The characteristic and the removal of suspended particulates by microscale air ionizer of carbon nanotubes
Date Issued
2008
Date
2008
Author(s)
Lee, Pei-Chi
Abstract
The air ionizer had become increasingly popular for removing suspended particulates. In this study, we utilized the Carbon nanotubes(CNTs) as a microscale air ionizer worn 20cm below the nose and established the best operational system. In this study, we investigated the characteristic of negative air ions(NAIs) generated by negative electric discharge using Carbon nanotubes(CNTs) needle of different growth methods. According to the unique efficient field emission property of the CNTs, the results were shown that used the CNTs produced by arc-discharge method and Plasma-enhanced Chemical vapor deposition method could decrease the threshold voltage strongly, reaching voltage value at 0.4kv, and the maximum NAIs concentration were 209.73×103 ions/cm3 and 1236.00×103 ions/cm3 respectively. At the voltage 0.9kv and 1.0kv, both CNTs could generate NAIs stably. But at the voltage 0.8kv, the NAIs generated by CNTs of PECVD method decayed evidently, and the NAI enhancement removal efficiency of particulates was only 5.1%. Compared to the PECVD method, the CNT produced by arc-discharge method could generate the NAIs stably at the lower voltage of 0.6kv, and the NAIs concentration decayed evidently until the voltage decreased at 0.5kv. Besides, at the voltage 0.6kv, the NAI still had the effect of removing the particulates, the NAI enhancement removal efficiency was 17.6%. It was obvious that apply the CNT produced by arc-discharge method to ionize the air could make the experiment system more steady and had the better operation. n this study, we also established the NAI enhancement removal efficiencies of particulates in the breathing zone. We used the CNT produced by arc-discharge method and set the discharge voltage at 1.0kv. It was shown that the NAIs had the best average enhanced efficiency among the breathing area 3cm below the nose.(17.9%). The NAIs still had the obvious effect among the breathing area at the nose, and the average enhanced efficiency was 13.8%. But among the breathing zone 3cm above the nose, NAIs had no evident enhancement removal efficiency of particulates(7.08%). It was also shown that the vertical distance played a more important role for the NAI enhancement removal efficiency than horizontal distance.
Subjects
Carbon Nanotubes (CNTs)
Negative Air Ion (NAI)
suspended particulates
Arc discharge
Plasma-enhanced Chemical vapor deposition (PE-CVD)
enhanced efficiency
Type
thesis
File(s)![Thumbnail Image]()
Loading...
Name
ntu-97-R95541109-1.pdf
Size
23.53 KB
Format
Adobe PDF
Checksum
(MD5):2d2bed4350d5df2867b3dbf3c975fd95