[{"data":1,"prerenderedAt":73},["ShallowReactive",2],{"q-fire-107-1-fire-science-025":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-025","fire-107-1-fire-science-025",107,1,25,"下列何者並非複燃（backdraft）發生之原因？",{"A":16,"B":17,"C":18,"D":19},"通風不佳","燃料濃度高於可燃上限","空氣忽然進入","具爆裂物","D",null,[],false,"本題考點：複燃（backdraft）的成立條件——密閉不良通風的區劃內累積過濃未燃氣體，遇突然供氧而急速燃燒。\n【正解理由】複燃是通風控制火災的產物：區劃密閉、供氧不足，火勢雖受抑制但高溫持續進行熱裂解，室內充滿一氧化碳等未燃可燃氣體，濃度已高過燃燒上限而暫時無法燃燒；此時若門窗突然開啟或玻璃破裂，空氣湧入把混合氣稀釋回燃燒範圍內，遇高溫即瞬間燃燒並產生火球與壓力波。爆裂物是獨立的爆炸能量來源，不屬於複燃的成因，故選 D。\n【逐項排除】\n(A) 通風不佳：使燃燒轉為通風控制、未燃氣體不斷累積，是複燃的前提條件。\n(B) 燃料濃度高於可燃上限：氣體過濃而暫時無法燃燒，正是等待空氣稀釋的蓄勢狀態，屬成因之一。\n(C) 空氣忽然進入：提供稀釋與供氧的觸發動作，是複燃的引爆點。\n(D) 具爆裂物：爆裂物自身即含氧化劑、可獨立分解爆炸，與複燃的缺氧蓄積機制無關，為本題答案。\n【記憶點】複燃三要件：關得密、燒得久、門一開。","複燃與閃燃是火災學最常被混淆的一組現象，差別可從三個面向切開。第一是發生階段：閃燃出現在成長期末、由局部燃燒轉為全面燃燒的瞬間，屬燃料控制轉向通風控制的分界；複燃則多發生在火災已進入通風控制、甚至看似衰退之後，因外力供氧而重新猛烈燃燒。第二是缺乏的要素：閃燃缺的是熱，靠上層熱煙輻射把室內可燃物同時加熱到著火；複燃缺的是氧，室內可燃氣體早已具備、只等空氣。第三是表現形式：閃燃是室內全面起火、溫度陡升；複燃常伴隨火球由開口向外噴出與明顯壓力波，對開門者威脅極大。\n複燃的前兆判讀是消防搶救的重要知識：門窗玻璃內側附著油狀碳化物且被燻黑、看不到明火卻感到門板燙手、煙由開口呈脈動式進出（吸氣與吐煙交替）、煙色濃黑並帶黃褐、開口處出現高速旋流的煙流，這些都顯示區劃內處於高溫缺氧的蓄勢狀態。控制原理在於先於高處排煙洩壓、讓過濃氣體向上排出並降溫，避免自低處正面開啟形成大量進氣。\n數值可以掛一組上去輔助理解：一氧化碳的燃燒範圍約 12.5% 至 74%、自燃溫度約 600℃，區劃內熱裂解產生的一氧化碳濃度在缺氧狀態下極易衝過上限，而火場殘火與熾熱表面早就超過其自燃溫度，這正是空氣一進來、濃度落回範圍內就立刻起燃的原因，也是複燃不需要另有明火即可發生的關鍵。\n觀念補充：可燃氣體只有落在燃燒下限與上限之間才能燃燒，濃度高於上限的狀態常被形容為「過濃」，看似安全實則最危險，因為任何進氣都會把它推回燃燒範圍。相關考點還有滾燃（rollover），指未燃氣體在天花板下方成層並被引燃形成滾動火舌，屬閃燃前兆，與複燃須分別記憶。",true,[28,32,36,40,44,48],{"webId":29,"stem":30,"number":31,"year":11,"session":12},"fire-107-1-fire-science-024","容易著火之燃料具下列何種特性？",24,{"webId":33,"stem":34,"number":35,"year":11,"session":12},"fire-107-1-fire-science-026","在火勢擴大的過程中，下列那一現象並非成長期的常見特徵？",26,{"webId":37,"stem":38,"number":39,"year":11,"session":12},"fire-107-1-fire-science-023","熱傳導之熱流動方向為何？",23,{"webId":41,"stem":42,"number":43,"year":11,"session":12},"fire-107-1-fire-science-027","下列何者並非高科技廠房火災之特性？",27,{"webId":45,"stem":46,"number":47,"year":11,"session":12},"fire-107-1-fire-science-022","燃燒塔每分鐘需消耗 5.8 kg 之丁烷（C4H10），請估算在 NTP（25℃，1 大氣壓）之條件下，此燃燒塔每小時所需之燃燒理論空氣體積（LV）約為下列何者？",22,{"webId":49,"stem":50,"number":51,"year":11,"session":12},"fire-107-1-fire-science-028","下列何者並非古蹟火災防護之特性？",28,[53,57,61,65,69],{"webId":54,"year":55,"stem":56,"number":13},"fire-113-1-fire-science-025",113,"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？",{"webId":58,"year":59,"stem":60,"number":13},"fire-112-1-fire-science-025",112,"對可燃性氣體而言，下列那一種特性或條件所衍生的燃燒或爆炸風險相對較高？",{"webId":62,"year":63,"stem":64,"number":13},"fire-111-1-fire-science-025",111,"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？",{"webId":66,"year":67,"stem":68,"number":13},"fire-110-1-fire-science-025",110,"請依據可燃性氣體完全燃燒時的化學理論濃度，計算丙烷的燃燒下限？",{"webId":70,"year":71,"stem":72,"number":13},"fire-109-1-fire-science-025",109,"有關火羽流的敘述，下列何者錯誤？",1785129967852]