[{"data":1,"prerenderedAt":73},["ShallowReactive",2],{"q-fire-107-1-fire-science-036":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-036","fire-107-1-fire-science-036",107,1,36,"下列何項不是閃燃發生之條件？",{"A":16,"B":17,"C":18,"D":19},"火載量大","在侷限空間內","通風不佳","火場溫度高","C",null,[],false,"本題考點：閃燃發生所需的條件,關鍵在於「氧氣供應必須充足」這一項。\n【正解理由】閃燃是室內可燃物表面幾乎同時著火的瞬間,需要三件事同時成立:足夠的火載量提供持續裂解的可燃氣體、侷限空間使熱煙氣蓄積於天花板下形成高溫輻射源、以及足夠的空氣供應維持燃燒放熱不斷增強。通風不佳時燃燒受氧氣限制而轉為通風控制型,熱釋放率被壓抑、溫度無法續升,火勢往往轉為陰燃甚至自行衰退,只在蓄積未燃氣體後遇突然供氧才走向另一種現象,並不是閃燃的條件,故選 C。\n【逐項排除】\n(A) 是條件:火載量大代表可燃物與可燃氣體供應充足,才足以支撐全室同時燃燒。\n(B) 是條件:侷限空間才能蓄熱蓄煙,形成足以回輻射至地板面的高溫上層氣體。\n(C) 非條件:通風不佳會抑制熱釋放率與溫升,與閃燃需要充足氧氣的要求正好相反,理由如上。\n(D) 是條件:上層煙氣溫度與地板受熱達到臨界值,是全面著火的直接觸發因素。\n【記憶點】閃燃要「料夠、閉得住、燒得旺」——缺氧的房間閃不起來。","閃燃的成立條件可拆成四個面向理解:燃料面要有足夠火載量與易裂解的可燃物表面積;空間面要有天花板與四周牆面圍成的侷限體積以蓄積熱煙;熱力面要達到上層煙氣約攝氏五百至六百度、地板面輻射熱通量約每平方公尺二十千瓦的臨界值;通風面則要有足以維持燃燒的空氣供應。前三項考生多半答得出來,第四項正是本題的鑑別點——空氣既是助燃物,不足時燃燒無法持續放大。\n這裡牽涉燃料控制型與通風控制型的轉換。火災初期空氣充裕,熱釋放率由燃料裂解速率決定,屬燃料控制型;閃燃之後火勢受開口供氧限制,轉為通風控制型,可用通風因子(開口面積乘以開口高度平方根)推估最大熱釋放率。若一開始通風就不足,火勢便停在低熱釋放率狀態,溫度上不去,自然到不了閃燃的臨界條件。\n易混淆對照正是複燃(backdraft):它恰恰發生在通風不佳的密閉空間,氧氣被消耗殆盡、火焰轉為陰燃,室內卻蓄滿高溫未燃的一氧化碳與熱裂解氣體;當門窗被開啟或玻璃破裂突然導入空氣,混合氣瞬間爆炸性燃燒並產生火球逆噴。因此「通風不佳」是複燃的條件,不是閃燃的條件,兩者在考題中常被對調誘答。\n開口條件對閃燃並非愈大愈好:開口過小則供氧不足、達不到臨界熱釋放率;開口過大則熱煙氣與輻射熱大量外洩,上層溫度同樣拉不上來,因此閃燃最容易發生在開口適中的一般居室。內裝材料的可燃性與空間高度也是變數,可燃內裝愈多、天花板愈低,達到臨界輻射熱通量的時間愈短。\n延伸考點:降低閃燃風險的思維包括控制火載量、以早期偵知與撒水設備在成長期抑制熱釋放率、以及利用排煙削減上層煙氣蓄熱;另有滾燃作為閃燃前兆、閃燃與可用避難時間的關係,都屬同一主線的高頻命題。",true,[28,32,36,40,44,48],{"webId":29,"stem":30,"number":31,"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":33,"stem":34,"number":35,"year":11,"session":12},"fire-107-1-fire-science-037","針對連鎖反應之滅火機制為何？",37,{"webId":37,"stem":38,"number":39,"year":11,"session":12},"fire-107-1-fire-science-034","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？",34,{"webId":41,"stem":42,"number":43,"year":11,"session":12},"fire-107-1-fire-science-038","以下那一現象為燃燒完全度高之火災特徵？",38,{"webId":45,"stem":46,"number":47,"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":49,"stem":50,"number":51,"year":11,"session":12},"fire-107-1-fire-science-039","因電器設備而發生之火災為何？",39,[53,57,61,65,69],{"webId":54,"year":55,"stem":56,"number":13},"fire-111-1-fire-science-036",111,"下列有關燃燒速度之敘述，何者錯誤？",{"webId":58,"year":59,"stem":60,"number":13},"fire-110-1-fire-science-036",110,"為防止靜電發生放電時引火造成火災，請問下列有關靜電災害之防止對策何者錯誤？",{"webId":62,"year":63,"stem":64,"number":13},"fire-109-1-fire-science-036",109,"房間的體積為 V=6 m×5 m×3 m，其中 O2 占 0.21 V，請問至少要加入多少公升（L）的 CO2 讓燃燒作用無法持續？",{"webId":66,"year":67,"stem":68,"number":13},"fire-108-1-fire-science-036",108,"下列何者不是 IG-541 氣體滅火藥劑的成分？",{"webId":70,"year":71,"stem":72,"number":13},"fire-106-1-fire-science-036",106,"在一大氣壓力狀態下，假設空氣中氧（O2）之重量占整體空氣的 23%，試問 1 kg 之硫（S）完全燃燒，約需多少公斤之空氣？",1785123163844]