層流混合對流於通道內之熱傳分析

ANALYSIS OF LAMINAR MIXED CONVECTION FLOW IN A CHANNEL

本研究以數值方法探討平行板通道內之層流混合對流熱傳問題，假設等壁溫之邊界條件及均勻入口速度下，觀察雷諾數、平板傾斜角度及Gr/Re^2等參數比改變時，對平板內之速度、溫度場及紐賽數的影響。由分析結果中可知，平行板通道內，當Gr/Re^2 = 10時，流體流動至某一位置時，於中心部分均有回流的現象；Gr/Re = 1時，此 流體回流的現象發生的位置會往下游移動，而Gr/Re^2 = 0.1時，則並無發現任何回流之現象。紐賽數方面Gr/Re^2 = 0.1時，傾斜角對Nu之影響不大，而Gr/Re^2 = 10時，傾斜角越大時，所得到之Nu越小；另外Gr/Re^2越大時，所求得之Nu越大。最後，期待本論文的結果能在未來對於此型相關熱交換器的設計上提供一些幫助。 This study numerically investigates the laminar flow for mixed convection heat transfer problem between parallel plates. Constant plate wall temperature and uniform flow entry are assumed. Parameters of Reynolds number, inclined angle, and Gr / Re^2 are varied to obtain the velocity and temperature distributions in the channel. The results show that backflow in the center of the flow is observed in the channel at a certain distance from the inlet for Gr/Re^2 = 10 . This phenomenon also takes place for Gr/Re^ = 1 but it occurs with the position shifting downstream. No backflow is found for Gr/Re^2 = 0.1. The effects of inclination on Nu is insignificant for Gr/Re^2 = 0.1 . As the inclined angle increases, Nusselt number decreases for Gr/Re^2 =10. In addition, the Nu in the channel increases with Gr/Re^2 . Finally, it is expected that the results of this study may facilitate the prospective design of relevant heat exchangers.