In Situ Growth Of Inorganic Nanostructure On Copper-based Surface And Dropwise Condensation Heat Transfer Performance Study

Condensation heat transfer as a common phase change process, is widely applied in chemical industry, seawater desalination and environmental control field. Dropwise condensation compared to filmwise condensation can improve the update rate of the droplets. In addition, the surface hydrophobic modification will further strengthen the condensation heat transfer. This paper, take this as the breakthrough point. Condensation interfacial phenomena and dropwise condensation heat transfer performance of microdroplets were observed and quantitative measured after the in situ growth of ZnO nanowire clusters and Cu(OH)2 ribbednanoneedles on the surface of copper test combined with modification of low surface energy material. Meanwhile, the efficient heat transfer mechanism is analyzed briefly. The study has important significance for understanding the relationship between structure and heat transfer properties. Meanwhile, it also provides conditions for the development of new heat transfer nanomaterials and devices so as to achieve efficient energy utilization.This article main research contents are as follows:(1) Dropwise condensation heat transfer performance study on copper-based ZnO nanowire clusters. A facile electrochemical deposition combined with chemical bath method was used for the in situ growth of ZnO nanowire clusters on copper substrates. Through modification of low surface energy material, these structures can realize coalescence and efficient self-removal of condensation microdroplets. Combining with the interfacial phenomena, we proved that the structure samples compared with the hydrophobic smooth samples can enhance the droplets update rate and can maintain the interface droplet size microscale and self-removal over long time. Researches show that the nanostructure samples can greatly improve the heat transfer performance: at 40°C steam temperature, compared to the smooth samples, the heat flux can improve more than 200%, the highest heat transfer coefficient improves 270%.(2) Dropwise condensation heat transfer performance study on copper-based Cu(OH)2 ribbed-nanoneedles. In situ construction of copper-based Cu(OH)2 ribbed-nanoneedles with hierarchical nanomorphology and very low solid-liquid interface adhesion, make small scale condensation droplets fast update with high-density nucleation and efficient self-removal. Further researches show that the nanostructure samples can greatly improve the heat transfer performance: at 40°C steam temperature, compared to the smooth samples, the heat flux can improve more than 200%, the highest heat transfer coefficient improves 125%. Research shows that adhesion of van der Waals caused by the attraction of dissipation and the pinning effect of the line tension effect on the structure sample surface is far lower than the smooth sample surface. Therefore, the droplets can achieve faster update rate, thereby greatly improving the heat transfer efficiency.