A Study of Mass Transport in Osmotic Distillation
Date Issued
2005
Date
2005
Author(s)
Chou, Jing
DOI
zh-TW
Abstract
本研究針對聚四甲基-1-戊烯（TPX）複合膜之製備與滲透蒸餾程序加以探討，並利用化簡後的dusty-gas model(DGM)來模擬滲透蒸餾的通量表示式，最後再把它與兩種商業化膜材(PTFE與PP)進行比較。
完整的DGM表示式比較複雜，很難從實驗結果來計算擴散係數。在牛血清蛋白(BSA)溶液的滲透蒸餾，由於水蒸氣在膜孔中的氣相莫耳分率很低(<0.05)，利用泰勒展開式把DGM的通量化簡為簡單的線性表示式，利用實驗結果可以計算出有效擴散係數。在乙醇水溶液的滲透蒸餾，也把乙醇與水的通量用此線性式表示，同樣可以計算出擴散係數值。
結果顯示：在本系統，化簡後的DGM可以成功地模擬出雙成份系統與三成份系統的表示式；水在TPX膜中的擴散係數(6.0x10-6m2/s)與其他兩種膜很接近，但由於TPX與乙醇的親和性，使乙醇的擴散係數值比其他兩種膜低。
In the present research, the osmotic distillation of Poly(4-methyl-1-pentene) (TPX) composite membranes and other commercial membranes was investigated. The simplified dusty-gas model was employed to describe the mass transfer inside pores and evaluated effective diffusivities of molecules.
The general form of DGM is too complicate to combine with experiment results. Base on low gaseous molefraction of water (<0.05) in BSA osmotic distillation system, the two-component dusty-gas model can be transformed into linear equation by Taylor series. The linear equation was also capable of predicting effective diffusivities of ethanol and water in ethanol solution osmotic distillation process.
The results show that the simplified DGM can express the mass transfer mechanism of this work successfully including two-component and three-component systems. And water diffusivity in TPX membrane is competitive with commercial membranes, but the ethanol diffusivity in TPX is lower than other two membranes because of the interaction between them, which raised the surface diffusion effect in the pores.
Subjects
滲透蒸餾
質傳
Osmotic distillation
mass transport
Type
thesis
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