哈爾濱理工大學學士學位論文哈爾濱理工大學學士學位論文#Methanolisoneofthelowmolecularweightalcoholsthoughttoactasanactivatorspeciesintheureaprocess.?Thepreseneeofmethanolisthoughttoincreasethesolubilityofureainthefuel,whichresultsinamorecompleteurea/alkanereactionandfasterreactiontimes.AlsoshowninFigure2istheDSCcurveforfueltreatedwithamixtureofureaandmethanol.Theaboveprocedurewasrepeatedwiththeadditionof1mLofmethanol.Thefigureshowsthattheurea/methanoltreatmenteliminatesthefreezingexothermoutbelow-65°C,providingashiftintheexothermpeakbymorethan10°C.Thisshowsthattheurea/methanoltreatmenthasthepotentialtoproducefuelthathasimprovedlow-temperaturepropertiesbeyondthatofin-specificationJPTS(seeFigure1forcomparison).Toconfirmthattheimprovedlow-temperaturebehaviorisduetotheremovalofnormalalkanes,asexpectedfrompreviousstudies,andtostudytheselectivityoftheprocessforvarioussizealkanes,weusedgaschromatography(GC)tomeasurethechangeinconcentrationofthenormalalkanesuponureatreatment.Figure3showsachromatogramofthe3219fuel,whichshowsthatthisfuelcontainsnormalalkanesprimarilyintherangeCtoC,withonlyverysmallamountsofC(<0.0591617mol%).Figure4showsthepercentdecreaseinconcentrationofthesenormalalkanesaftertheurea/methanoltreatmentdescribedabove.Thesmalleralkanes,CtoC,aredecreasedby10to25%.Thelargernormal913alkanes(>C)areremovedtothegreatestextent,withessentially100%14removalofn-C.Thisshowsthattheurea/methanoltreatmentprocessis16selectivetowardthelargernormalalkanespresentinjetfuel.Thisselectivitytowardlong-chainn-alkanesisquitedesirable,asthesespecieshavebeenimplicatedasbeingthefirstspeciestocrystallizeuponthecoolingofthesefuels.12_1Theinitialcrystallizationofthesespeciescausesfuelclouding,whichatlowertemperaturesand/orlongertimes,resultsinfuelgelationandtheinhibitionoffuelflow.Aprimarybenefitoftheurea哈爾濱理工大學學士學位論文哈爾濱理工大學學士學位論文哈爾濱理工大學學士學位論文哈爾濱理工大學學士學位論文adductionprocessisinthisselectivitytowardremovalofthespeciesthatformsolids(relativelylargenormalalkanes),whilebeingmuchlesslikelytoreactwithotherfuelspecies,suchasaromatics,branchedalkanes,andcycloalkanes(naphthenes).Also,theprocesssignificantlylowersthemeasuredfreeze,cloud,andpourpoints(seebelow),whiletheuseofcold-flow-improvingadditiveshasnotdemonstratedsignificantchangesinFigure3Chromatogramoffuel3219showingnormalalkanes.Figure4Plotofpercentdecreaseofvariousnormalalkanesafterurea/methanoltreatment.xcix哈爾濱理工大學學士學位論文哈爾濱理工大學學士學位論文哈爾濱理工大學學士學位論文哈爾濱理工大學學士學位論文附錄CCIM.s.密呂.紹s.i.ABlii.tw.u?-w.rBRs.Flic<=■UJ0三E?SIi$SH.-￡Eiw^Ei5E*wk=FIeax!*jfKfs!署加.啟宜鬲芒一奩貝川町tb-困醫■l-sprELH涇軌日吏0R134站里UImg曲r^.K.ss—sT7Ayh§org爼廬v蚤巧：.F「<」ITII—o1占1營邕拾240蚩fn.Enthalpy軒二閃一1]V、A\-fvCP崑tetjtug譽醬C