纳米多孔铜表面结构制造及其强化沸腾性能分析

发布时间：2018-06-29 02:14

本文选题：纳米多孔 + 强化沸腾　；参考：《华南理工大学》2015年硕士论文

【摘要】：纳米多孔结构通过有效的增大传热面积、改善表面润湿性能、保持优异热传导率、以及提高潜在汽化核心密度,可显著提高沸腾传热性能。其在强化沸腾方面具有广阔的应用前景。强化沸腾由于能大幅度提高能源利用率和解决高热流密度元器件散热问题,在热能动力、新能源、核电、石油化工等传统工业领域以及微电子散热等高新技术领域得到了广泛的应用。本文采用了一种新型电镀/热处理/脱合金组合工艺路线进行纳米多孔表面制备。通过选择恰当制备参数可获得具有单一成分、均匀三维连续孔隙结构、以及良好润湿性能的纳米多孔表面。热处理参数,脱合金溶液,脱合金时长等制备参数对纳米多孔铜表面特性产生重要影响。本文主要探讨了对表面形貌、化学成分和表面润湿性等表面特性的影响。本文设计并搭建了饱和池沸腾测试系统,利用高速摄影技术进行了可视化研究,对比了不同热流密度下纳米多孔表面与光滑表面的汽泡动力学特征差异。在低热流密度阶段,纳米多孔表面与光滑表面汽泡动力学特征差异包括:出现过冷沸腾现象,饱和沸腾阶段提前,汽泡数量增多,汽泡直径减小,汽泡生长脱离频率增加,大量汽泡形成汽柱。在高热流密度阶段,纳米多孔表面能延缓汽块以及大汽泡的生成。从沸腾传热系数和临界热流密度的角度研究了纳米多孔铜表面沸腾传热性能。与光滑表面相比,纳米多孔表面具有显著强化沸腾性能效果,并能有效提高临界热流密度。纳米多孔表面的表面形貌,表面成分和表面润湿性能等表面特性对其沸腾传热性能有着重要影响。结合纳米多孔表面与光滑表面在汽泡动力学特征、表面特性和沸腾换热性能方面的差异,对纳米多孔结构强化沸腾传热机理进行分析。在饱和池沸腾环境中,长期处于核态沸腾阶段的纳米多孔铜能保持良好化学稳定性且其微观形貌会发生自相似演化。最后,利用电镀锌/热扩散/脱合金组合工艺路线的易操作性,制备了微纳米复合结构表面。池沸腾测试结果显示:微纳米复合结构表面结合了微槽道结构和纳米多孔结构这两种强化结构的优势,进一步增大了沸腾传热系数和临界热流密度。
[Abstract]:By effectively increasing the heat transfer area, improving the surface wettability, maintaining excellent heat conductivity and increasing the potential vaporization core density, the boiling heat transfer performance of nano-porous structure can be improved significantly. It has broad application prospect in strengthening boiling. Enhanced boiling can greatly improve energy efficiency and solve heat dissipation problems of components with high heat flux, in thermal power, new energy, nuclear power, Traditional industries such as petrochemical industry and high-tech fields such as micro-electronic heat dissipation have been widely used. In this paper, a new electroplating / heat treatment / dealloying process was used to prepare nano porous surface. By choosing the appropriate preparation parameters, the nano-porous surface with single composition, uniform three-dimensional continuous pore structure and good wettability can be obtained. The preparation parameters, such as heat treatment parameters, dealloying solution and dealloying time, have an important effect on the surface characteristics of nano-porous copper. In this paper, the effects on surface morphology, chemical composition and wettability are discussed. In this paper, a saturated pool boiling measurement system was designed and constructed. The visualization study was carried out by high speed photography, and the differences of bubble dynamics between nano-porous surface and smooth surface at different heat flux were compared. At the stage of low heat flux, the differences of bubble dynamics between nano-porous surface and smooth surface include the phenomenon of supercooled boiling, the advance of saturated boiling stage, the increase of bubble number, the decrease of bubble diameter and the increase of bubble growth detaching frequency. A large number of bubbles form columns of steam. At the stage of high heat flux, nano-porous surfaces can delay the formation of steam blocks and large bubbles. The boiling heat transfer performance of nano-porous copper surface was studied from the point of view of boiling heat transfer coefficient and critical heat flux. Compared with the smooth surface, the nano-porous surface has obvious enhancement effect on boiling performance and can effectively increase the critical heat flux. The surface morphology, surface composition and wettability of nano-porous surface have an important effect on the boiling heat transfer performance. Based on the differences of bubble dynamics, surface characteristics and boiling heat transfer properties between nano-porous surface and smooth surface, the mechanism of enhancement of boiling heat transfer by nano-porous structure was analyzed. In the saturated pool boiling environment, the nano-porous copper in the nucleated boiling phase can maintain good chemical stability and its microscopic morphology will evolve from the same. Finally, the micro-nano composite structure surface was prepared by the easy operation of zinc electroplating / thermal diffusion / dealloying process. The results of pool boiling test show that the surface of micro-nanocomposite structure combines the advantages of micro-channel structure and nano-porous structure, and further increases the boiling heat transfer coefficient and critical heat flux.
【学位授予单位】：华南理工大学
【学位级别】：硕士
【学位授予年份】：2015
【分类号】：TB383.1;O614.121

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