Yasuyuki Sakai

Theoretical Investigation of Intramolecular Hydrogen Shift Reactions in 3-Methyltetrahydrofuran (3-MTHF) Oxidation.

3-Methyltetrahydrofuran (3-MTHF) is proposed to be a promising fuel component among the cyclic oxygenated species. To have detailed insight of its combustion kinetics, intramolecular hydrogen shift reactions for the ROO to QOOH reaction class are studied for eight ROO isomers of 3-MTHF. Rate constants of all possible reaction paths that involve formation of cyclic transition states are computed by employing the CBS-QB3 composite method. A Pitzer-Gwinn-like approximation has been applied for the internal rotations in reactants, products, and transition states for the accurate treatment of hindered rotors. Calculated relative barrier heights highlight that the most favorable reaction channel proceeds via a six membered transition state, which is consistent with the computed rate constants. Comparing total rate constants in ROO isomers of 3-MTHF with the corresponding isomers of methylcyclopentane depicts faster kinetics in 3-MTHF than methylcyclopentane reflecting the effect of ring oxygen on the intramolecular hydrogen shift reactions.

Reduction of Reaction Mechanism for n -Tridecane Based on Knowledge of Detailed Reaction Paths

A detailed chemical kinetic mechanism for n-tridecane generated by KUCRS, contains 1493 chemical species and 3641 elementary reactions. Reaction paths during ignition process for n-tridecane in air computed using the detailed mechanism, were analyzed with the initial temperatures of 650 K, 850 K, and 1100 K in the τ1 dominant, negative temperature coefficient, and non-τ1 regions, respectively. Based on full knowledge derived from the reaction path analysis, a reduced mechanism containing 49 species and 85 reactions, was developed and validated. The reduced mechanism includes C3H7, C2H5, and CH3 as representative fragmental alkyl radicals, C7H14, C3H6, and C2H4 as representative alkenes, and C3H7CHO and CH2O as representative aldehydes. Ignition delay times with different initial temperatures between 600 K and 1200 K using the reduced mechanism, and their dependences on pressure and equivalence ratio agree well with those using the detailed mechanism. The profiles of fuel, CH2O, H2O2, and CO concentrations agree roughly with those using the detailed mechanism.