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.edu/comocheng
Victor R. Lambert & Richard H. West
9th US National Combustion Meeting
20 June 2015
1
r.west@neu.edu richar...
Identification, Correction, and Comparison

of Detailed Kinetic Models
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Model Complexity is increasing
2-methylalkanes/Sarathy
n-Heptane/Mehl
n-Octane/Ji
Heptamethylnonane/Westbrook
Isobutene/Di...
Transforming data into knowledge—ProcessInformatics for combustion chemistry
Michael Frenklach *Department of Mechanical E...
“the key obstacle is the inconsistency of accumulating
data and proliferating reaction mechanisms.
Process Informatics int...
Model Complexity is still increasing
2-methylalkanes/Sarathy
n-Heptane/Mehl
n-Octane/Ji
Heptamethylnonane/Westbrook
Isobut...
Model Complexity is still increasing
2-methylalkanes/Sarathy
n-Heptane/Mehl
n-Octane/Ji
Heptamethylnonane/Westbrook
Isobut...
Assoc. Lib Director, ORNL Computing
APPENDIX D
THERMO DATA (FORMAT AND LISTING)
The order and format of the input data cards in this appendix are given in the...
NASA (Chemkin) format is very dense –

not much room for species identifiers
Chemical Formula Parameters for H(T), S(T)Spec...
Space constraints led to “creative” 

naming schemes
MVOX
IIC4H7Q2-T
C3H5-A C3H5-SC6H101OOH5-4
TC4H8O2H-I
C4H8O1-3
C3KET21...
Sometimes the same species appears twice
in a model, with different names
• C3KET21 is generated from alkyl peroxy radical...
We need a tool to help identify species
Reaction Mechanism Generator (RMG-Py)
has many of the required features
• Represent molecules and recognize duplicates

• ...
Algorithm is like solving a Sudoku puzzle.
• Identify species with only one possible structure

• CO2

• H2O

• C3H8

• Th...
Identifying ‘sc3h5co’ from its reactions:
The first thing the tool will do is to check previously imported models for matc...
Identifying ‘sc3h5co’ from its reactions:
The first thing the tool will do is to check previously imported models for matc...
Identifying ‘sc3h5co’ from its reactions:
The first thing the tool will do is to check previously imported models for matc...
Identifying ‘sc3h5co’ from its reactions:
The first thing the tool will do is to check previously imported models for matc...
Identifying ‘sc3h5co’ from its reactions:
R1-R6
R7
The first thing the tool will do is to check previously imported models...
‘sc3h5co’ is but-2-enoyl
Human-Computer team can
identify species more quickly
• Our new tool uses RMG to generate reactions to
compare with the ta...
• Model compiled over many years by many authors

• Recently replaced core chemistry, merged methyl
cyclohexane, replaced ...
60 papers in Reaction Kinetics division

33 mention or use Chemkin software

28 have supplementary material

17 are kineti...
Of 13 models in the 34th Symposium,
77% are at least 77% identified
113
113
852
137
1686
380
1064
202
488
296
94
125
335
11...
Some species have many names
• Note that A1 means either benzene or phenyl
Species Names
propen-2-yl radical C3H5-T, ch3cc...
Thermochemistry:
Of 1039 Species found in 2 or more models…
😀 408 (39%) have identical thermo

😊 731 (70%) span < 5 kJ/mol...
Of 60 species also in Argonne/Ruscic’s
Active Thermochemical Tables…
😀 3 are always within the ATcT
uncertainty bounds

😊 ...
Of 60 species also in Argonne/Ruscic’s 

Active Thermochemical Tables…
😊 52 (87%) are sometimes within 1 kJ/
mol of ATcT u...
Kinetics:
Of 1303 reactions in 3 or more models…
😉 432 (33%) have identical rates

😊 721 (55%) agree within a factor of 2
...
Often, unannounced changes are made when
merging from one model to another.
⇄
⟶ + +
+
Examples of reactions slowed by 50 o...
M1 M2 M3 M4 M5 M6 M7 M8 M9 M10 M11 M12 M13
C6H13-2 + O2 <=> C6H12-1 + HO2 -19.4 11.5 -19.4 -19.4
IC3H7 + O2 <=> C3H6 + HO2...
M1 M2 M3 M4 M5 M6 M7 M8 M9 M10 M11 M12 M13
C6H13-2 + O2 <=> C6H12-1 + HO2 -19.4 11.5 -19.4 -19.4
IC3H7 + O2 <=> C3H6 + HO2...
log10(k)

