Application of Gliding Arc Discharge for Control of VOC …滑动控制VOC的电弧放电中的应用… .ppt

unipolarinjectionofchargeintoquiescentgaseousdielectricsalexeiv savelievdepartmentofmechanicalandaerospaceengineeringnorthcarolinastateuniversitypresentedatworkshopon electrostaticatomizationofelectricallyinsulatingfluids principlesandapplications universityofsouthampton march2 2009 outline 1 introductionplasmaandionizedgases2 breakdownofgaseousdielectricsuniformfield paschen slawnon uniformfieldbreakdownpositiveandnegativecoronascoronachargeinjectiondevicespulsedstreamercoronadischarges3 dischargeinitiationinsupercriticalfluidsscfsasaclusterfluidgenerationofscfplasmaincarbondioxidepotentialapplicationsofscfplasmas4 breakdownandchargingonliquid gasinterfaces plasmasandionizedgases plasmaisanionizedgasconsistingofchargedandneutralparticlesandexhibitingcollectivebehavior langmuir 1929 plasmamaycarryacurrentplasmaisoftenconsideredtobeelectricallyneutralplasmaisanionisedgasionizedgasisnotalwaysplasma non thermalelectricaldischarges electronsareacceleratedintheelectricfieldgainingenergysufficientforionizationofneutralmoleculessecondaryelectronsareproducedincollisionsformingelectronavalanchepropagatingintheinterelectrodegap ar e e e ar developmentofelectronavalanche1ev 10000kionizationenergy 10eve nparameterme i thermalplasmate ti tgnon thermalplasmate ti tg e fieldbreakdown elementaryprocesses ionizatione ar 2e ar electronattachmente o2 o2 electrodeprocesses ionimpact thermionicemission fieldemission kineticsofionsandelectrons fowler nordheim 1928 e fieldbreakdown uniformfield townsendcriterion multiplicationofchargesduringavalanchepropagation d breakdownvoltageandbreakdownreducede fieldbetweentwoparallelelectrodes paschen slaw breakdowninnon uniformfield peek sformulaecr criticale fieldinkv cm r radiusofinnersphereincm relativeairdensity modifiedtownsendcriterion coronadischarge coronaconfigurationsa wire in cylinder b sphere in sphere c point and plane d parabola to plane e wire to plane e applicationsofcoronadischarge charginganddischargingofsolidsandfluidsmanufactureofozoneelectrostaticprecipitatorspollutioncontrol vocs sox nox processingofmaterialsurfacesphotocopyionicwinddevicesgasionizersformassspectrometersanddma dccoronacurrent typicalvoltage currentcharacteristicsfornegativepoint to planecorona solutionforwireincylindercoronavcr ignitionvoltage positivecorona streamerpropagationandbranching streamerpropagationmodes veldhuizenandrutgers j phys d appl phys 35 2002 streamermodel streamerpropagationandbranching fastintensifiedccdimagingofthefasttransientplasmagenerationwith5nsgating a pulsedcoronadischargeinair b pulsedcoronadischargeinco2 a b morphology length andvelocityofstreamersareextremelyimportantfordischargestructureandiongenerationefficiency positivecorona existenceregionsforpositivesphere to planecoronaformsinatmosphericair r 10mm negativecorona existenceregionsfornegativesphere to planecoronaformsinatmosphericair dccoronachargers theneedformoreefficientmethodstochargegasandaerosolstreamshasresultedinarenewedinterestincoronadischargeionizers spacechargebuildupinthepositivewire to cylindercorona r e cathode anode ionizationregion dccoronadiffusionchargers severaltypesofsuchchargershavebeenproposedinrecentyears mostofthembasedontheoriginaldesignofhewitt 1957 distributionofionconcentrationatvariouspressures biskosetal journalofelectrostatics63 2005 dccoronadiffusionchargers totalionnumberconcentrationationizeroutlet alguacilandalonso aerosolscience37 2006 sharp pointelectrodeionizer pulsedstreamercoronadischarge pulsedcoronadischargecanbereadilygeneratedatatmosphericpressurevoltageisappliedtothesharpelectrodeasaseriesoffastrisingpulses 100nsduration10nsrisetime20kvpeakvoltageelectronenergiesupto20ev 230 000k generatesandefficientlyseparatesthecharges