重力场中轴向槽道热管的传热实验研究

【作者】 曲燕；

【导师】 程林； 栾涛；

【作者基本信息】 山东大学 ， 工程热物理， 2005， 硕士

【摘要】 本文对常温梯形轴向槽道铝-氨热管的传热特性进行了实验研究,着重分析了热管的倾斜角度、冷却方式、热源的数量和分布位置,对热管轴向温度分布、轴向最大温差、最大传热量、总热阻、管内工质的流动压降以及蒸发段和冷凝段当量换热系数的影响。 实验结果表明,第一,热源在下倾斜放置的热管的传热能力明显好于热源在上倾斜放置的热管。主要表现在:相同的蒸发段输入热流量,热源在下倾斜放置的热管能在更低的工作温度下运行,轴向温差更小;水冷方式下,热源在下垂直放置热管的蒸发段和冷凝段的当量换热系数分别是水平放置热管的1.5倍和2.5倍;热源在上倾斜放置的热管、水平放置的热管、热源在下倾斜放置的热管的平均总热阻成10的数量级递减。 第二,提高冷凝段的冷却效果能极大地提高单热源热管的传热能力。热源在下垂直放置的热管和水平放置的热管,水冷的最大传热量分别是空冷的5.9倍和1.2倍。 第三,与改变冷却方式相比,增加热源数量对热管最大传热量的影响要小得多。另外,增加热源的数量未必使热管的最大传热量增加,关键要看热源在热管上的布置位置和热管的放置位置。双热源水平放置的热管,热源分别放在热管的中间和一端要优于热源分置热管两端的情况:端-中布置方式下热管的最大传热量比单热源热管增加了31.5%,端-端布置方式下热管的最大传热量比单热源热管减小了25.8%。双热源垂直放置的热管,端-中和端-端布置方式下热管的最大传热量相差不大,分别比单热源热管增加了14.3%和5.2%。 第四,管内工质的流动压降很小。在水冷方式下,流动压降小于1Pa,表明正常工作下的热管有很好的轴向等温性。更多还原

【Abstract】 An experimental investigation of thermal characteristics of trapezoidal axial grooved heat pipe (AGHP) is presented in this paper. The material of tested AGHP is aluminium alloy and the working fluid is pure ammonia. The effects on thermal performance of heat pipe inclination, cooling methods and heat source number and distribution mode are analyzed.The results are obtained in terms of axial temperature distribution, axial temperature difference, heat transfer capacity, total heat resistance, equivalent heat transfer coefficients of evaporator section and condenser section, etc.Experimental results indicate that firstly thermal characteristic of heat pipe with bottom-heating mode is much better than that with above-heating mode. With the same amount of heat input at the evaporator section, the working temperature and axial temperature difference are much lower for bottom-heating mode heat pipe. At the water cooling mode, the equivalent heat transfer coefficients of evaporator and condenser section with bottom-heating vertical mode are respectively the 1.5 and 2.5 times than that of horizontal mode. The total thermal resistances of heat pipe at above-heating mode, horizontal, bottom-heating mode are decreased with the order of ten.Secondly, heat transfer capacity can be greatly enhanced with water cooling compared with air natural convection cooling. For vertical orientation with bottom-heating mode and horizontal orientation, the heat transfer capacity with cooling water are respectively the 5.9 times and 1.2 times than that with air natural convection cooling.Thirdly, heat source amounts have less influence on the heat transfer capacity compared with the cooling modes. The heat transfer capacity unnecessarily can be enhanced with the addition of heat sources. It also depends on heat pipe orientation and heat sources distribution mode. To horizontal orientation heat pipe with double heat sources, the end-middle distribution mode is much better than end-end distribution mode because the heat transfer capacity of the former increase by 31.5% while the latter decrease by 25.8% compared with that under single heat source at air cooling mode. To vertical orientation heat pipe with double heat sources, the maximum heat transfer capacity of end-middle distribution mode and end-end distribution mode respectively increase by 14.3% and 5.2% than that with single heat source at air cooling mode.In addition, the flow performance of this kind of axial grooved heat pipe is also involved. At water cooling mode, the vapor and liquid pressure drop is not more than 1Pa, indicating excellent axial temperature uniformity.更多还原