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研究生:陳春樹
研究生(外文):Chun-Shu Chen
論文名稱:串式衝擊器收集盤性能改善之研究
論文名稱(外文):Investigation on Improving the Performance of the Collection Plate of Cascade Impactor
指導教授:郭景宗郭景宗引用關係
指導教授(外文):Jing-T Kuo
學位類別:碩士
校院名稱:國立臺灣大學
系所名稱:機械工程學研究所
學門:工程學門
學類:機械工程學類
論文種類:學術論文
論文出版年:2004
畢業學年度:92
語文別:中文
論文頁數:73
中文關鍵詞:式衝擊器收集盤收集效率
外文關鍵詞:Collection PlateCascade ImpactorCollection Efficiency
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微粒反彈現象常使衝擊器收集效率降低,所以一般串式衝擊器之使用上為了避免微粒反彈,通常在收集盤表面上塗敷一層黏性油,然而當收集後之微粒需要進行進一步之分析時,例如收集燃燒所產生之煤灰,收集盤上之黏性油將會影響微粒之化學組成成分及重量分析,且在高溫環境下採樣時,黏性油因為溫度升高使得黏性降低,收集效率也因此降低。 在本研究中,為了避免微粒反彈,在傳統收集盤上新增一阻礙板。微粒反彈高度及沉積位置係以數值方法決定,並根據其結果決定阻礙板高度bH及阻礙板與噴嘴中心線之距離bL。由數值分析得知,當微粒直徑小於15µm時,比值最大值應為1,微粒直徑小於10,在距離噴嘴邊緣1m處約等於0.526~1.05;實驗結果亦顯示,當,阻礙板太靠近噴嘴邊緣,影響微粒的沉積,而降低收集效率;時,收集效率隨著增加而減少,意即當值增加時,阻礙板高度增加,造成切線方向流量增加,而使鄰近噴嘴已沉積之微粒再度揚起,因而降低收集效率。
Particle bounce is the main factor that causes the reduction of collection efficiency in cascade impactor. In practice, the collection plate is usually coated with grease to reduce bounce effects. However, grease coating is not suitable in sampling of many aerosols such as those from coal combustion because it could interface with chemical and gravimetric analysis and would be ineffective in high –temperature sampling. In this study, we use a collection plate with barrier to reduce particle bounce. The height of the barrier, bH, and the distance between the centerline of the nozzle and the barrier, bL, are theoretically determined according to particle deposition patterns and the altitude of bounce. Numerical results show that the maximum value of the ratio of bL to jet diameter, , is 1 for bL/Wpd<15µm, and is approximately equal to 1mm at the position apart 1mm from the jet edge. In order to influence the deposition of particles, must be greater than 1. Experimental results show that if , the deposition of particle is interfered by the barrier and consequently the collection efficiency is lowered. Collection efficiency decreases as the ratio increases if , which is due to cross flow.
目 錄

摘要 I
Abstract II
目錄 III
圖目錄 V
表目錄 V
符號說明 VI
第一章 緒論 1
1-1 前言 1
1-2 影響收集效率的因素 3
第二章 文獻回顧 8
第三章 研究方法 17
3-1 基本原理 17
3-2 微粒運動軌跡 20
3-3 Cunningham修正係數 22
3-4 微粒之氣動直徑Aerodynamics Diameter 24
3-5 微粒反彈模擬 25
第四章 實驗設備及步驟 28
4-1 衝擊器設計原理 28
4-2 實驗設備 32
4-3 實驗步驟 33
第五章 結果與討論 36
5-1 增加阻礙板對流場之影響 36
5-2 微粒沉積位置及反彈後軌跡 38
5-3 阻礙板距離對微粒反彈之影響 41
5-4 阻礙板高度對微粒反彈之影響 42
第六章 結論與建議 44
參考文獻 45
附錄A 微粒沉積圖 47
附錄B 微粒反彈軌跡 50
附錄C 增加阻礙板後微粒軌跡 54

