Energy Frontier Research Center for Combustion Science ...
Transcript of Energy Frontier Research Center for Combustion Science ...
Energy Frontier Research Center for Combustion Science
Stanford University Contribution
R. K. Hanson and D. F. DavidsonDepartment of Mechanical Engineering
Stanford University
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• Butanol Studies
• Ignition Delay Times
• Species Time-Histories
• Reaction Rate Constants
• Methyl Ester Studies
• Ignition Delay Times
Long-Term Objectives
• Generate high-quality fundamental kinetics database using shock tube/laser absorption methods
Leading to:
• Improved detailed mechanisms for next-generation fuels
First Targets:
• Isomers of butanol; large bio-derived methyl esters
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Stanford Shock Tube & Laser Facilities
DriverSection
Shock TubeDriven Section
Ring Dye Lasers(UV & Vis)
Diode Lasers(Near IR & Mid-IR)
CO2 Lasers(9.8-10.8 µm)
Shock Tubes (4)
Large Diameter Tubes (15 cm and 14 cm)
High Pressure Tube (5 cm) heatable to 150C
Aerosol Tube (11 cm)
Optical Diagnostics
Laser Absorption(UV, Vis, Near-IR, Mid-IR)
Advantages of Shock Tubes Near-Ideal Constant Volume Test PlatformWell-Determined Initial T & P Clear Optical Access for Laser Diagnostics
Ti:Sapphire Laser(Deep UV)
He-Ne Laser(3.39 µm)
UV/Vis/IREmissionDetectors
Transmitted Beam Detector
PressurePZT
VS VRSP5 T5
Butanol Studies:
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1. Ignition Delay Times of the 4 Isomers1050-1500 K, 1.5-42 atm, φ=0.5, 1, 4% O2
2. Multi-Species Time-Histories in 1-ButanolOH, H2O & butanol during pyrolysis and oxidation
3. Direct Rate Constant Measurements1-butanol+OH products
1-Butanol Ignition Delay Times:Pressure Dependence (1.5 to 42 atm)
• Data acquired using both low-pressure and high-pressure shock tubes
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0.65 0.70 0.75 0.80 0.85 0.90 0.95 1.00
100
1000
1-Butanol, 4% O2, Φ = 1
1.5 atm
19 atm
1111 K1250 K1429K
t ign
[µs]
1000/T5 [1/K]
3.0 atm
42 atm
1-Butanol Ignition Delay Times:Pressure Dependence (1.5 to 42 atm)
• Data acquired using both low-pressure and high-pressure shock tubes
• τign scales as P-0.67
over wide pressure range for φ=1
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0.65 0.70 0.75 0.80 0.85 0.90 0.95 1.00
100
1000
1-Butanol, 4% O2, Φ = 1
1111 K1250 K1429K
t ign
[µs]
1000/T5 [1/K]
All data (1.5-42 atm)normalized to 20 atmusing P-0.67
1-Butanol Ignition Delay Times:Comparison with MIT Mechanism (1.5 to 42 atm)
• Low Pressures: Good agreement with MIT mechanism (Harper,Green 8/10)
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0.65 0.70 0.75 0.80 0.85 0.90 0.95 1.00
100
1000
P = 1.5 atm
Lines (MIT 2010)
1-ButanolΦ = 1, 4% O2/Ar
1111 K1250 K1429K
t ign
[µs
]
1000/T [1/K]
P = 3 atm
1-Butanol Ignition Delay Times:Comparison with MIT Mechanism (1.5 to 42 atm)
• Low Pressures: Good agreement with MIT mechanism (Harper,Green 8/10)
• High Pressures:Significant differences (up to 50%) between model and experiment
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0.65 0.70 0.75 0.80 0.85 0.90 0.95 1.00
100
1000
1000K P = 1.5 atm
P = 19 atm
Lines (MIT 2010)
1-ButanolΦ = 1, 4% O2/Ar
1111K1250K1429K
t ign
[µs
]
1000/T [1/K]
P = 3 atm
P = 42 atm
Butanol Ignition Delay Times:Variation with Isomer (1.5 atm)
• 1-butanol fastest
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0.60 0.64 0.68 0.72 0.76 0.80 0.84
100
1000
1-butanol2-butanoliso-butanoltert-butanol
1190 K1389 K
t ign
[µs]
1000/T [1/K]
1667 K
Butanol Ignition Delay Times:Variation with Isomer (1.5 atm)
• 1-butanol fastest
• 2-butanol and iso-butanol similar
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0.60 0.64 0.68 0.72 0.76 0.80 0.84
