Design and fabrication of triangle-pattern superwettability hybrid surface with high-efficiency condensation heat transfer performance

Utilizing superwettability micro/nanostructures to enhance the condensation heat transfer (CHT) performance of engineering materials has attracted great interest due to its values in basic research and technological innovations. Currently, exploring facile micro/nanofabrication approaches to create high-efficiency CHT surfaces has been one of research hotspots. In this work, we propose and demonstrate a type of new superwettability hybrid surface for high-efficiency CHT, which consists of superhydrophobic nanoneedle arrays and triangularly-patterned superhydrophilic microdots (SMDs). Such hybrid surface can be fabricated by the facile growth of densely-packed ZnO nanoneedles on the Zn-electroplated copper surface followed by fluorosilane modification and mask-assisted photodegradation. Through regulating the diameters and interspaces of SMDs, we obtain the optimized triangularly-patterned hybrid surface, which shows 42.7 % higher CHT coefficient than the squarely-patterned hybrid surface and 58.5 % higher CHT coefficient than the superhydrophobic surface. The key of such hybrid surface design is to considerably increase CHT coefficient brought about by SMD-triggered drop sweeping at the cost of slightly reducing heat transfer area of superhydrophobic functional zone for drop jumping. Such new strategy helps develop advanced CHT surfaces for high-efficiency electronic cooling and energy utilization.