HCCI engines

Applying multizone detailed chemical kinetics models tounderstanding fundamentals of HCCI operation

Extending and applying multizone modeling tools tohandle non-homogeneous, but HCCI-like,combustion regimes: PCCI, SCCI

Modeling and experiments to understand fundamentaland practical issues in HCCI

HCCI with binary fuel mixtures using Carbon-14 tracing Studying chemi-ionization as a practical means for combustion

timing measurement


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We have long standing partnershipswith industry and academia

Cummins

Currently involved in CRADA partnership

Previous CRADA produced 2 joint papers

Caterpillar

Providing experimental support

Close collaboration on natural gas HCCI

Sandia National Laboratories

Detailed analysis of experimental data, paper

Lund Institute of Technology 3 joint papers, collaboration on analysis

University of Wisconsin

joint work on KIVA analysis

6 joint papers UC Berkeley

joint experimental and numerical work, >20 jointpapers

graduate students obtaining degrees on HCCI U Michigan

PhD research conducted at LLNL


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Our experiments and modeling advance both practicaland fundamental understanding of HCCI and PCCI

Characterized the role of turbulence on HCCIcombustion through multizone modeling

Completed development of Fully Integrated KIVA3V-multizone (KIVA3V-MZ) model for simulation of HCCIand PCCI combustion

Parallelized KIVA3V-multizone (KIVA3V-MZ-MPI)chemistry solver to significantly reduce computationaltime

Developed rugged and low cost combustion timingsensor for HCCI combustion through ion sensing

Investigated fuel and additive effects on HCCIcombustion using C14 tracing of emission sources


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What is the role of turbulence in HCCI engines?

Lund Institute studied HCCI operation in high and low turbulenceengines

These experiments showed that burn durations in higherturbulence configuration were significantly longer

Debate raised about turbulence influence on the ignition process

Lower turbulencepiston crown

Higher turbulencepiston crown

E i t h l b d ti


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Experiments show longer burn durationfor higher turbulence geometry

Our hypothesis: Chemistry timescales are far too rapid to beaffected by local turbulence timescales, thereforeturbulence plays only an indirect role through heat transfer

O M lti h h t f HCCI


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Our Multi-zone approach has proven accurate for HCCIcombustion with wide range of fuels and engine geometries

KIVA3V is run until aspecific Transition point

Multi-zone HCT model usedfor simulating cycle aftertransition point

KIVA Temps mapped one-wayonto multizone HCT

High resolution CFD with detailed chemistry at every


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High resolution CFD with detailed chemistry at everygrid point exceeds capability of todays computers

Possible Approaches:

Few grid points for CFD and Chemistry

Many grid points for CFD, a few grid points for chemistry (Our approach)- works when chemistry and turbulence weakly interact ( e.g. HCCI)

1 Hour

1 Month

1 Decade

1 Day

Kinetics

CFD

Engine Cycle Simulation(single processor)Axisymmetric CFD grid~200 chemical species

Engine Cycle Simulation(single processor)Axisymmetric CFD grid~200 chemical species 1 Year

We have analyzed HCCI operation both low and high


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We have analyzed HCCI operation both low and highturbulence geometries using the multizone approach

Flat crown (60K cells)Square Bowl Crown (400K cells)

Kiva simulations show the flow pushed into the square


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Kiva simulations show the flow pushed into the squarebowl near TDC with high turbulence geometry

Very little change in swirl velocity occurs with flat top


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Very little change in swirl velocity occurs with flat-toppiston geometry during compression

Flat piston Square bowl piston

Substantial recirculation occurs in square-bowl piston


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Substantial recirculation occurs in square-bowl piston,very little with flat-top

Flat piston Square bowl piston

Higher turbulence yields more heat transfer and


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Higher turbulence yields more heat transfer andbroader temperature distribution within the cylinder

0

0.005

0.01

0.015

0.02

0.025

0.03

0.035

0.04

0.045

900 920 940 960 980 1000

temperature, K

massfractionat1Ktemperature

bins

disc, peak heat release at 3 ATDC

square, peak heat release at 3 ATDC

Our multizone model shows that broader temperature


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Our multizone model shows that broader temperaturedistribution explains the lengthening of the burn duration

Heat release rate, flat piston Heat release rate, square bowl

Conclusion: HCCI is dominated by chemical kinetics,


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Conclusion: HCCI is dominated by chemical kinetics,turbulence plays an indirect role through heat transfer

0 2 4 6 8 10 12

0

2

4

6

8

10

12

Burnduration,

CAD

crank angle for peak heat release rate

solid line: experimental

squaredisc

dotted line: numerical

Our Multi-zone approach has proven accurate for HCCI


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Our Multi zone approach has proven accurate for HCCIcombustion with wide range of fuels and engine geometries

But great interest in partially stratified HCCI for bettercontrol and higher power output (PCCI, SCCI)

KIVA is run until aspecific transition point

Multi-zone HCT modelused for simulating cycleafter transition point

KIVA Temps mappedone-way onto multizoneHCT

We extend this model to map between CFD and Multi-


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We extend this model to map between CFD and Multizone detailed kinetic solver throughout the engine cycle

