區劃空間火災閃燃及回燃現象實驗及十二吋晶圓廠防火性能設計之研究

Abstract

本論文共分兩部份。第一部份為火災房間實驗及數值模擬，係針對火災房間探討回燃現象，以及天花板及牆壁裝修對閃燃現象之影響為主要研究目標。總共進行了五次貨櫃屋全尺寸燃燒實驗，其中第一次至第三次為回燃實驗，其中有二次成功的形成回燃現象，另一次則可探討回燃失效成因；第四次及第五次為閃燃實驗，其中一次成功的形成閃燃現象，另一次則成功的阻止閃燃發生。從以上實驗分析，發現天花板及牆壁之有無裝修或裝修材質的異同，為影響是否產生閃燃及回燃現象之重要因素，亦了解到使用固體燃料及氣體燃料所形成回燃之機制的差別。從溫度曲線發現有呈現二次波峰的溫度變化，即第一次波峰為缺氧下未達600℃時即降溫產生悶燒現象，之後由於打開開口產生氧氣重力流的第二次波峰，且燃燒溫度超過600℃以上，瞬間產生爆波的猛烈燃燒現象，則所謂回燃。另外在數值模擬方面，由於場模式與區域模式之燃燒模式均運用完全燃燒的化學計量方程式，所以火災溫度有高估的現象，且由於貨櫃本身係鑄鋼所構成，因金屬不易蓄熱導致其輻射回櫃效應不如水泥，所以閃燃與回燃發生時間應較使用水泥者為長，但整體而言，也與二種模式的模擬結果與實驗數據均有不錯的近似。在閃燃實驗中，發現以下結論（1）天花板裝修材質的異同，為影響是否產生閃現象之重要因素。（2）從第一次實驗的溫度曲線發現有呈現一次波峰現象，溫度高達600℃以上，之後即維持全盛期燃燒，此第一次波峰現象，為成長期轉變為全盛期的溫度急速上升的過渡階段，此即所謂閃燃。 本論文第二部分是以SFPE性能式設計程序來評估設計十二吋晶圓廠無塵室煙控系統，本研究使用NIST所發展的CFD火災煙控軟體FDS (Fire Dynamics Simulator)模擬無塵室中火災煙流動情形。在避難模式方面，利用動態避難模擬軟體SIMULEX模擬出晶圓廠人員避難情形以評估人員避難安全。分別使用上排煙及下排煙系統結合起火區空調系統降載至0.1m/s及關閉，非起火區空調系統增載至0.6 m/s的試驗設計，並針對3MW及800kw的火源，進行四個案例的模擬分析。結果發現下排煙系統在3MW的火源下，無法有效將煙侷限在起火區劃內，無法滿足財產安全標準，但仍可滿足生命安全標準，而其他三個案例則均可滿足生命及非生命安全標準。而在人員疏散方面，由SIMULEX結果顯示總體避難時間為164秒，均小於在規格式設計下，煙沉降至1.8公尺所需模擬時間，因此，模擬結果可以證明無論人員可以在晶圓製程區成功地避難，已達到人命安全的目的。

This study consists of two parts. The first part performed five full-scale compartment (steel container) fire tests and the corresponding numerical simulations to study the flashover and backdraft phenomena. The backdraft experiments performed three full-scale room (steel container) fire tests and the corresponding numerical simulations. The measured temperatures and oxygen indexes, obtained from the failed one and the two successful ones, could identify the backdraft mechanism. To produce the backdraft phenomena, the internal decoration of the container house should use flammable materials on both walls and ceiling. From the simulation and experiment data, backdraft causes two temperature peaks. The first one is below 600□C. Then, an abrupt opening of the front door leads to a supply of a large amount of fresh air, followed by an indication of sudden temperature rise. The second peak temperature is over 600□C. Meanwhile, the deflagration will cause the gases to heat and expand within the fire space, thus forcing unburned gases out of the vent ahead of the flame front. Comparing both cases with natural gas and solid loveseat as the fuel in backdraft, it can be found that the former can achieve pre-mixture state and create easily the instant explosion wave phenomenon, however, this wave will disappear immediately. On the other hand, the solid loveseat used as the fuel in this study produced backdraft within 30-50 seconds after opening door. After the occurrence of backdraft, fire will maintain a period of fully developed stage, which is consistent with the conditions in actual fires. In addition to the experiments, this study also carries out the simulations by using fire models. In the field and zone models, backdraft phenomena were identified. However, both models only considered complete combustion kinetics with oxygen, causing the overpredicted fire temperatures. The simulations did reproduce the phenomena similar to the backdraft fire. The flashover experiments performed the fire performance evaluations for both water-ceiling (a brand name) and common-used wooden ceiling. They are summarized as follows. (1) The flashover occurs in the first fire test, whereas the second experiment using the special fire-proof water-ceiling can successfully suppress the occurrence of flashover. It indicates that the fire-performance properties of ceiling material can significantly determine whether the flashover occurs or not; (2) It is also found that in the first experiment a peak above 600□C in the temperature curve is reached, and then it turns into the fully developed stage. The first temperature peak marks the transition of a sudden increase in temperature from the growth into the fully developed stages, i.e., flashover. In the second part, this study adopts the SFPE Performance-based design procedure to evaluate the performance of upwards and downwards desmoke systems, respectively, in a wafer fabrication zone. The tools used for this purpose include FDS (Fire Dynamics Simulator) and SIMULEX. The design fires are 800 kW (scenario 1) and 3 MW (scenario 2), respectively. Both desmoke systems in scenarios 1, 2 and 4 meet the performance criteria, whereas the downward system in scenario 3 cannot satisfy the property protection requirement. However, the downward desmoke system can still be utilized, provided it complies with some restrictions in fire protection design, for example materials used and the provision of an acceptable emergency plan. For occupant evacuation, the SIMULEX result shows that the total evacuation time is 164s. FDS simulations involving the installation of smoke curtain confirm that the evacuation time is less than the smoke layer descending time, indicating that the occupants can safely evacuate in the event of a fire.