@1000K
A 

(cm3/mol/s)
n
(T=1K)
Ea 

(cal/mol)
Reference
–19.4 4.5E-19 0 5,020
Curran (1998)
Discusses but gives...
log10(k)

@1000K
A 

(cm3/mol/s)
n
(T=1K)
Ea 

(cal/mol)
Reference
–19.4 4.5E-19 0 5,020
Curran (1998)
Discusses but gives...
.edu/comocheng
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Richard H. West
20 May 2015
34
r.west@neu.edu richardhwest rwest
Grant No. 1403171
2015 US Combustion Meeting - West - Identification, Correction, and Comparison
 of Detailed Kinetic Models
2015 US Combustion Meeting - West - Identification, Correction, and Comparison
 of Detailed Kinetic Models
2015 US Combustion Meeting - West - Identification, Correction, and Comparison
 of Detailed Kinetic Models
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2015 US Combustion Meeting - West - Identification, Correction, and Comparison
 of Detailed Kinetic Models

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Presentation at the 9th US National Combustion Meeting in May 2015.
"Identification, Correction, and Comparison
 of Detailed Kinetic Models"

Extended abstract available from http://www.northeastern.edu/comocheng/2015/05/uscombustionmeeting/

This material is based upon work supported by the National Science Foundation under Grant Number 1403171. Any opinions, findings, and conclusions or recommendations expressed in this material are those of the author(s) and do not necessarily reflect the views of the National Science Foundation.

Published in: Science
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2015 US Combustion Meeting - West - Identification, Correction, and Comparison
 of Detailed Kinetic Models

