由於靜電集塵器(electrostatic precipitation, EP)內部流場為紊流且並不均勻，再加上電場效應，不僅對粉塵流動造成影響，也會在流體中產生離子風效應，更增加了內部流場的複雜性。故瞭解並掌握粉塵流體在靜電集塵器內部之行徑模式，有助於除塵效率之提升。本文包括 (1) 首先建立電腦數值模擬分析之物理模型，包括紊流流場，非均勻電場、以及粉塵微粒運動軌跡(particle trajectory)及微粒充電機制之控制方程式等。 (2) 開發一套數值方法(numerical method)及副程式(subroutine)可求解靜電除塵器內之電壓V以及空間電荷密度ρc之分佈，以便將來與計算流體力學CFD軟體相互結合。 (3) 再配合商業計算流體力學軟體CFD-RC，以數值方法探討不同粉塵粒徑對於其模擬上充電量、飄移速度與實驗上集塵效率之影響。並於不同之操作環境模擬其行進軌跡，如:不同進口流速(1m/s、1.5 m/s)、不同微粒介電係數(5.1、10)、不同微粒密度(600 kg/m3、2000 kg/m3、5000 kg/m3)。而集塵板上堆積層之模擬則以自行撰寫之程式計算，模擬內容包含不同堆積層厚度(1 mm、3 mm、5 mm)、不同堆積電阻係數下探討對壁面上電流密度、電壓及電荷密度之影響，並更深入探討堆積層中帶有電荷(ρdust)所產生之逆電暈(Back Corona)現象會對壁面上電流密度、電壓及內部電場強度之影響。 (4) 結合實驗與模擬編寫出兩套VB程式，分別計算微粒充電量與計算EP除塵效率，工程師可於輸入各參數後，獲得其EP除塵效率，方便日後設計。

In this study, a Computational Fluid Dynamics (CFD) model for description of operation of electrostatic precipitators (EP) has been developed. Next, considered five discharge electrodes in the geometry configuration, the discharge electrode wire-to-wire distance is 500 mm, and placed between two collecting electrodes having 300 mm spacing between them. Afterward simulated the particle trajectories in the Electrostatic Precipitator within different inlet flow velocity (1m/s, 1.5 m/s), particles diameter(5μm, 50μm), particles permittivity(5.1, 10) and different applied voltage (56 kV, 63 kV). Results showed that the EP efficiency is increased for larger particle diameter, particle permittivity and applied voltage. Such as the particles diameter (dp) from 5μm to 50μm for εr=5.1 and V0 =63 kV, the particle charge can be improved about 80 times. Particles permittivity (εr) from 5.1 to 10, the particle charge can be advanced about 16%. Applied voltage (V0) from 56 kV to 63kV for dp=5μm and εr=5.1, the particle charge can be increased about 10%. Finally, if the charged particles are accumulated on the collecting electrode that can probably result in Back Corona. This paper will calculate the effect of current density on collecting electrode(J), electric potential(V), and electric field intensity(E) while Back Corona occur.

KEYWORDS: Electrostatic Precipitator; Numerical analysis;
particle trajectory, back corona

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