纳米流体对热管导热性能影响的研究

发布时间：2018-05-25 02:45

本文选题：纳米流体 + 重力热管　；参考：《天津科技大学》2015年硕士论文

【摘要】：随着人们环保意识的日益增强以及科学技术的快速发展,各种生产设备趋于集成化,人们对各种设备的散热以及热交换性能的指标要求也越来越高,以传统液体作为工质的热管已经很难满足一些特殊条件下的传热要求。热管是利用其内部工质的气液相变化进行传热的,所以工质对热管的传热性能具有很大的影响。近年来,研究人员开始将一种新型的传热工质—纳米流体填充在热管中,以进一步强化热管的导热性能。本文以纳米流体作为热管工质,考察纳米流体对无芯材重力热管传热性能的影响。实验前期通过烧结玻璃热管对热管内部工质的流动形态进行观察。然后通过设计并制作多根重力热管,考察工质种类、热管充液率、加热温度等条件对重力热管导热性能的影响,根据测量结果计算分析纳米流体热管与去离子水热管之间传热性能的差异。本实验中,热管工质有四种：Al2O3-H2O纳米流体,TiO2-H2O纳米流体,CuO-H2O纳米流体以及去离子水。实验发现,相同工作条件下纳米流体热管的启动性能较去离子水热管的好,纳米流体热管各部分的管壁温度上升速度较快。达到稳定工作状态时,纳米流体热管冷凝段管壁温度均比去离子水的高,且两端温差较小。对于同一种热管工质来说,重力热管换热性能随着工质充液率的增加呈现出先增大后减小的变化趋势,这就说明在本实验条件下,不同的工质都存在着一个最佳充液率值,使热管传热性能达到最佳状态。实验中,纳米流体的最佳充液率值均为30%,而去离子水热管为40%。实验还对各工质热管冷凝段的热阻进行计算,结果表明,纳米流体热管的传热系数比去离子水热管高,热阻比去离子水热管小,其中CuO-H2O纳米流体对热管的强化作用最明显。通过分析实验结果可知,当以纳米流体作为热管工质时,能显著提高重力热管的换热系数,强化热管的换热性能。
[Abstract]:With the increasing awareness of environmental protection and the rapid development of science and technology, all kinds of production equipment tend to be integrated. The heat pipe with traditional liquid as working fluid has been difficult to meet the heat transfer requirements under some special conditions. The heat pipe is heat transfer by the change of gas and liquid phase, so the working fluid has a great influence on the heat transfer performance of the heat pipe. In recent years, researchers have begun to fill a new heat transfer medium, nano-fluid, in heat pipes to further enhance the thermal conductivity of heat pipes. In this paper, the effect of nano-fluid on the heat transfer performance of coreless gravity heat pipe was investigated with nano-fluid as the working medium of heat pipe. In the early stage of the experiment, the flow morphology of the working fluid in the heat pipe was observed by sintered glass heat pipe. Then through the design and manufacture of several gravity heat pipes, the effects of working fluid types, heat pipe filling rate and heating temperature on the thermal conductivity of gravity heat pipe are investigated. According to the measurement results, the difference of heat transfer performance between nanofluid heat pipe and deionized water heat pipe is analyzed. In this experiment, there are four kinds of nano-fluids in heat pipe: TiO2-H2O nano-fluid, CuO-H2O nano-fluid and deionized water. It is found that the starting performance of the nanofluid heat pipe is better than that of the deionized water heat pipe under the same working conditions, and the wall temperature of each part of the nanofluid heat pipe rises faster than that of the deionized water heat pipe. The wall temperature of the condensation section of the nanofluid heat pipe is higher than that of the deionized water, and the temperature difference between the two ends is smaller. For the same heat pipe working fluid, the heat transfer performance of gravity heat pipe increases first and then decreases with the increase of the liquid filling rate of the working fluid, which shows that there is an optimum liquid filling rate value for different working fluids under this experimental condition. The heat transfer performance of the heat pipe is optimized. In the experiment, the optimum filling rate of nano-fluid is 30 and that of deionized water heat pipe is 40. The results show that the heat transfer coefficient of the nanofluid heat pipe is higher than that of the deionized water heat pipe, and the thermal resistance is smaller than that of the deionized water heat pipe, and the enhancement effect of the CuO-H2O nanofluid on the heat pipe is the most obvious. The experimental results show that the heat transfer coefficient of gravity heat pipe can be significantly improved and the heat transfer performance of heat pipe can be enhanced when nano-fluid is used as the working medium of heat pipe.
【学位授予单位】：天津科技大学
【学位级别】：硕士
【学位授予年份】：2015
【分类号】：TQ021.3

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