100
1000
1-butanol2-butanoliso-butanoltert-butanol
1190 K1389 K
t ign
[µs]
1000/T [1/K]
1667 K
OH
OH
Butanol Ignition Delay Times:Variation with Isomer (1.5 atm)
• 1-butanol fastest
• 2-butanol and iso-butanol similar
• Tert-butanolslowest (~2-3x) with larger EA
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0.60 0.64 0.68 0.72 0.76 0.80 0.84
100
1000
1-butanol2-butanoliso-butanoltert-butanol
1190 K1389 K
t ign
[µs]
1000/T [1/K]
1667 K
Butanol Ignition Delay Times:Comparison with MIT Mechanism (1.5 atm)
• 1-, 2-butanol:Good agreement with MIT (8/10) model
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0.60 0.64 0.68 0.72 0.76 0.80 0.84
100
1000
1-butanol2-butanol
1190 K1389 K
t ign
[µs]
1000/T [1/K]
1667 K
Butanol Ignition Delay Times:Variation with Isomer (1.5 atm)
• 1-, 2-butanol:Good agreement with MIT (8/10) model
• iso-, tert-butanol:Poorer agreement with model
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0.60 0.64 0.68 0.72 0.76 0.80 0.84
100
1000
iso-butanoltert-butanol
1190 K1389 K
t ign
[µs]
1000/T [1/K]
1667 K
Butanol Ignition Delay Times:Comparison with Other Laboratories
• 1-Butanol (low P):Good agreement with Moss et al. (RPI)
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0.55 0.60 0.65 0.70 0.75 0.80
100
1000
Current Study Moss et. al. (2008)
1333 K
t ign
[µs]
1000/T [1/K]
1667 K
1-Butanol/3%O2/Ar
1.2 atm, φ=1
MIT Model (2010)
Butanol Ignition Delay Times:Comparison with Other Groups
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0.55 0.60 0.65 0.70 0.75 0.80
100
1000
1333 K1667 K
Current Study Oehlschlaeger et al. (RPI)
t ign
[µs]
1000/T [1/K]
2-Butanol/6%O2/Ar1.2 atm, φ=1
MIT Model (2010)
• 1-Butanol (low P):Good agreement with Moss et al. (RPI)
• 2-, tert-, & iso-butanol :Poor agreement with RPI data
Species Time-Histories:1-Butanol
Pyrolysis and Oxidation
Species: OH, H2O, 1-Butanol
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1-Butanol Pyrolysis:OH and H2O Species Time-Histories
• First speciestime-history data for 1-butanol pyrolysis
• Goal: quantify evolution of all keyC, H & O species
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1431 K, 1.49 atm,1% 1-butanol in argon
10 100 1000
10
100
1000
10000 H2O
Mol
e Fr
actio
n [p
pm]
Time [µs]
OH
1-Butanol Pyrolysis:OH and H2O Species Time-Histories
• Significant differences between MIT model and data
• Future Work: Carbon and oxygen closure by addition of CO, CH2O, CH4, C2H4, C3H6, C2H2measurements
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1431 K, 1.49 atm,1% 1-butanol in argon
10 100 1000
10
100
1000
10000 H2O
Mol
e Fr
actio
n [p
pm]
Time [µs]
OH
MIT Model
1-Butanol Oxidation:OH and H2O Species Time-Histories
• First time-history data for 1-butanol oxidation
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1433 K, 1.51 atm, φ=1 1000 ppm 1-butanol in O2/argon
10 100 1000
10
100
1000
10000
H2O
Mol
e Fr
actio
n [p
pm]
Time [µs]
OH
1-Butanol Oxidation:OH and H2O Species Time-Histories
• First time-history data for 1-butanol oxidation
• Major differences in model and data time scales
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1433 K, 1.51 atm, φ=1 1000 ppm 1-butanol in O2/argon
10 100 1000
10
100
1000
10000
H2O
Mol
e Fr
actio
n [p
pm]
Time [µs]
OH
MIT Model
1-Butanol Oxidation:OH and H2O Species Time-Histories
• First time-history data for 1-butanol oxidation
• Major differences in model and data time scales
• Future: Complete picture of ignition by addition of fuel, intermediates, and product profiles
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1433 K, 1.51 atm, φ=1 1000 ppm 1-butanol in O2/argon
10 100 1000
10
100
1000
10000
H2O
Mol
e Fr
actio
n [p
pm]
Time [µs]
OH
Elementary Reaction Rate Constant Measurements:
1-Butanol+OH Products
