Flame Kinetics and Transport of Alkanes and Aromatic Mi t ... · Flame Kinetics and Transport of...
Transcript of Flame Kinetics and Transport of Alkanes and Aromatic Mi t ... · Flame Kinetics and Transport of...
Flame Kinetics and Transport of Flame Kinetics and Transport of AlkanesAlkanes and Aromatic Mi t resand Aromatic Mi t resAlkanesAlkanes and Aromatic Mixturesand Aromatic Mixtures
Sang Hee Won, Pascal Diévart, Jeffrey S. Santner, Hwan Ho Kim, g yYiguang Ju
Department of Mechanical and Aerospace EngineeringDepartment of Mechanical and Aerospace EngineeringPrinceton University, Princeton, NJ 08544
M lti A C di ti C itt f C b ti R h (MACCCR)Multi Agency Coordination Committee for Combustion Research (MACCCR)Sept. 20 – 22, 2011, Argonne National Laboratory
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PRINCETONMechanical and Aerospace Engineering
Questions to addressQuestions to address1. Do the MURI surrogate fuel models work for flame
extinction?2. How to address the issue of kinetic and transport
interaction between aromatics and alkanes in flames?3. How to isolate kinetic, fuel heating value, and transport3. How to isolate kinetic, fuel heating value, and transport
effects from the global flame experiments and obtain a general correlation?
4 Can we build the missing kinetic building block of the 2nd4. Can we build the missing kinetic building block of the 2generation jet fuel surrogate?
n‐dodecane, i‐octane, n‐propyl‐benzene1,3,5 trimethyl–benzene?
5. Can we collaboratively validate this mechanism (experiments)?(experiments)?
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PRINCETONMechanical and Aerospace Engineering
Research ThrustResearch Thrust• Develop and validate MURI surrogate fuel formulations of Jet fuels
H/C ratio, DCN, TSI, and MW• Understand Kinetics and Transport Interaction b lk d i i lbetween alkanes and aromatics in Flames
• Develop a comprehensive correlation of flame ti ti d t t h i t i f tiextinction and extract chemistry information
• Develop a kinetic oxidation mechanism for 135 trimethyl benzenetrimethyl benzene
• Develop a high pressure spherical bomb for flame measurement of liquid fuelsflame measurement of liquid fuels
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PRINCETONMechanical and Aerospace Engineering
Diffusion Flame Experimental SetupDiffusion Flame Experimental Setup
• Extinction limits and OH measurements– Using FTIR measurements to check thermal decomposition and
concentration variation: Concentration fluctuation < 1%– OH radical measurement: Q1(6) excitation ~ 282.93 nm
Heater & insulation
Nitrogen
Heater & insulationHeater
FuelT
T1 T2
To burner
Schematics of evaporation system
PRINCETONMechanical and Aerospace EngineeringExperimental Measurements of OH Concentration
by using laser induced fluorescence
• PLIF: Q1(6) transition (282.93 nm), linear regime, beam height 80 mmQuenching, Soot, PAH correctionsQuenching, Soot, PAH corrections
PAH LIFLII (soot)
OH LIF
Q1(6) line1
Stagnation plane
Schematic photo for Rayleigh scattering and PLIF
detuned subtraction
nPB diffusion flames
PRINCETONMechanical and Aerospace Engineering
Surrogate Model Flame Validation on Jet POSF 4658
Surrogate Fuel: Mole Fraction DCN H/C MW / g mol-1 TSI•1st generation surrogate model (3 components)
Surrogate Fuel: Mole Fraction DCN H/C MW / g mol TSIJet‐A POSF 4658 47.1 1.957 142.01 21.4
n-decane iso-octane Toluene0.4267 0.3302 0.2431 47.1 2.01 120.7 14.1
•2nd generation surrogate model (4 components)•n-dodecane/iso-octane/ propyl benzene / 1,3,5 trimethyl benzenep py , , y
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PRINCETONMechanical and Aerospace EngineeringValidation: Extinction of Diffusion Flames
POSF 4658 vs. 1st generation surrogateg g
5000.2 0.3 0.4 0.5 0.6
Fuel mass fraction, Yf
400
Princeton JetA surrogateJetA
e, a
E [1/s
]
200
300
stra
in ra
te
100
Extin
ctio
n
00 0.03 0.06 0.09 0.12 0.15
E
Fuel mole fraction, Xf
Mass fraction does not match!Problem:
Mass fraction does not match!
