大分子直链烷烃O₂QOOH异构化反应速率规则优化与验证

To explore the reliability of existing rate rule of reaction class for describing low temperature kinetics of macromolecular straight-chain alkanes, two widely used chemical kinetic models, LLNL and CAI models, were tested experimentally, and a rate rule of selected important reaction class of O₂QOOH isomerization was verified theoretically. In this study, ignition delay times of n-decane were measured in reflected shock conditions covering temperature range of 650-1 550 K, pressures of 0.1, 0.5 and 2.0 MPa, and equivalence ratios of 0.5 and 1.0. Theoretical calculation values and new rate rule of the target reaction class were initially derived by combining with statistical methods. Experimental results revealed that the ignition delay times of n-decane exhibit crossover behavior due to increased reaction competition at both equivalence ratios at high temperatures and 0.1 MPa, while present NTC behavior at 0.5 and 2.0 MPa. Both LLNL and CAI models showed generally poor predictions in the ignition delay times especially in NTC regime, and LLNL model even showed a deviation from the experimental data up to 11 059 μs. It is found that the maximum difference of rate coefficient applied in LLNL model and the lower limit of the rate rule can be nearly 3.5 orders of magnitude for the migration process of O₂QOOH isomerization reactions involving 1, 4-H, 1, 5-H and 1, 7-H H-atom transition. It implies that the rate coefficients for O₂QOOH isomerization adopting directly analogy with RO₂ isomerization could remain unacceptable uncertainty. After the updated rate rule is incorporated, the LLNL model shows a faster prediction in the ignition delay time over temperature range of 660-1 050 K, while the CAI model shows a slightly faster prediction below 800 K and agrees well with the experimental measurements under high pressure. The new rate rule can provide a reference for the kinetic description in low temperature O₂QOOH isomerization mechanism of macromolecular straight-chain alkanes.