本研究以聚四氟乙烯薄膜(PTFE)利用平板型直接接觸薄膜蒸餾系統蒸餾海水，主要探討系統內流體流動型態對薄膜蒸餾之滲透通量的影響情形，並預測蒸餾海水之理論滲透通量。實驗將以溫度差、進料流量、模組傾斜、曝氣量、改良模組及超音波等六種操作方式影響進料側流體流動型態。
    在單一液相薄膜蒸餾系統中，隨著溫度差上升則滲透通量有明顯增加，但極化現象也最嚴重。進料流量提高僅增加對流熱傳係數，因此滲透通量提昇很有限。而若將模組傾斜45°時，會由於不穩定自然對流關係促進滲透通量提昇最多。然而在改良模組實驗中，進側側模組之小範圍凹孔會造成流體亂流使得滲透通量明顯提高。至於超音波則在單一液相系統且適當操作時間下較能發揮其效果，但滲透通量提昇有限。
    在氣液兩相系統中，隨著進料側曝氣量越大則滲透通量提昇越多。而隨著曝氣量的增加，若改變模組傾斜角會使滲透通量變化幅度越大。又因曝氣已能有效減緩極化現象，因此若再增加其它操作條件，如改良模組、超音波，則滲透通量增加的會很有限。
    藉由Dusty-Gas model並假設海水相當NaCl溶液濃度所預測薄膜蒸餾海水之理論滲透通量，其理論計算的結果與實驗相當符合。結果顯示出溫度極化係數介於0.4~0.6之間；濃度極化係數隨著溫度差或進料流速減少而有明顯的增加，故濃度極化現象為影響滲透通量的主要影響因素。因此為預測海水於薄膜蒸餾的行為所做之假設是為合理的，並可了解極化現象對滲透通量的影響情形，以便為提昇滲透通量而優先預防。

The effects of flow patterns on the permeate flux of direct contact membrane distillation (DCMD) was studied in this work. The operating parameters included temperature difference, feed flow rate, module inclination angle, gas flow rate,  module modification and ultrasonic irradiation. The DCMD experiment was conducted in a flat sheet module with using 0.2 µm pore size polytetrafluoroethylene (PTFE) membrane. The pre-filtrated seawater from Tamsui coast area was used as feed. Permeate fluxes were measured under various operating parameters. Theoretical flux prediction model was also presented for single-liquid phase and two phase in DCMD. 
    In the operation of single-liquid phase membrane distillation, the results showed that the permeate flux increased significantly with increasing the temperature difference, but increased slightly with the feed flow rate in presented laminar flow region. As the angle of inclination from the horizontal (flow below membrane) increased, the permeate flux increased, and reached a maximum at 45°, and then decreased. A small area of concave hole on the feed module side which caused turbulence to feed stream allowed flux enhancement significantly. The effect of ultrasonic irradiation enhance on the permeate flux was finite. 
    In the operation of two phase membrane distillation, the permeate flux increased apparently with increasing the air sparging in the feed side. With changing the membrane inclination, the flux enhancement also increased with increasing the gas velocity. However air sparging could already effectively reduce the polarization phenomena, the flux enhancement by other operational parameters was slight.
    The flux prediction model was derived from the Dusty-Gas model combined with assuming the seawater to the equivalent NaCl solution. The prediction fluxes agreed very well with the experimental results. The theoretical calculations showed that the temperature polarization coefficients were in the range of 0.4 to 0.6 that was reasonable for DCMD operation; and the concentration polarization coefficients increased significantly as the temperature difference increased or the flow rate decreased. The presented flux model can be applied to forecast the effect of polarization on the flux and then prevent it in advance.

目錄
誌謝			I
中文摘要	                   II
英文摘要	                   III
圖目錄			VII
表目錄			X
第一章	緒論	1
1.1	前言	1
1.2	薄膜分離程序	2
1.3	薄膜蒸餾	5
1.4	本研究之目標	7
第二章	文獻回顧	10
2.1	薄膜蒸餾相關研究	10
2.2	薄膜蒸餾法之種類	15
2.2.1	直接接觸式薄膜蒸餾	15
2.2.2	空氣間隙式薄膜蒸餾	15
2.2.3	空氣掃掠式薄膜蒸餾	16
2.2.4	真空式薄膜蒸餾	16
2.3	薄膜之性質	17
2.4	影響滲透通量的因素	18
2.5	提高滲透通量的方法	20
第三章	理論計算	34
3.1	直接接觸式薄膜蒸餾理論分析之假設	34
3.2	質量傳送	35
3.3	熱量傳送	39
3.4	極化現象之影響	41
3.4.1	溫度極化	41
3.4.2	濃度極化	42
3.5	熱質傳經驗方程式	45
第四章	實驗裝置與方法	50
4.1	實驗裝置	50
4.2	實驗設備	51
4.3	實驗藥品與薄膜材料	52
4.3.1	實驗藥品	52
4.3.2	薄膜材料	52
4.4	實驗步驟	52
4.5	操作條件	53
4.5.1	系統操作條件	53
4.5.2	流量計校正與雷諾數計算	54
4.6	分析方法	54
4.6.1	分析儀器	54
4.6.2	NaCl含量的分析方法與條件	55
4.6.3	陽離子的分析方法與條件	55
4.6.4	陰離子的分析方法與條件	55
4.6.5	濁度的分析方法與條件	56
第五章	結果與討論	65
5.1	海水定性與定量分析結果	65
5.2	薄膜純水滲透通量	67
5.3	單一液相流態系統	68
5.3.1	無傾斜模組下流速與溫度對滲透通量之影響	68
5.3.2	傾斜模組下進料流量對滲透通量之影響	68
5.3.3	改良進料側模板凹孔對滲透通量之影響	70
5.3.4	外加超音波對滲透通量之影響	71
5.4	氣液兩相流態系統	73
5.4.1	無傾斜模組下曝氣量對滲透通量之影響	73
5.4.2	傾斜模組下通氣量對滲透通量之影響	73
5.4.3	改良進料側模板凹孔下曝氣量對滲透通量之影響	75
5.4.4	外加超音波下曝氣量對滲透通量之影響	75
5.5	阻隔鹽類之效能與實驗前後純水滲透通量變化	77
5.6	理論計算	78
5.6.1	滲透通量之估算	78
5.6.2	DCMD系統中溫度極化之現象	81
5.6.3	DCMD系統中濃度極化之現象	82
第六章	結論	100
符號說明	102
參考文獻	105
附錄A			111
附錄B			112
附錄C			114
附錄D			116
 
