本文係以實驗量測與數值模擬方式探討相變化懸浮微粒之過冷現象對直立矩形容器自然對流熱傳之影響。在實驗方面，分別就容器內相變化微粒融解與凝固過程探討其過冷效應之影響。實驗結果發現因過冷效應乳液內相變化微粒無法凝固導致沒有發揮潛熱之效果，容器內穩態自然對流之熱傳效果比純流體差；在數值模擬方面，設定之相關參數為：萊利數RaT,f=104～106，次冷參數Sb=10，過冷參數Sp=0、5、10、15，史蒂芬數Ste=0.01，相變化微粒質量濃度cm=0.01，普朗特數Prf=8.5，數值模擬結果發現乳液中相變化微粒之過冷現象對容器內自然對流熱傳之影響取決於過冷參數與次冷參數之相對大小，當Sp≧Sb時，相變化材料微粒無發揮潛熱的效果，容器內乳液之自然對流熱傳效果比純流體差；而Sp＜Sb時，相變化材料微粒有融解與凝固，進而發揮吸收/釋放潛熱之效果，導致容器內自然對流熱傳之增益。

In the present study the effect of supercooling phenomenon of phase change material(PCM) suspension on steady state natural convection heat transfer in a vertical square enclosure has been investigated experimentally and numerically. In the experiments, both melting and freezing process were conducted to elucidate the existence of supercooling of the PCM particles. In the presence of the supercooling, freezing of the PCM particles in the suspension flow near the cold wall of the enclosure may be effectively inhibited; and as a result, the steady state heat transfer rate of the suspension across the enclosure was found to be markedly lower than that of pure water. In the numerical simulations, the relevant dimensionless parameters considered include: the thermal Rayleigh number RaT,f=104～106, the Prandtl number Prf=8.5, the subcooling factor Sb=10, the supercooling factor Sp=0 ~ 15, the Stefan number Ste=0.01, and the mass fraction of PCM particles cm=0.01. Numerical simulation clearly reveal that the magnitude of the supercooling factor relative to the supercooling factor dictates occurrence of the supercooling phenomenon. For the situation of , the supercooling effect prevails that in the steady buoyancy-driven suspension flow in the enclosure the PCM particles exist as either fully solid or liquid phase. On the other hand, the numerical simulation for show that in the absence of supercooling, significant heat transfer enhancement due to the latent heat release/absorption of the PCM particles in the suspension can be resulted.

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