行政院國科會專題研究計畫執行進度報告:綠植栽帶對室內外環境懸浮微粒傳輸及人體呼吸道沉積 之影響研究 (1/2)

本二年期研究計畫之主要目的在於進行 綠植栽帶對室內外環境懸浮微粒傳輸及人體 呼吸道沉積之影響研究。本研究第一年度藉 由計算流體動力學發展三維環境風場模擬模 式及三維微粒軌跡追蹤模式，以計算具綠植 栽帶建築物鄰近區域的環境風場、微粒運動 軌跡與微粒空間分佈。環境風場模式使用有 限體積法(FVM)與大漩渦模擬(LES)紊流模 式之亞格點尺度(subgrid scale)來模擬建築物 內外的紊流場，而微粒軌跡追蹤模式則主要 是以釋放大量微粒來追蹤其傳輸軌跡、沈降 路徑及終端沈積點，以期能了解多區間建築 物在不同通風策略、孔隙率綠植栽帶、氣象 因素(風速、風向)等條件下之環境風場與微 粒移除效果，並探討及周遭環境地形與各微 粒沈積機制間之相對關係。本研究所發展的 三維數值模式也將與前人風洞試驗量測結果 進行驗證比對。 第二年度將進行環境氣候箱實驗，考慮 不同綠植栽帶、通風配置、通風量及微粒導 入量之實驗條件所得逐時濃度變化，以驗證 第一年所進行之通風空間中室內外氣懸微粒 動態行為之三維度數值模式。此外，第二年 度亦將進行綠植栽帶過濾微粒之現地試驗， 試驗地點將選擇主要幹道旁之植栽帶，量測 在風速方向綠植栽帶前後微粒濃度，作為綠 植栽帶對於降低空氣中污染微粒改善效率之 參考。另外，本研究將利用由解剖學所推得 的兩種人體肺部幾何型態，並考慮了重力沈 降、布朗擴散和慣性衝擊三種微粒沈積機 制，發展環境氣懸微粒在人體肺部沈積之多 途徑顆粒沈積模式，探討綠植栽帶前後微粒 在經由呼吸作用進入人體肺部後的沈積情 形。 截至目前為止，本研究第一年已完成計 畫書之預期成果。研究中針對台灣較為常見 之室內多區間案例，以不同窗戶開口開關方 式進行室內外三維度環境風場及懸浮微粒軌 跡追蹤模擬，窗戶開口開關方式分為全開通 風、兩側通風、貫穿通風、交叉通風及短路 通風。同時亦針對室內無隔間案例作模擬， 以進行室內無隔間與有隔間之分析比較。The main objective of this two-year project is to study the effect of vegetative canopies on airborne particle transport in a naturally ventilated space and its deposition implication in the human respiratory system. In the first year, wind-driven airborne particles around vegetative canopies are tracked to investigate the transport trajectories and deposition patterns in vegetative canopies by combining a 3-D Eulerian wind flow model as well as a 3-D Lagrangian particle-tracking model. The former conducts large eddy simulation of the turbulent flows in vegetative canopies, and the latter performs raindrop trajectory calculations by releasing a large number of particles into the computational domain. The wind speed model is verified with available wind tunnel measurement. Numerical scenario simulations are carried out for various ventilation strategy, windbreak porosity, and meteorological factors (wind speed and direction) to study building airflow pattern and particle deposition around vegetative canopies. The relative relationship among three mechanism of particle deposition, i.e., sedimentation, Brownian diffusion and inertial impaction, are investigated. In the second year, road dusts collected from urban and suburban areas situated in northern Taiwan are used in an environmental chamber test to verify the 3-D numerical model. In addition, a field study of measuring the count and mass concentration of airborne dusts upwind and downwind of vegetative canopies is also carried out in the busy roads of Metropolis Taipei. The entrapment of particles by vegetative canopies is discussed. Results obtained from this research are expected to offer designers a control strategy for removal of concentrations of airborne road dust from vegetative canopies. The study develops a multiple-path model considering three deposition mechanisms, including sedimentation, Brownian diffusion and inertial impaction, to simulate particle deposition in the human lung. Two kinds of the human lung geometry, the typical-path lung model and the five-lobe symmetric lung model, are considered. The difference of deposition among four different breathing types (at rest, light, moderate, and heavy exercise) is compared. Traffic-induced particles in Metropolis Taipei are taken as an example. This report demonstrates the results of the first-year project. A common multi-room style in is selected to simulate the flow patterns of different kinds of building ventilation strategy, including complex ventilation, two side ventilation, piston ventilation, cross ventilation, and short-cut ventilation。It is concluded that piston ventilation can provide most effective air exchange and the downward-side windows are the key point of ventilation efficiency