[{"data":1,"prerenderedAt":73},["ShallowReactive",2],{"q-fire-113-1-fire-science-024":3},{"subject":4,"subjectSlug":5,"subjectKicker":6,"subjectShort":7,"question":8,"related":27,"sameNumber":52,"hasEssay":26},"火災學概要","fire-science","火災學 · Fire Science","火災學",{"id":9,"webId":10,"year":11,"session":12,"subject":4,"number":13,"stem":14,"options":15,"answer":20,"answerNote":21,"images":22,"imagesPending":23,"lawTimestamp":11,"explanation":24,"explanationDeep":25,"freq":12,"indexable":26},"fire-113-1-火災學概要-024","fire-113-1-fire-science-024",113,1,24,"木材加熱到引火溫度時，可燃性氣體析出量迅速增加，木材的引火溫度約為多少℃？",{"A":16,"B":17,"C":18,"D":19},"100","160","260","490","C",null,[],false,"本題考點：木材受熱的溫度階段，區別需要火源的引火溫度與不需火源的發火溫度。\n【正解理由】木材受熱後依序經歷乾燥、熱分解、引火與自燃。約 100℃ 起水分蒸發；約 160℃ 起開始明顯熱分解並析出可燃氣體；加熱至約 260℃ 時熱分解加劇，可燃性氣體析出量迅速增加，表面附近的混合氣濃度已達燃燒下限，只要有火源接觸即被引燃，此即木材的引火溫度；再升至約 400 至 490℃ 則不需火源即可自行起火，屬發火溫度。題目所述為需有火源的引火溫度。故選 C。\n【逐項排除】\n(A) 100℃ 為水的沸點，此階段木材僅蒸散所含水分，尚未產生足量可燃氣體。\n(B) 160℃ 為木材開始明顯熱分解的溫度，可燃氣體剛開始析出，析出量不足以被火源引燃。\n(C) 260℃ 時可燃性氣體析出量迅速增加，遇火源即可引火，為木材的引火溫度，為正解。\n(D) 490℃ 落在木材發火溫度的範圍，該溫度不需火源即可自行起火，與題述需有火源的引火溫度定義不同。\n【記憶點】木材溫度階梯：一百乾燥、一百六分解、二百六引火、四百以上自燃。","木材燃燒可分為四個階段。一為乾燥期，約 100℃ 前後蒸散水分，含水率愈高愈難引燃。二為熱分解期，約 160℃ 起半纖維素先行裂解，纖維素與木質素隨溫度上升陸續分解，產生一氧化碳、甲烷、甲醇、醋酸等可燃氣體與焦油。三為有焰燃燒期，可燃氣體濃度足夠且遇火源即引燃，約自 260℃ 開始。四為熾熱燃燒期，揮發分逸盡後由表面殘留的木炭進行表面燃燒，無火焰而有紅熱餘燼。\n引火溫度與發火溫度的對照是本科常考題型：引火溫度需要外部火源，數值較低；發火溫度不需火源，靠自身蓄熱使反應失控，木材一般取 400 至 490℃。另有一個易混概念是低溫長期加熱的碳化發火，木材若長期受 100 至 150℃ 的低溫加熱，會逐漸碳化為活性較高的多孔碳，其發火溫度隨受熱時間而下降，經數月至數年後可能在遠低於一般發火溫度的條件下起火，常見於嵌入牆體的煙囪、高溫管線周邊與長期照射的燈具附近。\n影響引燃難易的因素包括含水率、密度、表面積與體積之比、表面粗糙度及加熱速率。同樣的木料，薄片與刨花遠比實心方材容易引燃，這也是火載量之外仍須考量可燃物形態的原因。\n延伸考點：木構造的耐火時間常以炭化速度估算，一般取每分鐘約 0.6 至 0.8 公釐，斷面愈大者扣除炭化層後殘餘的承載斷面愈多；炭化層本身導熱性差，反而形成保護內部的隔熱層。另一常一併命題的數值是木材的發熱量，一般取每公斤約 4,000 至 4,500 kcal，火載量計算即以此把各種可燃物折算為等值木材重量，再除以樓地板面積得到單位面積的等值木材量。",true,[28,32,36,40,44,48],{"webId":29,"stem":30,"number":31,"year":11,"session":12},"fire-113-1-fire-science-023","根據 Burgess-Wheeler 定理，若丙烷的燃燒下限為 2.2%，其燃燒熱約為多少 kcal\u002Fmole？",23,{"webId":33,"stem":34,"number":35,"year":11,"session":12},"fire-113-1-fire-science-025","容器內氣體受到壓縮造成內部溫度升高，進而發火，此現象稱為？",25,{"webId":37,"stem":38,"number":39,"year":11,"session":12},"fire-113-1-fire-science-022","一物體在 27℃時輻射出的能量為 E，則當溫度升高到 627℃時輻射出的能量變為多少？",22,{"webId":41,"stem":42,"number":43,"year":11,"session":12},"fire-113-1-fire-science-026","有關燃燒上下限之敘述，下列何者正確？",26,{"webId":45,"stem":46,"number":47,"year":11,"session":12},"fire-113-1-fire-science-021","依建築物火災 t2 成長理論，若釋熱率達 1 MW 需時間 100 秒，則釋熱率達 4 MW 所需時間為多少秒？",21,{"webId":49,"stem":50,"number":51,"year":11,"session":12},"fire-113-1-fire-science-027","火災發生後至閃燃發生的時間稱為閃燃時間（F.O.T.），影響閃燃時間的重要因素，下列何者錯誤？",27,[53,57,61,65,69],{"webId":54,"year":55,"stem":56,"number":13},"fire-112-1-fire-science-024",112,"於空氣中加入氧氣會改變空氣組成，進而影響可燃性氣體的某些燃燒特性，下列何者所受的影響較為明顯？",{"webId":58,"year":59,"stem":60,"number":13},"fire-111-1-fire-science-024",111,"下列何者非影響建築物中煙霧流動與蔓延的主要因素？",{"webId":62,"year":63,"stem":64,"number":13},"fire-110-1-fire-science-024",110,"在充足的能量下，下列何種濃度（vol%）的氫氣（H2）為燃燒界限範圍內？",{"webId":66,"year":67,"stem":68,"number":13},"fire-109-1-fire-science-024",109,"在古蹟及歷史建築物火災風險評估指標中，有關防火因應措施安全評估項目中，不包括下列何項？",{"webId":70,"year":71,"stem":72,"number":13},"fire-108-1-fire-science-024",108,"下列有關燃燒上下限之敘述，何者錯誤？",1785129966316]