現代化社會中，生活人們待在室內活動的時間增加，加上對於懸浮微粒對人體造成的危害意識高漲，人們倍加重視如何提升室內空氣品質。除了一般商業建築外，製藥業、食品加工業、動物實驗室、和醫院等都需要能夠處理大氣流量的空氣清淨設備。建築的空調系統中，空間有限且工作氣流大，當中的空氣清淨設備需要兼具經濟和噪音控制，靜電集塵的技術可以達到此要求。在有限的空間和高氣流速度下，具有平板收集電極的傳統靜電集塵器的收集效率會顯著地下降。然而，將平板收集電極改為方波結構不但能增加質量收集效率，也能抑制高風速下微粒的再迴流。為了探討方波結構在不同氣流速度下對細懸浮微粒的影響，本論文引用 Stoke Number（慣性力與黏滯力比值）和 Electrostatic Number（靜電力與黏滯力比值）討論方波結構的深度和間距如何影響不同粒徑微粒的收集效率。結果發現風速越低、微粒粒徑越大，方波結構利於微粒的收集，1 μm 和 3 μm 的微粒在 7 m/s 的風速下收集效率超過 84%。方波結構的深度和間距決定迴流區大小、迎風側的收集面積、平均電場強度、和方波邊角的局部電場。較大的迴流區有助於 Stoke Number 小的微粒被收集；方波結構深度越深、間距越窄，有助於 Stoke Number 大的微粒在方波的迎風側被收集；方波結構深度越淺、間距越窄，收集區的平均電場強度越強，Electrostatic Number 大的微粒容易被收集；方波結構深度越深、間距越寬，方波邊角局部的電場強度增強，能使帶電的微粒轉向，有更高的機率進入迴流區，增加收集效率。

In modern society, people spend more time indoors. With the increasing awareness of the harm
caused by suspended particles to the human body, people pay more attention to how to improve
indoor air quality. In addition to general commercial buildings, the pharmaceutical industry, the
food processing industry, animal laboratories, and hospitals all require air purification equipment that can efficiently handle the big airflow. However, the air-conditioning system in the
building is set in limited space and use high working air velocity. The air cleaning equipment
needs to be economical and noise controllable. The electrostatic precipitation technology can
meet these requirements. The collection efficiency of a conventional electrostatic precipitator with a plate collecting electrode will decrease significantly under the conditions of being
built in limited space and working with high air velocity. However, changing the plate collecting electrode to a square-wave structure can not only increase the mass collection efficiency
but also suppress the re-entrainment of particles under high airflow velocity. In order to explore the influence of the square-wave structure on fine particulate matters at different airflow
velocity, this paper quotes the Stoke Number (the ratio of inertial force to air resistance) and
Electrostatic Number of particles (the ratio of electric force to air resistance) to discuss the impact of the depth and width of the square-wave structure on the collection efficiency of particles
in different size. The results show that square-wave structure performs well as flow velocity
gets higher or particle gets larger. The collection efficiency of 1 μm and 3 μm particles at 7
m/s is over 84%. The depth and width of the square-wave structure determine the size of the recirculation zone, the collection area on the upstream wall, the average electric field strength,
and the local electric field at the corners of the square wave. A larger recirculation zone helps
collect particles with a small Stoke Number; the deeper the depth and narrower the width of the
square-wave structure benefits the collection efficiency of particles with large Stoke Number
on the upstream wall of the square wave; the shallower the depth and narrower the width of
the square-wave structure creates a stronger average electric field in the collection area, and
the particles with large Electrostatic Number are easier to be collected; the deeper and wider
the structure leads to the increasing local electric field at the corners of the square wave, which
makes the charged particles turn and get more chance to enter the recirculation zone, increasing
collection efficiency.

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