長公路隧道縱式通風排煙系統之性能化分析

The Performance Analysis of Longitudinal Ventilation Systems in Long Road Tunnels

林明勳(Lin Ming-Shiun)

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(2007年)

https://doi.org/10.6833/CJCU.2007.00140

摘要

本研究使用Fire Dynamics Simulator（FDS）火場模擬軟體，著重觀察長公路隧道發生火災時，目前國內所設計之縱式通風排煙系統是否有足夠能力，將火災燃燒產生之濃煙順利往發生火災之下風處（依循車行方向）排除，以確保用路人可以不受濃煙影響下順利逃生。
研究結果發現，當隧道所設計主要通風排煙系統（豎井抽風口）之抽風量為443 CMS，而火源-豎井抽風口間距在350m之內，且無論是否設置噴流式風機之情況下，對於火源熱釋放率5MW、15MW以及20MW之火災大小而言，隧道內的通風排煙系統皆可將火災燃燒產生之大部分煙層順利往火災下風處排除，但於火災上風處會有煙層產生逆流現象，而該逆流煙層可被控制於某區間內，不致持續往隧道入口擴散，換言之倘若用路人可以順利逃離至逆流煙層範圍外之區域，將較不易受到濃煙之毒害；除此之外，從逆流煙層之擴散距離隨著火源熱釋放率增加而變遠之關係，本研究發展出一套得以預測不同火源熱釋放率範圍下，逆流煙層隨之變化的預測模式，且經由電腦模擬結果與理論預測公式相互驗證後得知，此模式應是能夠參考之預測模式。
另外，經由探討分析噴流式風機功能之模擬結果顯示，無論噴流風機係於火源上風處設置一組（兩具）或於火源下風處設置兩組（四具），純粹就縮短逆流煙層擴散距離之角度而言，皆有正面之助益
最後，根據溫度、輻射熱以及一氧化碳濃度之等高線圖分析可知，對於溫度與一氧化碳濃度而言，無論隧道內發生火源熱釋放率為5MW、15MW或20MW的火警事故，倘若位於起火源上風處2m以外且高度不超過3m的區域範圍內，大致屬於安全區域，同時代表受到高溫與一氧化碳傷害或毒害的風險皆相對地較低；而對於輻射熱強度而言，倘若隧道內發生火源熱釋放率小於20MW的火警事故，建議人員應處於起火源上風處15m以外且高度低於2m之區域，避免或降低受到輻射熱傷害之風險。

關鍵字

長公路隧道 ； 通風排煙系統 ； 噴流式風機功能

並列摘要

This study aims to find out the ability of domestic longitudinal ventilation system. The longitudinal ventilation system is designed to exhaust smoke produced by tunnel fire to leeward（along the car track）,insuring that road users can be evacuated free from smoke .This study uses Fire Dynamics Simulator（FDS） to analyze the performance of longitudinal ventilation system in long road tunnels.
When the capacity of the major ventilation in a tunnel is 443 CMS, and the distance between fire source and ventilation system is within 350m, whether jet fans are installed or not, smoke caused by fire with heat release rate of 5MW, 15MW, or 20MW can be exhausted to leeward.However, there will be smoke backflow at windward of fire source.The smoke backflow can be retained in a certain area, instead of continuing to diffuse to the entry of the tunnel.In short, if road users can successfully escape to area free from smoke backflow, they can not be harmed by the toxin of smoke. In accordance with the relationship between the heat release rate and the distance of smoke diffusion, we develop a formula to predict the distance of smoke diffusion in different heat release rates. Besides, we discover that whether we set up a jet fan at leeward or windwaed, it can effectively cut down the distance of smoke diffusion.
Finally, we analyze contour diagram of temperature, radiation intensity and carbon monoxide.In the aspect of temperature and carbon monoxide, when the heat release rate of fire source is 5MW, 15MW or 20MW, areas 2m away from the windward of fire source and less than 3m in heights are generally safe.In the aspect of radiation intensity, when the the heat release rate of fire source is less than 20MW,it is suggested that firefighters should stay in areas 15m away from the windward and less than 2m in heights, in order to minimize the risk of being harmed by radiation.

並列關鍵字

FDS ； tunnel ； longitudinal ventilation system ； jet fan

參考文獻

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