The analysis of the use of cone calorimeter data produced under different thermal environments

[[abstract]]摘要 圓錐量熱儀是國際間最被肯定及使用之小尺寸火災測試儀。其內之錐形加熱 器模擬一加熱環境，藉由電子點火器及其他分析設備，可量測材料受熱後之火害 反應參數，包括引燃時間、熱釋放率等。無庸置疑地，此受熱環境需符合欲模擬 之真實火場環境，本研究針對兩項課題進行探討，分析其加熱環境，希望可以提 昇圓錐量熱儀數據使用的正當性(validity)。第一，圓錐量熱儀所模擬之熱流場可 分水平及垂直兩種配置，而先前研究者在運用圓錐量熱儀所測得之數據時，常與 實際熱流場有所差異。為探討水平、垂直熱流環境是否有所差異？本研究針對引 燃臨界熱通量、特定加熱強度下之引燃時間、表、背面溫度、熱釋放率與燃燒時 間參數進行分析比較。另一項為牆面火災模擬工作，早期之牆面火災模擬實驗模 擬研究中，錐體加熱器加熱材料，所使用之熱通量採實驗所得之平均值，與實際 火焰預熱輻射強度分佈存在差異，所以本研究改變錐體加熱器與試體之幾何配 置，去模擬真實牆面火焰預熱範圍之強度分佈，期使其實驗結果輸入相關模擬程 式後能更準確預測其延燒速率。 本研究結果顯示，發現水平、垂直配置之引燃時間、表、背面溫度、熱釋放 率與燃燒時間參數間有明顯之差異，因此運用圓錐量熱儀之實驗結果應選用適合 實際熱流場之配置。 試體傾斜42°且上下邊緣距圆錐加熱器120 及44 mm 時引燃後加擋板推回90° 之受熱環境結果是最接近真實牆面火焰預熱範圍。與圓錐量熱儀試驗程序相比， 有下列差異：「試體與加熱器間傾斜角度」、「傾斜試體引燃後推回垂直角」、 「試體點火位置」及「加熱器之擋板效應」，本研究亦比較各項差異之效應並評估簡化改變之可行性。使用18 mmPMMA 進行實驗後，發現各項效應均甚為顯著， 無法簡化。此使用新實驗法獲得之熱釋放率數據預計將使模擬結果更接近真實狀 況。[[abstract]]ABSTRACT Cone calorimeter has been the most accepted fire testing apparatus in the world With the heating of a conical heater ignition by an electric spark and other associated facilities the cone calorimeter consequently is capable of measure the ignition time heat release etc It takes for granted that it is better if the heating environment is more similar to real fire scenario The study included two projects to evaluate the validity of using cone calorimeter data in combustibility testing and an upward flame spread model In the first project the effect of the orientation of heater (horizontal and vertical) was investigated for the orientation can be chosen but not considered carefully by testers Measurements made were critical ignition heat flux and time to ignition heat release history surface temperature with irradiances of 15 30 and 50 kW/m2 Our data showed that the critical ignition heat flux ignition time and peak heat release rate were higher with vertical specimens while the total heat release and surface temperature were identical This is caused by the concurrent direction of entrained air and pyrolysis gases with vertical specimens diluting the flammable gases and then delaying the ignition The second project tried to make a sample holder which can produce a heating environment closer to real wall fires For example to simulate a 100 mm wide wall fire the sample would be inclined 42o and 120/ 44 mm from the top/bottom of the holder to the heater The ignitor is located at the bottom of the sample After ignition the sample was returned to vertical orientation and a shield was set between the sample and heater Material used was 180 mm thick PMMA The data carried out with the alternative testing procedure would be more suitable in upward flame spread modelin