以多相流模式模擬掃流微過濾

Simulation of Cross-flow Microfiltration by Multiphase Flow Model

方巽禾(Hsun-He Fang)

指導教授 ： 吳容銘

淡江大學/工學院/化學工程與材料工程學系碩士班/碩士(2007年)

https://doi.org/10.6846/TKU.2007.00843

摘要

本研究以多相流模式模擬掃流微過濾之濾餅成長情形，探討濾餅的性質與結垢的機制，並進行掃流過濾實驗，取得數據作為比較，並了解掃流微過濾之特性。實驗中使用平均孔徑為0.1 μm的醋酸纖維膜（Mixed cellulose ester）過濾平均粒徑為0.8 μm的聚甲基丙烯酸甲酯（PMMA）粒子。在兩相流動的掃流微過濾中，改變懸浮液濃度與掃流速度，實驗結果顯示，懸浮液濃度越高與掃流速度越慢的條件下濾速越低，平均孔隙度也會逐漸降低。而利用計算流體力學（Computational Fluid Dynamics, CFD）軟體FLUENT6.2的多相流模式模擬濾餅成長是可能的，並可利用受力分析推測結垢機制。最後，根據動態實驗分析結果，得知濾餅的平均孔隙度隨著過濾時間的增加而減小，而濾餅阻力則是隨著過濾時間的增加而增加。

關鍵字

掃流微過濾 ； 多相流 ； 模擬 ； 計算流體力學

並列摘要

The study simulates cross-flow microfiltration by multiphase flow model. In order to discuss cake property and fouling mechanism, we experiment on cross-flow microfiltration. The data can be compared with simulation results and realize the property of cross-flow microfiltration. A filter membrane, made of mixed cellulose ester, with a mean pore size of 0.1 μm is used to filter 0.8 μm PMMA particles. On two-phase flow while varying suspension concentration and cross-flow velocity, we show that filtration rate is lowered with higher suspension concentration and lower cross-flow velocity, while average porosity is lowered as well. Also, we use Computational Fluid dynamics, CFD, software FLUENT6.2’s multiphase flow model to estimate cake growth and use force analysis to figure out fouling mechanism. Lastly, using results obtained from dynamic experiment, we know that cake average porosity is lower with filtration time, however, cake resistance is higher.

並列關鍵字

cross-flow microfiltration ； multiphase flow ； simulation ； CFD

參考文獻

Baker, R. J., A. G. Fane, C. J. D. Fell and B. H. Yoo, “Factors affecting flux in crossflow filtration”, Desalination, 53, p81-96, (1985)

Belfort, G., R. H., Davis, and A. L., Zydney, “The behavior of suspensions and macromolecular solutions in crossflow microfiltration”, Journal of Membrane Science, 96, p1-58, (1994)

Blake, N. J., I. W., Cumming and M., Streat, “Prediction of steady state crossflow filtration using a force balance model”, Journal of Membrane Science, 68, p205-216, (1992)

Chiu, T. Y., and A. E. James, “Critical flux enhancement in gas assisted microfiltration”, Journal of Membrane Science, 281, p274-280, (2006)

Hermia J., “Constant pressure blocking filtration laws-application to power-law non-newtonian fluids,” Transactions of the Institution of Chemical Engineering, 60, p183-187, (1982).