PRINCETONMechanical and Aerospace EngineeringValidation: Extinction of Diffusion Flames
POSF 4658 vs. 1st and 2nd generation surrogatesg g400
s]
300
te a
E[1
/s
200
trai
n ra
t
100nctio
n st
JetAPOSF 4658
Extin
JetA POSF 4658
1st generation
2nd generationTf = 500 K and To = 300 K
00.05 0.09 0.13
Fuel mole fraction Xf
PRINCETONMechanical and Aerospace Engineering
Validation: Extinction of Diffusion FlamesPOSF 4658 vs. 1st and 2nd generation surrogates
400Why is the mean
300a E[1
/s]
ymolecular weight a big deal?
Why can such a simple
200rain
rate
JETAPOSF 4658
Why can such a simple mixture model mimic a real fuel extinction limit so well?
100ctio
n st
r JETA POSF 4658
3 comp. Surrogate
4 comp Surrogate
Where does the H/C ratio and fuel heating value contribute to the100
Ext
inc 4 comp. Surrogate value contribute to the
problem?
What is the role of 0
0.2 0.3 0.4 0.5
Fuel mass fraction Yf
aromatics?
18001.50E-0460 % d 40 % l
Example: Complexity in Flame Chemistry:Kinetic coupling between n-decane and toluene in flames
15001.00E-04
m3 s
]60 % n-decane + 40 % toluene
near extinction, Xf = 0.1, a = 176 1/s
C6H5CH2+ H = C6H5CH3
H Diffusion loss
1200
0 00E+00
5.00E-05 Tempem
ole/
cm
C6H5CH2+ H = C6H5CH3
900
-5.00E-05
0.00E+00 erature n ra
te [m
overall decomposition of n-decane
300
600
1 50E 04
-1.00E-04
[K]
Reac
tion
C10H22=C2H5+C8H17-1C10H22=nC3H7+C7H15-1
overall decomposition of toluene
0-2.00E-04
-1.50E-04
0 85 0 9 0 95 1 1 05 1 1
R C10H22=CH3+C9H19-1C6H5CH3+H<=>C6H5CH2+H2C6H5CH3+OH<=>C6H5CH2+H2OC6H5CH3+H<=>A1+CH3
0.1 mm
0.85 0.9 0.95 1 1.05 1.1
Axial coordinate [cm]Won, Sun, Dooley, Dryer, and Ju, CF 2010
Extinction limit: Alkanes, Iso‐alkanes, aromatics500
n-decane T 500 K d T 300 K
400
E[1
/s]
n-decanen-nonanen-heptaneJETA POSF 4658P i t S t
n-alkanesTf = 500 K and To = 300 K
300rate
aE Princeton Surrogate
iso-octanenPBtoluene
aromatics
200n st
rain
124TMB135TMB
aromatics
100inct
ion
0
100
Ext
Different kinetics or transport or heating values?How to extract kinetic information from the data?
