Model development and experimental validation of diesel surrogate - - PowerPoint PPT Presentation

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Model development and experimental validation of diesel surrogate - - PowerPoint PPT Presentation

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1 Model development and experimental validation of diesel surrogate fuels using SRM-DI module simulations Alvaro Diez and Roy Crookes, Queen Mary University of London Terese Lvs, Norwegian University of Science and Technology STAR Global

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Model development and experimental validation of diesel surrogate fuels using SRM-DI module simulations

Alvaro Diez and Roy Crookes, Queen Mary University of London Terese Løvås, Norwegian University of Science and Technology

STAR Global Conference, March 19-21, 2012, Amsterdam

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Outline

  • Objectives
  • Auto-ignition characteristics
  • Experimental and numerical model
  • Model validation
  • Future work
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Objectives

  • Surrogate fuels are increasingly important to cut cost

in engine research

  • Surrogate fuels have known physical/chemical

properties and combustion characteristics similar to conventional fuels

  • Surrogate fuels are simpler in terms of composition

(mainly one or two component fuels)

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Objectives

  • New surrogate fuel models needed to mimic “new fuels”,

such as bio-fuels where lack of kinetic data is limiting

  • Even typical surrogate fuel components (n-heptane,

dodecane, hexadecane, toluene etc) have complex kinetics

  • Combustion characteristics become accordingly sensitive

to blending due to different fuel-air mixing

  • Crucial with modeling tools that enable detailed

description of the kinetics and the engine conditions

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Auto-ignition characteristics

  • Fuel-air mixing properties affects ignition
  • Injection profile affects ignition
  • Combustion phasing affects efficiency
  • Definition of ignition time affects ignition
  • The model should capture these effects
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Experimental validation rig

  • Optical chamber provides a compression-ignition zone
  • ptically accessible
  • Fitted with a piezoelectric pressure transducer for

cylinder pressure and energy conversion rate analysis

  • Fitted with a high pressure common rail injection system

with injection pressures up to 160 Mpa

  • LabVIEW custom built program as ECU
  • An independent intake manifold with an intake heating

up to 600 K

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Experimental validation rig

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  • Injector characteristics
  • Phantom V 4.3 high speed colour CMOS
  • The recording speed for this study 6000 fps

→1 crank angle per frame

  • The image resolution was 256 x 256 pixels

Siemens Lynx Injector Injection Pressure 80 MPa Number of Holes 7 Cone Angle 152° Hole Diameter 110 µm Type microsac

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Diesel: Dodecane:

Optical experiments:

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DI SRM model in DARS

  • Stochastic distribution of properties in the domain

→ important for direct injection systems

  • Accounts for free mixing of particles and heat transfer

to the walls

  • Accounts for detailed chemistry
  • Accounts for detailed engine specifications
  • Injection determined by user defined injection profiles

→ obtained directly from the experiments

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Reaction kinetic challenge

  • Surrogate fuel model:

– Detailed mechanism for n-alkanes (C8-C16) – E.g. Westbrook et al. mechanism: contains oxidation paths for both n-dodecane and n-hexadecane https://www-pls.llnl.gov/?url=science_and_technology- chemistry-combustion

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Westbrook et al.:

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Reduced Westbrook et al.:

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Side chamber specifics

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Definition of ignition delay

Experimental: luminosity vs pressure traces

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  • 40 -35 -30 -25 -20 -15 -10
  • 5

5 10 15 20 25 30 35 40 Cylinder Pressure / MPa

Crank Angle / degree ATDC Diesel Dodecane Hexadecane motoring

injection

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Definition of ignition delay

Numerical: OH initiation vs OH rise

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Results

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Results

0.5 1 1.5 2 2.5 3 3.5 4 700 750 800 850 900 950

Ignition delay / ms Temperature / K

Diesel (cylinder pressure) Diesel (luminosity) Dodecane (luminosity) Dodecane SRM (OH initiation) Dodecane SRM (OH rise)

Ignition delay in optical chamber for diesel and n-dodecane

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Results

0.5 1 1.5 2 2.5 3 3.5 4 700 750 800 850 900 950

Ignition delay / ms Temperature / K

Diesel (cylinder pressure) Diesel (luminosity) Hexadecane (cylinder pressure) Hexadecane (luminosity) Hexadecane SRM (OH initiation)

Ignition delay in optical chamber for diesel and hexadecane

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Future work

  • Combine more fuel blends
  • Investigate for different injection characteristics
  • Investigate for bio-fuels (BioEng project)
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Acknowledgement

  • EPSRC, funding of project “Design and assessment
  • f suitable surrogate fuels for diesel fuel modelling”
  • Nordic Councils’ Top Research Initiative, funding of

project “BioEng”