陳志傑臺灣大學:職業醫學與工業衛生研究所蕭美芳Hsiao, Mei-FangMei-FangHsiao2010-05-112018-06-292010-05-112018-06-292008U0001-2507200811531900http://ntur.lib.ntu.edu.tw//handle/246246/182303The purpose of this study was to investigate the filtration and loading characteristics of granular bed filters. Stainless steel holders (diameter 71.6 mm, height 70 mm) were fabricated to accommodate 500g of zirconium oxide (ZrO2) beads, as the packed media of granular bed. Monodisperse ZrO2 granules (0.3, 0.8, 2 and 4 mm in diameter) were used to demonstrate the effect of the granule size and packing geometry (uniformity of 0, 30 and 45) on both pressure drop and aerosol penetration. The ZrO2 granular bed filter has a constant porosity of 0.48 and is independent of granule size. The size distributions and number concentrations upstream and downstream of the granular bed filter were measured using a scanning mobility particle sizer and an aerodynamic particle sizer. Face velocities, ranging from 0.58 to 14.8 cm/sec, were varied to study the flow dependency. The experimental data were compared with empirical models developed in previous studies. For aerosol loading, 10 micrometer monodisperse acrylic powders was used. A fibrous filter was used in loading test for comparison purpose.he penetration test results showed that aerosol penetration increased greatly with increasing granule size of the filter beads. For submicrometer-sized aerosol particles, the aerosol penetration increased with increasing face velocity due to shorter retention time within filter media. For micrometer-sized particles, the aerosol penetration decreased with increasing face velocity, apparently due to higher inertial impaction. From the filter quality perspective, the selection of the ‘best” filter is complicate. Assuming a low face velocity (e.g., 0.58 cm/sec), large granular size is more cost-effective because of the higher filter quality factor. The phenomenon implies that the gain in filtration efficiency due to larger surface area (of small granules in the filter) did not compensate for the increase in air resistance. In the case of high face velocity, the “best” filter is dependent on the size of the particles to be removed. In order to remove large particles, small granules should be used. Large granules are preferred for removing small aerosol particles.n comparison to the more familiar fibrous filter, the granular bed filter had very different loading characteristics. The pressure drops across both fibrous the granular bed filters increased with increasing mass loaded on the filter. After the cake formation point, the dust cake on glass fiber filter became compressed. This dust cake compaction caused the pressure to drop precipitously and intermittently. In contrast, the rate of increase in pressure drop of the dust cake formed on the granular bed filters decreased with time probably due to the pinhole leaks in the increasing mass loading. The size and density of the pinholes are determined by the granule size, the face velocity and the size of the challenge aerosols.Abstract 1要 3. 研究背景與目的 5-1濾材使用的目的 5-2濾材的種類及特性 5-2-1編織性濾材 5-2-2纖維性濾材 5-2-3薄膜濾材 6-2-4顆粒狀濾材 6-3顆粒床與一般濾材的差別 7-3-1顆粒床與填充床 7-3-2顆粒床與一般纖維性濾材 7-4顆粒床的應用 8-5主要目的 8. 文獻探討 10-1顆粒床的過濾理論 10-2顆粒床壓降模式 13-3濾材負載特性 14-4濾材阻塞 15-5粉餅的孔隙度 16-6粉餅的壓縮特性 17. 研究方法 19-1顆粒床的過濾特性 19-1-1實驗設計 19-1-2實驗裝置 19-1-3實驗步驟 22-2顆粒床的負載特性 23-2-1實驗設計 23-2-2實驗裝置 23-2-3實驗步驟 24. 結果與討論 25-1顆粒床壓降 25-2不同顆粒床的填充粒徑之過濾情形 25-3不同流量對相同填充粒徑之過濾情形 26-4顆粒床過濾模式與實驗值比較 26-5顆粒床過濾品質 26-6不同表面傾斜度顆粒床之壓降變化 27-7不同表面傾斜度顆粒床之穿透率及過濾品質 27-8顆粒床的微粒負載 28-9顆粒床之粉餅結構 29. 結論與建議 31. 參考文獻 33application/pdf1215870 bytesapplication/pdfen-US顆粒床濾材過濾品質孔隙度氣膠量測微粒負載針孔granular bedfilter qualityporosityloadingpinholesthesishttp://ntur.lib.ntu.edu.tw/bitstream/246246/182303/1/ntu-97-R94841011-1.pdf