  1. 1. .edu/comocheng Victor R. Lambert & Richard H. West 9th US National Combustion Meeting 20 June 2015 1 r.west@neu.edu richardhwest rwest Identification, Correction, and Comparison
 of Detailed Kinetic Models Grant No. 1403171
  2. 2. Identification, Correction, and Comparison
 of Detailed Kinetic Models ! !" ! !" # ! !" ! ! !" ! !"# $ !" ! !" ! " #$ !"# !" !" !"# "#! !"# ! !" ! !" ! " #$ #$! " ! " #$ ! !" !"" # !"" # !"# !"#$" ! " #$ #$! ! !" !" ! ! ! !" ! !"# ! ! ! ! !"""# !""# $ !""# $ !" ! " #$ ! ! " #$ %! ! " #$ % ! " #$ % ! " #$ %! Elizabeth Becky Eliza Liz Beth with many names for the same thing... ...it is difficult to compare models... ...researchers give molecules nicknames. ...and easy to make mistakes! ...and create a unified database... with this we can:.. To publish in "CHEMKIN" format... Our tool to identify species... ...allows us to analyze models. ...find common parameters,.. ...detect mistakes,.. ...identify controversial rates,.. ...of all kinetic models!
  3. 3. Model Complexity is increasing 2-methylalkanes/Sarathy n-Heptane/Mehl n-Octane/Ji Heptamethylnonane/Westbrook Isobutene/Dias Ethanol/Leplat 1-butanol/Grana Acetaldehyde/Leplat Ethylbenzene/Therrien Methylcrotonate/Bennadji Methyloleate/Naik Furan/Yasunaga Methylhexanoate/Westbrook Methydecanoate/Herbinet H2 /KlippensteinH2 /ConnaireH2 /Marinov GRI-Mech Methane/Leeds Ethane C2 /Karbach Ethylene/Egolfopoulos C3 /Appel USC-MechMarinov Propane/Qin n-Butane Neopentane/Wang n-Heptane/Curran n-Heptane/Babushok 10 100 1000 10000 1995 2000 2005 2010 Numberofspeciesinmodel Year of publication
  4. 4. Transforming data into knowledge—ProcessInformatics for combustion chemistry Michael Frenklach *Department of Mechanical Engineering, University of California, and Environmental Energy Technologies Division, Lawrence Berkeley National Laboratory, Berkeley, CA 94720, USA Abstract The present frontier of combustion chemistry is the development of predictive reaction models, namely, chemical kinetics models capable of accurate numerical predictions with quantifiable uncertain- ties. While the usual factors like deficient knowledge of reaction pathways and insufficient accuracy of individual measurements and/or theoretical calculations impede progress, the key obstacle is the incon- sistency of accumulating data and proliferating reaction mechanisms. Process Informatics introduces a new paradigm. It relies on three major components: proper organization of scientific data, availability of scientific tools for analysis and processing of these data, and engagement of the entire scientific com- munity in the data collection and analysis. The proper infrastructure will enable a new form of scien- tific method by considering the entire content of information available, assessing and assuring mutual scientific consistency of the data, rigorously assessing data uncertainty, identifying problems with the available data, evaluating model predictability, suggesting new experimental and theoretical work with the highest possible impact, reaching community consensus, and merging the assembled data into new knowledge. Ó 2006 The Combustion Institute. Published by Elsevier Inc. All rigKeywo Proceedings of the Combustion Institute 31 (2007) 125–140 www.elsevier.com/locate/proci Proceedings of the Combustion Institute
  5. 5. “the key obstacle is the inconsistency of accumulating data and proliferating reaction mechanisms. Process Informatics introduces a new paradigm. It relies on three major components: • proper organization of scientific data, • availability of scientific tools for analysis and processing of these data, • and engagement of the entire scientific community in the data collection and analysis.” M. Frenklach, Proc. Combust. Inst. 31 (2006)
