Shock Tube Study of Ignition Delay Characteristics of n-Nonane and n-Undecane in Argon

Abstract

Ignition delay times of n-nonane and n-undecane in 4% oxygen/argon have been measured behind reflected shock waves in a heated shock tube at temperatures of 1168−1600 K, pressures of 2, 10, and 20 atm, and equivalence ratios of 0.5, 1.0, and 2.0. Ignition delay times are determined by using CH* emission and pressure signals monitored at the sidewall. Results show that ignition delay times of two fuels decrease as the temperature or pressure increases, and a decrease in equivalence ratio results in a shorter ignition delay time. For fuel-lean and stoichiometric mixtures, n-nonane has ∼25%−35% longer ignition delay times than n-undecane. For fuel-rich mixtures, ignition delay times of two fuels are very close. Correlations for ignition delay times of two fuels as a function of temperature, pressure, and equivalence ratio are formulated through regression analysis. The experimental data are in good agreement with shock tube data available, and the trends of experimental data were captured well by the predictions from the LLNL and JetSurF mechanisms under conditions studied. Comparison of ignition delay times for nine n-alkanes from propane to n-undecane reveals that the n-alkanes have the similar ignition delay behavior and their ignition delay times are close to each other. Reaction path analyses and sensitivity analyses are performed to investigate the consumption of fuels and identify the important reactions in the ignition process. To our knowledge, we provide the first ignition delay time data for n-undecane at elevated pressures, and our measurements for n-nonane are at a broader range of conditions than previous studies. Current results contribute toward understanding the ignition characteristics of n-nonane and n-undecane, and they provide validation targets for corresponding kinetic mechanisms.

Experimental and mechanistic investigation of benzene formation during atmospheric pressure flow reactor oxidation of n-hexane, n-nonane, and n-dodecane below 1200 K

“…The present status on modeling and experimental studies on n-hexane, n-nonane and n-dodecane is summarized in Table 1. The ignition delay times of the above three hydrocarbons are well investigated and investigations are available for atmospheric to high pressures (20 -60 atm) in the temperature range of 700 -1600 K [28][29][30][31][32][33][34][35][36][37]. The characteristic burning velocities are studied mostly at atmospheric conditions [38][39][40] except for n-hexane (2, 5, and 10 atm) [41].…”

Strategically Designed Hyperbranched Polyglycerol as an Efficient Integrated Additive for Hydrocarbon Fuels

“…Compared with other MIs, the solubility of CBHPG in hydrocarbon fuels is impressive. n -Undecane, a main component of RP-3, was chosen to be the model fuel . The aggregate size of 0.20 wt % CBHPG in n -undecane at 25 °C is displayed in Figure e.…”

“…n-Undecane, a main component of RP-3, was chosen to be the model fuel. 49 The aggregate size of 0.20 wt % CBHPG in n-undecane at 25 °C is displayed in Figure 3e. It is found that the dissolved particle size of CBHPG in n-undecane increases with molecular weight, but all the particle sizes are below 8 nm.…”

Comprehensive Comparison of the Combustion Behavior for Low-Temperature Combustion of n-Nonane

“…The detailed description of the existing experimental data on n -nonane combustion is shown in Table . ,− Although establishing a comprehensive n -nonane kinetic mechanism to describe its oxidation under a wide range of experimental conditions is important because of the complexity of large hydrocarbon fuels, the kinetic models currently used to describe n -nonane combustion are extremely rare, and are primarily acquired by manual construction. Among them, Westbrook et al developed a kinetic model (LLNL model) for describing the pyrolysis and oxidation of linear alkanes (from n -octane to n -hexadecane) over a wide temperature range; Wang et al developed a kinetic model (JetSurf 2.0 model) for the high-temperature oxidation of linear alkanes; cyclohexane; and methyl, ethyl, n -propyl, and n -butyl cyclohexanes.…”