Introduction
Stratifiedcombustionofcoal
Laminatedcoalcombustionistoloosentherawcoalthathasslippedfromthecoalbunkerthrougharotatingroller.Falltothesieveplate.Large-sizedparticlesfallfromthesieveplatetothegrate,andthesmallparticlesizeleakstothegrateunderthesieve.Asthegraterotates,thecoalfeedlevelofthelowerandtheupperisformed,sothatthecoalseamisevenlyventilatedandimproved.Increasethefurnacetemperature,whichisconducivetoburnout.
Thestratifiedcombustionoffuel
Theso-calledstratifiedcombustionsystemistorelyonintakeswirlormechanicalmethodstostratifytheconcentrationofthemixtureenteringthecylindertomakecombustionThemixtureinthechamberformsarichermixturenearthesparkplugthatiseasytoignite,(air-fuelratiois12to13.5)toensurereliableignition,andmostoftherestofthecombustionchamberisaleanmixture,andinsomeplacesitisevenJustair,inthisway,thetotalair-fuelratiointhecombustionchamberaveragesabove18:1,sometimesevenhigher.Duetotheignitionofthecombustionflameoftherichmixturenearthesparkplug,mostoftheleanmixtureinthecombustionchambercanbeburnednormally,soastoachievethepurposeofusingtheleanmixtureinthegasolineengine.Thiskindofenginethatdividesthemixtureintorichandleanpartsinthecombustionchamberforcombustioniscalledastratifiedcombustionsystem.
Thestratifiedcombustionmodehasarelativelylargethrottleopeningduringtheintakeprocess,whichreducesapartofthethrottleloss.Thekeytotheintakeprocessistoinstallaflapintheintakepipe,whichopensupwards(thenatureoftheprinciple,theactualmodelmaybedifferent)tosealthelowerintakepipe,allowingtheintakeairtoacceleratethrough,andcooperatewiththeomega-shapedpistoncrown.Phaseintotheintakevortex.
Instratifiedcombustion,thefuelinjectiontimeis60°beforetopdeadcenterto45°beforetopdeadcenter.Theinjectiontiminghasagreatinfluenceontheformationofthemixture.Thefuelisinjectedintothepitonthepistoncrown.Theinjectedfuelcombineswiththeswirlintaketoformamixture.Themixtureformationoccursintherangeofcrankshaftangleof40°to50°.Ifitislessthanthisrange,themixturecannotbeignited.Ifitisgreaterthanthisrange,itbecomesahomogeneousstate.Theexcessaircoefficientofstratifiedcombustionisgenerallybetween1.6-3.
Whenigniting,onlythegasinabettermixedstatearoundthesparkplugisignited.Atthistime,thesurroundingfreshairandthegasfromtheexhaustgasrecirculationformagoodheatinsulationprotection,whichreducestheheatdissipationofthecylinderarm.Improvedthermalefficiency.Thecontroloftheignitiontimingisalsoveryimportant,itisonlyinaverynarrowrangeattheendofthecompressionprocess.
Advantagesanddifficulties
Stratifiedcombustionofcoal
1.Thecombustionheatefficiencycangenerallybeincreasedbyabout8-12%.
2.Thecarboncontentoftheslagcanbereducedtoabout10%.
3.Improvetheadaptabilityofcoaltypes.
4.Afterthetransformation,theboilercanbeoperatedatfullload.
5.Quickheatingandpressureincrease,easytoignite.
6.Thefailurerateislow,sothattheoriginalburningoftheslagstopperandtheside-sealedcoal-burninghopperarefundamentallyeliminated.
7.Eliminatetheunevencoalfeedingstatethatcausedbygravitywhenthegrateentersthecoalscuttle,wheretherearemanyblocksonbothsidesandalotofpulverizedcoalinthemiddle,soastoachieveuniformcoaldistributionandstratification.
8.Therenovationcostisappropriate,thecostrecoveryisfast,andthecostisbasicallyrecoveredwithinthefirsthalfoftheyear.
Stratifiedcombustionoffuel
1.Stratifiedcombustionisdefinedas:combustionisdividedintoconcentrationlevels,thefuelconcentrationinthecenterofthecombustionzoneishigher,andtheperipheryofthecombustionzoneismoreair-rich.Many,thefinalresultis"completecombustion".
2.Itisrequiredthatatthemomentofignition,theconcentrationoffuelvaporattheelectrodeofthesparkplugisjustrightforreliableignition.Itdoesn'tmatteriftherearedeviationsinotherareas;butthisisthehardestthingtodoinyears.
3.Whentheengineisat"lowthrottle"oridling,onlyalittlerichgasinthesparkplugareaisrequiredinthecylinder,andtheotherareasarefilledwithfreshair,whichcanachievecompletefuelcombustion.
4.Becausethefinalresultofcombustionisthatthereisexcessoxygen-containingair,thecombustioncanbecompletelythorough,sothefuelefficiencyoftheengineisextremelyhigh,andtherearealmostnobadcombustionpollutantsofconventionalengines.
5.Theatomizationofthefuelfedintothecylinderisnaturallythefinerthebetter,buttheconcentrationrangeislargerthanthefuelconcentrationratiousedinconventionalengines,sotheadjustmentofthe"carburetor"issimplerandbetterDosomething.
6.Becauseexcessairseparatesthecombustionareafromthecylinderwallandpistonduringthe"lowthrottle",theengineisnotheatedveryseriously,andtheengineworkefficiencyisimprovedduetolessheatdissipation.
7.Most"stratifiedcombustion"enginestructuresusenozzlesaimedatsparkplugstoinjectmistfuel,implementhigh-concentrationfuelignitioninanignitionchamber,andthendiffusecombustiontoall.
8.Donotusealargeamountofhomogeneouscombustiongas,andthereisnoneedtoworryaboutlarge-scalecombustiongaspressuredeflagrationaccidents,sotheenginecompressionratiocanbeimproved,whichisverygoodforimprovingtheefficiencyoftheengineinnormaltimes.
9.Thistypeofcombustionmethodiscontrarytoconventionalengines.Theextremefuel-savingstateisparticularlygoodwhenthethrottleissmall,anditadaptstotheactualuseofmostvehiclesusuallyusingsmallthrottlesandoccasionallyusinglargethrottles.
10.Becausethecylinderisnotcompletelyfilledwithhomogeneouscombustionsteam,theengine’s"literpower"isslightlylower,buttheincreaseindisplacementandthedecreaseinheatdissipationsystem,thetotalweightoftheengineshouldbebasicallythesame.
Thepurposeof"stratifiedcombustion"istorationallyapplythearrangementof"moregasandlessoil"tocompletelyburntheoil.Therefore,stratifiedcombustionintheenginemustbebasedonthe"gasmoreoil"arrangement."Less"isthebasiclayout.Themostdifficultandmostcriticalpointisthattheconcentrationofthelocalfuelgasshouldbeadaptedtotheignitionoftheelectricspark.Aslongasthefirecanbeignited,thefuelinotherpartscanbemoreorlessthe"throttlesize".
Ignitionoftherightconcentrationinacylinderwithfierceairflowissimilartopouringacupoffueltoamatchthatisinstantlylittenmetersawayonawindyday.Itisabitdifficult.Inadditiontotheignitionproblem,therearemanyothertechnicalproblems;manydesignstructureshavebeentestedoverseasfordecades,butsofarthereisnoenginewithanidealperfectstandardstructure,andthedifficultycanbeseenfromthis.