  6. 6. Model Complexity is still increasing 2-methylalkanes/Sarathy n-Heptane/Mehl n-Octane/Ji Heptamethylnonane/Westbrook Isobutene/Dias Ethanol/Leplat 1-butanol/Grana Acetaldehyde/Leplat Ethylbenzene/Therrien Methylcrotonate/Bennadji Methyloleate/Naik Furan/Yasunaga Methylhexanoate/Westbrook Methydecanoate/Herbinet H2 /KlippensteinH2 /ConnaireH2 /Marinov GRI-Mech Methane/Leeds Ethane C2 /Karbach Ethylene/Egolfopoulos C3 /Appel USC-MechMarinov Propane/Qin n-Butane Neopentane/Wang n-Heptane/Curran n-Heptane/Babushok 10 100 1000 10000 1995 2000 2005 2010 Numberofspeciesinmodel Year of publication
  7. 7. Model Complexity is still increasing 2-methylalkanes/Sarathy n-Heptane/Mehl n-Octane/Ji Heptamethylnonane/Westbrook Isobutene/Dias Ethanol/Leplat 1-butanol/Grana Acetaldehyde/Leplat Ethylbenzene/Therrien Methylcrotonate/Bennadji Methyloleate/Naik Furan/Yasunaga Methylhexanoate/Westbrook Methydecanoate/Herbinet H2 /KlippensteinH2 /ConnaireH2 /Marinov GRI-Mech Methane/Leeds Ethane C2 /Karbach Ethylene/Egolfopoulos C3 /Appel USC-MechMarinov Propane/Qin n-Butane Neopentane/Wang n-Heptane/Curran n-Heptane/Babushok 10 100 1000 10000 1995 2000 2005 2010 Numberofspeciesinmodel Year of publication
  8. 8. Assoc. Lib Director, ORNL Computing
  9. 9. APPENDIX D THERMO DATA (FORMAT AND LISTING) The order and format of the input data cards in this appendix are given in the follow- ing table" Card order (a) (Final card) Contents Format Card column THERMO Temperature ranges for 2 sets of coefficients: lowest T. common T, and highest T Species name Date Atomic symbols and formula Phase of species (S, L, or G for solid, liquid, or gas, respectively) Temperature range Integer t Coefficients ai(i = 1 to 5) in equations (90) to (92) (for upper temperature interval) Integer 2 Coefficients in equations (90) to (92) (a6, a T for upper temperature interval, and a 1, a2, and a 3 for lower) Integer 3 Coefficients in equations (90) to (92) (a4, a5, a6, a, i for lower temperature interval) Integer 4 Repeat cards numbered 1 to 4 in cc 80 for each species END (Indicates end of thermodynamic data) 3A4 3F10.3 3A4 2A3 4(A2, F3. O) A1 2F10.3 I15 5(E15.8) 15 4(E15.8) I20 3A4 1 to6 1 to 30 1 to 12 19 to 24 25 to 44 45 46 to 65 80 1 to75 80 1 to75 80 1 to 60 8O ito3 aGaseous species and condensed species with only one condensed phase can be in any order. However. the sets for two or more condensed phases of the same species must be adjacent. If there are more than two condensed phases of a species, their sets must be either in increasing or decreasing order according to their temperature intervals. 168 ORIGINAL PAGE IS OF. POOR QUALITY nq
  10. 10. NASA (Chemkin) format is very dense –
 not much room for species identifiers Chemical Formula Parameters for H(T), S(T)Species Name
  11. 11. Space constraints led to “creative” 
 naming schemes MVOX IIC4H7Q2-T C3H5-A C3H5-SC6H101OOH5-4 TC4H8O2H-I C4H8O1-3 C3KET21 CH3COCH2O2H
  12. 12. Sometimes the same species appears twice in a model, with different names • C3KET21 is generated from alkyl peroxy radical isomerization pathway • CH3COCH2O2H is generated from low-temperature oxidation of acetone MVOX IIC4H7Q2-T C3H5-A C3H5-SC6H101OOH5-4 TC4H8O2H-I C4H8O1-3 C3KET21 CH3COCH2O2H
  13. 13. We need a tool to help identify species
  14. 14. Reaction Mechanism Generator (RMG-Py) has many of the required features • Represent molecules and recognize duplicates • Propose reactions from templates and rules • Estimate parameters quickly • Expand model based on known species • Modular and Extensible! ⇌RMG
