Multi zone modeling of HCCI combustion at University of Zagrebpowerlab.fsb.hr/ercoftac/Kozarac_Mahalec_Multi_zone_modelling_of... · Multi zone modeling of HCCI combustion at University

Multi zone modeling of HCCI combustion at Multi zone modeling of HCCI combustion at University of ZagrebUniversity of Zagreb

Kozarac D., Mahalec I.

Department of IC Engines and Mechanical Handling Equipment

Chair of IC engines and Motor Vehicles

25 May 2009 BOOST - HCCI 2

Content:Reason for HCCI modeling

Simulation of HCCI combustion

Conclusions and future work

Current multi zone simulation model (6)

Results

Validation of six zone simulation model


Reason for HCCI modelingWhat is HCCI combustion?Relatively new combustion process of IC engines

Combustion characteristics:

homogeneous mixture (SI like)

compression ignition (Diesel like)


combustion start controlAdvantages

Reason for HCCI modeling

Comparison with standard SI and CI engines

Problems

low fuel consumptionoperating windowlow NOx emission

low particulate emission small specific powerCO & HC emissionnoise and vibrations

Research


Simulation of HCCI combustionIC engine simulations: single zone models

multi zone modelsmulti-dimensional models(CFD)

HCCI simulations: chemical kinetics

Single and multi zone calculation + detailed chemical kinetics

CFD + reduced chemical kinetics

CFD + detailed chemical kinetics


Current multi zone simulation model

Comprehensive chemical kinetics

Cylinder is divided into six zones

Heat transfer between wall and boundary zones

Non sequential solverODEs of all zones are calculated simultaneously

Heat transfer between the zones

Possession of crevice zone (iso thermal)

Volumes of the zones are geometrically defined

Mass transfer between the zones

Temperature distribution at IVC

Features:

Connected with cycle simulation software (AVL Boost)


Description of six zones

1

4

2

3

56

δRZ

T = const

Boundary zones (2, 3, 4): δRZ

Central zones (5, 6): V5 = V6

Crevice zone (1): V1 = konst

Volumes of zones

geometrically defined

Push



ValidationCalculation (1Z, 6Z) vs Experiment

Engine – HCCI converted from Cummins B SAE 2003–01–0752SAE 2004–01–1910

isooctane

Load range: from well below idling

to onset of knockingincrement

Results: Pressure trace

Net Rate of Heat Release

Emissions (CO2, CO, HC)

φ = 0.04φ = 0.26φ = 0.02

Fuel:

Mechanism: Chen’s isooctane oxidation (291 s, 875 r)


ValidationLoad: φ = 0.24 Calculation constants: Δt=10-3 s, δ=0.9 mm

Heat transfer: Woschni 1990

0

50

100

150

200

250

300

350

400

450

-10 -5 0 5 10Crank angle [deg]

Net

RO

HR

[J/d

eg]

Experiment1Z calculation6Z calculation

0

10

20

30

40

50

60

70

80

90

100

300 330 360 390 420Crank angle [deg]

Pres

sure

[bar

]


ηc= 95.0 %ηc= 99.2 %ηc= 96.7 %


Validation

20

25

30

35

40

45

50

55

60

65

330 340 350 360 370 380 390Crank angle [°]

Net

RO

HR

[J/°]

Experiment

1Z calculation

6Z calculation

-10

0

10

20

30

40

50

60

330 340 350 360 370 380 390Crank angle [°]

Net

RO

HR

[J/°]

Experiment

1Z calculation

6Z calculation

Heat transfer: Woschni 1990ηc= 62.5 %ηc= 73.4 %ηc= 70.0 %

Load: φ = 0.14 Calculation constants: Δt=10-3 s, δ=0.9 mm


ValidationLoad: φ = 0.04 Calculation constants: Δt=10-3 s, δ=0.9 mm


20

25

30

35

40

45

50

55

330 340 350 360 370 380 390Crank angle [°]

Net

RO

HR

[J/°]

Experiment

1Z calculation

6Z calculation

-4

-3

-2

-1

0

1

2

3

330 340 350 360 370 380 390Crank angle [°]

Net

RO

HR

[J/°]

Experiment

1Z calculation

6Z calculation

ηc = 31 %ηc= 20.2 %ηc= 29.2 %


0102030405060708090

100

0 0.04 0.08 0.12 0.16 0.2 0.24 0.28

Fuel

C in

to e

mis

sion

[%] Experiment

1Z calculation6Z calculation

CO2

0

10

20

30

40

50

60

70

0 0.04 0.08 0.12 0.16 0.2 0.24 0.28

Fuel

C in

to e

mis

sion

[%] Experiment


CO

0

10

20

30

40

50

60

70

80

0 0.04 0.08 0.12 0.16 0.2 0.24 0.28

Fuel

C in

to e

mis

sion

[%] Experiment


HC

0102030405060708090

100

0 0.04 0.08 0.12 0.16 0.2 0.24 0.28

com

bust

ion

effic

ienc

y [%

]


eqivalence ratio φ [-] eqivalence ratio φ [-]

eqivalence ratio φ [-] eqivalence ratio φ [-]

