空氣中的懸浮微粒被人體吸入後會依粒徑大小沉積於呼吸道、肺泡、甚至血液中，造成眾多疾病。因此，如何捕獲這些微粒成為重要的公共衛生議題。靜電集塵器是利用電液動力學的原理來收集微粒的設備。傳統二階靜電集塵器通常由充電區與收集區兩個具有強電場的區域串聯而成。當微粒進入到充電區時，會先受到冠狀電極產生的電暈放電效應所充電。接著，帶電微粒會隨著氣流往收集區移動，且受到感應靜電力的影響而往收集電極方向移動，最終附著於收集電極上。欲產生電暈放電，冠狀電極附近的電場需要強大到足以解離空氣。而電場強度與冠狀電極幾何息息相關；另一方面，在強電場的作用下，冠狀電極的表面性質會隨著操作時間而改變，進而影響其電場特性。本論文使用兩種不同幾何（針狀和圓柱狀）的冠狀電極，分別探討其集塵效率、電場特性、以及可靠度。首先，比較針狀及線狀冠狀電極。結果表明，在相同操作條件下使用針狀電極可以達到較高的冠狀電流和集塵效率。此外，隨著針狀電極數量增加，冠狀電流與集塵效率亦隨著提升；降低針狀電極尖端的曲率半徑也能得到較佳的集塵效率。由結果可得，當針狀冠狀電極的數量為12 根時，使用曲率半徑最小的電極（0.015 mm）所得的集塵效率比曲率半徑最大的電極（0.03 mm）還高7.6%（微粒粒徑的範圍從0.03μm 至0.1 μm）。然而，使用曲率半徑越小的針狀冠狀電極時，會在冠狀電極附近產生更強的電場，加強了電暈放電的效應，使更多氧化物沉積於冠狀電極上，影響電極的介電常數，導致冠狀電極附近的電場強度及冠狀電流下降。再來，本論文也討論圓柱狀冠狀電極的特性。當使用外徑越小的圓柱冠狀電極，將於圓柱冠狀電極附近造成更強的電場，並得到較高的集塵效率、較佳的放電特性、但也產生更多氧化物沉積於電極表面上；當相鄰的冠狀電極間距增加時（數量固定），也能得到較高的電場強度以及較穩定的放電特性。由結果得知，當圓柱狀冠狀電極的間距固定為10 mm 時，使用外徑最小的電極（0.4 mm）所得的集塵效率比外徑最大的電極（1.0 mm）還要高28.6%（微粒粒徑的範圍從0.03 μm 至0.1 μm）。總結來說，當冠狀電極附近的電場強時，雖然能提升集塵效率與提供更穩定的放電特性，但亦會在冠狀電極的表面造成更嚴重的氧化反應，最終使長時間操作的電極放電性能下降。

Aerosol particles are considered as a source of risk for diseases because they can be inhaled by human body, based on different diameter of particles, they deposited in the respiratory tract, alveoli, and even in the blood. Electrostatic precipitator (ESP) is a particle collecting device, operating based on electrohydrodynamics. A traditional two-stage ESP consists of two regions, a charger and a collector, that have strong electric fields. Particles are getting charged when entering the charger because of corona discharging. When these charged particles pass by the collector, the induced electrostatic forces alter the trajectories of charged particles, making charged particles settle down on the collecting electrode. Initiating the corona discharging requires strong electric fields around the corona electrodes, while the electric field strength various with the geometry of the corona electrode. However, strong electric fields also bring the reliability issues, speeding up the oxidation and changing its surface characteristics. This thesis examines two geometries (needle, cylinder) of corona electrodes, including electrostatic characteristics and reliability. Firstly, the needle corona electrodes and the wire corona electrodes are compared. The results show that replacing wire corona electrode with needle corona electrodes in the charger ends up with a higher corona current and a higher collection efficiency. The results also show that the corona current and the collection efficiency gets higher with the increasing number of the spike corona electrodes. The collection efficiency of curvature 0.015 mm is 7.6% higher than curvature 0.03 mm, for 12 number of electrodes and particle size ranging from 0.03 μm to 0.1 μm. Nonetheless, using sharper needles improves the collection efficiency as well and strengths the corona discharging, but suffers more oxidation because of more oxidants and contaminants attracted, resulting in a lower electric field around and lowering the corona current after long operation. On the other hand, this thesis also investigates the electrostatic characteristic and the reliability of cylindrical corona electrodes at different diameters and pitches. The results show that smaller diameter of cylindrical corona electrode has stronger electric field strength, higher collection efficiency, better discharge characteristics, and more oxidants deposited. The collection efficiency using electrode with 0.4 mm diameter is 28.6% higher than 1.0 mm electrode diameter when pitch of cylindrical corona electrode is 10 mm and particle size ranging from 0.03 μm to 0.1 μm. When increasing the pitch of cylindrical corona electrode, it exhibits higher electric field and more stable discharge characteristics. In summary, using a corona electrode that is able to create a strong electric field increases the collection efficiency and provides more stable discharge characteristics, but it also causes more severe oxidation on the surface of the corona electrode, resulting in a decrease in the discharge performance of the electrode over time.

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