圖 目 錄
Figure 1-1 傳統串式衝擊器示意圖 2
Figure 1-2 慣性衝擊原理 2
Figure 1-3 理想衝擊器特徵 4
Figure 1-4 採樣管內空氣速度與氣流速度的關係 6
Figure 2-1 不同收集盤表面對收集效率之影(Rao, A., K.,1978) 11
Figure 2-2 虛擬衝擊器(Marple and Chilen , 1980) 12
Figure 2-3 兩種不同設計收集盤(Sioutas,1999) 13
Figure 2-4 杯狀微粒補捉器(Blswas and Flagan,1988) 14
Figure 2-5 四種不同收集盤設計(Tsai and Cheng,1995) 14
Figure 2-6 Ring-Gap impactor (John et al,1981) 15
Figure 2-7 本研究所使用之收集盤設計 16
Figure 3-1 流場計算網格 19
Figure 3-2 對於微粒軌跡之影響 27
Figure 4-1 噴器盤各部分尺寸 30
Figure 4-2 收集盤及阻礙板尺寸圖 31
Figure 4-3 實驗設備圖 35
Figure 5-1 增加阻礙板前後對流場影響 37
Figure 5-2 撞擊阻礙板微粒佔所有微粒百分比 40
Figure 5-3 阻礙板距離對收集效率之影響 41
Figure 5-4 阻礙板高度對收集效率之影響 43


表 目 錄
Table 3-1 Cunningham Factor修正係數之常數 22
Table 3-2 回復係數之經驗常數 26
Fuchs, N. A. (1964). The Mechanics of Aerosols, Pergamom Press, New York. Marple, V. A. (1970). A Fundamental Study of Inertial Impactors, Ph.D.thesis Rao, A. K., Whitby, K. T. (1978). Non-Ideal Collection Characteristics of Inertial Impactors-I. Single-Stage Impactors and Solid Particles, J. Aerosol Sci. 9:77-86. Rao, A. K., Whitby, K. T. (1978). Non-Ideal Collection Characteristics of Inertial Impactors-II. Single-Stage Impactors and Solid Particles, J. Aerosol Sci. 9:87-100. Cheng, Y. S., Yeh, H. C. (1979). Particle Bounce in Cascade Impactor, Environ. Sci. Technol. 13:1392-1396 Thomas, S., Hermann, G., Simon, K. (1988). Coating of Impaction Surface of Cascade Impactors: Necessary For Sampling Ambient Aerosols in Rural and Suburban Areas, J. Aerosol Sci. Vol. 19:993-996. George J. Newton(1988). Effect of Collection Substrates on Performance and Wall Losses in Cascade Impactors, J. Aerosol Sci. 21:467-470. Steven, S. Paks, Benjamin, Y. H. Liu, Keenneth, L. Rubow (1992). Effect of Coating Thickness on Particle Bounce in Inertial Impactors, Aerosol Sci. Technol. 16:141-150. Wang, H. C., John, W. (1987). Comparative Bounce Properites of Particle Material, Aerosol Sci. Technol. 7:285-299. Marple, V. A., Chilen, C. M. (1980). Virtual Impactor : A Theoretical
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Study, Environ. Sci. Technol. 14:976-984 Sioutas, C., Chang, M. C., Kim, S., Koutrakis, P., Ferguson, S. T. (1999). Design and Experimental Characteristics of a PM1 and a PM2.5 Personal Sampler, J. Aerosol Sci. 30(6):693-707. Biswas, P., Flagan, R. C. (1988). A particle trap impactor, J. Aerosol Sci. 19: 113-121. Kim, H. T., Kim, Y. J., Lee, K. W. (1998). New PM10 Inlet and Evaluation, Aerosol Sci. Technol. 29:350-354. Tsai, C. J., Cheng, Y. H. (1995). Solid Particle Collection Characteristics on Impaction Surface of Different Designs, Aerosol Sci. Technol. 23:96-106. Pak, S. S., Liu, B. Y. H., Rubow, K. L. (1992) The Effect of Coating Thickness on Particle Bounce in Inertial Impactors, Aerosol Sci. Technol. 16(3):141-150. Patrick F. Dunn, Raymond M. Brach, Michael J. Caylor (1995) Experiments on the Low-Velocity impactor of Microspheres with Planar Surface, Aerosol Sci. Technol. 23:80-95.
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