| Summary: | 碩士 === 國立臺灣大學 === 生物環境系統工程學研究所 === 92 === 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.
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