  15. 15. Algorithm is like solving a Sudoku puzzle. • Identify species with only one possible structure • CO2 • H2O • C3H8 • Then species with "borrowed" thermochemistry • Then “boot-strap” based on how these react…
  16. 16. Identifying ‘sc3h5co’ from its reactions: The first thing the tool will do is to check previously imported models for matching thermochemistry blocks. For example, it could tell the user that the LLNL model for n-Heptane [29] has a species with the same parameters that has already been identified as but-2-enoyl ( ), and that LLNL called it “SC3H5CHO”. This would probably be enough evidence for the user to confirm the match. If the species cannot be found in a previously imported model, the reactions give additional clues. The seven reactions containing sc3h5co in the methyl butanoate model are: R1 sc3h5cho + o2 ⇌ sc3h5co + ho2 + ⇌ + sc3h5co R2 sc3h5cho + oh ⇌ sc3h5co + h2o + ⇌ + sc3h5co R3 sc3h5cho + o ⇌ sc3h5co + oh + ⇌ + sc3h5co R4 sc3h5cho + ch3 ⇌ sc3h5co + ch4 + ⇌ + sc3h5co R5 sc3h5cho + h ⇌ sc3h5co + h2 + ⇌ + sc3h5co R6 sc3h5cho + ho2 ⇌ sc3h5co + h2o2 + ⇌ + sc3h5co R7 sc3h5co ⇌ c3h5-s + co sc3h5co ⇌ + The first six are all hydrogen abstractions from but-2-enal (assume for now that this species has already been identified), which has four types of hydrogen atom, implying sc3h5co could be one of four possible radi- cals. The seventh reaction is the decomposi- tion into propenyl and carbon monoxide, also limiting sc3h5co to four possible spe- cies. The Venn diagram in Fig. 4 shows that only one species satisfies all seven reactions: but-2-enoyl. The tool will present the user with this data, as well as a comparison of Fig. 4. Venn diagram showing identification of “sc3h5co” from reactions R1 through R7.
  17. 17. Identifying ‘sc3h5co’ from its reactions: The first thing the tool will do is to check previously imported models for matching thermochemistry blocks. For example, it could tell the user that the LLNL model for n-Heptane [29] has a species with the same parameters that has already been identified as but-2-enoyl ( ), and that LLNL called it “SC3H5CHO”. This would probably be enough evidence for the user to confirm the match. If the species cannot be found in a previously imported model, the reactions give additional clues. The seven reactions containing sc3h5co in the methyl butanoate model are: R1 sc3h5cho + o2 ⇌ sc3h5co + ho2 + ⇌ + sc3h5co R2 sc3h5cho + oh ⇌ sc3h5co + h2o + ⇌ + sc3h5co R3 sc3h5cho + o ⇌ sc3h5co + oh + ⇌ + sc3h5co R4 sc3h5cho + ch3 ⇌ sc3h5co + ch4 + ⇌ + sc3h5co R5 sc3h5cho + h ⇌ sc3h5co + h2 + ⇌ + sc3h5co R6 sc3h5cho + ho2 ⇌ sc3h5co + h2o2 + ⇌ + sc3h5co R7 sc3h5co ⇌ c3h5-s + co sc3h5co ⇌ + The first six are all hydrogen abstractions from but-2-enal (assume for now that this species has already been identified), which has four types of hydrogen atom, implying sc3h5co could be one of four possible radi- cals. The seventh reaction is the decomposi- tion into propenyl and carbon monoxide, also limiting sc3h5co to four possible spe- cies. The Venn diagram in Fig. 4 shows that only one species satisfies all seven reactions: but-2-enoyl. The tool will present the user with this data, as well as a comparison of Fig. 4. Venn diagram showing identification of “sc3h5co” from reactions R1 through R7.