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1-Butanol + OH Products
• Importance of OH+Fuel reactions under lean conditions
• No previous data
• Large uncertainty in estimations of OH rate constant for 1-butanol oxidation
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0.7 0.8 0.9 1.0 1.11E12
1E13
1E14 1000K
Reac
tion
Rate
[c
c/m
ol/s
]
1000/T, (1/K)
Black et al. 2010 (NUI) Moss et al. 2008 (RPI) Harper et al. 2010 (MIT) Westbrook model 2010 (LLNL)
1250K
1-Butanol + OH Products
3 Part Strategy:
1. Fast OH source: TBHP (tert-butyl-hydroperoxide)TBHP OH + CH3 + CH3COCH3
2. pseudo-first order removal1-butanol >> OH
3. Monitor OH using laser absorptionppm detection sensitivity
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Representative OH Laser Absorption Data
• OH laser absorption provides high SNR
• Strong sensitivity to title reaction
• Low overall uncertainty: +/- 14%
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Reflected Shock Conditions: 1165K, 2 atm
150ppm C4H9OH/10ppm TBHP/Ar
0 10 20 30 40 50 60
0
5
10
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k=2.1x1013 Best Fit k=1.0x1013
k=4.2x1013
OH
[pp
m]
Time [µs]
Arrhenius Plot: 1-Butanol+OH Products
• Excellent agreement with recent theory byZhou, Simmie et al. (2010)
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0.7 0.8 0.9 1.0 1.11E12
1E13
1E14 1000K
Reac
tion
Rate
[c
c/m
ol/s
]
1000/T, (1/K)
Zhou, Simmie (2010) Moss et al. 2008 (RPI) Westbrook et al. (LLNL) Black et al. 2010 (NUI) Harper et al. 2010 (MIT)
1250K
Methyl Ester Studies:
1. Use of Aerosol Shock Tubeaccess to low-vapor-pressure fuels
2. Bio-Derived Methyl Esters and Surrogatesmethyl decanoate, methyl oleate
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Aerosol Shock Tube for Low-Vapor-Pressure Fuels
• Does not require heated shock tube• Eliminates fuel cracking and partial distillation• Provides access to low-vapor-pressure fuels:
Jet fuel, diesel, bio-diesel surrogates
Laser
Detector
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Aerosol Shock Tube Operation Regime
• Unheated ST provides access up to C3 methyl esters
• Heated ST provide access up to methyl decanoate(C10:0)
• AST provides access up to large (C25:0) methyl esters
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Shock Tube Access to Fuels: Saturated Methyl Esters
T5=1000K, P5=10atmΦ=1 in air
Preliminary τign Data for Methyl Decanoateand Comparison with Diesel
• Previous AST studies have provided Diesel τign data
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Preliminary τign Data for Methyl Decanoateand Comparison with Diesel
• First ignition delay data for bio-diesel surrogate methyl decanoate(C11H22O2, C10:0)
• Critically needed for model validation
• Experiments in progress at other conditions
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First τign Data for Methyl Oleate (9/10/10)
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• Demonstrates abilityof 2nd Gen AST to study very-low vapor pressure compounds
C19H36O2, C18:1
Future Work• Rate constant measurements of Butanol+OH for all isomers
i.e., 2-butanol, iso-butanol, tert-butanol
• Extend τign measurements to low temperatures
• Establish ignition delay time and species time-history databasefor methyl oleate (C19H36O2), methyl stearate (C19H38O2)
• Extend species time-history measurementsto CO, CO2, CH2O, CH4, C2H4, C3H6, …
• Continued collaboration with EFRC mechanism team
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Acknowledgements
• Visit Stanford website http://hanson.stanford.edu/ for
Fundamental Kinetics Database Using Shock Tubes
• Thanks to our four shock tube/laser jockeys:
Dr. S. Vasu (OH) I. Stranic (τign) M. Campbell (τign) R. Cook (OH, H2O) 34