Removal of suspended particulates by microscale air ionizer of carbon nanotubes
Date Issued
2007
Date
2007
Author(s)
Kuan, Chun-ting
DOI
zh-TW
Abstract
The suspended particulate is one of the main indoor pollutants. Generally,the removal methods of the suspended particulate can be classified to filtration and electrostatic collection technologies. The purpose of this
work is to evaluate the control efficiency of NAI for removal of the different sizes and species suspended particulate. This study also evaluated the effective range of NAI for the removal of suspended particulate. In this
research, carbon nanotube tip was electrified to produce NAI (100000 ~ 300000 ion cm-3). This study used two species (NaCl and stearic acid)and two sizes (30 nm and 300 nm) particulate as the test aerosols which were injected into the chamber. Besides, the relative humidity of chamber was controlled at 30%, 50% and 65%. The sampling position was changed for the test of effective range.
Whenever the NAI generator was turned on or turned off, the coefficient of concentration decay (k) of 30 nm particulate is larger than 300 nm particulate ; the ECR of 30 nm particulate is also larger than 300 nm particulate. With regard to different species particulate, when the NAI
generator was turned off, the k of stearic acid particulate was larger than NaCl particulate; on the contrary, when the NAI generator was turned on, the k value of stearic acid particulate is smaller than that of NaCl particulate, so that the ECR of NaCl particulate is larger than that of stearic acid particulate. Relative humidity is not an important parameter for the natural decay of particulate, but when the NAI device was turned
on, the k value and removal efficiency of particulate increased with relative humidity. The results show that the best removal efficiency (99.48%), enhanced efficiency by NAI (37.21%) and ECR (111.3 Lpm) occurred when NAI removed 30 nm NaCl particulate at RH 65% environment. As for different sampling position, the NAI concentration
gradually decreased with increasing horizontal distance, and the correlation of them showed a logarithmic linear tendency. The ECR of particulate also deceased with an increase of horizontal distance. When horizontal distance be increased to 30 cm, removal efficiency of particulate for NAI application is not obvious. Both NAI concentration and the ECR of particulates gradually decreased with an increase in vertical distance. Results show that NAI concentration is the key factor for the removal of particulates by NAI.
Subjects
懸浮微粒
空氣負離子(NAI)
奈米碳管
相對濕度
ECR
suspended particulate
negative air ion (NAI)
carbon nanotube
relative humidity
Type
thesis
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