- 學位論文
奈米碳管產生空氣負離子微型裝置控制懸浮微粒之研究
Removal of suspended particulates by microscale air ionizer of carbon nanotubes
摘要
懸浮微粒為室內空氣主要污染物之一，而懸浮微粒控制技術一般可分為過濾移除及靜電移除兩種。本研究目的為評估空氣負離子(Negative Air Ion, NAI )對不同粒徑與物種懸浮微粒之移除能，並探討空氣負離子移除懸浮微粒之有效範圍。本研究使用奈米碳管尖端放電產生實驗所需之空氣負離子(100000 ~ 300000 ion cm-3)。本研究以NaCl 與stearic acid 為氣膠物種，選取30 nm 及300 nm 兩種粒徑分別注入環境模擬箱，並控制模擬箱內之相對濕度進行試驗。於有效範圍試驗時，本研究改變不同採樣位置進行試驗，以了解不同採樣位置對空氣負離子移除微粒效能之影響。 在不同粒徑微粒方面，不論是關閉或是開啟空氣負離子，30 nm 微粒之濃度衰減係數比300 nm 大；30 nm 微粒之有效清淨速率(effectivecleaning rate, ECR )亦比300 nm 微粒大。在不同氣膠物種方面，關閉空氣負離子時，stearic acid 氣膠微粒之濃度衰減係數較NaCl 氣膠微粒大；開啟空氣離子時，則是NaCl 氣膠微粒之濃度衰減係數較大，導致NaCl 氣膠微粒的ECR 較大。在不同相對濕度方面，相對濕度對於微粒自然沈降的影響並不明顯，但開啟空氣負離子時，微粒濃度衰減係數與微粒移除效率會隨著相對濕度升高而增加。實驗結果顯示，於相對濕度65% 時，空氣負離子對30 nm NaCl 微粒會有最佳移除效率( 99.48% )、增進效率( 37.21% )與ECR ( 111.3 Lpm )。在不同採樣位置方面，當採樣水平距離增加時，空氣負離子濃度會逐漸減少，兩者為對數線性關係。微粒的ECR 亦會隨著採樣水平距離增加而下降，當採樣水平距離增加至30 cm 時，空氣負離子對懸浮微粒移除效果已不明顯。當採樣垂直距離增加時，空氣負離子濃度與微粒之ECR 皆會下降。實驗結果顯示，空氣負離子濃度多寡是影響空氣負離子移除懸浮微粒效能之關鍵。
並列摘要
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.