Validation


Load: φ = 0.24


Mass in zones Temperatures in zones

0.000.050.100.150.200.250.300.350.400.450.50

340 350 360 370 380 390 400Crank angle [deg]

mas

s fr

actio

n of

zon

es [-

]

Zone 1Zone 2Zone 3Zone 4Zone 5Zone 6

φ = 0.24 base case

800900

100011001200130014001500160017001800

340 350 360 370 380 390 400Crank angle [deg]

Tem

pera

ture

[K]

φ = 0.24

T mean

T zone2

T zone3

T zone4

T zone5

T zone6

T zone1 = 455 K

1

4

2

3

56 δRZ

Calculation constants: Δt =10-3 s, δRZ=0.9 mm

Results


Load: φ = 0.24


0

100

200

300

400

500

600

700

340 350 360 370 380 390 400Crank angle [deg]

mas

s fr

actio

n of

HC

[ppm

]

Zone 1Zone 2Zone 3Zone 4Zone 5Zone 6All zones

φ = 0.24base case

050

100150200250300350400450500

340 350 360 370 380 390 400Crank angle [deg]

mas

s fr

actio

n of

CO

[ppm

]

Zone 1Zone 2Zone 3Zone 4Zone 5Zone 6All zones

= 0.24base case

Mass fraction of HC species in cylinder Mass fraction of CO in cylinder

1

4

2

3

56

φ = 0.24

Calculation constants: Δt =10-3 s, δRZ=0.9 mmδRZ

Results


Results EthanolBoundary conditions Iso-octane Ethanol BC1 Ethanol BC 2

Tintake 428 428 450

Fuel mass fraction 0.0171 0.0285 0.0285

0

10

20

30

40

50

60

70

80

90

340 350 360 370 380Crank angle [deg]

Pres

sure

[bar

]

Iso-octaneEthanol BC 1Ethanol BC 2 600

700800900

1000110012001300140015001600170018001900

340 350 360 370 380Crank angle [deg]

Tem

pera

ture

[K]

Comparison with isoocaneLoad: φ = 0.26


0

0.1

0.2

0.3

0.4

0.5

0.6

0.7

0.8

0.9

1

350 355 360 365 370Crank angle [deg]

Com

bust

ion

effic

ienc

y [-]

Iso-octaneEthanol BC 1Ethanol BC 2

0

50

100

150

200

250

300

350

350 355 360 365 370Crank angle [deg]

RO

HR

[J/d

eg]

Results EthanolComparison with isoocane


Results Ethanol – performance mapsMaps (SOC, CD, IMEP, BSFC vs EGR & Tintake)

Load: φ =0.22

355

356

357

358

359

360

440 450 460 470 480 490 500 510

Intake temperature [K]

Star

t of c

ombu

stio

n (S

OC

)

0

2

4

6

8

10

12

14

16

18

440 450 460 470 480 490 500 510 Intake temperature [K]

Com

bust

ion

dura

tion

[deg

]

2.4

2.5

2.6

2.7

2.8


IMEP

[bar

]

380

385

390

395

400

405

410

415

420


BSFC

[g/k

Wh]

EGR 20

EGR 30

EGR 40

EGR 50

EGR 60

EGR 70

EGR 0


ConclusionsNew calculation model represent a good progress in combustion modeling of HCCI combustion Correspondance of pressure and NetROHR is very good

Calibrated model enables an insight in sources of emissions especially emissions from crevice volumes

Partial possibility of predicting and analysis of emissions

Further development of HCCI model

Use of the model for R&D of HCCI engines

Future

Increasing number of zonesMaking simulations faster

Introducing more in-homogeneity


THE END

Thank you for your attentionQUESTIONS


Description of the simulation model


Chemical kineticsSimulation of HCCI combustion

Combustion is a sequence of chemical reactions

All chemical reactions take place at definite rate

Description of chemical reactions

Reaction mechanism(n species and m reactions)

7 16 2 7 15 2C H O C H HO∗ ∗+ → +

7 16 7 15C H X C H XH∗ ∗+ → +

7 15 2 7 15C H O C H OO∗ ∗+ →

7 15 7 14C H OO C H OOH∗ ∗→species production rates

ω [mol/(cm3 sec)]


Chemical kineticsSimulation of HCCI combustion

Detailed~(10000 reactions, 1000 species)

Comprehensive~(1000 reactions, 100 species)

Reaction mechanisms:

Skeletal~ (50 reactions, 10 species)

Curran iso-octane

Examples

~(3606 reactions, 857 species)

Chen iso-octane~(875 reactions, 291 species)

Tanaka PRF(55 reactions, 32 species)


Temperature distribution

model

Coupling with engine cycle simulation code – AVL BoostGas Exchange Boost

(single zone)High pressure cycle HCCI

(1Z or 6Z model)


Documents

Multi zone modeling of HCCI combustion at University of Zagrebpowerlab.fsb.hr/ercoftac/Kozarac_Mahalec_Multi_zone_modelling_of... · Multi zone modeling of HCCI combustion at University