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International audience; A comprehensive collection of technical aviation fuels enabled an experimental and numerical study on detailed combustion chemistry and pollutant formation presented in a series of 3 interlinking parts. Part-I: Experimental Flow Reactor Study focuses on the characterization of 42 technical jet fuels and provides experimental speciation data for model development presented in Part-II: Model and Surrogate Strategy. Model validation based on the presented technical fuels here is presented in Part-III: Model Application on Technical Jet Fuels.The fuels investigated in this study cover a broad range of approved SAFs (Sustainable Aviation Fuels), candidates for approval, and technical products outside the present ASTM-D7566 specification and is completed by reference fuels (ASTM-D1655). This includes SAF components such as HEFA (Hydroprocessed Esters and Fatty Acids), ATJ (Alcohol-To-Jet), SIP (Synthesized Iso-Paraffins), and Fischer-Tropsch-products as well as their blends.A systematic investigation of the soot precursor chemistry by analyzing the influence of the complex chemical fuel composition on the intermediate species pool is presented. The experimental set-up consists of an atmospheric flow reactor with coupled molecular-beam mass spectrometer (MBMS). Quantitative evolution of combustion reaction intermediates is recorded for fuel-rich (Φ = 1.2) and fuel-lean (Φ = 0.8) conditions at intermediate temperatures up to 1200 K including small intermediate species (e.g. ethylene, butene) and soot precursor species (e.g. benzene, naphthalene, phenanthrene).A general systematic dependency of the soot precursor concentration on the degree of unsaturation (Index of Hydrogen Deficiency) or the hydrogen content, respectively, is demonstrated. Furthermore, larger soot precursor concentrations depend on the naphthalene content of the fuel.

The stability of biofuels toward oxidation is currently one of the major challenges for its widespread use. In fact, insoluble deposits issued from biofuels degradation can cause several types of d...

The thermal and oxidation stability of fatty acids methyl esters (FAME) is arousing attention in the transport industry, since they are the main components present in biodiesel products used in the market. Low FAME stability can induce easy fuel degradation and produce oxidation products that can form sticky deposit causing serious malfunctioning and failures of engine and turbines components. We have focused the present work on the study of fuel oxidation process and the characterization of oxidation products in order to identify the main levers to avoid deposit formation. Soy and Rapeseed biodiesels were oxidized using an autoclave Parr reactor and characterized by FTIR, density and viscosity measurements. After oxidation, two different liquid phases were clearly observed. These two phases tend to form complex oil-oil emulsions after remixing as evidenced by optical microscopy. The separation behavior of the different liquid phases remixed after oxidation were studied using Multiple Light Scattering (TurbiscanTM). A comparison was made between the chemical functions of deposit obtained in the liquid phase after demixing (sedimented phase) and the solid deposit obtained on hot metallic surfaces. Results showed a that a complex oil-oil dispersion seems to form during the oxidation process. The phase separation rate of the oil-oil emulsified systems formed from oxidized fuels seems strongly related to the differences of polarity (e.g. oxygenates content) of both sedimented and supernatant phases. The understanding of this sedimentation or “demixing” process leading to deposit can be a key feature to develop strategies to prevent deposit formation in real systems.

In the present work, the oxidation stability of diesel, rapeseed (RME), and soybean (SME) fatty acid methyl esters (FAME) and a blend of diesel with 10% (v/v) RME (B10–RME) was studied. Fuel samples were aged in the PetroOxy test device from 383 to 423 K at 7 bar. Experiments were conducted in oxygen excess, and the global kinetic constants were determined. The global kinetic constants for diesel, B10–RME, and RME at 383 K were 7.92 × 10–6, 2.78 × 10–5, and 8.87 × 10–5 s–1, respectively. The oxidation products formed at different stages of the oxidation were monitored by Fourier transform infrared spectroscopy (FTIR), thermogravimetric analysis–differential thermal analysis (TGA–DTA), and gas chromatography/mass spectrometry (GC/MS). The impact of the FAME nature and level of blending on the kinetic rate constant and the oxidation products was investigated. Results show that RME oxidation forms C19 epoxy as the main oxidation product, in addition to a methyl ester FAME derivative and short-chain oxidation...

Because of the recent changes in the formulation and handling of middle-distillate fuels, oxidation stability is becoming an increasingly important issue. However, liquid-phase oxidation kinetics of middle-distillate fuels remains poorly understood. The purpose of this study was to gain an in-depth understanding of the impact of fatty acid methyl ester (FAME) addition on autoxidation kinetics. A detailed kinetic mechanism for the autoxidation of a n-dodecane/methyl oleate (MO) surrogate mixture was generated and validated against original well-controlled accelerated oxidation experiments. Results emphasize the nonlinear oxidation promoting effect of MO on n-dodecane autoxidation. Pathway analyses reveal that HO2 and OH propagation steps as well as the duration of initiation and propagation phases strongly affected sensitivity analysis by MO addition. On the basis of these analyses and the detailed mechanism, an analytical model was derived and validated against experiments on binary surrogate mixtures as ...