  18. 18. Identifying ‘sc3h5co’ from its reactions: The first thing the tool will do is to check previously imported models for matching thermochemistry blocks. For example, it could tell the user that the LLNL model for n-Heptane [29] has a species with the same parameters that has already been identified as but-2-enoyl ( ), and that LLNL called it “SC3H5CHO”. This would probably be enough evidence for the user to confirm the match. If the species cannot be found in a previously imported model, the reactions give additional clues. The seven reactions containing sc3h5co in the methyl butanoate model are: R1 sc3h5cho + o2 ⇌ sc3h5co + ho2 + ⇌ + sc3h5co R2 sc3h5cho + oh ⇌ sc3h5co + h2o + ⇌ + sc3h5co R3 sc3h5cho + o ⇌ sc3h5co + oh + ⇌ + sc3h5co R4 sc3h5cho + ch3 ⇌ sc3h5co + ch4 + ⇌ + sc3h5co R5 sc3h5cho + h ⇌ sc3h5co + h2 + ⇌ + sc3h5co R6 sc3h5cho + ho2 ⇌ sc3h5co + h2o2 + ⇌ + sc3h5co R7 sc3h5co ⇌ c3h5-s + co sc3h5co ⇌ + The first six are all hydrogen abstractions from but-2-enal (assume for now that this species has already been identified), which has four types of hydrogen atom, implying sc3h5co could be one of four possible radi- cals. The seventh reaction is the decomposi- tion into propenyl and carbon monoxide, also limiting sc3h5co to four possible spe- cies. The Venn diagram in Fig. 4 shows that only one species satisfies all seven reactions: but-2-enoyl. The tool will present the user with this data, as well as a comparison of Fig. 4. Venn diagram showing identification of “sc3h5co” from reactions R1 through R7.
  19. 19. Identifying ‘sc3h5co’ from its reactions: The first thing the tool will do is to check previously imported models for matching thermochemistry blocks. For example, it could tell the user that the LLNL model for n-Heptane [29] has a species with the same parameters that has already been identified as but-2-enoyl ( ), and that LLNL called it “SC3H5CHO”. This would probably be enough evidence for the user to confirm the match. If the species cannot be found in a previously imported model, the reactions give additional clues. The seven reactions containing sc3h5co in the methyl butanoate model are: R1 sc3h5cho + o2 ⇌ sc3h5co + ho2 + ⇌ + sc3h5co R2 sc3h5cho + oh ⇌ sc3h5co + h2o + ⇌ + sc3h5co R3 sc3h5cho + o ⇌ sc3h5co + oh + ⇌ + sc3h5co R4 sc3h5cho + ch3 ⇌ sc3h5co + ch4 + ⇌ + sc3h5co R5 sc3h5cho + h ⇌ sc3h5co + h2 + ⇌ + sc3h5co R6 sc3h5cho + ho2 ⇌ sc3h5co + h2o2 + ⇌ + sc3h5co R7 sc3h5co ⇌ c3h5-s + co sc3h5co ⇌ + The first six are all hydrogen abstractions from but-2-enal (assume for now that this species has already been identified), which has four types of hydrogen atom, implying sc3h5co could be one of four possible radi- cals. The seventh reaction is the decomposi- tion into propenyl and carbon monoxide, also limiting sc3h5co to four possible spe- cies. The Venn diagram in Fig. 4 shows that only one species satisfies all seven reactions: but-2-enoyl. The tool will present the user with this data, as well as a comparison of Fig. 4. Venn diagram showing identification of “sc3h5co” from reactions R1 through R7.
  20. 20. Identifying ‘sc3h5co’ from its reactions: R1-R6 R7 The first thing the tool will do is to check previously imported models for matching thermochemistry blocks. For example, it could tell the user that the LLNL model for n-Heptane [29] has a species with the same parameters that has already been identified as but-2-enoyl ( ), and that LLNL called it “SC3H5CHO”. This would probably be enough evidence for the user to confirm the match. If the species cannot be found in a previously imported model, the reactions give additional clues. The seven reactions containing sc3h5co in the methyl butanoate model are: R1 sc3h5cho + o2 ⇌ sc3h5co + ho2 + ⇌ + sc3h5co R2 sc3h5cho + oh ⇌ sc3h5co + h2o + ⇌ + sc3h5co R3 sc3h5cho + o ⇌ sc3h5co + oh + ⇌ + sc3h5co R4 sc3h5cho + ch3 ⇌ sc3h5co + ch4 + ⇌ + sc3h5co R5 sc3h5cho + h ⇌ sc3h5co + h2 + ⇌ + sc3h5co R6 sc3h5cho + ho2 ⇌ sc3h5co + h2o2 + ⇌ + sc3h5co R7 sc3h5co ⇌ c3h5-s + co sc3h5co ⇌ + The first six are all hydrogen abstractions from but-2-enal (assume for now that this species has already been identified), which has four types of hydrogen atom, implying sc3h5co could be one of four possible radi- cals. The seventh reaction is the decomposi- tion into propenyl and carbon monoxide, also limiting sc3h5co to four possible spe- cies. The Venn diagram in Fig. 4 shows that only one species satisfies all seven reactions: but-2-enoyl. The tool will present the user with this data, as well as a comparison of Fig. 4. Venn diagram showing identification of “sc3h5co” from reactions R1 through R7.
