Boiling Heat Transfer Performance And Mechanism Of Biomimetic Multi-scale Interlaced Wettability Surface

Boiling heat transfer technology has the best performance of heattransfer in many heat transfer technologies. It is significant to improve theheat flux or decrease superheat degree to enhance the pool boiling heattransfer for improvement of the efficient use of energy, reduction of heatexchanger of heat transfer surface area, and saving engineeringinvestment.Inspired by the Namib Desert beetle back’s structure, this paperproposes a novel biomimetic multi wettability surface structure, andprocesses the test samples with interlaced wettability surface. The boilingheat transfer performance and the rule of bubble growth are studiedthrough experiments and numerical simulations.First of all, through reviewing the literatures regarding the NamibDesert beetle back structure, the test samples with biomimetic interlacedwettability surface are available for the experiments. The micro squarecolumn structures on the copper surface were processed by EDM. Theoriginal surface cutting by EDM has hydrophilic property. We define theup surface as up layer and the bottom surface as bellow layer. Throughadding hydrophobic nano-structures of different size to different layer (chemical deposition of silver nitrate), the processing of the samples withmulti-scale biomimetic interlaced wettability surface were finished.Secondly, experiments of saturated nucleate pool boiling heattransfer performance of biomimetic surface were performed in low heatflux. The measurement of the heat transfer performance of four kinds ofsurface wettability with two kinds of micro-scale structure was carriedout with the visualization pool boiling system. The results show that thebiomimetic interlaced wettability surface has better heat transferperformance, compared with other surfaces. The boiling nucleation sites,the bubble growth and stable characteristics of boiling bubble detachmentfrequency were investigated as well. The results show that the biomimeticinterlaced wettability can enhance convective heat and accelerate themovement of bubbles. It can increase the transfer efficiency of qualityduring the phase change process of bubbles.Thirdly, design of experiments with four three-level factors arecarried out using L9(34) orthogonal testable. It is found that the sequenceof the factors affecting the boiling heat transfer performance from chief tosecondary is no nanostructures, groove width, depth and width of rib.Finally, the comparative simulations of the biomimetic surfacewettability and the bubble growth on other surfaces show that the microstructures can limit the growth of the bubble. The interlaced wettabilitysurface also can effectively promote the movement of the bubble and enhance the boiling of the working fluid and the heat convectiondisturbance.