管道流中含固體基座之多孔性介質對熱傳增益之研究

Abstract

本研究利用數值方法分析含基座之多孔性介質置於管道中高溫加熱面對於壁面熱傳的影響。探討多孔介質厚度比例、基座厚度比例、孔隙率等不同參數下對於高溫壁面熱傳之影響，並且和完全多孔介質、完全固體實心以及空渠道做熱傳增益效率之比較。 由數值計算結果得知，於多孔介質下加入固體基座能夠提升熱傳效果。而過度的增加多孔介質厚度並不會提升熱傳效果，反而會使阻抗過大而流體不易通過，導致熱量不易排出，反而降低熱傳效果。因此一般會選擇使用孔隙率較高之介質，較符合其增益效率。

A study of heat transfer enhancement by adding porous media combined with solid base in a channel flow is investigated. The characteristics of the flow and thermal fields are analyzed numerically. Effects of porous medium and the solid base with variable thickness and variable porosity on the heat transfer rate are examined. The results show that adding solid base under the porous medium increases the heat transfer, and is better than the whole porous one. An optional selection of the thickness and the porosity of the porous medium strongly depends on the flow condition. Considering the heat transfer rate with the pressure drop, it also shows that the higher porosity goes with the higher efficiency.