Measurements of laminar burning velocities and an improved kinetic model of methyl isopropyl ketone

Methyl isopropyl ketone (MIPK) is the simplest branched ketone and a promising biofuel. In this work, laminar burning velocities (SL) of MIPK + air flames were measured using the heat flux method at at-mospheric pressure, over initial mixture temperatures of 298-358 K and equivalence ratios of 0.7-1.4. With the help of the temperature dependence of the SL, data inconsistency between the present mea-surements and the experimental data reported by Li et al. (Proc. Combust. Inst. 38 (2021) 2135) was demonstrated. Moreover, existing kinetic models for MIPK combustion notably deviate from the present SL measurements. Therefore, the MIPK model suggested by Lin et al. (Proc. Combust. Inst. 39 (2023) 315) was updated by revisiting the MIPK H-abstraction reactions and methyl isopropenyl ketone sub-model. Furthermore, a new di-methyl ketene (critical intermediate during MIPK oxidation) sub-model was con-structed and integrated into the MIPK model. Flux and sensitivity analyses revealed that integration of the new di-methyl ketene model improves predictions of the laminar burning velocities as well as shock tube ignition delay times over the pressures of 1-40 bar due to converting di-methyl ketene into C3H5- T (CH2 = C CH3) rather than C3H6 or C3H5-S (C H = CHCH3) predicted by other MIPK models from the literature. Updates of the MIPK H-abstraction reactions yield more reasonable products branching ratios of formation of the primary fuel radicals, and improve prediction of the SL. It was also found that the rate constants of the MIPK decomposition reaction (MIPK ( + M) = CH3CO + IC3H7 ( + M)) in the model proposed by Li et al. (Proc. Combust. Inst. 38 (2021) 2135) are significantly underestimated, resulting in underestimation of the present SL measurements and significant overprediction of the ignition delay times.(c) 2023 The Author(s). Published by Elsevier Inc. on behalf of The Combustion Institute. This is an open access article under the CC BY license ( http://creativecommons.org/licenses/by/4.0/ )

Automated summary

In this study, laminar burning velocities of MIPK + air flames were measured, and it was found that existing kinetic models for MIPK combustion deviate from the measured data. The MIPK model was updated and a new di-methyl ketene sub-model was integrated, improving predictions of burning velocities and ignition delay times. Underestimation of the rate constants of the MIPK decomposition reaction in the previous model was identified, leading to underestimation of the measured burning velocities and significant overprediction of the ignition delay times.