分级纳米线结构对水滴毛细铺展速率的影响  

Effect of Hierarchical Nanowire Structure on Water Droplet Capillary Wicking

作　　者：春江[1] 徐晨 张羽飞[1] 孙良亮 郑毅[1] 温荣福[1] 郝婷婷[1] 马学虎[1] CHUN Jiang;XU Chen;ZHANG Yufei;SUN Liangliang;ZHENG Yi;WEN Rongfu;HAO Tingting;MA Xuehu(Liaoning Key Laboratory of Clean Utilization of Chemical Resources,Institute of Chemical Engineering,Dalian University of Technology,Dalian 116024,China)

机构地区：[1]大连理工大学化工学院,辽宁省化工资源清洁利用重点实验室,大连116024

出　　处：《工程热物理学报》2022年第6期1637-1642,共6页Journal of Engineering Thermophysics

基　　金：国家自然科学基金(No.51836002)。

摘　　要：液滴在固体壁面上快速铺展形成薄液膜现象广泛应用于微电子芯片散热、喷雾冷却、农药喷洒中,是薄液膜蒸发/冷凝、撞击铺展等过程的核心控制因素。基于毛细压力和黏性阻力之间的竞争关系,通过调控表面微结构的尺度提高毛细力和减少黏性力是实现薄液膜快速铺展的关键。本文为了克服毛细力和黏性阻力对于单一尺度的竞争关系导致的铺展速率的限制,引入了具有纳米线团簇和V形沟槽的复合分级纳米线结构,显著提高了液膜的毛细铺展速率,达6.54 mm·s^(-0.5),其中规则有序的纳米线团簇提供较大的毛细压力,而V形沟槽为流体输运提供了快速输运通道,显著减小了黏性阻力。在此基础上修正了毛细铺展动力学模型,在与实验结果吻合程度较好的前提下,进行了结构参数分析进一步明确了V形沟槽导致阻力的减小对于提高毛细铺展速率的重要作用。本研究通过引入分级纳米线结构,对于毛细铺展速率实现了有效调控,为设计和优化分级纳米线结构实现液膜快速铺展和强化蒸发传热提供策略。Capillary wicking on micro/nanostructured surfaces is of great significance to industrial applications including thermal management of electronic devices,spray cooling,and pesticide spraying.Wicking is driven by capillary pressure and resisted by viscous force,its capability is limited by the tradeoff between the capillary pressure and viscous resistance,which is dependent on the length scale on micro/nano structure.In this work,we report a rapid capillary wicking on the hierarchical surface composed of nanowire bunches and microscale V-grooves,whose wicking coefficient reaches6.54 mm·s^(-0.5).The higher wicking capability is attributed to the unique hierarchical organization,in which the nanowire bunches provide prominent capillary pressure and the V-grooves provide liquid film transport channels to reduce the viscous resistance.Furthermore,we present a modified theoretical model to predict the capillary wicking coefficient of hierarchical nanowired surfaces based on the balance between the capillary driving pressure and the viscous resistance.The significant contribution of microscale V-grooves,as the transport channel of liquid film,is further clarified by the modified model to be in well agreement with the experimental results.This work offers guidelines for designing hierarchical structures to enable ultrafast liquid film capillary wicking and enhancement of the evaporation heat transfer.

关 键 词：毛细铺展 纳米线团簇 V形沟槽 毛细压力 

分 类 号：TK124[动力工程及工程热物理—工程热物理]