Investigation of Particulate Matter Transport Behavior in Multi-Room Buildings by Three-Dimensional Particle Tracking Technique
Date Issued
2004
Date
2004
Author(s)
Kao, Hong-Ming
DOI
zh-TW
Abstract
本研究之主要目的在以拉格蘭日(Lagrangian)觀點之氣懸微粒軌跡追蹤模式進行三維度多區間建築物室內微粒軌跡傳輸行為之境況模擬。微粒軌跡追蹤模式搭配以尤拉(Eulerian)觀點所進行之三維度室內環境風場模擬，引入大渦漩模擬(Large Eddy Simulations，LES)為紊流模式，以計算紊流場對微粒傳輸行為之影響。在研究中，微粒軌跡追蹤模式在計算微粒受力之時，除了傳統採用的阻力與重力外，又增加考慮Saffman升力與布朗運動作用力對於微粒的影響。本研究首先進行微粒釋放粒數之敏感度分析，分析結果當微粒釋放粒數超過O(103)數目層次以上時，可確保氣懸微粒質量濃度與粒數濃度之精確度。
本研究所發展之微粒軌跡追蹤模式並與Lu等(1996)現地試驗數據進行相互驗證，其在微粒質量濃度的模擬方面有著良好的吻合性。本研究繼而應用四種不同自然通風策略，包括全開通風、貫穿通風、右側短路通風和左側短路通風等，以瞭解三維度多區間建築物在不同通風策略下的室內懸浮微粒之傳輸行為與排除效率。研究中亦加入兩組對照組進行，分別是無室內隔間與不同空氣交換率對氣懸微粒傳輸行為之比較。
在比較以上四種不同的自然通風策略後，結果指出在微粒追蹤10分鐘後，懸浮於室內之PM10濃度於全開通風策略為最低，右側短路通風次之，再次之為貫穿通風，而左側短路通風由於受到室內隔間的不良配置影響，成為排除室內微粒效率最差者。但針對PM2.5或是PM1的微粒，採用以上各案例中的自然通風策略，對排除PM2.5的微粒之效果皆為普通，至於PM1微粒在室內的排除效率則都不佳，所以採取自然通風對小微粒的排除效能並不顯著。在有無隔間的案例比較下，本研究發現室內微粒沉積現象是兩者間較為明顯的差異處，於室內有隔間的情形下，其沉積比例較室內無隔間者多了近1.75倍之多。至於在不同空氣交換率下的比較中可指出，空氣交換率小(ACH=1 1/h)的室內空間與空氣交換率大者(ACH=5 1/h )，對於室內微粒質量濃度排除到相同濃度時，所需的時間呈非線性增加之趨勢。
The main objective of this study is to investigate particulate matter transport behavior in three-dimensional multi-room buildings by using a Lagrangian particle trajectory tracking technique. The wind flow model uses the Eulerian viewpoint to simulate indoor airflow and conducts the large eddy simulations (LES) of turbulent flows. In this study, we not only add the drag force and the gravitational force into the Lagrangian particle tracking model, but also consider the Brownian motion effect and saffman lift force on indoor aerosol particles. Sensitive analysis of how many particle numbers are needed to release in the simulated 3-D multi-room buildings is firstly performed. The result indicates that as the released particle numbers are over O(103), mass and count concentrations generally approach to steady values.
The Lagrangian particle tracking model developed herein is verified by Lu’s available field measurement in 1996. Good agreement with the measured particle mass concentration is found. Four sets of numerical scenario simulation for various window openness strategies are next carried out. The natural ventilation strategies used include full-open ventilation, pass-through (piston) ventilation, right short-cut ventilation, and left short-cut ventilation. In addition, two comparison sets which have no indoor partition and different air change rate, respectively, are also simulated.
In comparison with the effect of the four aforementioned natural ventilation strategies on removal efficiency of PM10 mass concentration in multi-room building, the results show that the removal efficiency of the full-open ventilation is the best and the left short-cut ventilation is the worst after ten-minute particle tracking. Obviously, the full-open ventilation is an effective way to remove indoor concentration of aerosol particles. The left short-cut ventilation has improper indoor partition arrangement, so that it has the worst removal ability. On the contrary, regarding to PM2.5 or PM1, there is no distinct difference in removing indoor particles for all natural ventilation strategies.
Comparing the cases that have indoor partition and without indoor partition, it can be seen that there exists obvious difference in particle deposition amounts. The deposition amounts of the with-partition case is almost 1.75 times as large as the without-partition case. Furthermore, for different air change rates, good removal ability of indoor particles is expected as an indoor space has higher air change rate.
Subjects
多區間建築物
大渦漩模擬
微粒軌跡
微粒排除效率
空氣交換率
Particle trajectory
Particle removal efficiency
Type
thesis
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