The following table summarises the applicability of our reduced kinetic mechanisms and contains links to the source files required for practical use. These mechanisms are developed as part of the collaboration with the reactive flow group (UCSD).
The first two mechanisms are a subset of detailed chemistries (referred as skeletal mechanism in our articles) and have elementary rates. Further reduction requires the use of non-elementary rates, as detailed in the references below [1-5].
| Fuel | N reactions | premixed | diffusion | ignition | detonation | mechanism | rates | Ref |
|---|---|---|---|---|---|---|---|---|
| H2 | 12 | y | y | y | y | h2_12s.cti | elementary | [1] |
| H2/CO | 16 | y | y | y | y | h2_16s.cti | elementary | [2] |
| H2 | 3 | y | y | n | n | h2_3s.cti | h2_3s.f | [1,3] |
| H2 | 3 | y | y | y (T>Tc) | y (T<Tc) | h2_3s+.cti | h2_3s+.f | [1,3] |
| H2 | 3 | y | y | y | y | h2_3s+-.cti | h2_3s+-.f | [4] |
| H2/CO | 4 | y | y | n | n | h2_4s+-.cti | h2co_4s+-.f | [2,5] |
Tc corresponds to the temperature of the second explosion limit as described by Lewis and Von Elbe. In our first intent to encompass autoignition of H2 and syngas, only high-temperature ignition was considered [1]. These mechanisms are not valid for ignition below that limit (which is usually the case for high-pressure conditions).
Note that these descriptions are derived from the detailed chemistry description proposed in:
Testing a small detailed chemical-kinetic mechanism for the combustion of hydrogen and carbon monoxide
P Saxena, FA Williams – Combustion and Flame, 2006 – Elsevier
Updated rates are available here: The San Diego mechanism
Implementation
For the reduced descriptions proposed, the computation of the rates is non-elementary, and a specific routine has to be implemented in the code.
Cantera
Cantera does not allow custom chemistry descriptions in its original version. Here is a step by step tutorial to implement reduced chemistry descriptions into Cantera. The chemistry descriptions will then be available from all cantera interfaces (matlab, f77, f90, c++, python).
Chemkin
The routines are provided in Fortran 77, on a format similar to that used by Chemkin, so that their implementation in Chemkin is quite straight-forward (they correspond to the CKRAT routine in Chemkin). Routines are provided in kmol/m3, the unit used by Cantera. To use with Chemkin (mol/cm3), remove the 1.e-3 coefficient in the first lines (where each concentration is assigned to a variable), and the 1.e3 coefficient on the last lines (just before returning the rates).
References
[1] An explicit reduced mechanism for H2–air combustion
P Boivin, C Jiménez, AL Sánchez, FA Williams, Proceedings of the Combustion Institute 33 (1), 517-523
[2] A four-step reduced mechanism for syngas combustion
P Boivin, C Jiménez, AL Sánchez, FA Williams, Combustion and Flame 158 (6), 1059-1063
[3] Simulation of a supersonic hydrogen–air autoignition-stabilized flame using reduced chemistry
P Boivin, A Dauptain, C Jiménez, B Cuenot, Combustion and Flame 159 (4), 1779-1790
[4] Four-step and three-step systematically reduced chemistry for wide-range H2–air combustion problems,
P Boivin, AL Sánchez, FA Williams, Combustion and Flame 160 (1), 76-82
[5] Extension of a wide-range three-step hydrogen mechanism to syngas,
P. Boivin and F. A. Williams, Combustion and Flame, vol. 196, pp. 85 – 87, 2018.