An Autoignition Study of iso-Butanol: Experiments and Modeling

TL;DR

This study measures iso-butanol autoignition delays in a rapid compression machine and updates a chemical kinetic model to better understand low-temperature combustion pathways, finding reasonable agreement with experiments.

Contribution

The paper provides new experimental data on iso-butanol autoignition at various pressures and temperatures, and updates a kinetic model to include low-temperature pathways, improving predictive accuracy.

Findings

No NTC region observed at tested conditions.

Lower reactivity at φ=0.5 compared to φ=1.0.

Updated model shows reasonable agreement with experimental data.

Abstract

The autoignition delays of iso-butanol, oxygen, and nitrogen mixtures have been measured in a heated rapid compression machine (RCM). At compressed pressures of 15 and 30 bar, over the temperature range 800-950 K, and for equivalence ratio of $\phi$ = 0.5 in air, no evidence of an NTC region of overall ignition delay is found. By comparing the data from this study taken at $\phi$ = 0.5 to previous data collected at $\phi$ = 1.0 (Weber et al. 2013), it was found that the $\phi$ = 0.5 mixture was less reactive (as measured by the inverse of the ignition delay) than the $\phi$ = 1.0 mixture for the same compressed pressure. Furthermore, a recent chemical kinetic model of iso-butanol combustion was updated using the automated software Reaction Mechanism Generator (RMG) to include low- temperature chain branching pathways. Comparison of the ignition delays with the updated model showed reasonable agreement for most of the experimental conditions. Nevertheless, further work is needed to fully understand the low temperature pathways that control iso-butanol autoignition in the RCM.