pulsedelectrostaticprecipitators thefirstuseofcoronatoremoveparticlesfromanaerosolwasbyhohlfeldin1824electrostaticprecipitatorswerefirstusedinindustrytoremoveofsulfuricacidmistfromexhaustfumesinthebeginningofthe20thcenturymoderncontrolsminimizesparkingandpreventarcingbyapplyingpulsedvoltageandthusavoidingdamagetothecomponents pulsedcoronadischargeforvocremoval breakdowninsupercriticalfluids traditionalarea elevatedpressureplasmas nanoplasma microplasma liquidplasmas 1 m 1atm theareaofnon thermalplasmasisexpandingtoelevatedpressuregases liquidsandmicroplasmasforagivenvoltagevte f e n f v nd n neutraldensityd characteristicsystemsize thegenerationofnon thermalplasmainsupercriticalfluid scf mediaisinterestingbothfromfundamentalandappliedviewpoints sustainingplasmasinscfmediabridgesthegapbetweengaseousandliquidprocessingsincescfshavepropertiesthatareintermediatebetweenthegasandliquidstatesapplicationsofsupercriticalplasmas pollutantremoval bacterialdeactivation plasmapolymerization materialsynthesis scfplasma problemstatementandmotivation supercriticalcarbondioxide criticalpoint 304k 73barenvironmentallyfriendly green solventthepropertiesofsupercriticalfluidsareintermediatetocorrespondinggasandliquidstatesscfcombinesheterogeneouschemistrywithefficientmasstransferrealizedbythelowviscosity highdiffusivityandzerosurfacetension clustersinsupercriticalco2 scfisoftenreferredasaclusterfluidclustersareeffectivelyformednearthecriticalpointclustersaffectreactionandtransportpropertiesofscfclustersarecruciallyimportantforplasmabreakdownmechanism scfplasmareactor technicalapproach non thermalplasmaisinitiatedinsupercriticalcarbondioxideatpressuresabove75barusinghigh voltagepulsesofnanoseconddurationthepulsesareappliedtothesystemofmicroelectrodesarrangedinpoint to planeandwire to planegeometriesthedischargeandplasmaparametersarestudiedusingopticalandelectricaldiagnostics microbreakdowninsupercriticalco2 ieeetrans plasmasci 33 850 2005 d 80 m itoandterashima appl phys lett 80 2854 56 2002 electronkineticsinsupercriticalco2 ionization recombination attachment dissociation wire in cylindercoronadischarge dischargeinceptionvoltagesingaseousandsupercriticalco2 theoriginalpaschen sdataareshownforreference ieeetrans plasmasci 33 850 3 2005 wire in cylindercoronadischarge dependenceofcriticale ponpdingaseousairandco2foruniformandnon uniformfields ieeetrans plasmasci 34 2467 2006 atomicforcemicroscopy electrodeassembly electrodegap point to planecoronadischarge periodicpulsedcoronadischarge distance200 mneedletip5 mt 60 cp 83barvoltage13kv slidingliquid jetdischarge thehighvoltagenanosecondpulsesareappliedtothemicro jetoverchargedmicro jetgeneratescoronadischargewithsharpliquidelectrodeapplicationformaterialprocessingandsensorsplasmaasanignitionsourceforenginesandcombustorsusingliquidfuels 100 m experimentalsetup surfacedischargeoperation experimentalsetup dischargepropagation electrolytejet a b c d e dischargepropagationmodes thelowerelectrodeisanode r 840k l 18mm 2mm a lowcurrentdegeneratedglowdischargeatu0 10kv b conversionoftheglowdischargetothesingleslidingsurfacedischarge c d developedsurfacedischargeatu0 23kv e degeneratedarcdischargeatu0 30kv voltage currentcharacteristicsofthedischargefordistilledwater l 18mm q 0 3ml s d 0 4mm 0 47nf 1 1 2 2 3 3 4mm 4 i theareaofacontinueddegeneratedglowdischarge ii pulsedsurfacedischarge dischargemodes distilledwater voltage currentcharacteristicsat 0 73nf l 20mm d 0 5mm q 0 5ml s ringelectrodeof4mmdiameter 6 10 2 1 7 10 2 2 2 10 1 3 1 2s m 4 i theareaofacontinueddegeneratedglowdischarge ii thepulsesurfacedischarge iii continueddegeneratedarcdischarge dischargeregimes electrolytejet waterjetatomizationatq 0 5ml s u 2 a 10kv b appearingthesurfacedischargeatu 13kv c i 8maanditsdevelopmentatu 16k