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Several alternative synthetic fuels are in discussion as a replacement for conventional fuels like Jet A-1 to cope with limited supplies of crude oil as well as their emissions connected with its use such as the greenhouse gas CO 2 . One of the alternative fuels which have received high attention recently is farnesane (2,6,10-trimethyldodecane), a biofuel produced from sugar using a biotechnological process. In this paper, combustion characteristics of farnesane were investigated by measuring its ignition delay time using a shock tube at elevated pressure (16 bar) and two different stoichiometries ( φ  = 1.0 and φ  = 2.0) and the laminar burning velocity at atmospheric and elevated pressures (1, 3, and 6 bar). These results were compared to a conventional Jet A-1 fuel showing that farnesane has a similar combustion behavior. Furthermore, a reaction model was developed capable to predict the measured combustion properties. The calculation of the ignition delay times yields excellent results when compared to the measurements; the computations of the laminar flame speeds are in good agreement with the measurements. In addition, the reaction model was analyzed to get further insight into the main reaction steps of farnesane oxidation. [ABSTRACT FROM AUTHOR]

Oxymethylene ethers (OME n) are discussed as attractive carbon-reduced alternative fuels because they offer the potential to inhibit the formation of soot particles. In the present study, the effect of oxymethylene ether-1 (OME 1) addition to a gasoline surrogate, here the primary reference fuel 90 (PRF90), on ignition delay times and laminar burning velocities was investigated. Ignition delay times of OME 1 , PRF90, and their blend with OME 1 blending fraction of 70% (by liquid vol.) were measured in a shock tube over a wide range of conditions: fuel-air ratio φ = 1.0, dilution of 1:5 with N 2 , T = 950 K-2000 K, and initial pressures of 1, 4, and 16 bar. Laminar burning velocities of OME 1 , PRF90, and their blend with OME 1 blending fraction of 30% (w/w) were measured by using the cone angle method at a preheat temperature of 473 K, φ = 0.6–2.0, and at pressures of 1, 3, and 6 bar. The experimental data sets have been compared to predictions made using the in-house DLR reaction mechanism, which was developed for surrogate modeling of gasoline, diesel, and jet fuels as well as oxygenated species such as alcohols (C 1 C 4) and oxymethylene ether (OME n , n = 1–5). The results revealed that the DLR mechanism satisfactorily predicts the experimental data for ignition delay times and laminar burning velocities of both the individual fuels and the blend. Both the experimental and calculation results show that ignition delay times of OME 1 / PRF90 are shorter than those of PRF90 for 1, 4, and 16 bar. The values of the measured burning velocities also agree with the corresponding predicted laminar flame speed data, except at high pressure (6 bar) and at high φ values. The effects of increasing OME 1 fraction in the blend was tested, with the results showing a corresponding non-linear decrease of ignition delay times. Sensitivity analyses and radical mole fractions analysis calculations were performed to interpret the effect of adding OME 1 to PRF90 on ignition delay times and laminar flame speeds. [ABSTRACT FROM AUTHOR]

Abstract: The kinetics of oxidation, ignition, and combustion of Gas-to-Liquid (GtL) Fischer–Tropsch Synthetic kerosene as well as of a selected GtL-surrogate were studied. New experimental results were obtained using (i) a jet-stirred reactor – species profiles (10bar, constant mean residence time of 1s, temperature range 550–1150K, equivalence ratios φ= 0.5, 1, and 2), (ii) a shock tube – ignition delay time (≈16bar, temperature range 650–1400K, φ =0.5 and 1), and (iii) a burner – laminar burning velocity (atmospheric pressure, preheating temperature=473K, 1.0⩽ φ ⩽1.5). The concentrations of the reactants, stable intermediates, and final products were measured as a function of temperature in the jet-stirred reactor (JSR) using probe sampling followed by on-line Fourier Transformed Infra-Red spectrometry, and gas chromatography analyses (on-line and off-line). Ignition delay times behind reflected shock waves were determined by measuring time-dependent CH* emission at 431nm. Laminar flame speeds were obtained in a bunsen-type burner by applying the cone angle method. Comparison with the corresponding results for Jet A-1 showed comparable combustion properties. The GtL-fuel oxidation was modeled under these conditions using a detailed chemical kinetic reaction mechanism (8217 reactions vs. 2185 species) and a 3-component model fuel mixture composed of n-decane, iso-octane (2,2,4-trimethyl pentane), and n-propylcyclohexane. The model showed good agreement with concentration profiles obtained in a JSR at 10bar. In the high temperature regime, the model represents well the ignition delay times for the fuel air mixtures investigated; however, the calculated delays are longer than the measurements. It was observed that the ignition behavior of the surrogate fuel is mainly influenced by n-alkanes and not by the addition of iso-alkanes and cyclo-alkanes. The simulated laminar burning velocities were found in excellent agreement with the measurements. No deviation between burning velocity data for the GtL-surrogate and GtL was seen, within the uncertainty range. The presented data on ignition delay times and burning velocities agree with earlier results obtained for petrol-derived jet fuel. The suitability of both the current detailed reaction model and the selected GtL surrogate was demonstrated. Finally, our results support the use of the GtL fuel as an alternative jet fuel. [Copyright &y& Elsevier]