  21. 21. ‘sc3h5co’ is but-2-enoyl
  22. 22. Human-Computer team can identify species more quickly • Our new tool uses RMG to generate reactions to compare with the target model • A human reviews the evidence and confirms matches. Generate reactions, check for equivalents, propose matches Review evidence, confirm matches. proposed matches proposed matches Human Computer confirmed matches confirmed matches
  23. 23. • Model compiled over many years by many authors • Recently replaced core chemistry, merged methyl cyclohexane, replaced toluene, and still updating other submechanisms… • We found 51 unintended duplicates, now fixed. • Identifying species allowed reactions to be classified and correlated uncertainties estimated, for Uncertainty Quantification (talk 114RK-0445) Identified all 1.7k species in latest LLNL model
  24. 24. 60 papers in Reaction Kinetics division 33 mention or use Chemkin software 28 have supplementary material 17 are kinetic models 13 are usable We analyzed all mechanisms in proceedings of 34th Combustion Symposium
  25. 25. Of 13 models in the 34th Symposium, 77% are at least 77% identified 113 113 852 137 1686 380 1064 202 488 296 94 125 335 113 121 877 137 1924 1924 1350 202 662 355 277 125 392 0 500 1000 1500 2000 Veloo p.599 Sheen p.527 Darcy p.411 Liu p.401 Malewicki p.361 Malewicki p.353 Wang p.335 Husson p.325 Herbinet p.297 Dagaut p.289 Matsugi p.269 Labbe p.259 Somers p.225 Identified Unidentified C/H/O 
 Species (as of last week).
  26. 26. Some species have many names • Note that A1 means either benzene or phenyl Species Names propen-2-yl radical C3H5-T, ch3cch2, TC3H5 benzene A1, A, C6H6#, c6h6 phenyl radical A1J, A1, C6H5#, c6h5 1-butyl radical PC4H9, R20C4H9, NC4H9, NC4H9P 2-hexyl radical R72C6H13, hex2yl, C6H13-2 isoprene b13de2m, IC5H8
  27. 27. Thermochemistry: Of 1039 Species found in 2 or more models… 😀 408 (39%) have identical thermo 😊 731 (70%) span < 5 kJ/mol 😟 28 (3%) span > 50 kJ/mol Spread in ∆Hf(298K) in kJ/mol #ofSpecies
  28. 28. Of 60 species also in Argonne/Ruscic’s Active Thermochemical Tables… 😀 3 are always within the ATcT uncertainty bounds 😊 23 (38%) are always within 1 kJ/mol of ATcT uncertainty 😟 13 (22%) are sometimes more than 10 kJ/mol outside ATcT uncertainty Worst error in ∆Hf(298K) beyond uncertainty, in kJ/mol #ofSpecies
  29. 29. Of 60 species also in Argonne/Ruscic’s 
 Active Thermochemical Tables… 😊 52 (87%) are sometimes within 1 kJ/ mol of ATcT uncertainty 😧 4 are always more than 10 kJ/mol outside ATcT uncertainty Least error in ∆Hf(298K) beyond uncertainty, in kJ/mol #ofSpecies
  30. 30. Kinetics: Of 1303 reactions in 3 or more models… 😉 432 (33%) have identical rates 😊 721 (55%) agree within a factor of 2 😟 233 (18%) disagree by > 10x 😬 45 (3%) disagree by > 1000x
 span in log10(k @ 1000K) #ofReactions (16 outliers > 1010)
  31. 31. Often, unannounced changes are made when merging from one model to another. ⇄ ⟶ + + + Examples of reactions slowed by 50 orders of magnitude without comment: The present X model was coupled to the C5–C7 LLNL n-Heptane sub- mechanisms ...and some rates were divided by 10 50
