微電滲泵之暫態熱流研究; Transient Thermal and Flow Study for the Micro Electroosmotic Pump

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Please use this identifier to cite or link to this item: http://ir.lib.ncu.edu.tw/handle/987654321/2869

Title:	微電滲泵之暫態熱流研究;Transient Thermal and Flow Study for the Micro Electroosmotic Pump
Authors:	李俊鵬;Chung Peng
Contributors:	機械工程研究所
Keywords:	焦耳熱效應;電滲泵;電滲流;Joule heating effect;Porous media;Electroosmotic pump;Electroosmotic flow
Date:	2007-06-12
Issue Date:	2009-09-21 11:58:45 (UTC+8)
Publisher:	國立中央大學圖書館
Abstract:	電滲泵目前在生醫檢測晶片及微電子冷卻方面都有廣泛的應用，因此其流體輸送性能及溫度變化特性都相當重要。本文利用暫態模擬分析在微中空毛細管及多孔介質內電滲流之特性，搭配解析解及實驗數據的比對，探討包括速度、壓力及溫度等電滲泵重要參數。所使用的數學模型包含描述管內電位勢之Poisson-Boltzmann方程式、描述外加電場強度變化之Laplace方程式、描述速度場之修正型Navier-Stokes方程式及描述溫度場之能量方程式。模擬結果發現，包括電滲泵尺寸、流體種類、流體濃度、外加電場強度及外在冷卻條件等參數對溫度變化均有明顯影響。當焦耳熱效應不可忽略時，連帶所產生的焦耳自熱(auto-thermal)效應會使溫度大幅上升，由於流體黏滯係數及介電常數等參數對溫度變化敏感，進而影響電滲泵產生流率及壓力的能力。雖然溫度上升對有助於提升整體電滲泵性能，但是在電滲泵的應用中，對於操作溫度有上限，因此在設計電滲泵時，參數的選擇均須謹慎且適當。另外在微多孔電滲泵的數值模擬中，幾何管壁效應及電動管壁效應必須要列入考慮，否則模擬結果並不精確。 The electroosmotic pump (EOP) has been widely used in driving and controlling microfluidics in the biochemical applications, and it is being used for liquid transportation in the electronics cooling solution recently. Thus, the temperature variation and the performance of the EOP for fluid transporting are very important. This study presents a transient numerical analysis of the electroosmotic flow in micro tubes and in porous media, combining analytical solutions and the validation of experimental data, to investigate velocity, pressure and the temperature characteristics of EOP. The mathematical model include the Poisson-Boltzmann equations for electric potential, the Laplace equation for external applied electric field, the modified Navier-Stokes equations for velocity field, and the energy equations for temperature field. Numerical results reveal that several factors affect the temperature characteristics of the EOP including: the size of EOP, the strength of applied electric field, the concentration of fluid and the cooling condition surrounding the tube. When the Joule heating effect is severe, the auto-thermal phenomenon causes large temperature rise and variation of the fluid viscosity and the dielectric constant, results in modifying the performance of EOP. Although the temperature increases help to enhance the operation of EOP; however, there is an upper limit of operating temperature for most applications of EOP. Therefore, selecting proper conditions in designing EOP is very important. Besides, it is also found that the wall effect from both the geometry and the electrokinetic need to be considered in the simulation of electroosmotic porous flow, otherwise, calculation results will not accurate.
Appears in Collections:	[Graduate Institute of Mechanical Engineering] Electronic Thesis & Dissertation

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