矩形管道中流體經雙平板狀質源的混合對流實驗研究

在熱流現象的研究上，自然、混合、強制對流三種機制常為學術研究上的重點，其中以混合對流因兼具其他兩者效應而常被提出來討論。本實驗研究是將雙平板狀質源的質量傳遞引入矩形管道主流中，在不同的平板傾斜角度與水道傾斜角度、強制對流效應針對兩有限平板之極性變化來進行質混合對流研究。在此，混合對流係指利用幫浦所造成的強制對流（forced convection），在速度完全發展之後，再與質源傳遞所形成的自然對流（natural convection）合併之流體運動現象。實驗使用的工作流體為硫酸銅水溶液，藉由電化學系統於測試區（test section）之兩平板加上端電壓，使其成為電極，達成濃度梯度之建立。實驗採用雷射光暗影法（shadowgraph）作流場結構觀察及照相記錄，並作質量傳遞率的量測。無因次參數範圍如下：Ar=1 ，Sc=1700~2400，Re=50~300，Grm=2.38×105，θ= -15°~15°，ψ= -20°~20°, b/H =0.2， w/ b = 8 至於質傳遞率量測方面，固定傾斜角時，在不同邊界條件下，質傳遞率Sherwood數隨Reynolds數的增加而增加，當固定傾斜角度θ時，左右兩板皆有旋轉角度，Sh相對比銅板水平時來的大，尤其以左板ψ1＝-20°，右板ψ2＝20°時的Sh值最大；固定強制對流效應時，以水道下傾的質傳遞率較佳。

關鍵字

熱質強制對流；矩形管道；有限平板；電化學系統

並列摘要

An experimental investigation of mixed solutal convection in the duct flow passing through a channel with two finite flat plate sources. With the mass transport factor on the channel flow, the flow patterns have become more complex. The fluids from the anode or the cathode are denser or less dense so that they do not match the flow patterns in the pure fluid dynamics. Seldom research can be found on this subject. The flow of a CuSO4+H2SO4+H2O solution will be carried in an inclined rectangular channel with an electrochemical system. The shadowgraph technique is used to visualize the flow and to determine the nature and effect of solutal driven secondary flows in the inclined channel with the two finite flat plate sources inside. The ranges of the parameters in the present work are : Ar=1, Sc=1700~2400, Re=50~300, Grm=2.38×105, θ= -15°~15°, ψ= -20°~20°, b/ H =0.2, w/ b = 8. Some results about the mass transfer rate are also clearly found. With increasing the Reynolds number, the corresponding Sherwood number is increasing, for the Sherwood number is directly proportional to the Reynolds number. When the inclined angle θ is maintain steady, both of two copper finite flat plates are inclined, the Sh number which is been found meanwhile would be greater than in horizontal. Moreover, the largest Sh number would be found as ψ1=-20° and ψ2=20°. While the force convection efficiency is fixed, the mass transfer rate is greater as the fluid flows downward.

並列關鍵字

mixed convection ； finite flat plate ； rectangular channel ； electrochemical system

參考文獻

26. 王順立,『矩形管道中流體經有限平板質源（陽極）的混合對流實驗研究』，私立元智大學，碩士論文，民國96年。

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矩形管道中流體經雙平板狀質源的混合對流實驗研究

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