[{"data":1,"prerenderedAt":73},["ShallowReactive",2],{"q-fire-111-1-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-111-1-火災學概要-024","fire-111-1-fire-science-024",111,1,24,"下列何者非影響建築物中煙霧流動與蔓延的主要因素？",{"A":16,"B":17,"C":18,"D":19},"煙囪效應","浮力作用","相對濕度","空氣膨脹","C",null,[],false,"本題考點：建築物內煙層流動與蔓延的主要驅動力。\n【正解理由】煙在建築物內移動，靠的是壓力差與密度差。煙囪效應由室內外溫差在豎向通道造成壓差、浮力來自高溫煙氣密度低於周圍空氣、空氣膨脹則是燃燒放熱使氣體體積急遽增大而把煙擠出開口，三者都是直接推動煙流的力學因素；相對濕度只影響空氣含水量與人體感受，並不構成推動煙移動的壓差或密度差，故選 C。\n【逐項排除】\n(A) 煙囪效應在高層建築的樓梯間、電梯道等豎向通道最明顯，室內較暖時煙由中性帶以下被吸入豎道並向上竄出，是煙垂直蔓延的主因之一。\n(B) 浮力作用來自熱煙密度小於周圍冷空氣，是熱煙上升、在天花板下形成煙層並向水平擴散的根本原因。\n(C) 相對濕度並非煙流動與蔓延的主要因素，為本題應選者。\n(D) 空氣膨脹是燃燒使室內氣體受熱、體積增加，於火災初期把煙氣由開口與縫隙擠向相鄰空間，屬主要因素。\n【記憶點】推動煙的是溫差、浮力、膨脹與風壓，不是濕度。","煙的移動可以化約成一句話：哪裡有壓差，煙就往哪裡去。建築物內製造壓差的來源分成火災本身造成的與建築物固有的兩類。火災本身造成的有二：一是燃燒放熱使氣體受熱膨脹，火災初期室內壓力略高於周圍，把煙由縫隙與開口擠向相鄰空間；二是浮力，高溫煙氣密度小於冷空氣，上升後在天花板下堆積成煙層，並沿天花板水平擴散，煙層加厚後再由開口上緣溢出。\n建築物固有的則以煙囪效應為代表：樓梯間、電梯道、管道間等貫通上下的豎向通道，因室內外溫差在內部形成上升或下沉氣流，室內較暖時煙由中性帶以下被吸入豎道、向上竄出到高樓層，一棟高層建築可能在數分鐘內把煙送到頂層。此外還有外部風壓造成的迎風面正壓與背風面負壓、空調系統的送回風、電梯升降造成的活塞效應，都會改變煙的路徑。\n相對濕度影響的是空氣含水量、靜電累積難易與人的體感，並不產生驅動煙移動的壓差或密度差，故不列入主要因素；它與火災的關聯多在起火階段的靜電風險，而不在煙的流動。\n數值記憶：一般認為煙在水平方向的流動速度約每秒零點五至一公尺，與人步行速度接近；但在豎向通道內可達每秒數公尺，遠快於人往下跑的速度，這正是高層建築必須以防煙區劃、防煙垂壁、排煙設備與樓梯間加壓等手段先擋煙的理由。相關考點連結：中性帶位置的判斷、加壓防煙的壓差設定，以及煙層下降時間與可用避難時間的推估，都由本題這幾個驅動力延伸而來。\n易混淆對照：煙囪效應與浮力都與溫差有關，但煙囪效應描述的是建築物豎向通道整體的壓力分布，浮力描述的是單一煙團相對周圍空氣所受的淨向上力，前者決定煙會走哪一條垂直路徑，後者解釋煙為什麼會往上；空氣膨脹則只在火災初期短暫顯著，火勢一旦穩定，主導權便交還給浮力與煙囪效應。",true,[28,32,36,40,44,48],{"webId":29,"stem":30,"number":31,"year":11,"session":12},"fire-111-1-fire-science-023","建築物起火後，對於防止火焰由下層窗戶往上層延燒，下列敘述何者錯誤？",23,{"webId":33,"stem":34,"number":35,"year":11,"session":12},"fire-111-1-fire-science-025","近來消防機關大力推行安裝住宅用火災警報器，其安裝位置在天花板或牆壁上緣，主要考量因素為何？",25,{"webId":37,"stem":38,"number":39,"year":11,"session":12},"fire-111-1-fire-science-022","連棟式木造建築物引發火災，消防隊射水同時拆除未受火勢波及的房屋，請問其採取的滅火方法係下列何者？",22,{"webId":41,"stem":42,"number":43,"year":11,"session":12},"fire-111-1-fire-science-026","一公克水完全汽化成水蒸氣，溫度 327℃水蒸氣體積為 V1，溫度 727℃水蒸氣體積為 V2，則 V2\u002FV1 值？",26,{"webId":45,"stem":46,"number":47,"year":11,"session":12},"fire-111-1-fire-science-021","下列有關熱量傳遞的敘述，何者正確？",21,{"webId":49,"stem":50,"number":51,"year":11,"session":12},"fire-111-1-fire-science-027","下列關於乙炔的敘述，何者錯誤？",27,[53,57,61,65,69],{"webId":54,"year":55,"stem":56,"number":13},"fire-113-1-fire-science-024",113,"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℃？",{"webId":58,"year":59,"stem":60,"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":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？",1785129966826]