本文係以實驗方式探討直立方形封閉容器內Al2O3-水奈米流體自然對流熱傳遞特性。實驗所用奈米流體係將氧化鋁 (Al2O3) 奈米微粒分散於超純水中，並藉由靜電排斥力保持其穩定的懸浮狀態；且就所調製成之奈米流體測定其相關熱物理性質，諸如懸浮微粒粒徑大小分佈、黏滯係數、熱傳導係數等，隨微粒濃度與溫度之變化情形。本文探討直立方形封閉容器其物理模型為左/右直立壁分別為加熱/冷卻等溫壁面，其餘邊壁則為絕熱壁。熱傳實驗之主要參數及其值範圍分別為：萊利數，Ra = 7×10^5 ~4×10^6 ；奈米微粒體積濃度,Cv=0.1%、0.3%、1%、2%、3%、4%。本文所得實驗結果顯示封閉容器內Al2O3-水奈米流體之自然對流熱傳係數呈現隨其微粒體積濃度的增加而持續下降之趨勢，且皆低於純水之結果。

The present study deals with natural convection heat transfer characteristics in a vertical square enclosure filled with Al2O3-Water nanofluid. The nanofluid considered was prepared by dispersing various amount of alumina (Al2O3) nanoparticles in pure water as the base fluid through electrostatic stabilization mechanisms. In addition, thermophysical properties of the nanofluid prepared including the particle size, dynamic viscosity, and thermal conductivity were measured as a function of the volumetric fraction of the nanoparticles as well as temperature. The enclosure is heated differentially across the two vertical isothermal walls, while the other side-walls are thermally insulated. The heat transfer experiments for natural convection in the enclosure have been undertaken for the relevant parameters in the following range： Rayleigh number, Ra = 7×10^5 ~4×10^6, the volume fraction of nanoparticles,
Cv=0.1%,0.3%,1%,2%,3%,4%. The results obtained for the averaged heat transfer coefficient over the isothermally heated wall reveal a systematic decrease in the heat transfer rate of the nanofluid, in comparison with that of pure water, across the enclosure with increasing particle concentration.

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