提綱煙氣的特征光學(xué)特征如何利用煙氣火檢？如何測試評估火檢？如何調(diào)查火檢報警的有效性？2SootparticlesTransmissionelectronmicrographofasootparticle.Theoverallsizeoftheagglomerateisabout6m,andthediameteroftheindividualspherulesisabout0.03m.消光型火檢ProjectedBeam:LightObscurationBougher’sLaw:LI

Io感光器光源動態(tài)煙氣濃度測量Conecalorimeter-or-largercalorimeterHe-Nelaser-or-whitelightI煙氣羽流的消光作業(yè)由于煙氣生成導(dǎo)致消光效應(yīng)Obscurationduetosmokeproduction第一項:材料的產(chǎn)煙特征第二項：稀釋因子其中

是煙氣的體積流量煙氣的消光作用Bougher’sLaw假設(shè)沿著光程

pathlength,L方向上的煙氣密度均勻；光線的效果作用依賴于：煙氣粒子的特征尺寸分布濃度光線的波長（為產(chǎn)生消光作用，煙氣的粒子直徑必須大于光線的波長）煙氣的粒子特征聚氨酯泡沫陰燃庚烷的有焰燃燒%Obscuration/foot10%050010001500200025000.010.1110ParticleSize[mm]ParticleCount[ppm/s]050010001500200025000.010.1110ParticleSize[mm]ParticleCount[ppm/s]8火檢裝置的敏感性LeeandMulholland,1974光學(xué)火檢光電效應(yīng)：光線的散射Lightscattering光源感光器煙導(dǎo)致的光線散射光線散射取決于：煙氣粒子的特征直徑分布濃度光線的波長煙氣的折射率Refractiveindex光源與感光器的安裝角度。離子火檢Ionization(AM241source)-+---+-+++離子型探頭的響應(yīng)離子依附到煙氣粒子上的機理仍然沒有開發(fā)出來；探頭的引入特征沒有定量化；SmolderingCottonTowels(Torero)CORateofRise:~100ppmfrom1800–2400sec=0.17ppm/secTime(sec)CarbonMonoxide(ppm)500100015002000250030003500-200020040060080010001200評估煙氣火檢器的響應(yīng)特征

EvaluatingSmokeDetectorResponse敏感度：火檢器是否響應(yīng)最小最大濃度的煙氣粒子UL268testusingsmokedensitysensitivitychamberwithgraysmoke響應(yīng)時間：對于不同的煙氣，是否火檢器都能夠及時響應(yīng)？UL268testfireswith4fuelsinroomUniquetestsModelingUL煙氣密度與靈敏度測試室光學(xué)密度與消光系數(shù)

OpticalDensityvs.Obscuration光學(xué)密度與單位距離：百分比消光Percentobscuration:消光參數(shù)單位光程的百分比消光PercentobscurationperunitlengthRelate%Ob/LtoD/L:預(yù)報火檢探頭的響應(yīng)Estimate“slowest”responsebyconsideringmaximumDinUL268評估光學(xué)密度:帶入體積流量得到:質(zhì)量光學(xué)密度質(zhì)量光學(xué)密度

(withDminm2/g):有焰燃燒陰燃Smolderingfires導(dǎo)致火檢動作的火災(zāi)大小Solveforheatreleaserateinequationforopticaldensity,substituteUL268upperlimitforD:FireSizeatDetectionCeilingHeight(m)01000200030004000500005101520HeatReleaseRate@Detection(kW)0.0050.0100.050Dm/

aHc(m2/kJ)火檢分析的局限性煙氣粒子濃度依賴于光學(xué)密度燃料燃燒模式

(flaming,non-flaming)粒子老化現(xiàn)象煙色光源波長Wavelengthoflight火檢的瞬態(tài)響應(yīng)特征Transientresponsecharacteristicsofdetector不同燃燒模式SmolderingandFlamingFires

的煙氣粒子分布CusterandBright,1974光線波長和煙色對光線密度的影響B(tài)ukowski,1978粒子老化SmokeAging煙氣粒子的分布隨時間而變化粒子直徑增加Increaseindiameterofparticles粒子數(shù)量減少Decreaseinnumberofparticles原因是由于布朗運動碰撞造成粒子結(jié)團匯聚現(xiàn)象Cause:coagulationfromBrowniancollisions不同燃料的煙氣粒子老化現(xiàn)象MaterialInitialAvg.Diameter(m)Avg.Diameterafter900s(m)%changeMatch0.0090.01122PropaneGas0.00350.00543PineWood0.0070.01383BondPaper0.0100.01660Atmosphericambientparticles0.0130.0130VanLuik,FireTechnology,1974煙氣老化：SmolderingPunk103104105106107

N/logDp.001.0