[{"data":1,"prerenderedAt":73},["ShallowReactive",2],{"q-fire-107-1-fire-science-034":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-107-1-火災學概要-034","fire-107-1-fire-science-034",107,1,34,"建築物火災發生後，若火勢由局部火災擴散至全面火災之短時間現象稱為？",{"A":16,"B":17,"C":18,"D":19},"閃燃","閃火點","爆燃","爆轟","A",null,[],false,"本題考點：閃燃(flashover)的定義，以及它與其他「燃」字火災現象及物質性質參數的區辨。\n【正解理由】室內火災由局部起火經成長期發展，天花板下的高溫煙氣層持續蓄積，對地板面的輻射熱通量隨之升高，使室內幾乎所有可燃物表面同時達到熱分解與著火條件，於數十秒的短時間內由局部燃燒轉為全室全面燃燒，此一轉捩瞬間即稱為閃燃，是成長期與最盛期的分界。題幹所述「由局部火災擴散至全面火災之短時間現象」正是閃燃的標準敘述，故選 A。\n【逐項排除】\n(A) 正確：定義為室內火災全面化的瞬間現象，理由如上。\n(B) 錯誤：閃火點是可燃液體液面上蒸氣達到可燃濃度而能被引火源瞬間閃火的最低溫度，屬物質的性質參數，不是火災現象。\n(C) 錯誤：爆燃指火焰以低於音速傳播的燃燒爆炸，重點在傳播速度與壓力上升，與室內全面燃燒的定義不同。\n(D) 錯誤：爆轟是火焰面與震波耦合、以超音速傳播的爆炸現象，破壞力遠大於爆燃，更非本題所指。\n【記憶點】閃燃是「室內全面化的那一瞬間」——成長期結束、最盛期開始。","閃燃是室內火災的分水嶺，學理上常以兩個工程判準辨識：上層熱煙氣溫度約達攝氏五百至六百度，以及地板面接收的輻射熱通量約達每平方公尺二十千瓦。達到此條件後，室內所有可燃物表面同時裂解出可燃氣體並被引燃，熱釋放率在極短時間內躍升，火勢由燃料控制轉為通風控制，自此進入最盛期，對建築構件的耐火性能形成最嚴苛的考驗，也是室內人員生存機率趨近於零的時刻。\n閃燃常見的前兆是滾燃(rollover):天花板下未燃的熱裂解氣體被引燃，火舌沿頂棚快速滾動掠過，通常出現在閃燃前數十秒。與閃燃最容易混淆的是複燃(backdraft),兩者的通風條件恰好相反——閃燃需要充足空氣持續供應，複燃則發生於通風受限、氧氣耗盡而蓄滿高濃度未燃氣體的空間，當門窗突然開啟導入空氣時，氣體瞬間爆炸性燃燒並形成火球逆噴，前兆為門縫脈動吸吐、玻璃燻黑與黃褐色濃煙。\n本題其餘選項屬另一組概念：爆燃與爆轟依火焰傳播速度是否超過音速區分，爆轟伴隨震波，壓力上升遠高於爆燃；閃火點則與著火點、自燃點同屬液體或固體的性質參數，閃火點是能瞬間閃火的最低溫度，著火點是移除引火源後仍能持續燃燒的溫度，自燃點則不需外部引火源。\n影響閃燃早晚的因素也常入題：室內裝修材料的可燃性與表面延燒性愈高，愈快在頂棚累積熱裂解氣體；開口大小決定供氧與排熱的平衡，過小則蓄熱卻缺氧、過大則熱量散失，兩端都會延後閃燃；空間高度愈低、火載量愈集中，則愈早達到臨界輻射熱通量。\n延伸考點：室內火災成長曲線(起火、成長期、閃燃、最盛期、衰退期)、通風控制型與燃料控制型的轉換，以及閃燃前的避難時間評估，都是同一條主線上的高頻題型。",true,[28,32,36,40,44,48],{"webId":29,"stem":30,"number":31,"year":11,"session":12},"fire-107-1-fire-science-033","燃燒時若生成的熱與散失的熱保持平衡，燃燒溫度保持均勻之燃燒為下列何者？",33,{"webId":33,"stem":34,"number":35,"year":11,"session":12},"fire-107-1-fire-science-035","描述火勢大小之物理量為下列何者？",35,{"webId":37,"stem":38,"number":39,"year":11,"session":12},"fire-107-1-fire-science-032","下列何者並非防火區劃構件構造之性質？",32,{"webId":41,"stem":42,"number":43,"year":11,"session":12},"fire-107-1-fire-science-036","下列何項不是閃燃發生之條件？",36,{"webId":45,"stem":46,"number":47,"year":11,"session":12},"fire-107-1-fire-science-031","下列何者並非造成電氣火災的原因？",31,{"webId":49,"stem":50,"number":51,"year":11,"session":12},"fire-107-1-fire-science-037","針對連鎖反應之滅火機制為何？",37,[53,57,61,65,69],{"webId":54,"year":55,"stem":56,"number":13},"fire-113-1-fire-science-034",113,"有關熱傳導的敘述，下列何者正確？",{"webId":58,"year":59,"stem":60,"number":13},"fire-112-1-fire-science-034",112,"對於具有分解爆炸性質的可燃性氣體，下列敘述何者錯誤？",{"webId":62,"year":63,"stem":64,"number":13},"fire-111-1-fire-science-034",111,"下列何者非細水霧滅火系統的特性？",{"webId":66,"year":67,"stem":68,"number":13},"fire-110-1-fire-science-034",110,"液體變化為氣體之物理現象中，若變化速度至為急速時，因能量在極短的時間內大量放出，即形成爆炸現象，此現象之名稱為何？",{"webId":70,"year":71,"stem":72,"number":13},"fire-109-1-fire-science-034",109,"BLEVE 的發生，下列敘述何者錯誤？",1785129967907]