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.

本研究聚焦于采用外加热扩通道法，在升高的混合气温度下，测量第二代生物燃料二异丙基酮（di-isopropyl ketone，DIPK）与空气混合气的层流燃烧速度（laminar burning velocity，LBV）。实验在大气压条件下开展，混合气温度最高可达639 K，当量比范围覆盖0.7至1.3。将本次测得的LBV数据与现有实验结果，以及新近开发的DIPK综合化学动力学模型的预测值进行对比后发现：本次层流燃烧速度测量结果与现有实验数据吻合良好；Lin模型的预测结果在较低混合气温度（最高393 K）下也能较好匹配LBV值的变化趋势。但在高温工况下，Lin模型对本次测量结果出现了显著低估。通过敏感性分析，研究识别出关键反应，并基于NUIGMech1.3的最新机理更新了反应R84的速率系数。值得注意的是，更新后的反应R84：CH2 + O2 => CO2 + 2H的速率常数随温度升高而提升（2500 K时约为原系数的293%，750 K时约220%，500 K时约174%），从而提高了DIPK+空气混合气的层流燃烧速度。更新后的DIPK模型，在不同混合气温度与当量比条件下，与现有文献中的LBV测量数据，以及本次高温工况下的实验数据均展现出更优的吻合度。对反应R84的修正提升了层流燃烧速度，且对点火延迟时间与组分摩尔分数分布的影响可忽略不计。