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1HYDROCARBON LIQUID FUELS THERMAL STABILITY ANTIOXIDANTS INFLUENCE AND BEHAVIOUR

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Niveau: Supérieur, Doctorat, Bac+8
1HYDROCARBON LIQUID FUELS THERMAL STABILITY, ANTIOXIDANTS INFLUENCE AND BEHAVIOUR S. Gernigon1_, M. Sicard1, F. Ser1, F. BozonVerduraz2 1: ONERA, Fundamental and Applied Energetics Department (DEFA) Chemin de la Hunière, 91761 Palaiseau Cedex, France 2: ITODYS, Paris-Diderot, Bâtiment Lavoisier 15, rue Jean de Baïf, 75205 Paris Cedex 13, France _: main author, e-mail: Abstract Jet fuel undergoes an oxidative chemistry upon being heated in fuel system of advanced civil aircraft. The degradation process may lead to the formation of bulk and surface solids. For engines featuring a low-NOx combustion chamber based on multipoint injection, these deposits could plug the injection system. Deposits formation has different origins; one of them is dissolved oxygen. The aim of this study is to strongly decrease or inhibit the autoxidation reactions present during the fuel degradation. This is why the use of antioxidant additives is considered. Several molecules (n-dodecane, cyclohexylbenzene, 1,3-diisopropylbenzene, and 2,2,4,4,6,8,8- heptamethylnonane) are tested with and without antioxidants (2,6-di-tert-butyl-4-methyl phenol, 2,4-di-tert-butyl-phenol, and 2-tert-butyl-4-methylphenol).

  • jet fuel

  • formed during

  • rh ?

  • stability additives

  • study autoxidation

  • thermal oxidative

  • between thermal

  • r?


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HYDARNOTCIAORXBIDOANNLTISQIUNIFDLFUUEENLCSETAHNEDRBMEAHLASVTIAOBUIRLITY,AbstractS.Gernigon1#,M.Sicard1,F.Ser1,F.BozonVerduraz21:ONERA,FundamentalandAppliedEnergeticsDepartment(DEFA)ChemindelaHunière,91761PalaiseauCedex,France2:ITODYS,Paris-Diderot,BâtimentLavoisier15,rueJeandeBaïf,75205ParisCedex13,France#:mainauthor,e-mail:sterenn.gernigon@onera.frJetfuelundergoesanoxidativechemistryuponbeingheatedinfuelsystemofadvancedcivilaircraft.Thedegradationprocessmayleadtotheformationofbulkandsurfacesolids.Forenginesfeaturingalow-NOxcombustionchamberbasedonmultipointinjection,thesedepositscouldplugtheinjectionsystem.Depositsformationhasdifferentorigins;oneofthemisdissolvedoxygen.Theaimofthisstudyistostronglydecreaseorinhibittheautoxidationreactionspresentduringthefueldegradation.Thisiswhytheuseofantioxidantadditivesisconsidered.Severalmolecules(n-dodecane,cyclohexylbenzene,1,3-diisopropylbenzene,and2,2,4,4,6,8,8-heptamethylnonane)aretestedwithandwithoutantioxidants(2,6-di-tert-butyl-4-methylphenol,2,4-di-tert-butyl-phenol,and2-tert-butyl-4-methylphenol).Thecharacterizationofthevariousproductsformedduringdegradation(gas,liquid,andsolid)allowsknowingtheroleplayedbytheselectedmoleculesinthedegradationofjetfuel.GasChromatography,GasChromatography/MassSpectroscopy,andInfraRedarethecharacterizationtechniquesusedfortheanalyticpartofthisstudy.Theliquidanalysisshowstheformationofoxidizedproductslikeketones,carboxylicacids,andalcohols.ThereisnoformationofdepositforallhydrocarbonstestedinpresenceofBHT.BHTisthemosteffectiveforalkanesbutnotveryefficientforcycliccompounds.Keywords:jetfuel,n-dodecane,cyclohexylbenzene,1,3-diisopropylbenzene,2,2,4,4,6,8,8-heptamethylnonane,antioxidant,oxidativechemistry,oxidation;thermalstability,peroxides,alkylphenoladditives,the2,6-di-tert-butyl-4-methylphenol(BHT),the2,4-di-tert-butyl-phenol(2,4-DTBP),the2-tert-butyl-4-methylphenol(TBMP),GasChromatography(GC),InfraRedSpectroscopy(IR),MassSpectroscopy(MS).INTRODUCTIONInmilitaryorcommercialaircraft,jetfuelcanbeexposedtohightemperatures.Whenthefuelisheated,itundergoesadegradationprocesswhichcanleadtotheformationofbulkandsurfacedeposits(solubleandinsolubleproducts)inthefuelsystem.Thedepositscanreduceheatexchange,clogfilters,andfoultolerancevalvesandactuators.Oneofthedegradationoriginsisthedissolveddioxygenwhichinitiatesformationofperoxides.From150to300°C,thejetfuelthermalstabilityisgovernedbytheautoxidationchemistry.Researchhasproposedautoxidationmechanisms(1-2-3-4-5),ZabarnickandHeneghanproposedthefollowingpathway(2):1