| 摘要: |
| 采用焦耳加热法对直径分别为39.9mm～350.1mm的微细紫铜丝在空气中垂直放置时自然对流换热的Nu)进行了测量，并将实验值与前人所总结的多个准则方程式的计算值相比较，结果表明：所有准则方程式的计算值之间存在一定的差距，此差距随着细丝直径的减小而减小；所有计算值与实验值之间均存在偏差，随着细丝直径的减小偏差增大，最大偏差达到了50％；随着微细长竖圆柱直径的减小，细长圆柱表面换热增强，这可能是由于尺寸的微米化，使得微细长竖圆柱的边缘效应加强，贴壁层变薄，从而使换热得到强化。 |
| 关键词: 自然对流换热 微细长竖圆柱 准则方程 努塞尔数 |
| DOI： |
| 投稿时间：2012-04-08
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| 基金项目: |
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| Investigation on Natural Convective Heat Transfer of Outside Micro-slender Cylinders |
| Hou Yali,Wang Jianwen,Liu Zhigang |
| (School of Energy and Power Engineering, Inner Mongolia University of Technology;Energy Research Institute of Shandong Academy of Sciences) |
| Abstract: |
| The natural convection outside micro-slender cylinders placed vertically with outer diameters from 39.9μm to 350.1μm with air is experimentally investigated. The Joule heat method is employed to obtain the Nusselt numbers in the experiment. The results are compared with the values of classical correlation equations. The investigations show that all values of classical correlation equations are different from each other, and the differences will decrease with decrease of the diameter of micro-slender cylinder. The deviation between experimental results and values of classical correlation equations will increase with decrease of the diameter, which can reach 50％.The heat transfer coefficient of natural convection increases with the decrease of the diameter of the micro-slender cylinder. These phenomena may be due to the enhancement of the natural heat transfer caused by the thinner boundary layer which resulted from the edge effect when the diameter of the micro-slender cylinder becomes smaller. |
| Key words: natural convective heat transfer micro-slender cylinder classical correlation equations Nusselt |
