[{"data":1,"prerenderedAt":72},["ShallowReactive",2],{"q-fire-110-1-fire-science-003":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-110-1-火災學概要-003","fire-110-1-fire-science-003",110,1,3,"依據建築物火災的特性，當進入「穩態燃燒」階段時，釋熱率（Q）與時間（t）的關係為何？",{"A":16,"B":17,"C":18,"D":19},"與時間一次方成正比","與時間一次方成反比","與時間二次方成正比","與時間無關","D",null,[],false,"本題考點：建築物火災成長曲線各階段之釋熱率特性，尤其是穩態(最盛期)燃燒的定義。\n【正解理由】建築物火災依時間可分為成長期、穩態燃燒(最盛期)與衰退期。成長期釋熱率隨時間平方成長；進入穩態燃燒後，燃燒受限於開口所能供應之空氣量，單位時間可燃燒的質量趨於固定，釋熱率因而維持在近乎定值的平台，不再隨時間增減，故選 D。\n【逐項排除】\n(A) 與時間一次方成正比屬線性成長，描述的是釋熱率持續攀升的情形，只在火勢沿一維方向等速延燒等特例才近似成立，與穩態階段維持定值的特性不符。\n(B) 與時間一次方成反比意指釋熱率隨時間遞減，那是可燃物大量消耗後的衰退期特徵，不是穩態燃燒。\n(C) 與時間二次方成正比即 Q = α t²,係穩態之前的成長期特徵，兩個階段的曲線形狀不可混用。\n(D) 穩態燃燒之釋熱率由開口通風條件與可燃物供應速率決定，在該階段近乎定值、與時間無關，為本題應選者。\n【記憶點】成長期看 t²、最盛期是平台、衰退期往下掉。","穩態燃燒是室內火災曲線的中段平台，它之所以與時間無關，關鍵在燃燒模式已由燃料控制轉為通風控制。閃燃之後室內可燃物表面幾乎同時起火，熱裂解產生的可燃氣體遠超過室內殘氧所能燃燒的量，此時能燒多少完全取決於開口的進氣量，釋熱率因此被鎖在由開口尺寸決定的上限。經典的川越(Kawagoe)關係式即以開口因子 A√H(A 為開口面積、H 為開口高度)描述質量燃燒速率，約為每秒 0.09 A√H 公斤，再乘以可燃物之燃燒熱即得該階段釋熱率；開口愈大、愈高，平台愈高。\n這也解釋兩個常考現象：一是門窗玻璃破裂後火勢突然變猛，因為開口因子變大、平台被抬高；二是密閉空間可長時間悶燒，一旦開門讓大量新鮮空氣湧入，積蓄的未燃可燃氣體瞬間燃燒而形成回燃(backdraft)。\n三階段可整理成一張對照：成長期釋熱率 Q = α t²,屬燃料控制，是探測、初期滅火與避難的黃金時段；最盛期釋熱率近乎定值，屬通風控制，是防火區劃與構件耐火時效受考驗的階段；衰退期可燃物已消耗約七至八成，釋熱率隨時間遞減，溫度亦隨之下降。\n延伸考點：最盛期的定值特性正是防火區劃面積、構件耐火時效與標準升溫曲線設定的依據，並常與閃燃、回燃、通風控制與燃料控制的區辨合併命題；辨題時只要抓住「開口決定上限」這一句，多數階段辨識題都能解。另可留意兩個判別方向：燃料控制時，增加開口只會讓煙氣稀釋、釋熱率不見得上升；通風控制時，增加燃料量對釋熱率幾無影響，增加開口才會使火勢變猛。這兩句互為反面，常被拆開來當作是非敘述測驗。",true,[28,32,36,39,43,48],{"webId":29,"stem":30,"number":31,"year":11,"session":12},"fire-110-1-fire-science-002","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？",2,{"webId":33,"stem":34,"number":35,"year":11,"session":12},"fire-110-1-fire-science-004","在氣溫 20 ℃無風的情況下，一般木造建築物形成危險界限溫度之輻射熱通量超過多少 kcal \u002F m2 h 即有延燒之危險？",4,{"webId":37,"stem":38,"number":12,"year":11,"session":12},"fire-110-1-fire-science-001","下列物質各取 1 莫耳進行完全燃燒，何者所需的理論空氣量（kg）最少？",{"webId":40,"stem":41,"number":42,"year":11,"session":12},"fire-110-1-fire-science-005","已知乙烷、乙烯、乙炔的發火能量分別為 a、b、c，則 a、b、c 的大小關係為：",5,{"webId":44,"stem":45,"number":46,"year":47,"session":12},"fire-109-1-fire-science-040","有關預混合火焰特性，下列敘述何者錯誤？",40,109,{"webId":49,"stem":50,"number":51,"year":11,"session":12},"fire-110-1-fire-science-006","阿里山發生森林火災，已知火災當天的相對濕度為 60.0%，前一天相對濕度為 50.0%，再前一天相對濕度為 40.0%，試求火災當天的實效濕度？",6,[53,57,61,65,69],{"webId":54,"year":55,"stem":56,"number":13},"fire-114-1-fire-science-003",114,"下列有關儲槽火災之敘述何者錯誤？",{"webId":58,"year":59,"stem":60,"number":13},"fire-113-1-fire-science-003",113,"當起火區域產生閃燃時，人在其中是無法存活的，對於閃燃現象之敘述，下列何者錯誤？",{"webId":62,"year":63,"stem":64,"number":13},"fire-112-1-fire-science-003",112,"下列何者非為火災之特性？",{"webId":66,"year":67,"stem":68,"number":13},"fire-111-1-fire-science-003",111,"實效濕度低於多少時，日本即發布火災警報？",{"webId":70,"year":47,"stem":71,"number":13},"fire-109-1-fire-science-003","依用戶用電設備設置規則及建築技術規則，下列避雷設置敘述何者錯誤？",1785129966943]