- 學位論文
以靜電力輔助之渦流式空氣懸浮微粒收集器開發
Development of a particulate-matter-collector by using a vortex-aided device with an electrostatic force
摘要
隨著日益嚴重的空氣汙染問題，PM2.5已成為影響人類健康指標的重要因素之一，為了識別和評估環境中的污染源，可廣泛收集空氣懸浮微粒和鑑定其成分的方法，以提高檢測能力和準確性的預收集器已受到重視，其主要目的及功能是在短時間內快速收集及過濾出大量空氣，並可在較小的空間內收集懸浮微粒，使得收集到足夠數量的空氣懸浮微粒可用於後續分析處理。 在本研究中，將慣性衝擊與靜電吸附的微粒沉積概念應用於氣膠過濾領域，以開發高速懸浮微粒收集器，將利用快速膨脹的流道結構，在腔室內誘發渦旋流場以增加懸浮微粒的停留時間，並施加高壓靜電以迫使懸浮微粒收集於腔室內部的不銹鋼收集板上。研究方法則是以有限元素分析軟體來模擬流道結構內的空氣流場分布、壓降變化、電場分布及微粒運動情形，並以氣膠過濾實驗加以驗證其結果。由實際實驗驗證，在抽氣流率2.0 l/min下，50 nm至200 nm粒徑範圍內的效率可達到73.21％，壓降為3.686 kPa，而在200至710 nm粒徑範圍，平均收集效率為81.21%。應用此一預收集器，本研究開發一空氣微粒快速收集裝置，長寬高為22 cm× 13 cm×10 cm，重量約721.7 g，並成功以此裝置進行了街道的空氣採樣實測，於30分鐘內，將0.09 m3的空氣進行微粒的收集並聚集，並以電感耦合電漿體質譜法測得該場域的鋅與鋇之兩種重金屬的濃度值，在鋅與鋇的濃度量測上，對於校內外濃度相差約1.804倍與1.514倍，其結果證明本研究所開發的空氣微粒快速收集裝置能在短時間內測得固定區域及時間區間的空汙含量，並說明其可行性及機動性。
並列摘要
With increasingly global issues of air pollutions, the level of PM2.5 has become one of the important factors that correlates to human health. Extensive efforts have been made to develop methods to collect and evaluate the composition of particulate matters in air. In order to accelerate the detection capability and accuracy, the performance of the pre- collector plays an important role. Its main function is to quickly filter out and a large amount of particulate matters in a short period of time and to collect suspended PMs in a small space. Thus, a sufficient amount of particulate matters can be used for post-analysis. In this study, inertial impact and electrostatic adsorption are adopted to develop a high speed particulate-matter (PM) collector. A rapid expanding chamber with an inclined inlet is used to induce vortex inside the chamber and to increase the total resident time of particulate matters (PMs). A strong electrostatic field also is applied to force PMs being collected onto a stainless steel plate inside the chamber. The Finite element analysis is used to simulate distributions of the air flow, pressure drop, electric field and particle movements. The results are verified by aerosol filtration experiments. Experimental study demonstrated that the collection efficiency can reach 73.21% in the range between 50 nm to 200 nm with a pressure drop of 3.686 kPa. The average efficiency between 200 and 710 nm is 81.21% under a flow rate of 2 l/min. Using this design, a particulate-matter-collector is developed with 22 cm×13 cm×10 cm in size and 721.7 g by weight. Collect the particles in 0.09 m3 of air within 30 minutes. This collector is successfully applied to collect and study Zn and Ba heavy metal compositions of a regular road with heavy traffics. In the measurement of the concentrations of Zn and Ba, the difference between on- and off-campus are about 1.804 times and 1.514 times, respectively. These results verified that the particulate matter collector can measure the air pollution content in a fixed area and within a short period of time. The feasibility and mobility of this collector is verified.