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CO, CH2O, CH3OH, and Syngas: a "C1 Model"

"A Comprehensive Kinetic Mechanism for CO, CH2O, CH3OH Combustion"

J. Li, Z. Zhao, A. Kazakov, M. Chaos, F.L. Dryer, J. J. Scire Jr., International Journal of Chemical Kinetics 39 (2007) 109–136. DOI: 10.1002/kin.20218

New experimental profiles of stable species concentrations are reported for formaldehyde oxidation in a variable pressure flow reactor at initial temperatures of 850–950 K and at constant pressures ranging from 1.5 to 6.0 atm. These data, along with other data published in the literature and a previous comprehensive chemical kinetic model for methanol oxidation, are used to hierarchically develop an updated mechanism for CO/H2O/H2/O2, CH2O, and CH3OH oxidation. Important modifications include recent revisions for the hydrogen–oxygen submechanism (Li et al., Int J Chem Kinet 2004, 36, 566), an updated submechanism for methanol reactions, and kinetic and thermochemical parameter modifications based upon recently published information. New rate constant correlations are recommended for CO + OH = CO2 + H (R23) and HCO + M = H + CO + M (R24), motivated by a new identification of the temperatures over which these rate constants most affect laminar flame speed predictions (Zhao et al., Int J Chem Kinet 2005, 37, 282). The new weighted least-squares fit of literature experimental data for (R23) yields k23 = 2.23 × 105T1.89exp(583/T) cm3/mol/s and reflects significantly lower rate constant values at low and intermediate temperatures in comparison to another recently recommended correlation and theoretical predictions. The weighted least-squares fit of literature results for (R24) yields k24 = 4.75 × 1011T0.66exp(−7485/T) cm3/mol/s, which predicts values within uncertainties of both prior and new (Friedrichs et al., Phys Chem Chem Phys 2002, 4, 5778; DeSain et al., Chem Phys Lett 2001, 347, 79) measurements. Use of either of the data correlations reported in Friedrichs et al. (2002) and DeSain et al. (2001) for this reaction significantly degrades laminar flame speed predictions for oxygenated fuels as well as for other hydrocarbons. The present C1/O2 mechanism compares favorably against a wide range of experimental conditions for laminar premixed flame speed, shock tube ignition delay, and flow reactor species time history data at each level of hierarchical development. Very good agreement of the model predictions with all of the experimental measurements is demonstrated.

Notes:

The present kinetic model differs from the original Li et al. C1 Model cited above by a single updated rate constant expression for the reaction CO+HO2=CO2+OH. The rate has recently been studied by several investigators; we have adopted the new rate constant expression it since it improves model predictions of RCM ignition while maintaining the same quality of predictions against other targets. The H2/O2 submodel remains unaltered; its validation can be found in Li et al., Int. J. Chem Kin. 36 (2004), 566-575.

The kinetic model (below) has been commented extensively by Marcos Chaos.

Kinetic Model Files:

Before using this kinetic model please read:

  1. The readme.txt document in the downloadable .zip file.
  2. The header to the chem.inp file, which among other things, prompts the user to select the primary bath gas used in modeling.