No abstract

1-Hexanol is among the promising renewable long-chain alcohols usable as an alternative to petrol-derived gasoline and diesel fuels. To better understand the combustion characteristics of 1-hexanol, new experimental data for the oxidation and combustion of 1-hexanol were obtained. Stable species concentration profiles were measured in a jet stirred reactor (JSR) at 10 atm over a range of equivalence ratios and temperatures. Burning velocities of 1-hexanol/air mixtures were measured at 1−10 bar and 423 K, over a range of equivalence ratios. The effect of total pressure on flame speed was determined. The oxidation of 1-hexanol in these experimental conditions was modeled using an extended detailed chemical kinetic reaction mechanism (2977 reactions involving 600 species). The proposed mechanism shows good agreement with the present experimental data. Reaction path analyses and sensitivity analyses were performed to interpret the results.

The kinetics of oxidation of a Coal-to-Liquid (CtL) Fully Synthetic Jet Fuel (FSJF) was studied using three complementary experiments operating over a wide range of conditions: a jet-stirred reactor (p = 10 bar), constant mean residence time of 1 s, over the temperature range 770-1070 K, and for equivalence ratios ϕ = 0.5, 1.0, and 2.0; a shock-tube (p ~ 16 bar, temperature range between 900 and 1400 K, ϕ = 0.5 and ϕ = 1), and a conical flame burner (preheat temperature T 0 = 473 K, and for two pressure regimes: p = 1 bar for equivalence ratios ranging from 0.95 to 1.4, and p = 3 bar for equivalence ratios ranging from 0.95 to 1.3). Concentration profiles of reactants, stable intermediates, and final products in the jet-stirred reactor were obtained by probe sampling followed by on-line and off-line gas chromatography analyses and on-line Fourier Transformed Infra-Red spectrometry. Ignition delay times were determined behind reflected shock waves by measuring time-dependent CH* emission at 431 nm. Flame speeds were determined by applying the cone angle method. Comparison with corresponding results for Jet A-1 was performed showing similar combustion properties. The oxidation of the CtL-fuel under these conditions was modeled using a detailed kinetic reaction mechanism consisting of 8217 reactions and 2185 species and a 4-component surrogate fuel mixture (n-decane, iso-octane, n-propylcyclohexane, and npropylbenzene). A reasonable representation of the kinetics of oxidation of this FSJF was obtained. The model showed good agreement with concentration profiles measured in a jetstirred reactor at 10 bar over a range of temperatures (550-1150 K) and equivalence ratios (0.5-2). Good agreement between measured and predicted ignition delay times was found for the investigated fuel air mixtures, with significantly longer ignition delay times predicted. Also, the ignition behavior of the surrogate is mainly influenced by the n-alkane and not by the addition of iso-alkanes, naphthenes, and aromatics. In general, a reasonable agreement between predicted and measured burning velocity data exists, with larger deviations at higher pressure. No deviation is to be seen between burning velocity data for Jet A-1 and CtL, within the uncertainty range. Within the parameter range studied, the measured data of burning 4 velocity and ignition delay time agree with data obtained earlier for petrol-derived kerosene. Our findings support the potential of the CtL/air mixture investigated to serve as an alternative aviation fuel.

The kinetics of oxidation of two large n-alkanes (n-undecane and n-dodecane) was studied experimentally in a jet-stirred reactor (JSR) at high pressure (P = 10 bar), at temperatures ranging from 550 to 1150 K, at a constant residence time (τ) of 1 s, and for three equivalence ratios (ϕ = 0.5, 1.0, and 2.0). Chemical analyses by Fourier transform infrared (FTIR) spectrometry and gas chromatography allowed for the measurement of the mole fraction of reactants, stable intermediates (including substituted tetrahydrofurans), and final products as a function of the temperature. A similar behavior was observed for the oxidation of n-undecane, n-dodecane, and Jet A-1 in a JSR. However, it was shown that the pure n-alkanes oxidized faster than Jet A-1 under cool-flame conditions and intermediately yielded more ethylene. A kinetic reaction mechanism based on previous studies , was developed and validated by a comparison to the present experimental results. The proposed reaction mechanism consisted of 5864 reversible reactions involving 1377 species. Experimental data and simulation results obtained in the current work were compared to simulations performed with a literature model. Our model was also applied successfully to the modeling of the oxidation of n-dodecane under shock-tube conditions. , Species time histories and ignition delay times representing valuable complementary tests were simulated.