.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 Comparisonof Detailed Kinetic Models

Grant No. 1403171

Identification, Correction, and Comparisonof Detailed Kinetic Models

!

!"

!

!" #

!

!"

!

!!"

!

!"#$

!"

!

!"!"#$

!"#

!" !"

!"#"#!

!"#

!!"

!!"

!"#$

#$!"

!"#$

!!"

!""#

!""#

!"#

!"#$"

!"#$

#$!

!!"

!"

!

!

!

!"

!

!"#

!

!

!!

!"""#!""#

$

!""#$

!"

!"#$

!!"#$

%!

!"#$

%

!"#$

%!"#$

%!

Elizabeth

Becky

ElizaLizBeth

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!

Model Complexity is increasing2-methylalkanes/Sarathy

n-Heptane/Mehln-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-MechMethane/Leeds

Ethane

C2/Karbach

Ethylene/Egolfopoulos

C3/AppelUSC-MechMarinov

Propane/Qin

n-ButaneNeopentane/Wang

n-Heptane/Currann-Heptane/Babushok

10

100

1000

10000

1995 2000 2005 2010

Num

ber o

f spe

cies

in m

odel

Year of publication

Transforming data into knowledge—ProcessInformatics for combustion chemistryMichael 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.! 2006 The Combustion Institute. Published by Elsevier Inc. All rights reserved.Keywords: Kinetics; Modeling; Optimization; Consistency; Informatics; PrIMe

1. Introduction

1.1. Progress in combustion depends on reliablereaction kinetics

Research is motivated by the human desire toexplain phenomena surrounding us and the passionfor new discoveries. Driven by individual satisfac-tion such activities aim at improving the qualityof human experience. One can generalize the stimu-lus for research as developing the ability of makingpredictions. Indeed, predicting properties of a mate-

rial before it is synthesized, predicting performanceof a device before it is built, or predicting the mag-nitude of a natural disaster ahead of time all haveobvious benefits to society.In the area of combustion, we have all the aboveelements: the fascination with fire from ancienttimes, its broad application to numerous aspectsof everyday life, and the definite need for reliablepredictions (see Fig. 1). In recent decades the com-bustion research was largely driven by the desiredincrease in energy efficiency, reduction in pollutantformation, and material synthesis. The need fortying the research to practical applications was fur-ther emphasized in the Hottel address of the 28thSymposium by Professor Glassman [1].1540-7489/$ - see front matter ! 2006 The Combustion Institute. Published by Elsevier Inc. All rights reserved.

doi:10.1016/j.proci.2006.08.121

* Fax: +1 510 643 5599.E-mail address: myf@me.berkeley.edu

Proceedings of the Combustion Institute 31 (2007) 125–140

www.elsevier.com/locate/proci

Proceedingsof the

CombustionInstitute

“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)

Model Complexity is still increasing2-methylalkanes/Sarathy

n-Heptane/Mehln-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-MechMethane/Leeds

Ethane

C2/Karbach

Ethylene/Egolfopoulos

C3/AppelUSC-MechMarinov

Propane/Qin

n-ButaneNeopentane/Wang

n-Heptane/Currann-Heptane/Babushok

10

100

1000

10000

1995 2000 2005 2010

Num

ber o

f spe

cies

in m

odel

Year of publication

Model Complexity is still increasing2-methylalkanes/Sarathy

n-Heptane/Mehln-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-MechMethane/Leeds

Ethane

C2/Karbach

Ethylene/Egolfopoulos

C3/AppelUSC-MechMarinov

Propane/Qin

n-ButaneNeopentane/Wang

n-Heptane/Currann-Heptane/Babushok

10

100

1000

10000

1995 2000 2005 2010

Num

ber o

f spe

cies

in m

odel

Year of publication

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 follow-

ing table"

Card

order

(a)

(Final

card)

ContentsFormat 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

2F10.3I15

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

NASA (Chemkin) format is very dense –not much room for species identifiers

Chemical Formula Parameters for H(T), S(T)Species Name

Space constraints led to “creative” naming schemes

MVOX

IIC4H7Q2-T

C3H5-A C3H5-SC6H101OOH5-4

TC4H8O2H-IC4H8O1-3

C3KET21

CH3COCH2O2H

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-IC4H8O1-3

C3KET21

CH3COCH2O2H

We need a tool to help identify species

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

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…

Identifying ‘sc3h5co’ from its reactions:

