Investigation Of Steam Dropwise Condensation Heat Transfer On Copper Hydroxide Nanoneedle Array

Condensation is a common phase change in nature, as well as used in industry for applications including power generation, thermal management, desalination, and environmental control. In the past 80 years, researchers have focused on creating stable dropwise condensation surfaces allowing condensed droplets to be easily removed by gravity for enhanced heat transfer performance. Recent studies indicated that droplet mobility can be effectively accelerated by constructing a suitable super-hydrophobic interface, even coalescence-induced droplet can be self-propelled depend on release of coalesced energy, and theoretical studies have confirmed that the interface can be greatly enhanced condensation heat transfer performance. In this study, we build a copper hydroxide nanoneedle array based on cooper specimen and after chemical modification with low surface-energy, make nanostructure with self-propelled performance. And confirmed that it can enhance condensation heat transfer performance in the steam conditions. Specific studies and results are as follows.By using the method of electrochemical deposition, covered with a layer of copper hydroxide nanoneedle on the copper specimen. By regulating the reaction conditions and the surface hydrophobic treatment to give it super-hydrophobic performance. Then we characterized its surface self-propelled behavior in the atmospheric environment.Secondly, we researched that its heat transfer performance at low temperature, results indicated that the average heat flux of nanostructure specimen was three times than smooth specimen, and the heat transfer coefficient was as high as five times. Then we studied the dynamic behavior of the droplets in the copper hydroxide nanoneedle array at different subcooling observed through CCD systematically, found that the self-propelled mode requires a relative lower super saturation(S <1.12) and lower subcooling(△ T<2 K).Finally, we systematically studied condensation heat transfer of copper hydroxide nanoneedle array interface at different subcooling, found that by increasing the subcooling, the heat transfer coefficient first increased and then decreased. Through CCD observation, we found the self-propelled mode with the maximum heat transfer coefficient.In summary, we experimentally demonstrated that, self-propelled mode can be achieved in the super-hydrophobic copper hydroxide nanoneedle array interface at micro or nanometer scalable, and this structure has excellent heat transfer properties. Furthermore, it is not only provide new direction for the development of heat applied for copper surface, but also provide new ideas for development of condensation heat transfer performance for other materials.