[{"data":1,"prerenderedAt":73},["ShallowReactive",2],{"q-fire-107-1-fire-science-023":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-023","fire-107-1-fire-science-023",107,1,23,"熱傳導之熱流動方向為何？",{"A":16,"B":17,"C":18,"D":19},"高溫傳向低溫","高熱通量傳向低熱通量","高熱量傳向低熱量","高熱傳係數材料傳向低熱傳係數材料","A",null,[],false,"本題考點：熱傳導的方向性，依傅立葉定律由溫度梯度決定，與熱力學第二定律一致。\n【正解理由】傅立葉定律寫成 q＝−kA(dT\u002Fdx)，式中負號的意義即在於熱流方向恆與溫度梯度相反：熱一定由溫度高處流向溫度低處，直到兩端溫度相等而達熱平衡。這是熱力學第二定律對自發過程方向的限制，不會因材料種類或熱量多寡而改變，故選 A。\n【逐項排除】\n(A) 高溫傳向低溫：正確描述傅立葉定律與熱力學第二定律所界定的熱流方向。\n(B) 高熱通量傳向低熱通量：熱通量是單位面積熱流率，本身就是熱傳導的結果量，不是驅動熱流的原因，倒果為因。\n(C) 高熱量傳向低熱量：熱量是能量的總量，取決於質量與比熱，大質量低溫物體熱含量可能更大，卻仍由高溫小物體吸熱，故不能以熱量多寡判斷方向。\n(D) 高熱傳係數材料傳向低熱傳係數材料：熱傳導係數只影響傳遞的快慢，不決定方向；兩塊材料若溫度相同，係數再大也不會有淨熱流。\n【記憶點】熱只認溫度差，不認熱量多寡與材料好壞。","傅立葉定律 q＝−kA(dT\u002Fdx) 是熱傳導計算的起點：q 為熱流率（W），k 為熱傳導係數（W\u002Fm·K），A 為垂直於熱流方向的截面積，dT\u002Fdx 為溫度梯度。負號不是裝飾，而是宣告熱流與溫度上升方向相反，也就是題目問的方向性。對一維穩態平板可簡化為 q＝kA(T₁−T₂)\u002FL，厚度愈大、溫差愈小，熱流愈小。\n三種熱傳方式在火災學要能分辨：熱傳導靠分子振動與自由電子傳遞，需介質且以固體最顯著，是火焰經由金屬管線、梁柱傳到相鄰區劃的機制；熱對流靠流體本身的巨觀移動，是熱煙層在室內擴散、往上層蔓延的主因；熱輻射以電磁波傳遞、不需介質，遵守史蒂芬-波茲曼定律，熱流與絕對溫度四次方成正比，是閃燃前上層熱煙加熱地板可燃物與鄰棟延燒的主角。三者的共同點是熱都由高溫端流向低溫端。\n易混淆對照要一併記：熱量（J）是能量總量，熱通量（W\u002Fm²）是單位面積單位時間的能量流，溫度（K）則是分子平均動能的度量，只有溫度差才是熱流的驅動勢。另一組是熱傳導係數 k 與熱慣性 kρc：前者決定穩態導熱快慢，後者決定材料表面升溫的難易，兩者常在同一題組出現。\n數值感也要有：常溫下銅的熱傳導係數約 400 W\u002Fm·K、鋼約 50、混凝土約 1.4、木材約 0.15、玻璃棉等隔熱材可低到 0.04 上下，空氣靜止時僅約 0.026。這串數字說明兩件事：金屬是熱橋的主角，貫穿防火區劃的金屬管線會把熱帶到另一側；隔熱材之所以有效，是因為把空氣封在細小孔隙中、抑制對流，靠的仍是空氣本身的低導熱性。\n相關考點連結：本觀念常延伸考「為何金屬摸起來比木材冷」——同溫下金屬 k 大、導走體表熱量快；也常考防火區劃貫穿部的填塞，其原理即阻斷高溫端經由導體向低溫端的熱傳導路徑。",true,[28,32,36,40,44,48],{"webId":29,"stem":30,"number":31,"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":33,"stem":34,"number":35,"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":37,"stem":38,"number":39,"year":11,"session":12},"fire-107-1-fire-science-021","油罐車在灌裝作業中，其累積電壓為 16 kV（其體積為 20 m3，電容為 1000 pF），試估算此作業所產生靜電能量為多少毫焦耳（mj）？",21,{"webId":41,"stem":42,"number":43,"year":11,"session":12},"fire-107-1-fire-science-025","下列何者並非複燃（backdraft）發生之原因？",25,{"webId":45,"stem":46,"number":47,"year":11,"session":12},"fire-107-1-fire-science-020","為防止由窗口噴出的火焰向大樓上層延燒，下列措施何者錯誤？",20,{"webId":49,"stem":50,"number":51,"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,[53,57,61,65,69],{"webId":54,"year":55,"stem":56,"number":13},"fire-113-1-fire-science-023",113,"根據 Burgess-Wheeler 定理，若丙烷的燃燒下限為 2.2%，其燃燒熱約為多少 kcal\u002Fmole？",{"webId":58,"year":59,"stem":60,"number":13},"fire-112-1-fire-science-023",112,"在最小發火壓力以上，可燃性氣體的最小發火能量，會隨著下列那一種條件改變而下降？",{"webId":62,"year":63,"stem":64,"number":13},"fire-111-1-fire-science-023",111,"建築物起火後，對於防止火焰由下層窗戶往上層延燒，下列敘述何者錯誤？",{"webId":66,"year":67,"stem":68,"number":13},"fire-110-1-fire-science-023",110,"請問 2 公斤的氫氣（H2）完全燃燒，所需要的理論空氣量為多少公斤？",{"webId":70,"year":71,"stem":72,"number":13},"fire-109-1-fire-science-023",109,"若要看清某一物體，該物體與其背景間有一定之對比度。對比度之計算：C=(B\u002FB0)-1，有關對比度下列何者正確？",1785129967844]