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標題: | 管束型微反應器之滯留時間分布 Residence Time Distribution of a Bundle Cylindrical Microreactor |
作者: | Chung-Chieh Ting 丁中捷 |
指導教授: | 徐治平(Jyh-Ping Hsu) |
關鍵字: | 微反應器,滯留時間分布,電滲透流, microreactor,residence time distribution,electroosmosis, |
出版年 : | 2006 |
學位: | 碩士 |
摘要: | 本文利用free surface cell model的概念來分析及推導管束型微圓管中電滲透流的滯留時間函數分布。每個單一微圓管表面維持固定表面電位,以外加電場驅動反離子造成管中流動。藉由改變無因次電雙層厚度、外加軸向電場、外加軸向壓降以及微管束體積參數等因子,探討電滲透流速度及滯留時間分佈函數的變化。本文目的在於深入瞭解電動力在微反應器中的應用,並提供反應器設計上的資訊,且滯留時間函數分佈對分析反應轉化率有極大幫助。數值模擬結果顯示電雙層厚度、外加電場及大的管束體積會使電滲透流速度愈快,縮短滯留時間,並使滯留時間分佈圖形改變。而改變壓降造成的結果很微小,只有在整體流速分布緩慢的情形下才看的出影響。而隨著電雙層厚度的改變,我們也可以將反應器內流體大致分為plug flow 以及laminar flow兩種傳統流體加以分析近似。 The electrokinetic flow of an electrolyte solution through a microchannel which comprises a bundle of cylinders is investigated for the case of constant surface potential. The system under consideration is simulated by a unit cell model, and analytical expressions for the flow field and the corresponding residence time distribution under various conditions are derived. These results are readily applicable to the assessment of the performance of a microreactor such as that comprises a bundle of optical fibers. Numerical simulations are conducted to investigate the influences of the key parameters, including the thickness of double layer, the strength of applied electric field, the magnitude of applied pressure gradient, and the characteristic sizes of a microchannel, on the residence time distribution. We show that the followings could result in a shorter residence time: thin double layer, strong applied electric field, large applied pressure gradient, and small number of cylinders. Based on the thickness of double layer, criterions are proposed for the judgment of whether the flow field can be treated as a laminar flow or as a plug flow, two basic limiting cases in reactor design. |
URI: | http://tdr.lib.ntu.edu.tw/jspui/handle/123456789/32744 |
全文授權: | 有償授權 |
顯示於系所單位: | 化學工程學系 |
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