7

3. Implementation

3.1. How the importer tool will behave

To illustrate how the tool would help a user to identify a species, consider the species labeled “sc3h5co” from a large methyl butanoate combustion model [28]. The data on sc3h5co are a block of thermochemistry parameters and seven reactions in which it participates (from 1,219 reactions in the model). The thermochemistry block contains the chemical formula and expressions for enthalpy and entropy as functions of temperature:

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

sc3h5co 11/15/95 thermc 4h 5o 1 0g 300.000 5000.000 1392.000 21 1.25514754e+01 1.22521948e-02-4.22382101e-06 6.59184896e-10-3.83818826e-14 2-4.25349795e+03-4.02864145e+01 1.74191343e+00 3.97229536e-02-3.20061901e-05 3 1.38227925e-08-2.46272017e-12-6.64428100e+02 1.70762023e+01

Species label Chemical formula: C4H5O1 Parameters for H(T), S(T) expressions

Fig. 4. Venn diagram showing identification of “sc3h5co” from reactions R1 through R7.

Identifying ‘sc3h5co’ from its reactions:

7

3. Implementation

3.1. How the importer tool will behave

To illustrate how the tool would help a user to identify a species, consider the species labeled “sc3h5co” from a large methyl butanoate combustion model [28]. The data on sc3h5co are a block of thermochemistry parameters and seven reactions in which it participates (from 1,219 reactions in the model). The thermochemistry block contains the chemical formula and expressions for enthalpy and entropy as functions of temperature:

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

sc3h5co 11/15/95 thermc 4h 5o 1 0g 300.000 5000.000 1392.000 21 1.25514754e+01 1.22521948e-02-4.22382101e-06 6.59184896e-10-3.83818826e-14 2-4.25349795e+03-4.02864145e+01 1.74191343e+00 3.97229536e-02-3.20061901e-05 3 1.38227925e-08-2.46272017e-12-6.64428100e+02 1.70762023e+01

Species label Chemical formula: C4H5O1 Parameters for H(T), S(T) expressions

Fig. 4. Venn diagram showing identification of “sc3h5co” from reactions R1 through R7.

Identifying ‘sc3h5co’ from its reactions:

7

3. Implementation

3.1. How the importer tool will behave

To illustrate how the tool would help a user to identify a species, consider the species labeled “sc3h5co” from a large methyl butanoate combustion model [28]. The data on sc3h5co are a block of thermochemistry parameters and seven reactions in which it participates (from 1,219 reactions in the model). The thermochemistry block contains the chemical formula and expressions for enthalpy and entropy as functions of temperature:

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

sc3h5co 11/15/95 thermc 4h 5o 1 0g 300.000 5000.000 1392.000 21 1.25514754e+01 1.22521948e-02-4.22382101e-06 6.59184896e-10-3.83818826e-14 2-4.25349795e+03-4.02864145e+01 1.74191343e+00 3.97229536e-02-3.20061901e-05 3 1.38227925e-08-2.46272017e-12-6.64428100e+02 1.70762023e+01

Species label Chemical formula: C4H5O1 Parameters for H(T), S(T) expressions

Fig. 4. Venn diagram showing identification of “sc3h5co” from reactions R1 through R7.

Identifying ‘sc3h5co’ from its reactions:

7

3. Implementation

3.1. How the importer tool will behave

To illustrate how the tool would help a user to identify a species, consider the species labeled “sc3h5co” from a large methyl butanoate combustion model [28]. The data on sc3h5co are a block of thermochemistry parameters and seven reactions in which it participates (from 1,219 reactions in the model). The thermochemistry block contains the chemical formula and expressions for enthalpy and entropy as functions of temperature:

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

sc3h5co 11/15/95 thermc 4h 5o 1 0g 300.000 5000.000 1392.000 21 1.25514754e+01 1.22521948e-02-4.22382101e-06 6.59184896e-10-3.83818826e-14 2-4.25349795e+03-4.02864145e+01 1.74191343e+00 3.97229536e-02-3.20061901e-05 3 1.38227925e-08-2.46272017e-12-6.64428100e+02 1.70762023e+01

Species label Chemical formula: C4H5O1 Parameters for H(T), S(T) expressions

Fig. 4. Venn diagram showing identification of “sc3h5co” from reactions R1 through R7.

