WHAT'S NEW IN GRI-Mech 3.0

GRI-Mech 3.0 is an optimized mechanism designed to model natural gas combustion, including NO formation and reburn chemistry. It is the successor to version 2.11, and another step in the continuing updating evolution of the mechanism. The optimization process is designed to provide sound basic kinetics which also furnish the best combined modeling predictability of basic combustion properties. Improvements were made in the categories of updating the kinetics with recent literature results, including some new and improved target experiments to the optimization, expanding the mechanism and target selection, and examining the sensitivity to the thermodynamics.

Rate coefficient parameter changes are noted on the individual reaction Web pages.  The CH kinetics important to prompt NO formation were altered in light of new measurements. New expressions were also used for the H + O2 reactions, CH3 + O2, CH2O + H and CH2O decomposition. The methanol decomposition/chemical activation system was recomputed. The oxidation steps CH3 + O and CH2 + O2 feature new branching paths.

Two main additions were made to the kinetics mechanism, with the addition of 4 species. Acetaldehyde and vinoxy chemistry are included to better describe ethylene oxidation, and this path is now included among the Ox + C2Hy reaction products. Because natural gas contains propane (and some higher hydrocarbons that may be approximately represented by propane), a minimal set of propane kinetics is included to model this species, as a minor constituent only.

Other new target additions include a series of shock tube observations sensitive to the oxidation of the formaldehyde intermediate; a set of shock tube, low pressure flame, and flow reactor experiments concerning prompt NO formation and reburn; and a few targets concerning the shortening of methane shock tube ignition delays by small amounts of propane or ethane. The sets of shock tube ignition delays and laminar flame speeds were revised and expanded. Many of these changes reflect the acquisition of improved data.

The new mechanism contains 325 reactions (3 are duplicates because the sum of two rate parameter expressions is required) and 53 species (including argon). The final optimization to 77 targets altered 31 rate parameters.

The major results of the new mechanism optimization are:

1. Deviations from the target values are generally less than previously. (The chi square for the sum of common retained targets dropped from 0.96 to 0.81.)

2. Similar final values for the key rates CH3 + H, CH3 + OH, and CH3 + O2 were found.

3. Including formaldehyde target optimization did not require changes to the new expressions for the sensitive CH2O + M and CH2O + H rate constants. Other changes consistent with the rest of the targets sufficed.

4. Significant thermodynamics sensitivity was found only for HCN in some targets, leading to an alteration of the JANAF value.

5. A new, improved low pressure flame prompt NO target results in higher values for CH + N2, and predictions of increased prompt NO.

6. New lower experimental flame speed values remain overpredicted by the optimized mechanism. We have not examined transport uncertainties yet in this regard. Note also in making comparisons that some computational inaccuracies exist in the flame speed computations used for the GRI-Mech 1.2 target optimization.

Some details on the new optimization are provided.

 


GETTING THE FILES

The following files can be loaded into your computer (you may need to select a load to disk option in your Web browser)
grimech30.dat A reaction mechanism and rate coefficient file, in Chemkin format
thermo30.dat A thermochemical data file to be used with grimech30.dat, as NASA polynomial coefficients
transport.dat A file containing the parameters needed for calculating transport coefficients to be used in the Sandia flame code
bugfix.dat A file containing selected user questions, comments, and suggestions related to the implementation of GRI-Mech

These files may also be obtained by anonymous ftp from unix.sri.com, the directory gri.

 


HOW TO CITE GRI-MECH 3.0

To cite GRI-Mech 3.0, please refer this web page: Gregory P. Smith, David M. Golden, Michael Frenklach, Nigel W. Moriarty, Boris Eiteneer, Mikhail Goldenberg, C. Thomas Bowman, Ronald K. Hanson, Soonho Song, William C. Gardiner, Jr., Vitali V. Lissianski, and Zhiwei Qin http://www.me.berkeley.edu/gri_mech/

 


TARGETS

The rate parameters of 325 reactions were optimized against the following experimental targets (measurement uncertainties, when reported by the cited investigators, are indicated):
SHOCK-TUBE IGNITION DELAY MEASUREMENTS
IG.1a Seery, D.J., and Bowman, C.T. (1970) Combust. Flame 14, 37. 

