Ignition behavior and surrogate modeling of JP-8 and of camelina and tallow hydrotreated renewable jet fuels at low temperatures

Abstract

Tonghun, "Ignition behavior and surrogate modeling of JP-8 and of camelina and tallow hydrotreated renewable jet fuels at low temperatures" (2012 b s t r a c tThe autoignition characteristics of the conventional jet fuel, JP-8, and the alternative jet fuels, camelina and tallow hydrotreated renewable jet (HRJ) fuels, are investigated using a rapid compression machine and the direct test chamber charge preparation approach. Ignition delay measurements are made at low compressed temperatures (625 K 6 T c 6 730 K), compressed pressures of p c = 5, 10, and 20 bar, and equivalence ratios of / = 0.25, 0.5 and 1.0 in air. The HRJ fuels ignite more readily than JP-8 for all tested conditions, consistent with derived cetane number data in the literature. The camelina and tallow HRJ fuels exhibit similar autoignition characteristics, but the two fuels can be distinguished under stoichiometric conditions. Kinetic modeling is conducted with a 2-component surrogate (10% n-dodecane/90% 2-methylundecane) and a single component surrogate (2-methylnonane) to evaluate the potential to predict ignition behavior of the HRJ fuels. Modeling results indicate that the surrogate fuels can only provide useful predictions at a limited set of conditions (p c = 5 bar and / = 1.0), and that the agreement of the model and experimental data improves with decreasing compressed pressure. Under most conditions, the 2-component surrogate provides better prediction of ignition behavior, but the single component surrogate is superior at low pressures near the negative temperature coefficient region.

Ignition delay times of conventional and alternative fuels behind reflected shock waves

“…Several alternative fuels are being considered, these include coal-derived "iso-paraffinic kerosene" (IPK) [3], FischerTropsch (FT) "synthetic paraffinic kerosene" (SPK) [3], "hydro-processed renewable jet" (HRJ) derived from camelina and tallow [3,4], alcohol-to-jet fuels (ATJ), hydro-refined algal oil [5], terpene dimers (B.G. Harvey, C. Brophy, private communication, November 14, 2011), hydrogenated-pinene (B.G.…”

A comprehensive combustion chemistry study of 2,5-dimethylhexane

“…On the other hand, Mueller et al [18] concluded that utilizing large iso-alkanes representative of those found in real fuels could be advantageous. In a recent study on the ignition of JP-8 and hydrotreated renewable jet fuels, Allen et al [19] utilized surrogates principally composed of large mono-methylated alkanes [20] in chemical kinetic modeling simulations to predict combustion behavior of the real fuels. They suggested that utilizing a di-methylated alkane as a surrogate for the real fuels could improve predictability, if accurate chemical kinetic models were available.…”

Autoignition behavior of synthetic alternative jet fuels: An examination of chemical composition effects on ignition delays at low to intermediate temperatures

“…Overall, the shock tube and RCM data correlate favorably, with the exception of HRJ-5 and LINPAR 1416V where the RCM predicts faster ignition than the shock tube. This phenomenon has been previously noted [3,4], where ignition delays measured in RCMs can be shorter than observed in shock tubes for ignition delay times less than $8 ms due to preignition chemistry occurring prior to TDC, particularly for highly reactive n-paraffinic fuels such as HRJ-5 and LINPAR 1416V.…”

“…Understanding of the chemical kinetic behavior of alternative fuels, for example macroscopically exemplified through ignition delay, flame speed, and extinction limits, is needed for combustion model development. Kinetic targets for fuel characterization and model development have only become recently available in the literature for complex multi-component fuels, including autoignition studies for conventional, HRJ, and FT fuels [3][4][5][6][7]; however, little work has been performed regarding blends of conventional and alternative fuels. Additionally, the influence of fuel composition/structure on autoignition is sparse in the literature, particularly at lean conditions, that are becoming increasingly attractive for achieving reductions in production of harmful emissions.…”