Identifying ‘sc3h5co’ from its reactions:

R1-R6R7

7

3. Implementation

3.1. How the importer tool will behave

To illustrate how the tool would help a user to identify a species, consider the species labeled “sc3h5co” from a large methyl butanoate combustion model [28]. The data on sc3h5co are a block of thermochemistry parameters and seven reactions in which it participates (from 1,219 reactions in the model). The thermochemistry block contains the chemical formula and expressions for enthalpy and entropy as functions of temperature:

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

sc3h5co 11/15/95 thermc 4h 5o 1 0g 300.000 5000.000 1392.000 21 1.25514754e+01 1.22521948e-02-4.22382101e-06 6.59184896e-10-3.83818826e-14 2-4.25349795e+03-4.02864145e+01 1.74191343e+00 3.97229536e-02-3.20061901e-05 3 1.38227925e-08-2.46272017e-12-6.64428100e+02 1.70762023e+01

Species label Chemical formula: C4H5O1 Parameters for H(T), S(T) expressions

Fig. 4. Venn diagram showing identification of “sc3h5co” from reactions R1 through R7.

‘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 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

• 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

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

Of 13 models in the 34th Symposium, 77% are at least 77% identified

113113

852137

1686380

1064202

488296

94125

335

113121

877137

19241924

1350202

662355

277125

392

0 500 1000 1500 2000

Veloo p.599Sheen p.527Darcy p.411

Liu p.401Malewicki p.361Malewicki p.353

Wang p.335Husson p.325

Herbinet p.297Dagaut p.289Matsugi p.269

Labbe p.259Somers p.225 Identified

Unidentified

C/H/O Species

(as of last week).

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

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

# of

Spe

cies

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

# of

Spe

cies

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

# of

Spe

cies

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)

# of

Rea

ctio

ns

(16 outliers > 1010)

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

1050

M1 M2 M3 M4 M5 M6 M7 M8 M9 M10 M11 M12 M13C6H13-2 + O2 <=> C6H12-1 + HO2 -19.4 11.5 -19.4 -19.4IC3H7 + O2 <=> C3H6 + HO2 -19.4 -19.4 11.1 -19.4 -19.4 11.1 -19.4 11.4C3H5-A + HO2 <=> C2H3 + CH2O + OH -18.0 -18.0 12.8 11.5C5H11-2 + O2 <=> C5H10-1 + HO2 8.8 10.8 -19.4 8.8SC4H9 + O2 <=> C4H8-1 + HO2 -18.8 11.0 -18.8 11.2 -18.8 8.8 11.3NC3H7 + O2 <=> C3H6 + HO2 -19.2 10.9 -19.2 11.0 -19.2 -19.2PC4H9 + O2 <=> C4H8-1 + HO2 -18.8 11.0 8.1C5H11-3 + O2 <=> C5H10-2 + HO2 9.4 -19.2 9.4IC4H9 + 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:

M1 M2 M3 M4 M5 M6 M7 M8 M9 M10 M11 M12 M13C6H13-2 + O2 <=> C6H12-1 + HO2 -19.4 11.5 -19.4 -19.4IC3H7 + O2 <=> C3H6 + HO2 -19.4 -19.4 11.1 -19.4 -19.4 11.1 -19.4 11.4C3H5-A + HO2 <=> C2H3 + CH2O + OH -18.0 -18.0 12.8 11.5C5H11-2 + O2 <=> C5H10-1 + HO2 8.8 10.8 -19.4 8.8SC4H9 + O2 <=> C4H8-1 + HO2 -18.8 11.0 -18.8 11.2 -18.8 8.8 11.3NC3H7 + O2 <=> C3H6 + HO2 -19.2 10.9 -19.2 11.0 -19.2 -19.2PC4H9 + O2 <=> C4H8-1 + HO2 -18.8 11.0 8.1C5H11-3 + O2 <=> C5H10-2 + HO2 9.4 -19.2 9.4IC4H9 + 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:

⇄+ +

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.

⇄+ +

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

.edu/comocheng

!

!"

!

!" #

!

!"

!

!!"

!

!"#$

!"

!

!"!"#$

!"#

!" !"

!"#"#!

!"#

!!"

!!"

!"#$

#$!"

!"#$

!!"

!""#

!""#

!"#

!"#$"

!"#$

#$!

!!"

!"

!

!

!

!"

!

!"#

!

!

!!

!"""#!""#

$

!""#$

!"

!"#$

!!"#$

%!

!"#$

%

!"#$

%!"#$

%!

Elizabeth

Becky

ElizaLizBeth

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

.edu/comocheng

Richard H. West 20 May 2015

34

r.west@neu.edu richardhwest rwest

Grant No. 1403171