CH4-O2-Ar 
phi = 1.0, P = 1.8, 2.04 atm, T = 1500,1700 K

IG.1b
IG.2 Seery, D.J., and Bowman, C.T. (1970) Combust. Flame 14, 37. 

CH4-O2-Ar 
phi = 5.01, P = 3.8 atm, T = 1600 K

IG.6a Hidaka, Y., Gardiner, W.C., and Eubank, C.S. (1982) J. of Molec.Sci. (China) 2, p.141-53. 

 C2H6-O2-Ar 
phi = 0.275 - 0.764, P = 0.25 atm, T = 1600 K

IG.6b
IG.T1 Frenklach, M., and Bornside, D.E., (1984) Combust. Flame 56, 1 

 CH4-C3H8-O2-Ar (9.5%-1.9%-19%-69.6%) 
phi = 1.5, P = 2.5 atm, T = 1410 K 

IG.T2 Spadaccini, L.J., and Colket, M.B., (1994) Prog. Energy Combust. Sci. 20, 431. 

 CH4-C3H8-O2-Ar (3.4%-0.1%-7%-89.5%) 
phi = 1.043, P = 7.095 atm, T = 1640 K 

IG.St1a Spadaccini, L.J., and Colket, M.B., (1994) Prog. Energy Combust. Sci. 20, 431. 

CH4-C2H6-O2-Ar (3.29%-0.21%-7%-89.5%) 
phi = 1.045, P = 6.1 - 7.6 atm, T = 1356 - 1688 K 

IG.St1b
IG.St3a Seery, D.J., and Bowman, C.T., (1970) Combust. Flame 14, 37. 

CH4-O2-Ar (4.8%-19.1%-76.1%) 
phi = 0.5, P = 1.6 - 1.9 atm, T =1530 - 1845 K

IG.St3b
IG.St4a Peterson, E.L., Davidson, D.F., Rohrig, M., Hanson, R.K., and Bowman, C.T. (1995), to be published. 

 CH4-O2-Ar, phi = 1.0 
P = 34.6 - 83.9 atm, T =1408 - 1706 K

IG.St4b
SHOCK-TUBE SPECIES PROFILE MEASUREMENTS
CH3.C1a Maximum CH3 concentration Chang, A.Y., Davidson, D.F., DiRosa, M., Hanson, R.K., and Bowman, C.T. (1994) 25th Symposium (International) on Combustion, Poster 3 - 23. 

 CH4-O2-Ar (994 ppm-0.2021%-99.7%) 
phi = 0.984, P = 1.0 atm, T = 2000,2400 K

CH3.C1b
CH3.T1a Time of CH3 maximum
CH3.T1b
CH3.C2 Maximum CH3 concentration Chang, A.Y., Davidson, D.F., DiRosa, M., Hanson, R.K., and Bowman, C.T. (1994) 25th Symposium (International) on Combustion, Poster 3 - 23. 

 C2H6-O2-Ar (295 ppm-0.1055%-99.865%) 
phi = 0.769, P = 1.17 atm, T = 1794 K

CH3.T2 Time of CH3 maximum
CH3.C3 Maximum CH3 concentration Davidson, D.F., DiRosa, M., Chang, A.Y., Hanson, R.K., and Bowman, C.T. (1992) 24th Symposium (International) on Combustion, p.  589. 

C2H6-Ar (206 ppm) 
P = 1.35 atm, T = 1684 K

CH3.T3 Time of CH3 maximum
CH3.C4 Maximum CH3 concentration Chang, A.Y., Davidson, D.F., DiRosa, M., Hanson, R.K., and Bowman, C.T. (1994) 25th Symposium (International) on Combustion, Poster 3 - 23. 

