外裝型氣罩坦坡對捕集性能的影響

The Effect of the Tapers on the Capture Performance of an Exterior Hood

侯冠宇(Kuan-Yu Hou)

指導教授 ： 陳友剛

長榮大學/健康科學學院/職業安全與衛生研究所/碩士(2008年)

https://doi.org/10.6833/CJCU.2008.00189

摘要

室內環境空氣品質是環境污染與健康危害的重要議題，使用局部排氣系統是維持良好作業環境空氣品質的常用控制方法。外裝型氣罩則是目前最為普遍使用的局部排氣裝置氣罩形式，但因設計上對坦坡並無明顯規範，常見無法達到正確設計的案例，致使氣罩捕集能力無法發揮。坦坡之設計將影響氣罩開口面位置的判定，進而影響有害物發生源對氣罩距離或位置、以及氣罩吸氣風量及能源需求等的判定。
本研究針對氣罩模型進行測試，對不同張角的外裝型氣罩進行探討，測定氣罩開口表面風速以及特定位置氣罩吸氣風速變化趨勢，著重於吸氣開口的風速分佈均勻度。利用雷射光頁煙霧可視化技術觀察氣流形態。在此研究中發現，當坦坡半張角超過 45 度時，坦坡已不具使開口風速均勻分佈的功能，其功能反而更類似凸緣。在這種狀況下，氣罩底部與導管連接處才是實質的氣罩開口。此時，氣罩開口到污染物距離增加，同時降低氣罩的捕集能力。

關鍵字

通風、外裝型氣罩、局部排氣裝置、捕集風速、凸緣、坦坡

並列摘要

The indoor air quality is an important issue related to health hazard. Local exhaust device is a common-used method to maintain the indoor air quality. In the local exhaust device, the exterior hood is used most frequently to collect the air-borne contaminants. However, due to the ill-design of the hood taper, the capture of the hood can rarely perform properly. The arrangement of the taper affects the determination of the opening position, which further affects the distance between hood and contamination source, required, exhaust flow-rate, and the consumption of the energy.
This study used hood models to conduct a series of experiments. The models have different taper angles. The air speed and its distribution on the opening and the exhaust speed at specific locations are measured. The air flow pattern was also observed by the flow visualization technique involving water vapor illuminated by the laser light sheet. According to the experimental and observational results, when the taper angle is greater than 45 degree, the taper should be regarded as a flange. This means the opening is located at the connection of the hood the duct, which increases the distance between contamination and decreases the capture performance of the hood.

並列關鍵字

ventilation ； exterior hood ； local exhaust ventilation ； capture velocity ； flange ； taper

參考文獻

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