[{"data":1,"prerenderedAt":72},["ShallowReactive",2],{"q-fire-114-1-fire-science-002":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-114-1-火災學概要-002","fire-114-1-fire-science-002",114,1,2,"建築物火災成長過程中有關衰退期的敘述何者錯誤？",{"A":16,"B":17,"C":18,"D":19},"熱釋放率逐漸下降","煙生成量逐漸下降","建築物結構體崩塌風險逐漸下降","毒性氣體產生量逐漸下降","C",null,[],false,"本題考點：建築物火災成長四階段中「衰退期」的特徵，以及結構崩塌風險為何不隨衰退期而下降。\n【正解理由】衰退期是可燃物已大量消耗、燃燒速率下降的階段，室內溫度、熱釋放率與燃燒生成物的產生速率都隨之遞減。但結構安全與當下的室內溫度不是同一件事：柱、樑、樓地板在成長期與最盛期已長時間受高溫作用，鋼材強度隨溫度上升而降低、混凝土受熱剝落，這些損傷不會因為室溫下降而回復；加上構件內部升溫受熱傳遲滯影響，最高溫常出現在室內氣溫開始下降之後。崩塌風險因此不會隨衰退期逐漸下降，故選 C。\n【逐項排除】\n(A) 燃料減少使燃燒速率下降，熱釋放率隨之遞減，敘述正確。\n(B) 燃燒規模縮小，單位時間的煙生成量隨之減少，敘述正確。\n(C) 構件受熱損傷具累積性且有溫度遲滯，崩塌風險不隨衰退期遞減，敘述錯誤。\n(D) 毒性氣體是燃燒的產物，燃燒速率下降，其產生量亦隨之下降，敘述正確。\n【記憶點】衰退期是火在退、結構不退——室溫往下走，構件累積的受熱損傷仍留在原地。","室內火災通常分為起火（初期）、成長期、最盛期與衰退期四個階段，判斷階段最常用的量尺是熱釋放率隨時間變化的曲線。起火與成長期由可燃物本身的性質與擺放方式控制，屬燃料控制型燃燒；當上層熱煙層累積到足以對下方可燃物產生強烈輻射，室內可燃物幾乎同時起火而全面燃燒，即發生閃燃，火災進入最盛期，此時開口的進氣量往往成為燃燒速率的瓶頸，屬通風控制型燃燒；待可燃物大量消耗，熱釋放率下降，火災即進入衰退期。\n衰退期有三個重點。第一，溫度下降不等於結構安全。鋼構件的強度在高溫下顯著衰減，鋼筋混凝土的保護層可能已經爆裂剝落，斷面受損是不可逆的；而且大斷面構件內部的升溫落後於室內氣溫，最高溫可能出現在室溫回落之後，這是延遲崩塌的由來。第二，衰退期的通風條件若突然改變仍具危險：室內若殘留大量未燃的可燃性氣體而處於缺氧狀態，開門、破窗使空氣灌入時可能引發爆燃。第三，衰退期並非沒有煙毒危害，缺氧的不完全燃燒條件反而有利於一氧化碳生成，殘火與悶燒仍持續釋出毒性氣體，只是總量隨燃燒規模縮小而遞減。\n易混淆概念對照：閃燃是成長期轉入最盛期的瞬間現象，成因是熱煙層輻射使室內可燃物幾乎同時起火；爆燃則是缺氧狀態下突然獲得空氣而引發的急速燃燒，兩者的觸發條件與發生階段都不同，選項若把兩者的定義互換即為錯誤敘述。\n延伸考點：本科常把四階段與熱釋放率曲線、室內溫度曲線、通風控制與燃料控制的轉換合併命題。把每個階段的「哪一個量在升、哪一個量在降」列成一張表，比死背階段名稱有效；而本題的設計正是在一整排都在下降的量之中，塞進一個不隨溫度回落而下降的量。",true,[28,31,35,40,44,48],{"webId":29,"stem":30,"number":12,"year":11,"session":12},"fire-114-1-fire-science-001","火場中輻射為熱傳遞主要的方式之一，輻射熱之性質及其計算的方式下列何者錯誤？",{"webId":32,"stem":33,"number":34,"year":11,"session":12},"fire-114-1-fire-science-003","下列有關儲槽火災之敘述何者錯誤？",3,{"webId":36,"stem":37,"number":38,"year":39,"session":12},"fire-113-1-fire-science-040","有關複燃之敘述，下列何者錯誤？",40,113,{"webId":41,"stem":42,"number":43,"year":11,"session":12},"fire-114-1-fire-science-004","下列有關隧道火災之敘述何者錯誤？",4,{"webId":45,"stem":46,"number":47,"year":39,"session":12},"fire-113-1-fire-science-039","有關於液化石油氣之性質與事故發生之處置原則，下列敘述何者錯誤？",39,{"webId":49,"stem":50,"number":51,"year":11,"session":12},"fire-114-1-fire-science-005","火災煙毒氣體之危害主要是下列何種氣體？",5,[53,56,60,64,68],{"webId":54,"year":39,"stem":55,"number":13},"fire-113-1-fire-science-002","建築物為防止火焰透過大樓窗口向上層延燒，下列敘述何者正確？",{"webId":57,"year":58,"stem":59,"number":13},"fire-112-1-fire-science-002",112,"下列何者屬於準自然發火性物質？",{"webId":61,"year":62,"stem":63,"number":13},"fire-111-1-fire-science-002",111,"有關爆燃與爆轟，下列敘述何者錯誤？",{"webId":65,"year":66,"stem":67,"number":13},"fire-110-1-fire-science-002",110,"依據建築物火災 t2 成長理論，當釋熱率（Q）達到 4 MW 時，需要 300 秒的時間，表示火災成長之速度為下列何者？",{"webId":69,"year":70,"stem":71,"number":13},"fire-109-1-fire-science-002",109,"三個面積分別為 0.20 m ，0.40 m ，0.60 m 之開口相互串聯時，其等效流動面積為何？",1785129965930]