圖目錄
圖1.1	薄膜分離程序之分類	8
圖1.2	薄膜蒸餾物流流動示意圖	9
圖2.1	DCMD 示意圖	28
圖2.2	AGMD 示意圖	28
圖2.3	SGMD 示意圖	29
圖2.4	VMD 示意圖	29
圖2.5	提高濾速之方法	30
圖2.6	逆洗程序示意圖	31
圖2.7	流體亂流產生器	32
圖2.8	氣液兩相的流動型態	33
圖3.1	DCMD系統熱質傳示意圖	46
圖3.2	DCMD質傳阻力示意圖	47
圖3.3	Multipore size model之電路阻力類比示意圖	47
圖3.4	DCMD熱傳阻力示意圖	48
圖3.5	大氣壓下NaCl溶液的密度變化圖	49
圖4.1	DCMD 模組示意圖	57
圖4.2	DCMD 模組設計示意圖(進料側)	58
圖4.3	DCMD 模組設計示意圖(冷卻水側)	59
圖4.4	直接接觸薄膜蒸餾實驗裝置圖	60
圖4.5	進料流體流量計校正曲線	61
圖4.6	冷卻水流體流量計校正曲線	61
圖4.7	進料流體流量與掃流速度(uL)之關係圖	62
圖4.8	冷卻水流體流量與掃流速度(up)之關係圖	62
圖4.9	進料流體流量與Reynold number之關係圖	63
圖4.10	冷卻水流體流量與Reynold number之關係圖	63
圖5.1	海水樣品層析圖譜	84
圖5.2	不同溫度差下改變進料流量之實驗前純水滲透通量	84
圖5.3	不同溫度差下改變進料流量之滲透通量	85
圖5.4	不同進料流量下改變模組傾斜角度之滲透通量	85
圖5.5	模板凹孔於不同進料流量下對滲透通量的影響	86
圖5.6	凹孔於進料側模板之不同位置下對滲透通量的影響	86
圖5.7	不同進料流量下輸入150 W超音波對滲透通量的影響	87
圖5.8	輸入150 W超音波於進料側不同位置下對滲透通量的影響			87
圖5.9	不同進料流量下輸入150 W超音波於進料側之不同位置對滲透通量的影響	88
圖5.10	不同曝氣量下之滲透通量	88
圖5.11	不同曝氣量下改變模組傾斜角度之滲透通量	89
圖5.12	不同通氣量下模板凹孔對滲透通量的影響	89
圖5.13	不同曝氣量下輸入150 W超音波對滲透通量的影響	90
圖5.14	不同輸入150 W超音波之型式下對滲透通量的影響	90
圖5.15	滲透通量大小排序	91
圖5.16	不同溫度差下改變進料流量之滲透液導電度與濃度	92
圖5.17	不同曝氣量下改變模組傾斜角之滲透液導電度與濃度	92
圖5.18	改良模組下改變進料流量之滲透液導電度與濃度	93
 
圖5.19	輸入150 W超音波於進料側的不同位置下之滲透液導電度與濃度	93
圖5.20	不同操作條件下實驗前後純水滲透通量之變化圖	94
圖5.21	直接接觸式薄膜蒸餾理論計算流程圖	95
圖5.22	不同溫度差下改變進料流量之理論與實驗滲透通量比較圖	96
圖5.23	不同曝氣量下改變模組傾斜角之理論與實驗滲通量比較圖	96
圖5.24	不同進料流量下理論溫度極化係數之變化圖	97
圖5.25	不同進料流量下理論濃度極化係數之變化圖	97
圖5.26	凹孔於進料側模組之相對位置	98
圖5.27	超音波Probe於進料側模組之相對位置	98
圖A-1	NaCl檢量線	111
圖C-1	Cl- 檢量線	115
圖C-2	SO42- 檢量線	115
 
表目錄
表1.1	不同操作程序之驅動力分類	8
表3.1	NaCl溶液的物性參數	48
表4.1	平板薄膜性質說明	64
表5.1	標準海水組成之比較	99

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