00 0.05 0.1 0.15 0.2
Fuel mole fraction Xf
PRINCETONMechanical and Aerospace EngineeringA generic correlation for extinction limit:
Chemistry and TransportChemistry and TransportTheory of counterflow flame extinction
Extinction Damkohler number32
, 32
1 2 1( , , ) ( , ) expfO aF F F O F F
TY TLe P Le Le L LeD Y T T T T
Extinction Damkohler number
2,E F f a fDa e Y T T T T
E ti ti St i R t (f l dil t d b it )
iFF
e RTTC
QYa *
)(1 ,
Extinction Strain Rate (fuel diluted by nitrogen)
fpFTTCMM )(/
Transport Heat release/heat loss Fuel chemistry/reactivityRadical production rate
( Won et al. 2011, C&F )
By introducing a new concept:
Transport-Weighted Enthalpy:[fuel] Hc (MWfuel/MWnitrogen)-1/2
500
[1/s
]
n-decane
n-nonanen-heptane
iso-octane n-alkanes
300
400
n ra
te a
E
iso-octanenPBtoluene
124TMB135TMB
aromatics
200
300
tion
stra
in 135TMB
100
Extin
ct
T = 500 K and T = 300 Kiso-alkane
15
00.5 1 1.5 2 2.5 3
[Fuel]Hc(MWfuel/MWnitrogen)-1/2 [cal/cm3]
Tf = 500 K and To = 300 K
PRINCETONMechanical and Aerospace Engineering
Introducing:Introducing: Radical IndexRadical Index• Heat release and OH production/consumption
pathwaysH O OH O CO OH CO H d H OH H O H– H + O2 = OH + O, CO + OH = CO2 + H and H2 + OH = H2O + H
– Occur mainly in the core reaction zone• Quasi‐steady‐state approximation of OH• OH formation rate, ζOH = [OH]max × δOH × a• Radical Index = ζOHfuel/ ζOHn‐alkaneOH OH
– at either maximum or Da >= 2Fuel Radical index
n‐alkanes 1.0
iso‐octane 0.70
Toluene 0.56
PB 0 67nPB 0.67
124TMB 0.44
135TMB 0.36
PRINCETONMechanical and Aerospace Engineering
A General Correlation for A General Correlation for Extinction vs. Radical IndexExtinction vs. Radical Index
• Extinction limits are proportional toT W i h d E h l TWE– Transport‐Weighted Enthalpy, TWE
– Radical Index, Ri (population rate of OH)500
R² = 0.97400
500
a E[1
/s]
n-decane
n-nonane
n-heptane
iso-octane
n-propyl benzene
200
300
stra
in ra
te n propyl benzene
toluene
1,2,4-trimethly benzene
1,3,5-trimethly benzene
100
200
Extin
ctio
n
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00.5 1 1.5 2
Ri[Fuel]Hc(MWfuel/MWnitrogen)-1/2 [cal/cm3]
Tf = 500 K and To = 300 K
PRINCETONMechanical and Aerospace Engineering
RadicalRadical Index to predict extinction limitIndex to predict extinction limit
• 1st generation surrogate mixtures– nC10/iC8/toluenenC10/iC8/toluene– Ri1st gen. = Σ Xi × Rii = 0.79
n-decaneiso-octane
350
450
te a
E[1
/s]
iso octanetoluene1st generation surrogate for Jet-A POSF 4658Prediction from correlationPrediction from correlation
250
n st
rain
rat
150
Extin
ctio
n
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500.02 0.06 0.1 0.14 0.18
Fuel mole fraction Xf
Tf = 500 K and To = 300 K
PRINCETONMechanical and Aerospace EngineeringRadical Index to predict extinction limitRadical Index to predict extinction limit
• 2nd generation surrogate– nC12/iC8/nPB/135TMB, Ri2nd gen = 0.80 (Ri1st gen = 0.79)/ / / , 2nd gen ( 1st gen )
• S8 surrogate (nC12/iC8), RiS8 sur = 0.86450
From Radical Index correlation
350
e a E
[1/s
] S8 surrogate (nC12/iC8)2nd generation surrogate of Jet-A POSF 4658 (nC12/iC8/nPB/135TMB)
250
n st
rain
rat
150
Extin
ctio
n
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500.03 0.06 0.09 0.12 0.15
Fuel mole fraction, Xf
Tf = 500 K and To = 300 K
3 Kinetic Model Development for 1353. Kinetic Model Development for 135 trimethyl benzene: Ignition & flames
•Second generation surrogate model (4 components)•n-dodecanen dodecane•iso-octane•N-propyl benzene 1 3 5 t i th l b•1,3,5 trimethyl benzene
Lack of a kinetic mechanism!
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PRINCETONMechanical and Aerospace Engineering1,3,5 trimethyl benzene Model Development
1,3,5‐TriMethylBenzene A similar oxidation pathway f
m Xylene Submodel Kinetic parameters modified
subset to the one of toluene was adopted
m‐Xylene SubmodelBattin‐Leclerc et al. 2006
and Gail and Dagaut et al., 2008
Kinetic parameters modified and adopted from similar reactions in toluene subset
TOLUENE SubmodelMetcalfe , Dooley, and Dryer, 2011
H2/O2 subset proposed by Burke et al. adopted
Thermodynamic parameters of di- and tri-methyl related species re-estimated
PRINCETONMechanical and Aerospace Engineering
Oxidation of 135‐TMB in flame configurations
1,3,5‐TMB
35dmb1ch2
H abstraction reactions(H, OH)
H addition
CH3 addition35dmb1ch2
abduct 1‐Ethyl‐3,5‐beta-scission+O
.
