Mixed Convection Heat Transfer from a Vertical Cylinder in a Bidisperse Porous Medium

雙分散多孔介質在垂直圓柱表面之混合對流熱傳遞

鄭慶陽(Ching-Yang Cheng)

《中國機械工程學刊》 35卷1期 (2014/02) Pp. 47-55

摘要

本文研究具有均勻壁溫雙分散多孔介質在垂直圓柱表面之混合對流熱傳遞問題進行研究。利用雙速度與雙溫度的觀念，推導出系統的統制方程式。再使用座標轉換與數量級分析推導出邊界層統制方程式。並使用三次樣線定置法，求解邊界層統制方程式。研究混合對流參數、相間熱傳參數、修正熱導率比與滲透率比等因素對熱傳遞與流動特性之影響。結果顯示，增加混合對流參數、修正熱導率比或滲透率比可以有效增強雙分散多孔介質在垂直圓柱表面之混合對流熱傳遞。而且當相間熱傳參數或混合對流參數之數值偏小時，雙分散多孔介質之f相與p相間之熱不平衡效應會變得很明顯。

並列摘要

This work studies the mixed convection heat transfer from a vertical cylinder in bidisperse porous media with constant wall temperature. The twovelocity two-temperature formulation is used to derive the governing equations. The coordinate transformation and the order-of-magnitude analysis are then used to obtain the boundary layer governing equations. The cubic spline collocation method is then used to solve the boundary layer governing equations. The effects of mixed convection parameter, inter-phase heat transfer parameter, modified thermal conductivity ratio, and permeability ratio on the heat transfer and flow characteristics are studied. Results show that an increase in the mixed convection parameter, the modified thermal conductivity ratio, or the permeability ratio can effectively enhance the mixed convection heat transfer of the vertical cylinder in a bidisperse porous medium. Moreover, the thermal non-equilibrium effects between the f-phase and the p-phase becomes significant as the inter-phase heat transfer parameter or the mixed convection parameter is small.

並列關鍵字

mixed convection ； bidisperse porous medium ； vertical cylinder ； heat transfer ； boundary layer flow