铜基表面无机纳米结构的原位构筑及滴状冷凝传热性能研究

发布时间：2018-03-08 23:13

本文选题：金属基纳米结构　切入点：强化冷凝传热　出处：《济南大学》2015年硕士论文　论文类型：学位论文

【摘要】：冷凝传热作为一种普遍存在的相变过程,在化工、海水淡化及环境控制等领域都具有广泛应用。滴状冷凝相比于膜状冷凝可以提高液滴的更新速率,此外通过材料表面疏水化改性将进一步强化材料冷凝传热性能。本论文以此为切入点,在铜试件表面原位构筑了ZnO纳米线簇及Cu(OH)2楞状纳米针结构。经低表面能物质修饰后对样品表面微液滴的冷凝界面现象及滴状冷凝传热性能进行了观察及定量测量。同时对其实现高效冷凝传热的机理进行了简要分析。该研究对于理解纳米结构与传热性能的构效关系具有重要的意义,同时为开发新的传热纳米材料及器件以实现高效的能源利用提供了条件。论文主要研究内容如下:(1)铜基表面ZnO纳米线簇的滴状冷凝传热性能研究。采用电化学沉积结合化学浴的方法实现了ZnO纳米线簇结构在铜基表面的原位构筑,经过低表面能物质修饰后实现了纳米结构表面微尺度冷凝液滴的融合和高效自驱离行为。进一步结合冷凝界面现象证实该纳米结构样品相对于疏水光滑样品可以提升液滴更新速率且长时间保持界面液滴微尺度和自驱离。对其冷凝传热性能测试表明:该纳米结构样品可以极大提高传热性能,在40°C蒸汽温度下较光滑样品其热通量可提升200%以上,传热系数最高时可提升270%。(2)铜基表面Cu(OH)2楞状纳米针的滴状冷凝传热性能研究。采用电化学沉积法在铜基表面原位构筑了Cu(OH)2楞状纳米针结构,该结构具有分层次的纳米形貌且具有极低的固液界面粘附,促使小尺度冷凝微液滴高密度成核及高效自驱离,实现表面液滴的快速更新。进一步对其冷凝传热性能测试表明:该纳米结构样品可以极大提高传热性能,在40°C蒸汽温度下较光滑样品其热通量可提升200%以上,传热系数最高时可提升125%。研究表明结构样品表面由于van der Waals吸引力引起的粘附耗散和钉扎效应引起的线张力效应远低于光滑样品表面,因此,液滴可以实现更快的更新速率,从而大大提高了传热效率。
[Abstract]:As a common phase change process, condensation heat transfer has been widely used in chemical industry, seawater desalination and environmental control. In addition, the surface hydrophobic modification of the material will further enhance the condensation heat transfer performance of the material. The structure of ZnO nanowires and Cu(OH)2 corrugated nanowires were constructed in situ on the surface of copper samples. The condensation interface phenomena and heat transfer properties of droplets on the surface of samples were observed and quantitatively measured after modification with low surface energy material. At the same time, the mechanism of high efficiency condensation heat transfer is briefly analyzed. This study is of great significance for understanding the structure-activity relationship between nanostructures and heat transfer properties. At the same time, it provides conditions for the development of new heat transfer nanomaterials and devices to achieve efficient energy utilization. The main contents of this paper are as follows: 1) study on the drop condensation heat transfer performance of ZnO nanowires on copper surface. Electrochemical precipitation. The in-situ structure of ZnO nanowire clusters on the surface of copper was realized by the method of chemical bath. After modification with low surface energy material, the fusion and high efficiency self-expulsion behavior of micro-scale condensate droplets on nanostructure surface were realized. Further, it was proved that the nanostructured sample could be compared with the hydrophobic smooth sample by combining the condensation interface phenomenon. The condensation heat transfer performance of the nanostructured sample can be greatly improved by increasing the droplet regeneration rate and maintaining the interface droplet microscale and self-displacement for a long time. The heat flux of the smoother sample can be increased by more than 200% at 40 掳C steam temperature. When the heat transfer coefficient is the highest, the heat transfer property of the Cu(OH)2 corrugated nano-needle on the copper surface is studied. The structure of the Cu(OH)2 corrugated nano-needle on the surface of the copper substrate is in situ fabricated by electrochemical deposition. The structure has hierarchical nanometer morphology and very low adhesion between solid and liquid, which promotes high density nucleation and high efficiency self-expulsion of small scale condensing microdroplets. The condensation heat transfer performance of the nanostructured sample can be greatly improved, and the heat flux of the smooth sample can be increased by more than 200% at 40 掳C steam temperature. The results show that the adhesion dissipation and pinning effect on the surface of the structural sample due to the attraction of van der Waals is much lower than that on the smooth surface, so the liquid droplets can achieve a faster renewal rate. Thus, the heat transfer efficiency is greatly improved.
【学位授予单位】：济南大学
【学位级别】：硕士
【学位授予年份】：2015
【分类号】：TB383.1;TB306

【相似文献】