[{"data":1,"prerenderedAt":73},["ShallowReactive",2],{"q-fire-113-1-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-113-1-火災學概要-034","fire-113-1-fire-science-034",113,1,34,"有關熱傳導的敘述，下列何者正確？",{"A":16,"B":17,"C":18,"D":19},"熱量是由高熱量處往低熱量傳遞","傳導物體之厚度並不會影響熱傳導量","熱傳導係數越大，熱傳導量越大","熱傳導可以不須依靠媒介物質","C",null,[],false,"本題考點：傅立葉熱傳導定律中各參數與熱傳導量之間的正反比關係。\n【正解理由】依傅立葉定律，穩態一維熱傳導的熱流量等於熱傳導係數乘以垂直於熱流方向的截面積，再乘以兩側溫度差，最後除以傳導路徑的厚度。熱傳導係數位於分子，數值越大代表材料傳熱能力越強，在其餘條件相同時熱傳導量隨之越大，兩者成正比，故選 C。\n【逐項排除】\n(A) 敘述錯誤。熱是由高溫處往低溫處傳遞，驅動勢為溫度差而非熱量的多寡；質量龐大而溫度較低的物體可含有較多熱量，卻不會把熱傳給溫度更高的物體。\n(B) 敘述錯誤。厚度位於分母，厚度越大熱阻越大、熱傳導量越小，因此厚度確實會影響熱傳導量，隔熱材加厚即是利用此一關係。\n(C) 敘述正確，為應選項；熱傳導係數與熱傳導量成正比。\n(D) 敘述錯誤。熱傳導須藉由介質分子的振動與自由電子的移動逐層傳遞，必須有媒介物質；不需媒介而可在真空中傳遞的是熱輻射。\n【記憶點】傳導量與係數、面積、溫差成正比，與厚度成反比；不需介質的是輻射而非傳導。","傅立葉定律是熱傳三大模式中最早被定量化的一式，形式為熱流量等於負的熱傳導係數乘以面積再乘以溫度梯度，負號表示熱流方向與溫度上升的方向相反，也就是熱必然由高溫流向低溫，這正是熱力學第二定律在傳導問題上的具體呈現。工程上常改寫成熱阻形式，熱阻等於厚度除以熱傳導係數與面積之乘積，多層牆體則把各層熱阻相加。此一體例與電路的歐姆定律完全平行：溫度差對應電壓，熱流量對應電流，熱阻對應電阻。\n\n熱傳導係數的數量級是判斷題的好用工具：銅約為每公尺每度四百瓦，鋼約五十瓦，混凝土約一點四瓦，木材約零點一四瓦，靜止空氣約零點零二六瓦。由此可知多孔隔熱材之所以有效，是因為把大量靜止空氣封在孔隙之中；而金屬構件貫穿牆體會形成熱橋，在防護區劃的完整性上是常見的弱點。\n\n熱慣性則是本科更常考的延伸量，定義為熱傳導係數乘密度再乘比熱。熱慣性小的材料表面升溫快、容易引燃，並會縮短閃燃時間，這說明為何內裝材料的選用對火災成長速度影響甚鉅。防火區劃構件的耐火時效試驗亦以背火面的溫升作為判定基準之一，而背火面升溫的快慢正由構材的熱傳導係數與厚度共同決定，可見本題三個參數在防火性能評估上是成組出現的。\n\n易混淆概念對照：傳導需要介質且介質本身不移動；對流需要介質且介質整體流動，以牛頓冷卻定律描述，熱通量正比於對流熱傳遞係數與溫度差；輻射不需介質，以史蒂芬－波茲曼定律描述，熱通量正比於表面輻射率與絕對溫度的四次方。火場中的熱回饋以輻射為主，正因為四次方的關係，使高溫熱煙層一旦形成便迅速主導熱傳。",true,[28,32,36,40,44,48],{"webId":29,"stem":30,"number":31,"year":11,"session":12},"fire-113-1-fire-science-033","對於金屬鈉的敘述，下列何者錯誤？",33,{"webId":33,"stem":34,"number":35,"year":11,"session":12},"fire-113-1-fire-science-035","某鑄造工廠因高溫鋁水洩漏，遇水引發爆炸，此為何種爆炸？",35,{"webId":37,"stem":38,"number":39,"year":11,"session":12},"fire-113-1-fire-science-032","可燃物在大氣中僅因受熱致使溫度升高而引發燃燒的最低溫度稱為：",32,{"webId":41,"stem":42,"number":43,"year":11,"session":12},"fire-113-1-fire-science-036","依美國防火協會（NFPA）危險物品標示規定，黃色代表何種危險性？",36,{"webId":45,"stem":46,"number":47,"year":11,"session":12},"fire-113-1-fire-science-031","在電氣火災研究中，木材、電木等絕緣物中，受電氣火花而碳化，碳化部分會逐漸形成微量的結晶，而變成具有導電性，此現象稱為？",31,{"webId":49,"stem":50,"number":51,"year":11,"session":12},"fire-113-1-fire-science-037","主成分為碳酸氫鉀的乾粉滅火藥劑不適用下列何種火災？",37,[53,57,61,65,69],{"webId":54,"year":55,"stem":56,"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":58,"year":59,"stem":60,"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":62,"year":63,"stem":64,"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":66,"year":67,"stem":68,"number":13},"fire-109-1-fire-science-034",109,"BLEVE 的發生，下列敘述何者錯誤？",{"webId":70,"year":71,"stem":72,"number":13},"fire-108-1-fire-science-034",108,"化學物質災害搶救程序 H.A.Z.M.A.T.中有關區域管制事項，下列敘述何者正確？",1785129966377]