Fabrication Of Copper-based ZnO Nanostructures And Study On Dropwise Condensation Heat Transfer Performance

Condensation phase change heat transfer is a ubiquitous phase-change process that is an essential natural phenomenon and widely used in various industries for applications including power generation, thermal management, desalination, and environmental control. Enhancing thermal transport as well as heat transfer coefficient during condensation has been the subject of numerous scientific investigations. Compared with filmwise condensation, dropwise condensation is a type of more efficient heat transfer mode because discrete condensate drops have far lower thermal resistance than continuous liquid films and can release far more bare surface sites for performing more cycles of nucleation, growth and departure. In addition, the surface hydrophobic modification will further strengthen the condensation heat transfer.In this paper, take this as the breakthrough point. We report a type of copper-based closely-packed zinc oxide(ZnO) nanopencil arrays and super-thin well-aligned ZnO nanocone arrays. Subsequently, after low-surface-energy fluorosilane modification, we further investigate growth dynamic behaviours of condensate microdrops and condensation interfacial phenomena. Dropwise condensation heat transfer performance of samples were observed and quantitative measured, and the mechanism of efficient heat transfer is analyzed briefly. The study has important significance for understanding the relationship between structure and heat transfer properties. Meanwhile these findings offer an insight into how to develop advanced heat transfer interface nanomaterials and devices for high-efficiency energy utilization and thermal management.This article main research contents are as follows:(1) A facile chemical bath method was used for the in situ growth of ZnO nanopencil arrays on copper substrates. After low-surface-energy chemistry modification, the in-situ grown nanopencil arrays surfaces show ideal superhydrophobic nature and condensate microdrop self-propelling function. Combined with observation of the high-speed high-resolution three-dimensional microscopic imager, we have systematically compared the different dynamic behaviors and the self-departure models of the condensate microdrop on the superhydrophobic surface and hydrophobic smooth surface. And further confirmed that when it compared with the hydrophobic smooth samples, the nanosamples can enhance the microdrops update rate and maintain high-density nucleation and efficient self-propelling over a long time. Condensation heat transfer researches show that the nanopencil samples can greatly improve the heat transfer performance, and reveals the related mechanism of how to realize efficient heat transfer on the nanostructure surface.(2) We have optimized our method to realize controllable preparation of ultrathin well-aligned closely-packed non-sticky nanocones on the copper substrates. Combining with observing the high speed and high resolution 3D Microscopic images and analyzing the detailed data statistics, we have systematically studied the dynamic behavior and related details of the condensate microdrop on the nanostructure surface. We also have illuminated the self-propelling mechanism of small-scale condensed microdrops on the superhydrophobic nanostructure surface. what is more, we have explained the elementary regulations of how to design the superhydrophobic nanostructure surface. In the condensation heat transfer test, the nanocone structure surface, we have explored the related behavior characteristics of small-scale microdroplet on the nanocone surface when it worked on the negative pressure condition. In the end, our experiments and rationalized theoretical model analyses into the condensation behavior and the heat transfer performance of these nanostructures, we have summarized the law about the effect of the characteristic parameter of nanostructures on condensation heat transfer performance.