San Diego Mechanism 2016/08/15 A number of new reactions involving n-butane have been added to the main mechanism, along with the corresponding thermal and transport data. These reactions are based on the latest work of F.A. Williams and J.C. Prince which is accepted for publication at the Combustion and Flame. The paper is titled "A reduced reaction mechanism for the combustion of n-butane" San Diego Mechanism 2014/10/04 - Correction as of Nov. 16th The presentation of rates for the reactions HO2+OH<=>H2O+O2; 2 HO2<=>H2O2+O2; and H2O2+OH<=>H2O+HO2 has been corrected to reflect these reactions are bi-molecular and bi-Arrhenius. San Diego Mechanism 2014/10/04 Efficiency of H2O2 in the step OH + OH + M = H2O2 + M has been revised to become 6.0. Rate parameters in the reaction CH3OH + O = CH2OH + OH have been updated to A=3.88 E5, n=2.5, E=3080 cal/mol = 12.89 kJ/mol based on Driver et al (1992). The previous values were A=1.000E+13, n = 0.0, E= 4684.51 cal/mol. Rate parameters for the first entry in the reaction HO2 + OH = H2O + O2 have been revised to become A=7.00 E12, n=0, E=-1094.62 cal/mol = - 4.58 kJ/mol based on Hong et al (2013). The previous values were 2.890E+13, n=0.0, E=-497.13 cal/mol. San Diego Mechanism 2014/02/12 - July 2014 Correction The 3rd Troe parameter in both Chemkin and FlameMaster formats for several reactions which was explicitly listed as zero, has been changed to a very small non-zero number (1.000E-30) to avoid division by zero. San Diego Mechanism 2014/02/12 Reaction rates, Troe fall-off parameters and Chaperon efficiencies have been revised for several hydrogen chemistry reactions. Those are detailed in the publication by A. Sanchez and F. Williams in Progress in Energy and Combustion Science, 2013. San Diego Mechanism 2012/09/07 We have updated our thermodata and transport data to ensure all species are consistent. San Diego Mechanism 2011/11/22 Several changes were made to the ethanol chemistry that were detailed in Li at al. (2004) and Saxena et al. (2007). A few reactions were added dealing with the C3 chemistry. Those are detailed in J. C. Prince et al. (2011). San Diego Mechanism 2009/11/01 The Frequency Factor of the reaction CH3OH + HO2 -> CH2OH + H2O2 was changed from 6.200E+12 to 8.000E+13. This change is documented in "Detailed and reduced chemistry for methanol ignition" by Seiser et al. (2011). San Diego Mechanism 2005/12/01 Reactions related to combustion of ethanol are added to the existing San Diego Mechanism. Most of those reactions are adopted from Juan Li, Ph.D. thesis (2004), Princeton University. We have also added thermodynamic and transport data for the additional species associated with ethanol. San Diego Mechanism 2005/10/11 Updates are made to several sensitive reactions involving formaldehyde, methane, ethane, ethylene, acetylene and methanol, based on more recent literature. San Diego Mechanism 2005/06/15- Revision as of 2005/08/17 We have edited the current thermodynamic data file to include several species from our previous data relevant to heptane reactions as well as JP10 and nitrogen chemistry. San Diego Mechanism 2005/06/15 We have added He as an additional third body. We revised the rates for H+O+M->OH+M step based on results of Yetter et al. (1991). The reaction H2+O2->OH+OH has been removed from the mechanism following recommendations of Michael et al. (2000), Proceedings of Combustion Institute, Vol. 28. The rate parameters are updated for the H+H+M->H2+M step based on recommendations of Baulch (1992) where Ar is used as a bath gas. We have also revised the prefactor in the H+OH+M->H2O+M reaction after reviewing appropriate literature. In addition, Chaperon efficiencies for He and Ar have been changed in the above step as well as in O+O+M->O2+M. We have revised rate parameters and Troe fall-off in the H+O2+M->HO2+M reaction based on Troe (2000) recommendations for the use of N2 as bath gas. We have also modified the rate parameters in the following steps: HO2+H->OH+OH and HO2+H->H2+O2. We have added CO+O2->CO2+O reaction to improve ignition time calculations for the mixture of carbon monoxide and hydrogen. Finally, we have adjusted and corrected several literature