2,3-Dimethyl-2-butene (TME) is a potential fuel additive with high research octane number (RON) and octane sensitivity (S), which can improve internal combustion engine performance and efficiency. However, the combustion characteristics of TME have not been comprehensively investigated. Thus, it is essential to study the combustion characteristics of TME and construct a detailed chemical kinetic model to describe its combustion. In this paper, two high-pressure shock tubes and a constant-volume reactor are used to measure ignition delay times and laminar flame speeds of TME oxidation. The ignition delay times were measured at equivalence ratios of 0.5, 1.0, and 2.0 in “air”, at pressures of 5 and 10 bar, in the temperature range of 950 – 1500 K. Flame speeds of the TME/ “air” mixtures were measured at atmospheric pressure, at a temperature of 325 K, for equivalence ratios ranging from 0.78 to 1.31. Two detailed kinetic mechanisms were constructed independently using different methodologies; the KAUST TME mechanism was constructed based on NUIGMech1.1, and the MIT TME mechanism was built using the Reaction Mechanism Generator (RMG). Both mechanisms were used to simulate the experimental results using Chemkin Pro. In the present work, reaction flux and sensitivity analyses were performed using the KAUST mechanism to determine the critical reactions controlling TME oxidation at the conditions studied.

This study presents new ignition delay time data for two multi-component natural gas (NG) blends composed of C1–C7 n-alkanes with methane as the major component. New experimental data were recorded using a high-pressure shock tube (HPST) at reflected shock pressures (p5) of 10–30 bar, at temperatures (T5) in the range 770–1480 K, and at equivalence ratios (φ) of 0.5–1.5 in ‘air’. The current results together with published rapid compression machine (RCM) measurements show that higher concentrations of larger molecular weight n-alkanes in the NG blends increase fuel reactivity by more than an order of magnitude with mixtures that have ∼18.75% of C3–C5 components compared to mixtures that have ∼44.4% of C3–C7 components at temperatures below 1000 K. On the contrary, at higher temperatures the effect of increasing reactivity is reduced. NUIGMech1.2 is used to simulate the conditions studied and shows good agreement with the experimental ignition delay time data. A correlation equation is developed through regression analyses using NUIGMech1.2 to predict ignition delay times for a wide range of C1–C7 NG mixtures, in the pressure range 10–50 bar, at temperatures in the range 950–2000 K, and at φ = 0.3–3.0 in air. The proposed correlation expression that employs a traditional Arrhenius form is successfully validated against the new experimental data as well as previously published HPST experimental data.