Revisiting the Combustion Kinetics of Di-Isopropyl Ketone: New Insights from Elevated Temperature LBV Measurements

This study focuses on measuring the laminar burning velocity (LBV) of the second-generation biofuel di-isopropyl ketone (DIPK) + air mixtures using an externally heated diverging channel method at elevated mixture temperatures. Experiments were conducted at elevated mixture temperatures of up to 639 K across a range of equivalence ratios varying from 0.7 to 1.3 under atmospheric pressure conditions. The obtained LBV measurements were compared with existing experimental data and predictions from a recently developed comprehensive chemical kinetic model of DIPK. The results demonstrated good agreement between the present LBV measurements and existing data, and the predictions from the Lin model also showed a good trend of LBV values at lower mixture temperatures (up to 393 K). However, the Lin model exhibited significant underpredictions at elevated temperatures when compared to the present measurements. From the sensitivity analysis, key reactions were identified, and the rate coefficients of reaction R84 were updated from the recent mechanism of NUIGMech1.3. Notably, the updated rate coefficients for reaction R84: CH2 + O2 => CO2 + 2H showed an increase in the rate constant with temperature (∼293% at 2500 K, ∼220% at 750 K, and ∼174% at 500 K), enhancing the LBV of DIPK + air mixtures. The updated DIPK model demonstrated improved agreement with LBV measurements from existing literature across various mixture temperatures and equivalence ratios, as well as with the present experimental data at elevated temperatures. The modification of R84 improves LBV, with a negligible impact on ignition delay times and species mole fraction profiles.