Fully Integrated KIVA and Multi-zone model (KIVA-MZ)

High resolution CFDsolver handles mixing,advection and diffusion

(>10K cells)

Solutions are mapped backand forth between solvers

throughout the cycle

Chemistry handled bymultizone detailed kineticssolver (10-100 zones)

Significant reduction in computational time with


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g pCFD+multizone approach, but

This approach still requires 50-100 chemistry zones Stillcomputationally intensive, esp. with big mechanisms

Multi-zone model is readily parallelized, parallel multizonechemistry solver now implemented within KIVA3V,yields near linear speedup with number of processors

Fully integrated KIVA3V-MZ-MPI handles chemistry


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y g ypart of simulation in parallel

Fluid mechanics still handled with single processor

Chemistry handled with additional processors, chemistry

speedup scales almost linearly with number ofprocessors (up to ~ number of zones)

Process 0

Fluid

mechanicsstep

Processes 1 (N-1)

Zone1 Zone 2 Zone 3 Zone M

High resolution CFD with detailed chemistry at every


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g y ygrid point exceeds capability of todays computers

Possible Approaches:

Few grid points for CFD and Chemistry Many grid points for CFD, a few grid points for chemistry (Our approach)

- works when chemistry and turbulence weakly interact ( e.g. HCCI)

1 Hour

1 Month

1 Decade

1 Day

Kinetics

CFD

Engine Cycle Simulation(single processor)Axisymmetric CFD grid~200 chemical species

Engine Cycle Simulation(single processor)Axisymmetric CFD grid~200 chemical species 1 Year

Parallelizationcan shiftkinetics costdramatically

lower

Simulations were conducted to analyze Isooctane HCCI


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yin the Sandia Engine (Experiments SAE 2003-01-0752)

5.88 mm

(0.2314 in)

5.23 mm

(0.206 in)

9.01 mm

(0.355 in)

0.305 mm

(0.0120 in)

102 mm

(4.02 in)

Our fully integrated KIVA3V-MZ-MPI solver predicts


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pressure very well compared to Sandia experiments

30

40

50

60

70

80

90

-10 -5 0 5 10 15 20

Crank Angle, Degrees

Pre

ssure

(bar)

Phi=0.26 Experiment

Phi=0.20 Experiment

Phi=0.16 Experiment

Phi=0.10 ExperimentPhi=0.26 Simulation

Phi=0.20 Simulation

Phi=0.16 Simulation

Phi=0.10 Simulation

KIVA3V-MZ-MPI emissions predictions are also in good


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agreement with the experiment

010

20

30

40

50

60

70

80

90

100

0.1 0.12 0.14 0.16 0.18 0.2 0.22 0.24 0.26

phi

FuelCarbonIntoEm

issions

%Fuel C into CO [%] Experiment

%Fuel C into CO2 [%] Experiment

%Fuel C into HC [%] Experiment

%Fuel into OHC [%] Experiment

%Fuel C into HC [%] Simulation

%Fuel into OHC [%] Simulation

%Fuel C into CO [%] Simulation

%Fuel C into CO2 [%] Simulation

Strength of the fully integrated KIVA3V-MZ-MPI solver


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is simulation of non-homogenous HCCI-like processes

Using validated cases as a baseline, simulationsconducted to investigate imposition of stratification oncombustion

High Stratification

Mild Stratification

Uniform

Comparison of equivalence ratio at 35 degrees BTDC (=0.26 Overall)

HC and OHC lower with increased stratification, CO


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higher for some higher stratification conditions

Consistent with experimental observations for early directinjection engines

0

1000

2000

3000

4000

5000

6000

7000

8000

0.1 0.12 0.14 0.16 0.18 0.2 0.22 0.24 0.26

Phi

CO(ppm)

steep

shallow

uniform

400

600

800

1000

1200

1400

1600

0.1 0.12 0.14 0.16 0.18 0.2 0.22 0.24 0.26

Phi

HC

orO

HC

(ppm)

steep (HC)

shallow (HC)

uniform (HC)

steep (OHC)

shallow (OHC)

uniform (OHC)

NOx emissions increase due to higher locali l i i h i d ifi i


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equivalence ratio with increased stratification

0

2

4

6

8

10

12

14

0.1 0.12 0.14 0.16 0.18 0.2 0.22 0.24 0.26

Phi

NOx

(ppm)

steep

shallow

uniform

KIVA3V-MZ-MPI simulation is currently being used toi ti t PCCI ith l di t i j ti


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investigate PCCI with early direct injection

Early Direct injectionusing KIVA spraymodel for diesel fuel

100 zone (with 100processors) simulationwith n-heptane diesel

fuel surrogate


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Summary: We continue to use our simulation capabilitiesto complement HCCI R&D in Industry Nat Labs Universities


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to complement HCCI R&D in Industry, Nat Labs, Universities