references in the mechanism. San Diego Mechanism 2005/03/10 We have replaced the existing thermodata with the new set to improve the calculations. In particular, we adopted the thermodata from A. Burcat for most of the species, except for C3H5 and OH which are taken from H. Wang. As to the C3H4 species, representing both allene and propyne, we are now using allene thermodata. A number of changes have been made in our main hydrocarbon mechanism. The prefactor A has been increased in the H+OH+M->H20+M to improve burning-velocity agreement. The third-body efficiency of water has been increased in the H+O2+M->H02+M reaction in order to agree with new autoignition data in wet atmospheres. We have slightly revised the rates in the HO2+H->OH+OH reaction to improve burning-velocity predictions for hydrogen and propane. We have added a falloff for higher pressures for the following reaction: OH+OH+M->H202+M. We have also revised the rates of the CH3+HO2->CH3O+OH step, in order to improve agreement with propane autoignition times. We have added the CH3OH+M->CH3+OH+M step to be able to address high-temperature methanol autoignition. We have slightly revised the rates for the CH2CO+H->CH3+CO reaction in order to improve agreement with measured propane autoignition times. We have revised a number of steps in the mechanism involving C3 chemistry. These revisions enabled us to obtain better results for propane, propene, allene and propyne. In particular, we have included a falloff as well as the third body efficiencies in the propane initiation step C3H8->CH3+C2H5, based on the evaluation of Baulch. Five propyl radical steps have been included in the mechanism, less than half of the earlier number of such reactions, because many of them did not have appreciable influence on predictions. In particular, we have found it very important to include falloff in the propyl decomposition steps. As to the propene oxidation steps, we have retained seven of these, where the rate parameters were taken from Davis et al. We have also revised the parameters for propene autoignition steps. Of the two C3H5 isomers, we have included only allyl, since that appeared to be sufficient. Regarding the allyl rate parameters, we followed the reasoning of Davis et al. As to the decomposition steps C3H5->C3H4 +H and C3H5->C2H2+CH3, we have estimated the falloff conditions which would agree with the reported results by Davis, Law and Wang. With respect to the C3H5+O2->C3H4+HO2 step, we used the results of Bozelli and Dean for their channel to allene while neglecting other channels included previously. We have added the reactions C3H5+OH->C3H4+H20, C3H5+HO2->C3H6+02 and C3H5+HO2->C2H3+CH20+OH, where in the last of these we have decreased the rate by Baulch et al. by slightly more than a factor of two, to significantly improve predicted C3H8 ignition times. We have estimated the falloff in the C3H4->C3H3+H reaction, since we find it important for higher temperatures. We have added five steps associated with C3H3 species, in which the rate parameters follow recommendations of Davis et al. Rate parameters for C3H4 reactions are taken from Davis et al. If the same reaction was present for both propyne and allene, the faster rate constant of the two was chosen. Finally, we have modified the prefactor A in the following reaction: HCCO+NO->HNCO+CO. This detail is given in our Nitrogen Chemistry section. San Diego Mechanism 2003/08/30-Revision as of 2004/12/09 We have added one reaction to the Nitrogen Chemistry Section (see the appropriate section for details). Also, we have corrected a discrepancy in the appearance of I-C3H7 species in the transport data file. San Diego Mechanism 2003/08/30-Additon as of 2004/03/11 We have added some plots which illustrate comparison between computations based on our mechanism and experiments for some fuels. San Diego Mechanism 2003/08/30 The 3rd-body efficiency for H2O in the H+O2+M -> HO2+M reaction has been changed from 7.0 to 12.0 as a result of comparisons between homogeneous, adiabatic, isobaric induction time calculations and the recent experimental data from Wang et al. The fall-off effect for that reaction has been included based on