本文主要為藉由數值模擬的方法來探討水平矩形容器內含相變化微粒懸浮液體之二維自然對流熱傳特性，所探討之物理模型為一底部加熱及上部冷卻的水平矩形容器，且左右直立邊界為絕熱壁。數值模擬考慮之主要參數範圍為：萊利數 = 1000、2000、5000、7000、10000；史蒂芬數Ste = 0.01、0.05、0.005；次冷參數Sb = 0、0.5、1.0、10；初始濃度cm,i =0 %、3 %、5 %、10 %、20 %；PCM微粒無因次粒徑Dp = 5×10 -4，容器高寬比AR =1，普蘭特數Pr = 15，路易士數Le=3.2×10 5，過冷參數 ，PCM微粒時間延遲參數 ，質熱傳浮力比N＝1。本文著重於萊利數、史蒂芬數、次冷參數及初始濃度對容器內添加PCM懸浮微粒自然對流熱傳遞影響。結果顯示出添加PCM微粒可以使得容器內產生自然對流之臨界萊利數大幅降低，尤其隨PCM微粒濃度之提高而下降。此外，本文結果顯示加入PCM懸浮微粒可以有效的提升水平矩形容器之自然對流熱傳率。隨著PCM微粒濃度的增加或史蒂芬數之降低，容器之熱傳率可較純流體顯著提升至67%。次冷參數主要是控制相變化區域的分佈以及PCM微粒融點等溫線的相對於冷壁之位置。

This thesis is to investigate numerically natural convection heat transfer characteristics of phase-change-material suspensions in a two dimension horizontal rectangular enclosure. The horizontal rectangular enclosure is heated from the bottom and cooled from the top, while the vertical side walls are assumed adiabatic. The numerical simulations have been conducted for the dimensionless parameters in the following range : ( Rayleigh number) = 1000，2000，5000，7000，10000； Ste ( Stefan number) = 0.01，0.05，0.005； Sb ( Subcooling factor ) = 0，0.5，1.0，10； cm,i( initial concentration ) = 0 % ， 3 % ， 5 % ， 10 % ， 20 %. Dp ( dimensionless PCM particle diameter ) = 5×10 –4； AR =1； Pr( Prandtl number ) = 15；Le( Lewis number )=3.2×10 5； ；N( buoyancy ratio ) ＝ 1. The numerical results are presented to emphasize the parameter effects of the Rayleigh number, thre Stefan number, the Subcooling factor and the initial concentration of PCM particles on heat transfer in a horizontal rectangular enclosure. The result show that critical Rayleigh numbers for the onset of natural convection of the PCM suspension in the enclosure are substantially lower then those for the pure fluid. Furthermore, the heat transfer rates of PCM suspension through the horizontal enclosure are found to be considerably enhanced in comparison with those of the pure fluid. Increase of the initial concentration on decrease of the Stefan number can lead to considerable enhancement in heat transfer rate ( about 20~170% ) through the PCM suspension in the enclosure.

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