本文選題：正滲透　切入點(diǎn)：外濃差極化　出處：《大連理工大學(xué)》2016年碩士論文　論文類型：學(xué)位論文

【摘要】：正滲透是一種新興水處理技術(shù),因具有能耗低、耐污染、水回收率高等優(yōu)勢(shì),在污水處理、海水淡化等領(lǐng)域有著廣泛的應(yīng)用前景。但濃差極化現(xiàn)象嚴(yán)重降低了正滲透過(guò)濾效率。本文針對(duì)其中的外濃差極化問(wèn)題,將折板結(jié)構(gòu)引入到正滲透膜組件的設(shè)計(jì)中,使廊道沿流動(dòng)方向呈波浪形,以促進(jìn)廊道內(nèi)渦流的產(chǎn)生與發(fā)展,從而減緩?fù)獠顦O化。文中采用實(shí)驗(yàn)測(cè)試和流體力學(xué)計(jì)算的方法,對(duì)折板膜組件性能和作用機(jī)理進(jìn)行了研究。將折板膜組件與傳統(tǒng)的平板膜組件進(jìn)行對(duì)比測(cè)試,以平板膜組件為基準(zhǔn),評(píng)估折板膜組件減緩?fù)鉂獠顦O化的性能表現(xiàn)。實(shí)驗(yàn)表明,折板能夠減緩?fù)鉂獠顦O化,具體表現(xiàn)為提高水通量。2M氯化鈉溶液為汲取液,去離子水作原料液時(shí),活性層朝向原料液和活性層朝向汲取液兩種運(yùn)行模式下,水通量提升幅度分別為17.45%和18.55%。2 M氯化鈉溶液為汲取液,0.5 M氯化鈉溶液作原料液時(shí),對(duì)應(yīng)值為分別為15.97%和17.12%。與此同時(shí),折板形狀對(duì)正滲透膜的選擇性無(wú)明顯不利影響。折板膜組件的形狀影響水通量提升幅度,較大波形角度和較小的波長(zhǎng),均有利于水通量的提高。雷諾數(shù)影響折板膜組件性能,雷諾數(shù)小于800時(shí),雷諾數(shù)越大,水通量提升幅度越大；雷諾數(shù)大于800時(shí),水通量提升幅度隨雷諾數(shù)增大略微下降。原料液和汲取液濃度影響濃差極化程度,進(jìn)而影響折板膜組件減緩?fù)鉂獠顦O化的性能表現(xiàn)；汲取液濃度較高或原料液濃度較低時(shí),水通量較大,水通量提升幅度也較大。折板膜組件不能有效減輕內(nèi)濃差極化。膜污染與濃差極化共存時(shí),折板膜組件能夠減緩膜污染,提高水通量。采用計(jì)算流體力學(xué)軟件Fluent,對(duì)膜組件單側(cè)廊道內(nèi)流動(dòng)特征進(jìn)行分析。結(jié)果表明平板膜組件內(nèi)流動(dòng)相對(duì)穩(wěn)定,無(wú)渦流出現(xiàn),流體完全沿x軸方向流動(dòng)：折板膜組件能夠促進(jìn)廊道內(nèi)渦流的產(chǎn)生,同時(shí)提升壁面剪切力。折板結(jié)構(gòu)通過(guò)引入渦流改善了水力條件,提升了水通量。折板膜組件的形狀影響廊道內(nèi)的流動(dòng)特征,波長(zhǎng)較小、波形角度較大時(shí),廊道內(nèi)渦流較強(qiáng),壁面剪切力較大。雷諾數(shù)也會(huì)影響廊道內(nèi)的流動(dòng)特征,雷諾數(shù)較大時(shí),折板模組件內(nèi)渦流較強(qiáng),壁面剪切力也較大；此時(shí),折板膜組件對(duì)壁面剪切力的提升幅度也較大。
[Abstract]:Due to its advantages of low energy consumption, high pollution resistance and high water recovery rate, positive osmosis is a new water treatment technology in wastewater treatment. Seawater desalination and other fields have a wide application prospect, but the concentration polarization seriously reduces the filtration efficiency. In this paper, the folded plate structure is introduced into the design of orthoosmotic membrane assembly, aiming at the problem of external concentration polarization. In order to promote the generation and development of eddy current in the corridor and to reduce the heterodyne polarization, the corridor is wave-shaped along the flow direction. In this paper, the methods of experimental test and hydrodynamic calculation are used. The performance and mechanism of foldable membrane assembly were studied. The performance of folding plate membrane assembly was evaluated by comparing it with the traditional plate membrane assembly and taking the flat membrane assembly as the benchmark to evaluate the performance of the folded plate membrane assembly in reducing the polarization of the external concentration difference. The folding plate can slow down the polarization of the external concentration difference. The concrete manifestation is that the water flux. 2 M sodium chloride solution is the extraction solution. When deionized water is used as the raw material solution, the active layer moves towards the raw material solution and the active layer towards the extraction solution. The increase of water flux is 17.45% and 18.55.2 M sodium chloride solution is the extract solution and the corresponding value is 15.97% and 17.12, respectively, when the absorbent solution is 0.5 M sodium chloride solution as raw material solution, and the corresponding values are 15.97% and 17.12 respectively. The shape of the folded plate membrane has no significant adverse effect on the selectivity of the membrane. The shape of the foldable membrane module affects the increase of water flux, the larger waveform angle and the smaller wavelength, which are beneficial to the improvement of the water flux, while the Reynolds number affects the performance of the membrane module. When the Reynolds number is less than 800, the increase of water flux is larger, and when the Reynolds number is greater than 800, the increase of water flux decreases slightly with the increase of Reynolds number. The concentration of feedstock and extract affects the degree of concentration polarization, and when the Reynolds number is greater than 800, the increase of water flux increases slightly with the increase of Reynolds number. Furthermore, the performance of folding membrane module to slow down the polarization of external concentration difference is affected. When the concentration of absorbent liquid is higher or the concentration of raw liquid is lower, the water flux is larger. When membrane fouling and concentration polarization coexist, the membrane module can reduce membrane fouling. The flow characteristics in the monolateral corridor of the membrane assembly are analyzed by using the computational fluid dynamics software Fluent.The results show that the flow in the flat membrane assembly is relatively stable and there is no eddy current. The flow of fluid is completely along the x-axis: the laminated membrane assembly can promote the formation of eddy current in the corridor, and at the same time, the wall shear force is increased. The folding plate structure improves the hydraulic conditions by introducing eddy current. The flow characteristics in the corridor are affected by the shape of the foldable membrane module. When the wavelength is small and the waveform angle is larger, the eddy current in the corridor is stronger and the shear force on the wall is larger. Reynolds number will also affect the flow characteristics in the corridor. When the Reynolds number is larger, the eddy current is stronger and the wall shear force is larger in the laminate module, and in this case, the lifting range of the wall shear force of the foldable plate membrane assembly is also larger.
【學(xué)位授予單位】：大連理工大學(xué)
【學(xué)位級(jí)別】：碩士
【學(xué)位授予年份】：2016
【分類號(hào)】：TQ028.8

【參考文獻(xiàn)】

相關(guān)期刊論文 前1條

1 江山;張京偉;吳崇健;許清;彭文波;;基于FLUENT的90°圓形彎管內(nèi)部流場(chǎng)分析[J];中國(guó)艦船研究;2008年01期

相關(guān)碩士學(xué)位論文 前1條

1 吳晴;正滲透過(guò)程中驅(qū)動(dòng)溶質(zhì)反滲規(guī)律研究[D];哈爾濱工業(yè)大學(xué);2013年

，

本文編號(hào)：1628867