排煙口開口特性對排煙效應影響之分析與探討

The Study of Opening Effects on Exhaust Systems

周士凱(Shih-Kai Chou)

指導教授 ： 何三平

長榮大學/健康科學學院/職業安全與衛生研究所/碩士(2009年)

https://doi.org/10.6833/CJCU.2009.00060

摘要

本研究首先將蒐集大樓建築物煙控系統之相關文獻加以分析整理，並利用CFD-model電腦模擬軟體，配合各種模擬條件，在最佳開口位置探討分析中發現，無論天花板頂端或側邊排煙口以環繞開口最佳。另外，以側邊環繞開口優於頂端環繞開口；當排煙口面積佔樓地板面積2%時，在不同樓地板面積之情境下，排煙口為天花板頂端環繞、天花板側邊環繞，模擬結果可知樓地板面積225 m2時，天花板頂端開口適用火源為0.25MW、天花板側邊開口適用火源為1.07MW；樓地板面積500 m2時，天花板頂端開口適用火源為0. 5MW、天花板側邊開口適用火源為5MW；樓地板面積625 m2時，天花板頂端開口適用火源為0.7MW、天花板側邊開口適用火源為7.4MW，若欲符合法規排煙口面積佔樓地板面積2%、火源熱釋放率為5MW，其有效排煙口為側邊環狀開口。本研究亦發現在防煙垂壁高度（天花板下方0.5m）處，排煙口開口面積佔樓地板面積臨界值與樓地板面積是有關係的，因此提出預測在不同樓地板面積下，排煙口面積佔樓地板面積臨界百分比之公式，以提供將來參考之依據。
在高樓建築物模擬火災時，防火鐵捲門失效其能見度較正常來的佳，但濃煙瀰漫於各樓層亦增加各樓層人員避難風險。因此，倘若火災發生時，仍保持防火鐵捲門的正常啟動或兩段式啟動，將足以增加各樓層人員避難逃生之時間。爾後，將火源位置由避難樓層變更為頂端樓層時，其能見度與輻射熱值皆由有效符合判斷基準變更為無法有效符合，故建議大樓火災審查模擬時，除了將火源位於補氣良好的避難層中庭處外，應增設火源於頂端樓層，以有效評估排煙口之效益。最後，運用預測公式運算大樓樓地板面積1200m2，其臨界開口為2.5%與實際模擬得知的12.5%不符。原因為大樓火災模擬補氣不佳，導致排煙口開口面積需比預測公式來的大。

關鍵字

大樓；煙控設計；自然排煙；FDS；能見度；防煙區劃

並列摘要

When the size of the opening was 2% of the 500m2 floor area, the required fire size that the FDS simulated was 0.5 MW and 5 MW for the roof opening and the opening on top of the side walls respectively based on fire code requirements.
When the size of the opening was 2% of the floor area, the required fire size was 0.25 MW and 0.7 MW for 225m2 and 625 m2 floor area respectively for the roof opening, and it was 1.07 MW and 7.4 MW respectively for the opening on the top of the side walls. It was easier to vent smoke from the opening on the top of the side walls than from the one on the roof, because the jet flow of smoke helped vent the smoke from the horizontal opening. This result showed the fire code was needed to discuss in a more serious manner for the natural smoke venting.
A series of correlations were developed to predict the smoke layer based on different fires and floor areas. The larger vent area was required in this research than in Hinkley’s correlation.
A lower smoke layer was found when the fire was set on the top floor than on the first floor for a high-rise building, because it was hard for air to entrain when the fire located on the top floor. An opening, which size was 12.5% of the floor area, was required to vent smoke for 1.8m high evacuation in this high-rise building simulation.

並列關鍵字

high-rise building； smoke control；Smoke Vent；FDS；visibility；Smoke Compartment

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