We now have the tools to computationally optimize thegeometry, and fuel-air-EGR distributions in HCCI andHCCI-like engines

KIVA3V-MZ-MPI is a computationally efficient andaccurate tool coupling fluid mechanics and detailedchemical kinetics for prediction HCCI

We have extended multizone tools to handle non-homogeneous direct injected PCCI regimes

Experiments, numerical modeling, and other uniquecapabilities applied to fundamental and practical issuesof HCCI

Future Plans: We will continue to develop tools andanalysis to guide HCCI engine design


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analysis to guide HCCI engine design

Continue applying KIVA3V-MZ-MPI to early direct liquidfuel injection PCCI

Apply modeling to support optical engine PCCIexperiments (Dec, Steeper)

Investigate non-homogeneous engine operationtowards higher load and lower HC and CO emissions

Investigate effects of fuels and fuel mixtures on PCCIand HCCI operation

Study practical strategies of combustion timingmeasurement and control for multi-cylinder engines

Recent and Upcoming Publications (1)


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p g ( )

1) Analysis of the Effect of Geometry Generated Turbulence on HCCI

Combustion by Multi-Zone Modeling SAE Paper 2005-01-2134.Collaboration: Lund Inst., U Wisconsin

Highlights: Detailed study of Role of Turbulence in HCCI combustion

2) A Fully Integrated CFD and Multi-zone Model with DetailedChemical Kinetics for the Simulation of PCCI EnginesInternational Journal of Engine Research (in press).

Collaboration: U Michigan, U Wisconsin

Highlights: Development of approach for Fully Integrated Kiva-Multi-zoneDetailed chemical kinetics code for simulation of HCCI and PCCIengines

3) Effect of the Di-Tertiary Butyl Peroxide (DTBP) additive on HCCICombustion of Fuel Blends of Ethanol and Diethyl Ether SAEPaper 2005-01-2135.

Collaboration: UC Berkeley, CAMS(LLNL)

Highlights: Carbon 14 tracing investigating role of ignition enhancingadditives on HCCI combustion with fuel mixtures.



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4) Experimental and Numerical Investigation of Effect of Fuel on Ion

Sensor Signal to Determine Combustion Timing in HCCI Engines,International Journal of Engine Research (in press).

Collaboration: UC Berkeley

Highlights: Developed ion formation model for HCCI engines for multiple

fuels, verified model with experiments

5) EGR effect on Ion Signal in HCCI Engines, SAE 2005-01-2126.


Highlights: Experimental verification of ion formation chemical kinetics forHCCI with high EGR, for conditions ranging from very lean to slightly richconditions

6) Combustion Timing in HCCI Engines Determined by Ion-Sensor:Experimental and Kinetic Modeling, 30th International Symposiumon Combustion.

Collaboration: UC Berkeley, U Heidelberg

Highlights: First application and experimental verification of ion chemicalkinetic mechanism applied to HCCI engines.



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7) Investigation of HCCI Combustion of Diethyl Ether and Ethanol

Mixtures Using Carbon 14 Tracing and Numerical Simulations,30th International Symposium on Combustion.

Collaboration: UC Berkeley, CAMS(LLNL)

Highlights: Carbon 14 tracing used to investigate sources of emissions

from dual component fuel blends in HCCI engines

8) Spatial Analysis of Emissions Sources for HCCI Combustion at

Low Loads Using a Multi-Zone Model, SAE Paper 2004-01-1910.

Collaboration: SNL, U Wisconsin, UC BerkeleyHighlights: Detailed chemical kinetic analysis of geometry dependent

emissions from an HCCI engine at low loads

9) Analysis of Homogeneous Charge Compression Ignition (HCCI)Engines for Cogeneration Applications, Proceedings of the ASMEAdvanced Energy Systems Division, 2004

Collaboration: Oregon State University

Highlights: evaluation of the multiple advantages of HCCI for CHP



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10) Thermal Management for 6-Cylinder HCCI Engine: Low Cost,

High Efficiency, Ultra-Low NOx Power Generation, Proceedings ofthe ASME Internal Combustion Engine Division, May 2004


Highlights: Characterization of HCCI combustion for stationary power

11) Improving Ethanol Life Cycle Energy Efficiency by DirectCombustion of Wet Ethanol in HCCI engines, Proceedings of the

ASME Advanced Energy Systems Division

Highlights: how HCCI combustion of wet ethanol can greatly improveenergy balance for ethanol production

12) Source Apportionment of Particulate Matter from a Diesel Pilot-

Ignited Natural Gas Fuelled Heavy Duty DI Engine, SAE Paper

2005-01-2034

Collaboration: University of British Columbia

Highlights: C-14 analysis for identification of source of pollutants in a dualfuel engine

Other collaborative activities


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Ongoing participation at MOU meetings with vehicleand engine manufacturers

Invited presentation at SAE HCCI symposium

Invited presentation at ECI Lean CombustionTechnology II workshop

Several publications with National Laboratories andUniversities in US and abroad:

SAE

The Combustion Institute

International Journal of Engine Research

2005 Deer Flowers

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