單極離子噴射式產生器對微粒帶電特性影響之研究

Effect of a Unipolar Ion Jet Generator on Characterization of Particle Charging

呂紹豪(Shao-Hao Lu 呂紹豪)

指導教授 ： 林文印

國立臺北科技大學/工程學院/環境工程與管理研究所/碩士(2013年)

https://doi.org/10.6841/NTUT.2013.00632

摘要

奈米微粒(dp≦100nm)具有優異的光電特性，其充電方式主要以擴散充電為主。主要影響微粒充電的因子有：離子濃度和微粒粒徑，但由於奈米微粒粒徑過小，以致會有部分充電的現象發生，並且在充電的過程中會受到電場的庫倫力和管壁表面的鏡像力等影響，造成帶電微粒的損失，影響後端的產出。因此為了改善以上的現象以及進一步探討微粒帶電特性，本研究設置一單極離子產生器，利用空氣通過此裝置內部產生高濃度離子，噴射進入微粒充電區，使微粒帶電，探討不同空氣流量對於不同微粒粒徑之平均電荷數、電荷分佈、微粒損失率和臭氧產生率等之特性。
研究結果顯示出微粒平均電荷數隨著流量增加而增加，且在流量為2lpm時，20nm、50nm和80nm均可以得到1個以上平均電荷數。微粒帶電特性以微粒電荷分佈進行觀測，80nm相較於其它測量微粒可以帶有+3電荷分佈，可以得知有較大表面積的微粒可以吸附較多的離子於表面上。在微粒損失方面，不同微粒粒徑的帶電微粒損失均低於25%，且損失率主要以鏡像力所造成。綜觀上述結果，本研究自製之單極離子產生器，能夠有效避免微粒受到電場庫倫力的影響，減少過多的損失，並使奈米微粒表面得到1個以上電荷數，但由於產生器的內部電場強度過強，導致有較高濃度的臭氧產生。

關鍵字

奈米微粒 ； 單極離子產生器 ； 微粒電荷分佈

並列摘要

Nanoparticle (dp≦100 nm) charging plays an important role in both scientific studies and practical applications related to aerosols, such as nano-structure patterning, contamination control, and aerosol instrumentation. However, the average charges of nanoparticle might be below one elementary charge. Therefore, it is necessary to improve the charge efficiency of nanoparticle.
A charge system was set up in this study, including aerosol generator system and unipolar ion generator. The objectives of this research were to study the average charges of particle, particle charge distribution, particle loss and ozone concentration at different ion air flow rate.
The experiment results indicated that the charge of nanoparticle increased with increasing air flow rate. When the air flow rate was 2lpm, the charge of 20, 50, and 80nm particle was above one elementary charge. Besides, the +3 charges distribution of 80nm could be produced because of more ion attached to the larger surface area of particles. All the charged particle loss was less than 25% due to the image force. In addition, the coulomb force effect could be neglect as using the unipolar ion generator in this research. However, the unipolar ion generator had higher electric field that caused higher ozone concentration exhaust.

並列關鍵字

nanoparticle ； unipolar ion generator ； particle charge distribution

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