(2 aromatic rings) diMethylBenzene
3 5‐ 1 3 dimethyl
+O
3,5diMethylBenzAldehyde
1,3 dimethylphenyl CH2O
+OCHO
Xylene radicals
H abstractionCHO
PRINCETONMechanical and Aerospace Engineering
Validation of 135TMB Model: Ignition Validation of 135TMB Model: Ignition
Shock Tube Ignition delay for stoichiometric135TMB/air mixture at 20.6 atm
Oehlsclaeger et al. 2011
PRINCETONMechanical and Aerospace Engineering
Validation of 135TMB Model: Validation of 135TMB Model: extinction and flow reactorextinction and flow reactor
– Diffusion flame extinction at 1 atm, Tf = 500 K, To = 300 KFlow reactor oxidation at 12 5 atm 930 K 1111 ppm– Flow reactor oxidation at 12.5 atm, 930 K, 1111 ppm135TMB, 13300 ppm O2
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4. Measurement4. Measurements of s of Flame SpeedFlame Speed of of surrogate fuelssurrogate fuelssurrogate fuelssurrogate fuels
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PRINCETONMechanical and Aerospace EngineeringDevelopment of “Spherical” Bomb for liquid fuelsDevelopment of “Spherical” Bomb for liquid fuels
Pre-vaporizationchamber
P Thermocouple
Fan
Oven P Pressure gauge
Thermocouple
Liquid fuel injectionwith syringe
herm
ocou
ple
electrodes Heated tube
Air cylinder
To vacuum pump
Air or N2/O2
T
heater heater
(Pressure relief)
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heater heater
Overview
PRINCETONMechanical and Aerospace EngineeringTransient Flame Trajectories and speedsTransient Flame Trajectories and speeds
J A POSF 4658 d i d 135TMB135TMB– JetA POSF 4658, n‐decane, iso‐octane, and 135TMB135TMB500
Unstretchedfl d
400
[cm
/s]
flame speed
Multi-stage flames at300
velo
city
Sb [
Equivalence
near limit conditions
100
200 0.7 0.8 0.91 0rn
ed g
as v
Equivalence ratio
0
100 1.0 1.1 1.2 1.4
Bu
Transition from ignition to propagation
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0 500 1000 15000
Stretch rate [cm-1]Stretch rate at Critical Radius
Numerical modeling200 iso-C8H18/air
1atm, 298K, Phi=0.8 •ASURF code
s)
150 A•AdaptiveChemistry(PFA method)
Sb
(cm
/s
100 B
CKA = 320 s-1
KB = 450 s-1
KC = 470 s-1
•Adaptivegrids
50
C
0 200 400 600 8000
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K (1/s)0 200 400 600 800
PRINCETONMechanical and Aerospace Engineering
Validation of 135TMB Model: Flame speedValidation of 135TMB Model: Flame speed
– Laminar flame speed at 1 atm, 400 K60
50
60
[cm
/s] at 400 K
40
velo
city
30
ar b
urin
g
20
Lam
ina
princeton [Spherical bomb]Uconn [Counterflow twin flames]135TMB model, Diévart et. al
100.5 0.7 0.9 1.1 1.3 1.5
Eqivalence ratio
PRINCETONMechanical and Aerospace EngineeringConclusion
h t d d i f l d l f j1. The 1st and 2nd generation surrogate fuel models for jet A were validated against extinction limits.
2 Aromatics play an important role in affecting flame extinction2. Aromatics play an important role in affecting flame extinction via kinetic and transport coupling.
3. A comprehensive correlation for diffusion flame extinction plimits of alkanes, isoalkane, aromatics, and real fuel was obtained by using Transport weighted enthalpy and radical indexindex.
4. Chemical kinetic model for 135TMB has been developed and validated through collaborative MURI team/RPI work. Thevalidated through collaborative MURI team/RPI work. The surrogate model building blocks were completed.
5. A nearly constant pressure spherical bomb was developed to measure liquid fuel burning velocity and transient flame regimes at elevated pressures. 30