High Pressure Single Pulse Shock Tube (HPST) Experiments

Kenneth BrezinskyMechanical Engineering

University of Illinois, Chicago

2007 AFOSR MURI Kick-Off MeetingGeneration of Comprehensive Surrogate Kinetic Models andValidation Databases for Simulating Large Molecular Weight

Hydrocarbon Fuels

Holiday Inn, Princeton100 Independence Way

Princeton, NJ 08540

September 17, 2007

Background

Single Pulse Shock TubeDriver DrivenDiaphragm

Dump Tank

Shock tube sections heated to 100o C preventing loss of large condensable species

Eight pressure transducer ports lie along the sidewall to determine shock velocity

One on the end port to determine ignition delay

Heating the Shock Tube

Water present100 +/- 2 °C over last 30 inches of tubeOmega Controllers

2 controllers for tube

700 720 740 7601200

1300

1400

1500 Ideal Calibrated

100 atm Calibration

T5 (K

)

Extrapolated Shock Velocity (m/s)

0 5 10 15 20 25 30 35

80

90

100

110

120

Temperature Distribution

Tem

pera

ture

(C)

Distance from end wall (in)

GC and GC/MS

Two Hewlett-Packard 6890 series Gas Chromatographs and a Hewlett-Packard 5973 series Mass Spectrometer

Detectors - PDD, TCD, FID

Mass Spectrometer

Chemical Thermometers

Treal = (-E/R)/ln{[-ln(1-x)]/At}

x = {[CF3 CH3 ]0 - [CF3 CH3 ]f }/ [CF3 CH3 ]0

From loss of parent molecule:

CF3 CH3 → CF2 CH2 + HFC6 H10 → C4 H6 + C2 H4

Two ‘thermometers’

1150 K - 1350 K1050 K - 1150 KEa/R = 33.4 K Ea/R = 39.0 K

Note: Calibration performed for every pressure range

Reaction Time

0.0000 0.0006 0.0012 0.0018 0.0024

0

2000

4000

6000

8000

10000t=1.43 ms

Pmax

80% of Pmax

P5=600 barT5-avg.=1300 Kτ=1.43 msP

ress

ure

/psi

Time /s

Toluene Oxidation Species Profiles

Stable species

Radicalspecies

Quenchingperiod

Reactingperiod

0.0000 0.0005 0.0010 0.0015 0.0020 0.00250

5

10

15

20

25

(a) C6H5CH3

T5-avg.=1300 K

Symbols: Constant T5, P5Lines: With T5, P5 correction

Time /sM

ole

frac

tion

/ppm

τ=1.43 ms

0.0000 0.0005 0.0010 0.0015 0.0020 0.00250.000

0.005

0.010

0.015

0.020

0.025

0.030

Time /s

Mol

e fr

actio

n /p

pm

OH(c)

Symbols: Constant T5, P5Lines: With T5, P5 correction

T5-avg.=1300 Kτ=1.43 ms

Well Characterized Shock Tube for Chemical Kinetic Studies under Non-ideal Conditions

From W. Tang, K. Brezinsky, Int. J. Chem. Kin., 38, 2006, 75-97

Constant T and P approximations:Acceptable with a

A. Lifshitz, "Ignition Delay Times", in Handbook of Shock Waves,

Volume 3, Pages 212-256, Eds. Gabi Ben-Dor, Ozer Igra and Tov Elperin, Academic Press, 2001.

Ignition Delay

Examples

Benzene PyrolysisPressure range from 30 - 50 barsTemperature range of 1200 - 1800 KReaction times from 1.2 - 1.5 ms.Two reagent mixtures, 84 and 800 ppm

Toluene Pyrolysis and OxidationPressure range from 25 - 610 barsTemperature range from 1200 - 1500 KMixtures with 8 - 85 ppm of Toluene

Benzene PyrolysisC6H6 - 25 atm, 65ppm

010203040506070

1200 1400 1600 1800 2000

Temperature/T5 K

PPM

Experimental

Final

Laskin-Lifshitz

Wang

Proc.2004+BenzUpdate

1200 1400 1600 18000

1

20

102030

Mol

e Fr

actio

n/ p

pm

T/ K

050

100150

Toluene Pyrolysis -

ExperimentalP ~ 27 and 45 bars, T ~ 1100-1900 K

[C6

H5

CH3

]i

~ (1-5)x10-8

mol/cc

[●] –

C6

H5

CH3

, [▲] –

C2

H2

, [□] -

C6

H6

, [◊] –

CH4

, [X] –

C4

H2

, [+] –

C8

H10

, [ο] –

C8

H6

, [Δ] –

C9

H8

27 bars

1200 1400 1600 18000

1

20

102030

Mol

e Fr

actio

n/ p

pm

T/ K

050

100150

45 bars

Toluene Oxidation : 600 bar, Φ=1Mixture 1

[C6

H5

CH3

]o = 8ppm

1240 1280 1320 1360 1400

0

2

4

6

8

10

12

14

16

Con

cent

ratio

n /p

pm

Temperature /KC6

H5

CH3 C6

H6 CO CO2Species Observed in Trace Amounts : 1,3-C4

H6

and C2

H4

Experimental KBG

KBG Model Comparison to High Pressure Data

(a) : Klotz, S.D., Brezinsky, K., Glassman, I., Proc. Symp. Int.

