【安全课件】第7章室内火灾简介

Chapter7CompartmentFireLesson1DevelopmentofCompartmentFireKeyWords&PhrasesCompartmentfire室内火灾Flashover轰燃Pre-flashover轰燃前post-flashover轰燃后Flammable(Flame)可燃的Combustible(combustion)可燃的Smoulder阴燃、无焰燃烧Smoulderingfire无焰燃烧Flamingfire有焰燃烧Ventilate(ventilation)通风VentilationFactor通风因子OpeningFactor开口因子KeyWords&Phrases1.DefinitionofcompartmentfireFireshappeninaroom,abus,acar,ashiportraincompartment,etc.areallcompartmentfires.Acompartmentfire(室内火灾)meansafirethattakesplaceinacompartment.Acompartmentisanenclosurewithwalls,roofandopenings(suchaswindowsanddoors).WTC911ThebigGarleybuildingfire,1996,HongkongAirportterminalfire,1996,Duesseldorf,GermanyMTRtraincompartmentarsonfire（纵火）,January2004(up)Shipfire:ThefirebrokeoutanhouraftertheshiplefttheportofMiami(Right)Busfires:Burnttothetopwithin10minBurntcompletelywithin10min2.Whycompartmentfirespresentaddeddanger?Compartmentfiresarequitedifferentfromthosefiresburningintheopenairbecauseofthewallsandceiling.Whenafireoccursinfreespace,heatandsmokegeneratedwouldbelosttotheambient(环境)rapidly.Butforacompartmentfire,mostoftheheatandsmokegeneratedwouldbeconfinedintheupperpartofthecompartment.Outdoors,firegrowssteadily.Indoors,trappedheatandsmokecausetemperaturetosuddenlygoup.3.Ignition(点燃)ofaCompartmentFireForignitionofafiretooccur,afuelmustbeheatedaboveitsauto-ignitiontemperature(自燃点)inthepresenceofsufficientoxidizer（氧化剂）forafiretooccur.Anignitionsourceisanythingwhichcanheatevenasmallportionofafueltoitsauto-ignitiontemperature.SmoulderingFiresAfterignitiontwokindsoffiresmayfollow:Afireinsolidfuelwhichisheat-limited(energy-limited)orventilationlimitedwillsmoulder.3.DevelopmentofaCompartmentFire3.Ignition(点燃)ofaCompartmentFireFlamingFires3.1SmoulderingFiresAHeat-limitedSmoulderingFireAVentilation-limitedSmoulderingFireFateofaSmoulderingFireThesmoulderingfiremayeventuallygainenoughheat(throughreflectedradiationorenhancedventilation)toburstintoflames;Alternatively,thefiremayself-extinguishduetoradiantheatlossorlackoffueloroxygen.AfterIgnitionTwoKindsofFiresMayFollow:3.2FlamingFiresAflamingfiremaydevelopimmediatelyafterignition,particularlyincasesofarson(纵火),ormaydevelopfromasmoulderingfireafteradelaywhichmaybehours.AFlamingFireFateofaFlamingFire:Thefireburnitselfoutwithoutinvolvingotheritemsofcombustiblematerial;Ifthereisenoughfuelbutinadequateventilation,thefiremayself-extinguishorcontinuetoburnataveryslowratedictatedbytheavailabilityofoxygen;Ifthereissufficientfuelandventilation,thefiremayprogresstofullroominvolvementinwhichallexposedcombustiblesurfacesareburning.TemperatureTime4.DevelopmentofacompartmentfireFlashover轰燃Growthstage(pre-flashover)初期增长阶段Fullydevelopedstage(post-flashover)充分发展阶段Decay衰减阶段4.1Growthstage(Pre-flashover)(1)Averagetemperatureislow.(2)Firelocalizationissmall.Inthegrowthorpre-flashoverstage,theaveragecompartmenttemperatureisrelativelylowandthefireislocalizedinthevicinityofitsorigin.4.2Fullydevelopedstage(post-flashover)(1)Averagetemperatureishigh.(2)Thewholecompartmentisinfire.Inthefullydevelopedorpost-flashoverfire,allcombustibleitemsareonfire.Flamesappeartofillthewholecompartmentandemergefromthewindowsandotherventilation(通风)openings.Thismaycontinueuntiltheavailablefuelisconsumed.4.2Fullydevelopedstage(post-flashover)4.3DecayStageAverageT≤80%TmaxThedecayperiodisoftenidentifiedasthestageoffireaftertheaveragetemperaturehasfallento80%ofitspeakvalue.Atthisstage,firebecomessmallerandtemperaturedropslowerduetotheconsumptionoffuel.4.4FlashoverGrowthstageFullydevelopedstageTransitionFlashoverThetransition(转变)isveryshort.Soflashoverisconsideredasaneventnotastage.Temperaturewillincreasequickly.Temperaturecanreachashighas1000℃.Duringflashover,flameswillspreadrapidlyfromtheareaoflocalizedburningtoallcombustiblesurfaceswithintheroom.Onceflashoverhasoccurredinonecompartment,it’shardlyfortheoccupantsoftherestofthebuildingtoevacuate(疏散).Thedurationfromonsetofburningtoflashoverisdirectlyrelevanttolifesafetywithinthebuiding.5.TheNecessaryConditionforSafeEvacuationWheretpisthetimeelapsedfromignitiontotheperception(感觉)thatafireexists;taisthetimebetweenperceptiontothestartoftheescapeaction;trsisthetimetakentomovetoaplaceofrelativesafety;tuisthetime(fromignition)forthefiretoproduceuntenable(难以忍受的)conditionsatthelocation.tp+ta+trs≤tu6.FactorsAffectingFireGrowthThenature,amountanddistributionofthecombustiblecontents;Thesizeandshapethecompartment;Thewidthandheightoftheventilationopenings.InfluencesofVentilationVentilationfactorAH1/2(m5/2)Burningrate(kg/min)VentilationFactorm2/15.5AHm2/109.0AHmkg/minkg/sorHereAH1/2iscalledventilationfactor.opening.theofheighttheHandareaopeningAthefuel,theofrateburningmasstheiswheremTheoreticalDeductionoftheVentilationFactorgyPP101gyPP00222:equationBernoulli22222111vPvP222200110vgyPgyP212/11102)(2gyv2/10)(2FFFgyv2/1000)(2gyvF0000:InflowhdairdyvBCmFhFFdFdyvBCm0:Outflow2/10002/30)2()(32FdairghBCm2/1002/3)2()(32FFFdFghBCm2/15.5AHm2/109.0AHmkg/minkg/sorVentilationFac