摘要
在固体表面布置纳米结构是一种强化固-液界面传热的简单有效的方法.但是,当固-液界面相互作用较弱时,由于纳米结构并不能被液体浸润,纳米结构的存在反而会弱化固-液界面之间的传热,而外电场的施加则可以解决这一问题.本文基于分子动力学模拟的方法,研究了纳米结构固-液界面在外电场作用下的传热特性.通过在2块平行金属板布置数量相同的正负电荷,产生垂直于板面的均匀电场,并在下层金属板上布置了不同尺寸的纳米结构.结果表明:在外电场作用下,纳米结构处会产生电润湿现象,固-液界面的润湿状态能够从Cassie态变为Wenzel态,界面处的Kapitza热阻长度明显减小,因而热流密度显著增大;当电荷量增至发生电冻结的临界值,液态水会产生电冻结现象,其热导率骤增至1.2 W/(m·K),热流密度也随之发生骤增;继续增加电场强度,由于电冻结现象的发生,固-液界面热阻则基本保持不变.
With the size of high-performance electronic device decreasing(down to nanoscale),and the accompanying heat dissipation becomes a big problem due to its extremely high heat generation density.To tackle the everdemanding heat dissipation requirement,intensive work has been done to develop techniques for chip-level cooling.Among the techniques reported in the literature,liquid cooling appears to be a good candidate for cooling high-performance electronic devices.However,when the device size is reduced to the sub-micro or nanometer level,the thermal resistance on the solid-liquid interface cannot be ignored in the heat transfer process.Usually,the interfacial thermal transport can be enhanced by using nanostructures on the solid surface because of the confinement effect of the fluid molecules filling up the nano-grooves and the increase of the solidliquid interfacial contact area.However,in the case of weak interfacial couplings,the fluid molecules cannot enter into the nano-grooves and the interfacial thermal transport is suppressed.In the present work,the heat transfer system between two parallel metal plates filled with deionized water is investigated by molecular dynamics simulation.Electronic charges are applied to the upper plate and lower plate to create a uniform electric field that is perpendicular to the surface,and three types of nanostructures with varying size are arranged on the lower plate.It is found that the wetting state at the solid-liquid interface can change from Cassie state into Wenzel state with strength of the electric field increasing.Owing to the transition from the dewetting state to wetting state(from Wenzel to Cassie wetting state),the Kapitza length can be degraded and the solid-liquid interfacial heat transfer can be enhanced.The mechanism of the enhancing hart transfer is discussed based on the calculation of the number density distribution of the water molecules between the two plates.When the charge is further increased,electrofreezing appears,and a solid hydrogen bonding network i
作者
齐凯
朱星光
王军
夏国栋
Qi Kai;Zhu Xing-Guang;Wang Jun;Xia Guo-Dong(Key Laboratory of Enhanced Heat Transfer and Energy Conservation,Ministry of Education,Beijing Key Laboratory of Heat Transfer and Energy Conservation,Beijing University of Technology,Beijing 100124,China)
出处
《物理学报》
SCIE
EI
CAS
CSCD
北大核心
2024年第15期154-161,共8页
Acta Physica Sinica
关键词
电润湿
纳米结构
外电场
固-液界面热阻
分子动力学
electrowetting
nanostructure
external electric field
solid-liquid interfacial thermal resistance
molecular dynamics
