Experimental Investigation On Surface With Copper Nanowire Arrays For Enhanced Pool Boiling Heat Transfer

Enhanced pool boiling heat transfer technology is a very important aspect in the field of heat transfer enhancement. With the development of nanotechnology, people have already prepared a variety of micro-nano structure, and used to strengthen the study of boiling heat transfer. In recent years, the surface of the copper nanowire arrays have been shown to strengthen the pool boiling heat transfer.In this paper, include such two main aspects as preparation of copper nanowire arrays direct on flat copper surface and experimental determination of the influence of nanowired surface on pool boiling performance.Through the two-step method, a new technique utilising DC electrochemical deposition with the assistance of porous anodic alumina(PAA) membranes as the fabrication template is developed to directly grow copper nanowires on a plain copper substrate. Compared with other preparation methods, this technique can grow nanowire arrays directly on copper surface for boiling heat transfer, which can reduce the thermal contact resistance. The surface morphology of the nanowire arrays produced in different types of electroplating solution were compared, the results show that the pyrophosphate plating solution is more suitable for the preparation of a large aspect ratio, uniform nanowire arrays. Different heights of nanowire arrays were prepared by changing the plating time while control of other experimental conditions unchanged, the growth rate of the copper nanowire arrays is about5μm per hour.The surface of the copper nanowire arrays with different heights were examined under pool boiling with water. The results show that the nanowired surface can significantly increase the pool boiling heat transfer effects, the critical heat flux of the nanowired surface is much higher than the plain surface, the highest critical heat flux is227W/cm2, as much as1.5times that on a plain surface, the superheat can be mostly reduced about6.6℃at the critical heat flux. The pool boiling heat transfer performance of the surface with nanowire arrays is enhanced with the increasing of the nanowire arrays heights.