  32. 32. M1 M2 M3 M4 M5 M6 M7 M8 M9 M10 M11 M12 M13 C6H13-2 + O2 <=> C6H12-1 + HO2 -19.4 11.5 -19.4 -19.4 IC3H7 + O2 <=> C3H6 + HO2 -19.4 -19.4 11.1 -19.4 -19.4 11.1 -19.4 11.4 C3H5-A + HO2 <=> C2H3 + CH2O + OH -18.0 -18.0 12.8 11.5 C5H11-2 + O2 <=> C5H10-1 + HO2 8.8 10.8 -19.4 8.8 SC4H9 + O2 <=> C4H8-1 + HO2 -18.8 11.0 -18.8 11.2 -18.8 8.8 11.3 NC3H7 + O2 <=> C3H6 + HO2 -19.2 10.9 -19.2 11.0 -19.2 -19.2 PC4H9 + O2 <=> C4H8-1 + HO2 -18.8 11.0 8.1 C5H11-3 + O2 <=> C5H10-2 + HO2 9.4 -19.2 9.4 IC4H9 + O2 <=> IC4H8 + HO2 -18.8 -18.8 9.1 Many Radical + O2 = Alkene + HO2 reactions vary by 28–31 orders of magnitude at 1000 K ⇄+ + Some models all fast Some models all slow Some modes a mixture log10(k@1000K in cm3/mol/s) for each of 13 modelsReaction Example:
  33. 33. M1 M2 M3 M4 M5 M6 M7 M8 M9 M10 M11 M12 M13 C6H13-2 + O2 <=> C6H12-1 + HO2 -19.4 11.5 -19.4 -19.4 IC3H7 + O2 <=> C3H6 + HO2 -19.4 -19.4 11.1 -19.4 -19.4 11.1 -19.4 11.4 C3H5-A + HO2 <=> C2H3 + CH2O + OH -18.0 -18.0 12.8 11.5 C5H11-2 + O2 <=> C5H10-1 + HO2 8.8 10.8 -19.4 8.8 SC4H9 + O2 <=> C4H8-1 + HO2 -18.8 11.0 -18.8 11.2 -18.8 8.8 11.3 NC3H7 + O2 <=> C3H6 + HO2 -19.2 10.9 -19.2 11.0 -19.2 -19.2 PC4H9 + O2 <=> C4H8-1 + HO2 -18.8 11.0 8.1 C5H11-3 + O2 <=> C5H10-2 + HO2 9.4 -19.2 9.4 IC4H9 + O2 <=> IC4H8 + HO2 -18.8 -18.8 9.1 Many Radical + O2 = Alkene + HO2 reactions vary by 28–31 orders of magnitude at 1000 K ⇄+ + Some models all fast Some models all slow Some modes a mixture log10(k@1000K in cm3/mol/s) for each of 13 modelsReaction Example: ⇄+ +
  34. 34. log10(k)
 @1000K A 
 (cm3/mol/s) n (T=1K) Ea 
 (cal/mol) Reference –19.4 4.5E-19 0 5,020 Curran (1998) Discusses but gives no numbers 11.1 1.26E+11 0 0 Tsang (1988) 
 Literature Review 11.4 1.2E+12 0 3,000 Ranzi / Milan (in models since pre-2008) 11.4 1.4E+12 0 5,000 Battin-Leclerc / Nancy
 (Generated by EXGAS in 2001) 11.2 6.7E+20 -3.02 2,504 DeSain, Klippenstein, et al. 2003. 
 Ab initio/ master equation The slow rates all come from one source 
 (through a variety of citations) • Used by 5 of the 13 models • “C3 sub-models” attributed to Ji (2012), Sarathy (2012), Sarathy (2011), Sivaramakrishnan (2007), Peterson (2007), Curran (2002), Pope (2000), Curran (1998)… • Trail leads to Curran, Gaffuri, Pitz, Westbrook, Combust. Flame, 114 (1998). Page 154 talks in depth about this family of reactions, which are chemically activated via excited adduct, but no rates are given. ⇄+ +
  35. 35. log10(k)
 @1000K A 
 (cm3/mol/s) n (T=1K) Ea 
 (cal/mol) Reference –19.4 4.5E-19 0 5,020 Curran (1998) Discusses but gives no numbers 11.1 1.26E+11 0 0 Tsang (1988) 
 Literature Review 11.4 1.2E+12 0 3,000 Ranzi / Milan (in models since pre-2008) 11.4 1.4E+12 0 5,000 Battin-Leclerc / Nancy
 (Generated by EXGAS in 2001) 11.2 6.7E+20 -3.02 2,504 DeSain, Klippenstein, et al. 2003. 
 Ab initio/ master equation* The fast rates come from a variety of estimates ⇄+ + *for comparison. Not used in these models
  36. 36. .edu/comocheng ! ! !" # ! !" ! ! !" ! !"# $ !" ! !" ! " #$ !"# !" !" !"# "#! !"# ! !" ! !" ! " #$ #$! " ! " #$ ! !" !"" # !"" # !"# !"#$" ! " #$ #$! ! !" !" ! ! ! !" ! !"# ! ! ! ! !"""# !""# $ !""# $ !" ! " #$ ! ! " #$ %! ! " #$ % ! " #$ % ! " #$ %! Elizabeth Becky Eliza Liz Beth with many names for the same thing... ...it is difficult to compare models... ...researchers give molecules nicknames. ...and easy to make mistakes! ...and create a unified database... with this we can:.. To publish in "CHEMKIN" format... Our tool to identify species... ...allows us to analyze models. ...find common parameters,.. ...detect mistakes,.. ...identify controversial rates,.. ...of all kinetic models! Richard H. West r.west@neu.edu Grant No. 1403171
  37. 37. .edu/comocheng Richard H. West 20 May 2015 34 r.west@neu.edu richardhwest rwest Grant No. 1403171

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