 CH4-O2-Ar (0.2021%-0.1%-99.7%) 
phi = 4.02, P = 1.02 atm, T = 2264 K

CH3.T4 Time of CH3 maximum
CH3.StC6 Time of CH3 maximum Chang, A.Y., Davidson, D.F., DiRosa, M., Hanson, R.K., and Bowman, C.T. (1994) 25th Symposium (International) on Combustion, Poster 3 - 23. 

 CH4-O2-Ar (0.1%-0.4%-99.5%) 
phi = 0.5, P = 1 atm, T = 1932 - 2454 K

CH3.StC7
OH.1a Time to half of OH maximum Chang, A.Y., Davidson, D.F., DiRosa, M., Hanson, R.K., and Bowman, C.T. (1994) 25th Symposium (International) on Combustion, Poster 3 - 23. 

 CH4-O2-Ar (0.1%-0.2%-99.7%) 
phi = 1, P = 1.0 atm, T = 2000 - 2200 K

OH.1b
OH.2 Chang, A.Y., Davidson, D.F., DiRosa, M., Hanson, R.K., and Bowman, C.T. (1994) 25th Symposium (International) on Combustion, Poster 3 - 23. 

 C2H6-O2-Ar (300ppm-0.105%-99.89%) 
phi = 0.079, P = 1.21 atm, T = 1817 K 

OH.3a Time to half of OH maximum Yu, C.L., Wang, C., and Frenklach, M. (1995) J.Phys.Chem. 99, 14377. 

CH4-O2-Ar, phi = 0.04, P = 1.51 atm, T = 1750 K

CO.C1a Maximum CO concentration
CO.T1a Time to half of CO maximum
OH.3b Time to half of OH maximum Yu, C.L., Wang, C., and Frenklach, M. (1995) J.Phys.Chem. 99, 14377. 

CH4-O2-Ar, phi = 0.04, P = 1.64 atm, T = 1900 K

CO.C1b Maximum CO concentration
CO.T1b Time to half of CO maximum
OH.3c Time to half of OH maximum Yu, C.L., Wang, C., and Frenklach, M. (1995) J.Phys.Chem. 99, 14377. 

CH4-O2-Ar, phi = 0.667, P = 1.51 atm, T = 1750 K

CO.C1c Maximum CO concentration
CO.T1c Time to half of CO maximum
OH.3d Time to half of OH maximum Yu, C.L., Wang, C., and Frenklach, M. (1995) J.Phys.Chem. 99, 14377. 

CH4-O2-Ar, phi = 0.667, P = 1.64 atm, T = 1900 K

CO.C1d Maximum CO concentration
CO.T1d Time to half of CO maximum
OH.ST8 Time to half of OH maximum Yu, C.L., Wang, C., and Frenklach, M., 'Chemical Kinetics of Methyl Oxidation by Molecular Oxygen,' (1995) J.Phys.Chem. 99, 14377.

CH4-O2-Ar (1%-1.5%-97.5%) 
phi = 1.33, P = 2.45 atm, T = 1865 K

CO.ST8 Time to half of CO maximum
CO.SC8 Maximum CO concentration
BCO.T1 Time to half of CO maximum Eiteneer, B., Yu, C.-L., Goldenberg, M., and Frenklach, M., J. Phys. Chem. 102, 5196, (1998). 

CH2O-Ar  P = 1.17 atm, T = 2124 K

BCO.T2 Eiteneer, B., Yu, C.-L., Goldenberg, M., and Frenklach, M., J. Phys. Chem. 102, 5196, (1998). 

CH2O-Ar  P = 1.51 atm, T = 1724 K

BCO.T3 Eiteneer, B., Yu, C.-L., Goldenberg, M., and Frenklach, M., J. Phys. Chem. 102, 5196, (1998). 

