微管內非牛頓流體之電滲流熱傳

近年來微流體裝置廣泛運用在生醫檢測、藥物輸送等，其所處理的流體種類繁多，包括：聚合物溶液、油類、懸浮液（如血液）、蛋白質等，若將這些液體視為牛頓流體並不適合，所以微流道內非牛頓流體傳輸現象值得深入研究。微流道中因界面電現象會在壁面附近形成所謂的電雙層，此電荷層是呈擴散分佈的。當微流道兩端施加電壓時，流道中溶液會因電雙層的存在而產生整體的流動現象，此即一般所稱的電滲流。本文主要目的在於探討微管內非牛頓流體之電滲流熱傳現象，並詳細探討焦耳熱及黏性熱逸散對微管流熱能傳輸之影響，研究發現本問題有四個統御參數，包括：流動特性指數、長度尺度比、焦耳熱參數(焦耳熱與壁面熱通量之比) 以及布林克曼數。本研究求解電位場、動量方程式、能量方程式，求得溫度分佈、紐賽爾數之解析表示式，並進行數值積分得到數值解，並進而獲得電雙層中之電位分佈與熱傳特性。

關鍵字

微管之微流道；非牛頓流體；焦耳熱；黏性耗散；電滲流

並列摘要

In recent years, microfluidic devices are widely used in biochemical detection and drug delivery. Common type of fluids handled in microfluidic devices include whole polymer solution, oils, suspension (such as blood), proteid, etc. Biofluids usually exhibit non-Newtonian fluid behaviors, and this fact renders Newton’s law of viscosity insufficiently to completely describe the constitutive behavior of biofluids. Most solid surfaces carry electrostatic charges and these charges will attract the counter-ions in the liquid. The rearrangement of the charges on the solid surface and the balancing charges in the liquid are called the electrical double layer (EDL). Electroosmotic flow is the flow induced by the application of electric field across the channel and due to the presence of EDL close to the channel wall. An analysis is performed to investigate the heat transfer characteristics of non-Newtonian power-law fluids in a microtube microchannel. The present problem is found to be governed by four parameters, namely, the flow behavior index, the length scale ratio, the Joule heating parameter (ratio of Joule heating to surface heat flux), and the Brinkman number. The governing system of equations includes the electrical potential field, momentum equation, and energy equations. The solutions for flow and heat transfer parameters are obtained by numerical integrations of the analytical expressions.

並列關鍵字

Microtube ； Non-Newtonian fluid ； Joule heating ； Viscous dissipation ； Electroosmotic flow

參考文獻

[1]S. J. Kim and D. Kim, ”Forced Convection in Microstructures for Electronic Equipment Cooling”, ASME J. Heat Transfer, 121,pp.639-645, (1999).

[2]H. Y. Zhang, D. Pinjala , T. N. Wong , K. C. Toh , and Y. K Joshi, ”Single-Phase Liquid Cooled Microchannel Heat Sink for Electronic Packages”, Appl. Therm. Eng., 25, pp.1472-1487, (2005).

[3]G. L. Morini and , M. Spiga , ”The Role of the Viscous Disspation in Heated Microchannel”, ASME J. Heat Transfer, 129, pp308-318, (2007).

[4]C. H. Chen”Forced Convection Heat Transfer in Microchannel Heat Sinks”, Int. J. Heat Mass Transfer, 50, pp.2182-2189, (2007).

[5]T. Bourouinay, A. Bosseboeuf, J.-P. Grandchamp, Design and simulation of an electrostatic micropump for drug-delivery applications, J. Micromech. Microeng 7, 186-188, (1997).

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微管內非牛頓流體之電滲流熱傳

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