Nucleate boiling performance was enhanced up to an order of magnitude through direct deposition of Cu nanorods on a planar Cu surface. The methodology that enables order of magnitude improvement in boiling performance without fabricating complicated surface structures or changing the working fluid will have broad impact on metal-liquid type two-phase heat exchangers. In this study, discussion was focused on bubble dynamics on the nanostrucured Cu surfaces. We observed striking differences in bubble dynamics through nucleation boiling process for the nanostructured surface including smaller bubble diameters, higher release frequencies and nucleation site density, and large fluctuations in bubble diameter prior to release. These differences during the boiling process are responsible for the enhanced heat transfer. High quality images were captured through a well-designed visualization system, which comprises of a high-speed charge-coupled device (CCD) camera, microscope and data acquisition system. This visualization study aims to quantitatively study the bubble dynamics on the nanostructured Cu surfaces.

Using Sutton-Chen many-body potential, the mechanical characteristics of silver nanorod subjected to 001 uniaxial tensile strain are simulated with molecular dynamics. The results indicate that the tensile deformation process consists of an elastic and a plastic periods. The atomic configurations change little in elastic period but change obviously in plastic period. The changes of atomic configurations directly determine the corresponding stress-strain relation. The stress increases linearly as strain grows within the process of elastic deformation. The stress fluctuates greatly in plastic period. With detailed analysis, the dislocations and slips of atoms lead to the stress oscillation. The influences of size effects on tension properties are investigated simultaneously. Young’s modulus heightens and the elastic ultimate stress decreases with the increasing global size of nanorod. Both of them approach to that of macroscopic material as the global size increases. At the same time, the tension properties of Silver nanorod with vacancy defects are investigated. When the vacancy density is less than 0.1%, the Young’s modulus of defect crystals are almost same as that of free-defect crystals, but the elastic ultimate stress is less than that of free-defect crystals. The Young’s modulus and elastic ultimate stress and strain are all decrease with the increment of vacancy density.