the published work of Troe. The Troe coefficients fca and fcb in the expression for the fall-off effect in the N-C3H7 -> H + C3H6 reaction have been revised to correct the misprint which occured previously. San Diego Mechanism 2003/04/30 The rate constants in the propene reactions: C3H6 -> C3H5 + H and C3H6 -> C2H3 + CH3 have been revised by using the results from the published work by Davis et al. In particular, we replaced these reactions with their appropriate counterparts in reverse direction, taking into consideration the effects of pressure dependence. The results based on revised rate constants agree better with the laminar flame speed data. San Diego Mechanism 2002/10/01- Revision as of 2003/04/15 Mechanism files in PDF format containing appropriate literature references have been added to the main mechanism directory as well as to the corresponding subdirectories for NOx, Heptane and JP-10 chemistry. The mechanism files in Flame Master format have been edited to properly include comments and literature references. San Diego Mechanism 2002/10/01 A separate directory has been created for JP10 chemistry. Heptane reactions have been included into the mechanism based on Held et al. Those reactions have been put into an appropriate separate directory. Additional species associated with heptane chemistry have been included in the thermodata and transport data files. Butadiene and pentadiene reactions have been removed from the main mechanism file and included into the appropriate files associated with JP10 and heptane chemistry. Several reactions associated with CH3CHO species as well as I-C3H7 have been removed from the main mechanism since they proved to be unimportant for the computation results. The portion of the main mechanism associated with propane chemistry has been updated to reflect a more thorough examination of the reaction constants based on recent literature. San Diego Mechanism 2002/08/12 A separate directory has been added to address the details of nitrogen chemistry. Additional species associated with nitrogen chemistry have been put into the thermodata file. In order to insure compatability of calculations in Chemkin and Flame Master formats, 3-CH2 species has been renamed as T-CH2 and introduced into both mechanism formats as well as thermodata and transport data files. Correspondingly, 1-CH2 species has been renamed as S-CH2 and introduced into all the formats as such. The keyword "FC" in Chemkin format has been replaced with "TROE" for one reaction. C10H16 species in FlameMaster format has been renamed as JP10-C10H16. All {fc=} formulations in FlameMaster format have been replaced with {fca,fcta,fcb...} to preclude potential errors in resulting Chemkin format. C6H5C2H, IC8H14 and CH3CHCCH species have been commented out and ANTHRACN, CH3CCCH2, NC5H12, IC5H12 as well as NEO-C5H12 have been removed from transport data file as a result of dual entry and/or redundancy. Note: no transport data for JP-10 or C10H16 present. San Diego Mechanism 2002/06/03 Thermodynamic data have been updated to reflect the revised OH heat of formation as 8.92 kcal/mol, according to recent Stanford work. San Diego Mechanism 2002/05/20 Reaction (a137f) C3H6 -> C2H2+CH4 added for completeness, based on the results from Y. Hidaka et al. San Diego Mechanism 2002/02/05 Hydrogen Reactions were changed and propane reactions were added. Reaction (a5f) H + O + M2 -> OH + M2 added for completeness. Reaction (a6f) H2 + O2 -> OH + OH added for low temperature hydrogen ignition. Reaction (a11f) O + OH + M -> HO2 + M added for completeness. Propane reactions p127f to p152f added after studying propane ignition 03/13/2002 Reaction rates for the propane reaction C3H8 -> CH3 + C2H5 have been revised, to account for the effects of pressure dependence. San Diego Mechanism 2001/11/05 02/09/2001 Reaction H + O2 + M -> HO2 + M updated based on recent data from Petersen et al. 02/09/2001 Reaction OH + OH + M -> H2O2 + M updated based on recent data from Petersen et al. 04/12/2001 The following reactions were updated Reactions 157: C5H8 -> C3H4 + C2H4 { a = 0.3160E+13 n = 0.000 E = 238.8 } 158: C5H8 -> C3H5 + C2H3 { a = 0.3160E+13 n = 0.000 E = 238.8 }