简介:Porousnanocarbonswithaverageparticlesize20–40nmweredevelopedusingbiowasteoilpalmleavesasaprecursor.Simplepyrolysiswascarriedoutat700°Cundernitrogenatmosphere.Obtainedporousnanocarbonsshowedexcellentporousnaturealongwithsphericalshape.Symmetricsupercapacitorfabricatedfromporousnanocarbonsshowedsuperiorsupercapacitanceperformancewherehighspecificcapacitanceof368F/gat0.06A/gin5MKOHwerereported.Italsoexhibitedhighstability(96%over1700cycles)andenergydensityof13Wh/kg.Lowresistancevalueswereobtainedbyfittingtheimpedancespectra,thusindicatingtheavailabilityofthesematerialsassupercapacitorselectrode.Thepresentedmethodiscosteffectiveandalsoinlinewithwastetowealthapproach.
简介:Inordertounderstandthebreakupperformanceofcoaxialporousinjectors,thespraysofcoaxialporousinjectorswithtwodifferentporousmaterialcylinderlengthswerecomparedwiththoseofconventionalshearcoaxialinjectors.Toallowcomparison,thewallinjectionlengthsweredesignedtobeequivalenttothevalueoftherecessdepth.Coldflowsprayswerevisualizedusingback-litphotographymethodsandanalyzedquantitativelywithalaserdiffractionapparatus,inordertostudytheeffectsofthemomentumfluxratioandWebernumberonthebreakupforeachtypeofinjector.Incaseoftheshearcoaxialinjector,thelargeliquidcorewasobservedinlowairmassflowratecondition.However,thedestabilizationoftheliquidjetfromthecoaxialporousinjectorisalmostcompletewithintheinnerregion,neartheinjectorfaceplate.Additionally,betterbreakupperformanceinlowgasflowrateconditionwasobtainedwhentheporouscylinderlengthdecreased,whiletheshearcoaxialinjectorsshowedbetterbreakupefficiencywhentherecesslengthincreased.Inconclusion,thedifferentbreakupprocesscausedbytheradialmomentumintheinnerregionoftheporousinjectordisintegratedtheliquidcore.
简介:多孔的碳膜是有利地通过polyacrylonitrile(平底锅)的热分解制作了先锋,它与没有模板的technique-thermally导致的阶段分离被准备。这些碳膜拥有层次毛孔,包括越过在矩阵以及在毛孔墙上的整个膜和小毛孔的细胞的macropores。氮吸附显示micropores(1.47和1.84nm)和mesopores(2.21nm)在碳膜内存在,导致他们象1062m2/g一样大的特定的表面区域。碳膜被用来基于他们层次毛孔结构和大特定的表面区域的优点从水的答案吸附器官的染料(甲基橘子,刚果红,和玫瑰精B)。膜向甲基橘子介绍选择吸附,是特别地引人注目的,其分子的尺寸(1.2nm)是比刚果红(2.3nm)和玫瑰精B(1.8nm)的那些小的。这吸引人的结果能被归因于在分子的尺寸和毛孔之间匹配尺寸,而非静电的吸引力的位的结构。而且,使用的碳膜能容易被改革由盐酸酸,和他们的恢复吸附比率上面甚至在第三个周期维持90%。这个工作可以经由一条没有模板的途径为基于碳的吸附物向一条新线路提供层次毛孔,它能有希望地被使用有选择地在水的自河移开染料沾染物。
简介:Self-similarsteadynaturalconvectionthermalboundarylayerflowfromarotatingverticalconetoanisotropicDarcianporousmediumisinvestigatedtheoreticallyandnumerically.Thetransformednon-dimensionaltwo-pointboundaryvalueproblemisreducedtoasystemofcoupled,highlynonlinearordinarydifferentialequations,whicharesolvedsubjecttorobustsurfaceandfreestreamboundaryconditionswiththeMAPLE17numericalquadraturesoftware.Validationwithearliernon-rotatingstudiesisincluded,andalsofurtherverificationofrotatingsolutionsisachievedwithavariationalfiniteelementmethod(FEM).Therotational(spin)parameteremergesasaninversefunctionoftheGrashofnumber.Theinfluenceofthisparameter,primaryDarcynumber,secondaryDarcynumberandPrandtlnumberontangentialvelocityandswirlvelocity,temperatureandheattransferratearestudiedindetail.ItisfoundthatthedimensionlesstangentialvelocityincreaseswhilstthedimensionlessswirlvelocityandtemperaturedecreasewiththeswirlDarcynumber,tangentialDarcynumberandtherotationalparameters.Themodelfindsapplicationsinchemicalengineeringfiltrationprocessing,liquidcoatingandspinningconedistillationcolumns.