CH2O-O2-Ar, phi = 5.88  P = 2.32 atm, T = 1784 K

BCO.T4 Eiteneer, B., Yu, C.-L., Goldenberg, M., and Frenklach, M., J. Phys. Chem. 102, 5196, (1998). 

CH2O-O2-Ar, phi = 0.25  P = 1.89 atm, T = 1442 K

BCO.T5 Eiteneer, B., Yu, C.-L., Goldenberg, M., and Frenklach, M., J. Phys. Chem. 102, 5196, (1998). 

CH2O-O2-Ar, phi = 1.68  P = 0.911 atm, T = 1768

BCO.T6 Eiteneer, B., Yu, C.-L., Goldenberg, M., and Frenklach, M., J. Phys. Chem. 102, 5196, (1998). 

CH2O-O2-Ar, phi = 0.17  P = 2 atm, T = 1515 K

BCO.T7 Eiteneer, B., Yu, C.-L., Goldenberg, M., and Frenklach, M., J. Phys. Chem. 102, 5196, (1998). 

CH2O-O2-Ar, phi = 1  P = 1.51 atm, T = 1720 K

BCH2O.T1 Time to half of CO maximum Hidaka, Y., Taniguchi, T., Tanaka, H., Kamesawa, T., Inami, K., and Kawano, H. (1993) Combust. Flame  92, 365. 

CH2O-O2-Ar, phi = 2.0 - 4.0 
P = 1.55 - 2.31 atm, T = 1256 - 1591 K

BCH2O.T2
BCH2O.T3
REACTORS
SR.10c Temperature where [CO2] = 500 ppm Kristensen, P.G., Glarborg, P., and Dam-Johansen, K. (1995), unpublished data. 
LAMINAR FLAME SPEED
F1 Vagelopoulos, C.N., and Egolfopoulos,F.N., 'Direct Experimental Determination of Laminar Flame Speeds,' Paper WSS/CI 97S-022, Western States Section/Combustion Institute Meeting, Livermore, CA, April 1997. 

 CH4-air, T(0) = 300 K 
phi = 0.98, P = 1 atm

F2 Vagelopoulos, C.M., Egolfopoulos, F.N., and Law, C.K., 'Further Considerations on the Determination of Laminar Flame Speeds with the Counterflow Twin-Flame Technique,' (1994) 25th Symposium (International) on Combustion,  p. 1341. 

 CH4-air, T(0) = 300 K 
phi = 1.43 - 0.67, P = 1 atm

F3
F4 Egolfopolous, F.N., Cho, P., and Law, C.K., 'Laminar Flame Speeds of Methane-Air Mixtures under Reduced and Elevated Pressures,' (1989) Combust. Flame 76, 375. 

 CH4-air, T(0) = 300 K 
phi = 1.0, P = 3 atm

F5 Just, Th. (1994) Private communication. 

 CH4-air, T(0) = 400 K 
phi = 1.0, P = 4.9 - 19.7 atm 

F6
SF7 McLean, I.C., Smith, D.B., and Taylor, S.B., (1994) 25th Symposium (International) on Combustion, p. 749. 

 CO-H2-air, (20.8%, 20.8%, 58.4%) T(0) = 300 K 
phi = 1.69, P = 1.0 atm 

StF8 References: Vagelopoulos, C.N., and Egolfopoulos,F.N., 'Direct Experimental Determination of Laminar Flame Speeds,' Paper WSS/CI 97S-022, Western States Section/Combustion Institute Meeting, Livermore, CA, April 1997. 

 C2H6-air, T(0) = 300 K 
phi = 1.0, P = 1.0 atm 

PROMPT NO
SNO.C11 NO (2 cm) concentration Luque, J., Smith, G.P., and Crosley, D.R. (1996) 26th Symposium (International) on Combustion, 959. 