Comb., 27, 1998, 337.

Ф=1, 610 bar, [C6

H5

CH3

]o

=12 ppm

1250 1300 1350 1400 1450 15002

4

6

8

10

12

14

[C6H

5CH

3] /p

pm

T5 /K

Ф=5, 610 bar, [C6

H5

CH3

]o

=14 ppm

KBG Model a

: 98 species, 529 reactions.Model validated : P=1atm and T

Sensitivity Analysis

Normalized Sensitivity Coefficient

Φ=1 Φ=5

Sensitivity Spectrum [C6

H5

CH3

]P=600 bar, T=1350 K, t=1.4 ms

-0.3 -0.25 -0.2 -0.15 -0.1 -0.05 0 0.05 0.1

1

Rxn # Reactions in KBG Model

2. O+OH=H+H2

0

4. H+O2 (+M)=HO2

(+M)

458. C6

H5

+O2

=C6

H5

O+O

484. C6

H5

CH2

+H=C6

H5

CH3

486. C6

H5

CH3

+O2

=C6

H5

CH2

+HO2

492. C6

H5

+C6

H5

CH3

=C6

H6

+C6

H5

CH2

495. C6

H5

CH2

+O=C6

H5

CHO+H

C6

H5

+CH2

O+OHC6

H5

CHO+H+OHC6

H5

CH2

+HO2498.497.498

495

492

486

484458

4

2

Model Modifications

1. Glarborg et al., Int. J. Chem. Kin., 2000. 2. Just et al., Proc. Symp. Int. Comb., 1994. 3. Colket et al.,Proc. Symp. Int. Comb., 1994. 4. Baulch et al., J. Phys. Chem., 1992. 5. Scherer et al., Proc. Symp. Int.Comb., 2000. 6. Colussi et al., J. Phys. Chem., 1988. 7. Miller et al., Combustion and Flame., 1992.a. Klotz et al., Proc. Symp. Int. Comb., 27, 1998, 337.

b. Baulch et al., J. Phys. Chem. Ref. Data., 1994.

3971701.81E+12C6H5CH3+O2=C6H5CH2+HO2486b4140003.00E+14C6H5CH3+O2=C6H5CH2+HO2486a

81702.87E+14C4H3+C2H3=C6H65366

14002.92.80E+03C4H3+C2H2=C6H55377

7100003.00E+15C5H5=C2H2+C3H35383, adj

00 7.50E+12C3H3+C3H3=C6H6535510743009.00E+15C6H6=C4H4+C2H253447000002.00E+14C6H5CH2=C2H2+C5H55333, adj8360002.00E+14C6H5CH2=C4H4+C3H35323898203.00E+13C6H5+O2=p-C6H4O2+H5312

008.50E+13C6H5O+O=p-C6H4O2+H5301

cal (mol K) -1cc (mol s)-

1

E bA ReactionReaction Number

3971701.81E+12C6H5CH3+O2=C6H5CH2+HO2486b4140003.00E+14C6H5CH3+O2=C6H5CH2+HO2486a

81702.87E+14C4H3+C2H3=C6H65366

14002.92.80E+03C4H3+C2H2=C6H55377

7100003.00E+15C5H5=C2H2+C3H35383, adj

00 7.50E+12C3H3+C3H3=C6H6535510743009.00E+15C6H6=C4H4+C2H253447000002.00E+14C6H5CH2=C2H2+C5H55333, adj8360002.00E+14C6H5CH2=C4H4+C3H35323898203.00E+13C6H5+O2=p-C6H4O2+H5312

008.50E+13C6H5O+O=p-C6H4O2+H5301

cal (mol K) -1cc (mol s)-

1

E bA ReactionReaction Number

Modified ModelComparison to High Pressure DataФ=1,

610 bar, [C6

H5

CH3

]o

=12 ppmФ=5,

610 bar, [C6

H5

CH3

]o

=14 ppm

Experimental Modified KBG 2 KBG

1250 1300 1350 1400 1450 15002

4

6

8

10

12

14

[C6H

5CH

3] /p

pmT5/ K

1240 1280 1320 1360

2

4

6

8

10

12

14

[C6H

5CH

3] /p

pm

T5/ K

R. Sivaramakrishnan, R.S. Tranter, K. Brezinsky., Proc. of the Comb. Inst., 30, 2005, 1165–1173

Summary

HPSTDetermine ignition delayExamine pyrolytic and oxidative chemistrySurrogate components, component mixtures of increasing complexity and real fuelsInitial studies: n-propyl benzene, 1,3,5 trimethyl benzene

Experimental ConditionsHigh pressures (10-40atm)Temperature (800-2500K)Equivalence ratios (0.5-4)Residence times (0.5-3.0msec)

GC and GC/MS will analyze gas samples

Slide Number 1�Single Pulse Shock Tube Slide Number 4Heating the Shock TubeGC and GC/MSSlide Number 7Reaction TimeSlide Number 9Well Characterized Shock Tube for Chemical Kinetic Studies under Non-ideal ConditionsIgnition DelayExamplesBenzene PyrolysisSlide Number 14Slide Number 15Slide Number 16Slide Number 17Slide Number 18Model ModificationsSlide Number 20Summary