简介:Wepresentadesignmethodforcalculatingandoptimizingsoundabsorptioncoefficientofmulti-layeredporousfibrousmetals(PFM)inthelowfrequencyrange.PFMissimplifiedasanequivalentidealizedsheetwithallmetallicfibersalignedinonedirectionanddistributedinperiodichexagonalpatterns.Weuseaphenomenologicalmodelintheliteraturetoinvestigatetheeffectsofporegeometricalparameters(fiberdiameterandgap)onsoundabsorptionperformance.ThesoundabsorptioncoefficientofmultilayeredPFMsiscalculatedusingimpedancetranslationtheorem.Todemonstratethevalidityofthepresentmodel,wecomparethepredictedresultswiththeexperimentaldata.Withtheaveragesoundabsorption(lowfrequencyrange)astheobjectivefunctionandthefibergapsasthedesignvariables,anoptimizationmethodformulti-layeredfibrousmetalsisproposed.Anewfibrouslayoutwithgivenporosityofmulti-layeredfibrousmetalsissuggestedtoachieveoptimallowfrequencysoundabsorption.Thesoundabsorptioncoefficientoftheoptimalmulti-layeredfibrousmetalishigherthanthesinglelayeredfibrousmetal,andasignificanteffectofthefibrousmaterialonsoundabsorptionisfoundduetothesurfaceporosityofthemulti-layeredfibrous.
简介:Anewmethodforfabricatingorderedporoussiliconisreported.Atwo-dimensionalsilicananospherearrayisusedasatemplatewithahydrofluoricacid-hydrogenperoxidesolutionforetchingthenanospheres.Theinitialdiameteranddistributionoftheholesintheresultingporoussiliconlayeraredeterminedbythesizeanddistributionofthesilicananospheres.Thecorrosiontimecanbeusedtocontrolthedepthsoftheholes.ItisfoundthatthepresenceofaSiO_2layer,formedbytheoxidationoftheroughinternalsurfaceofthehole,istheprimaryreasonallowingthecorrosiontoproceed.Ultravioletreflectionandthermalconductivitymeasurementsshowthatthediameteranddistributionoftheholeshaveagreatinfluenceonpropertiesoftheporoussilicon.
简介:Inthiswork,aseriesofMIL-101-SO3H(x)polymericmaterialswerepreparedandfurtherusedforthefirsttimeasefficientheterogeneouscatalystsfortheconversionoffructose-basedcarbohydratesinto5-ethoxymethylfurfural(EMF)inarenewablemixedsolventsystemconsistingofethanolandtetrahydrofuran(THF).Theinfluenceof–SO3HcontentontheacidityaswellasonthecatalyticactivityoftheporouscoordinationpolymersinEMFproductionwasalsostudied.HighEMFyieldsof67.7%and54.2%couldbesuccessivelyobtainedfromfructoseandinulininthepresenceofMIL-101-SO3H(100)at130°Cfor15h.Thecatalystcouldbereusedforfivetimeswithoutsignificantlossofitsactivityandtherecoveryprocesswasfacileandsimple.Thisworkprovidesanewplatformbyapplicationofporouscoordinationpolymers(PCPs)fortheproductionofthepotentialliquidfuelmoleculeEMFfrombiomassinasustainablesolventsystem.
简介:Thispaperdiscussesastatisticalsecond-ordertwo-scale(SSOTS)analysisandcomputationforaheatconductionproblemwitharadiationboundaryconditioninrandomporousmaterials.Firstly,themicroscopicconfigurationforthestructurewithrandomdistributionisbrieflycharacterized.Secondly,theSSOTSformulaeforcomputingtheheattransferproblemarederivedsuccessivelybymeansoftheconstructionwayforeachcell.Then,thestatisticalpredictionalgorithmbasedontheproposedtwo-scalemodelisdescribedindetail.Finally,somenumericalexperimentsareproposed,whichshowthattheSSOTSmethoddevelopedinthispaperiseffectiveforpredictingtheheattransferperformanceofporousmaterialsanddemonstratingitssignificantapplicationsinactualengineeringcomputation.
简介:Facileproductionofhighqualityactivatedcarbonsfrombiomassmaterialshasgreatlytriggeredmuchattentionpresently.Inthispaper,aseriesofinterconnectedporouscarbonmaterialsfromlotusrootshellsbiomassarepreparedviasimplepyrolysisandfollowedbyaKOHactivationprocess.Thepreparedcarbonsexhibithighspecificsurfaceareasofupto2961m~2/gandlargeporevolume~1.47cm3/g.Inaddition,theresultantporouscarbonsservedaselectrodematerialsinsupercapacitorexhibithighspecificcapacitanceandoutstandingrecyclingstabilityandhighenergydensity.Inparticular,theirspecificcapacitanceretentionwasalmost100%after10500cyclesatacurrentdensityof2A/g.Remarkabely,theimpactofthetailoredspecificsurfaceareasofvariouscarbonsamplesontheircapacitiveperformancesissystematicallyinvestigated.Generally,itwasbelievedthatthehighly-developedporosityfeatures(includingsurfaceareasandporevolumeandporesize-distributions),togetherwiththegoodconductivityofactivatedcarbonspecies,playakeyroleineffectivelyimprovingthestorageenergyperformancesoftheporouscarbonelectrodematerialsinsupercapacitor.