 CH4-O2-N2 (13.8%-25.9%-60.3%) 
phi = 1.07, P = 0.033 atm

SCH.C11 Maximum CH concentration Luque, J., Smith, G.P., and Crosley, D.R. (1996) 26th Symposium (International) on Combustion, 959 

 CH4-O2-N2 (13.8%-25.9%-60.3%) 
phi = 1.07, P = 0.033 atm

SCH.C12 Maximum CH concentration Berg, P.A., Hill, D.A., Noble, A.R., Smith, G.P., Jeffries, J.B., and Crosley, D.R., 'Absolute CH Concentration Measurements in Low Pressure Hydrocarbon Flames: Comparison with Model Predictions,' (1997) 35th Aerospace Sciences Meeting, Paper 97-0905, Reno. 

CH4-O2-N2 
phi = 0.8 - 1.27, P = 0.033 - 0.0395 atm

SCH.C13
CH.St Maximum of CH concentration without NO doping Woiki, D., Votsmeier, M., Davidson, D.F., Hanson, R.K.,and Bowman, C.T., 'CH-Radical Concentration Measurements in Fuel Rich CH4/O2/Ar and CH4/O2/NO/Ar Mixtures Behind Shock Waves', (1998) Combust. Flame 113, 624. 

 CH4-O2-Ar 
phi=1.6, P = 1.8 atm, T = 2800 K

HCN OXIDATION
NFR1 HCN relative concentration Flow Reactor: Glarborg, P., and Miller, J.A. (1994) Combust. Flame  99, 475. 

HCN-CO-O2-H2O-N2 
(318 ppm-1710 ppm-2.4%-2.8%-94.6%) 
P = 798 torr, T = 1165K, residence time = 54 ms

NFR2 NO relative concentration
NFR3 N2O relative concentration
NF6 Maximum NO mole fraction Sandia Flame: Miller, J.A., et al. (1984) 20th Symposium (International) on Combustion, p.  673. 

H2-O2-HCN-Ar 
phi = 1.5, P = 25 torr

NF7 Maximum CN mole fraction
REBURNING
NF11 Ratio of CH maximum concentrations at two levels of NO doping NRL Flame: Williams, B.A., and Fleming, J.W. (1994) Combust. Flame  98,  93. 

 CH4-O2-Ar-NO or N2O (1.2%) 
phi = 1.0, P = 10 torr

NF12/13 Ratio of CN maximum concentrations for NO and N2O doping
NFR4 NO mole fraction at reactor exit Flow Reactor: Alzueta, M.U., Glarborg, P., and Dam-Johansen, K., 'Low Temeprature Interactions between Hydrocarbons and Nitric Oxide. An Experimental Study,' Combust. Flame 109, 25. 

 CH4-C2H6-O2-NO-H2O-N2 (2864 ppm - 298 ppm - 5090 ppm - 947 ppm - 2.16% - 96.92%) 
phi = 1.33, P = 1.05 bar, T = 1323 K, residence time = 207 ms

NFR5 HCN mole fraction at reactor exit
CHNO.St Maximum of CH concentration with NO doping Woiki, D., Votsmeier, M., Davidson, D.F., Hanson, R.K.,and Bowman, C.T., 'CH-Radical Concentration Measurements in Fuel Rich CH4/O2/Ar and CH4/O2/NO/Ar Mixtures Behind Shock Waves', (1998) Combust. Flame 113, 624. 

 CH4-O2-NO-Ar 
phi=1.6, P = 1.8 atm, T = 2800 K

 

PERFORMANCE THAT WE KNOW ABOUT

Ignition Delays

Species Profiles in Shock-Tube Ignition Experiments

Laminar Flame Speeds

Comments on GRI-Mech 1.2 flame speed computations.

Laminar Flame Species Profiles

Flow Reactor Experiments

Stirred Reactors

Propane-Oxygen and Propane-Methane-Oxygen Ignition Delays


GRI-Mech Main Menu