兩相流對直接接觸薄膜蒸餾法增益研究

Effect of Two Phase Flow in Direct Contact Membrane Distillation

李昆壕(Kun-Hao Li)

指導教授 ： 林育才

元智大學/工程學院/先進能源研究所/碩士(2009年)

摘要

薄膜蒸餾之所以無法達到商業化最主要的原因在於無法解決溫度與濃度極化現象，造成蒸發效率偏低的情況，因此本研究以打入氣泡的方式擾動流場而增加熱流機制來破壞溫度邊界層，藉此降低邊界層所產生的溫度和濃度極化現象，提高薄膜蒸餾模組之蒸發效率，來改善此技術上的缺點。本文以的進料端出入口均溫為50℃、60℃、70℃，而滲透端出入口均溫固定在23℃，打入氣體的乾度為0.0006、0.0009、0.0012。並以單向流的實驗結果做比較，來觀察不同溫度、不同乾度下所造成的氣泡大小與數量對於擾動流場提高蒸發量的結果。本文的流道為垂直擺放方式，垂直擺放可以讓氣泡快速通過流道，不會造成在流道內累積造成而無法順暢通過流道擾動流場。結果顯示，進料端出入口均溫50℃時、乾度0.0012、進料端流量130ml/min時，所達到蒸發量最大效率為22.2%，此時的氣泡直徑約在2mm~3.5mm之間，氣泡數有6顆。進料端出入口均溫60℃時、乾度0.0012、進料端流量260ml/min時，所達到蒸發量最大效率為14%，此時的氣泡直徑範圍約在0.25~2.25mm，氣泡數有12顆。在進料端出入口均溫70℃時、乾度0.0012、進料端流量390ml/min時，所達到蒸發量最大效率為19%，氣泡直徑範圍約在1.75~2.75mm，氣泡數有18顆。

關鍵字

薄膜蒸餾 ； 溫度極化 ； 兩相流

並列摘要

The reason that membrane distillation can’t be commercialized is due to the unsolved problem of temperature and concentration polarization, which causes low efficiencyof the process.In this study bubbles arepumped into the flow channel, to induce disturbance flow field and heat transfer enhancement by adding various deflectors in flow channels, it is expected that temperature and concentration polarization can be thus reduced.
Three different average temperatures of 50℃、60℃、70℃ are chosen for the, feed side and the permeate side temperature is fixed at 23℃. The qualities of feed side flow are 0.0006, 0.0009, 0.0012, respectively. Asingle phase flow is also studied for reference to compare the flux value with that of the two phase flow, The effect of different temperatures and qualities bubble diameter and quantity and the corresponding flux are also investigated, The results show that when the feed side temperature is 50℃ and the quality is 0.0012, the flux can reach a maximum efficiency of 22.2% and, the range of the six bubble diameter (mm) is between 2mm and~3.5mm. When the feed side temperature 60℃ and the quality is 0.0012, the flux maximum efficiency is 14%, and the range of the twelve bubbles diameter (mm) is between 0.25~and 2.25mm. When the feed side temperature is 60℃ and the quality is 0.0012, the flux maximum efficiency 19%,and the range of the eighteen bubble diameter (mm) is between 1.75~and2.75mm.

並列關鍵字

membrane distillation ； temperature polarization ； two phase flow

參考文獻

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