摘要
纳米流体是一种高效传热的工质,广泛应用于换热设备中。由于体系内微观力相互作用,纳米颗粒容易团聚并沉积于加热面上。少量沉积会改变加热面性质,影响气泡生长和沸腾传热特性。本文采用分子动力学探究了横直、横错位、竖直和竖错位团聚体沉积对Cu/Ar纳米流体气泡生长和池沸腾特性的影响。结果表明,与横向排列的团聚体对比,竖向排列的团聚体气泡成核与气膜层脱离时间分别延后了14.3%和37.2%。竖直团聚体的扩散系数最小,为横直团聚体的28.4%。这说明传质阻力大,孤立小气泡不易聚合形成气膜层,延长核态沸腾时间,有利于热量传递。同时,团聚体沉积改变了颗粒-基液-加热面的相互作用力,竖直团聚体的Cu-Ar原子间的相互作用力(5.1437eV)最大,比作用力最小的横直团聚体提高了138%。这是因为Ar原子被大面积吸附在团聚体表面,形成致密的固液界面层,Cu-Ar原子间的高导热通道更长,强化了传热。该结果可为设计高效传热的纳米流体及纳米级粗糙加热面以延长核态沸腾进程提供了理论依据。
Nanofluids,recognized for the superior heat transfer capabilities,are increasingly utilized in heat exchange systems.Due to the interparticles interactions,nanoparticles easily tend to agglomerate and deposit onto the heating surface.The agglomerate deposition can alter the characteristic of heat surface and significantly affect bubble growth and boiling heat transfer.The influence of agglomerate deposition with transverse,transverse misalign,vertical and vertical misalign on the bubble growth and pool boiling heat transfer characteristics of Cu/Ar nanofluids was explored by molecular dynamics simulation.The results demonstrated that the agglomerate deposition with vertical align delayed bubble nucleation and gas film layer detachment by 14.3%and 37.2%,respectively,compared to the agglomerate deposition with horizontal align.Additionally,the diffusion coefficient of vertical agglomerates was observed to be the lowest,at 28.4%of that of horizontal agglomerates,indicating a significant increase in mass transfer resistance.This resistance hindered the coalescence of isolated small bubbles into a gas film layer,thus prolonging the nucleation boiling process and enhancing heat transfer.Furthermore,agglomerate deposition was found to alter the interaction forces of particle-substrate-heating surface.The interaction force of Cu-Ar atom for vertically aligned agglomerates(5.1437 eV)was 138%greater than that for horizontally aligned agglomerates,attributed to the larger surface area of Ar atom adsorption on the agglomerate.This led to the formation of a dense solid-liquid interface layer and an extended heat transfer path between Cu and Ar,thereby improving heat transfer efficiency.These findings offer critical insights to design the nanofluids with high thermal performance and optimize the heating surfaces with nanoscale rough to extend the nucleation boiling process.
作者
彭一倩
翟玉玲
陈华株
李舟航
王华
PENG Yiqian;ZHAI Yuling;CHEN Huazhu;LI Zhouhang;WANG Hua(Faculty of Metallurgical and Energy Engineering,Kunming University of Science and Technology,Kunming 650032,Yunnan,China)
出处
《化工进展》
北大核心
2026年第1期95-105,共11页
Chemical Industry and Engineering Progress
基金
国家自然科学基金(52266002)。
关键词
纳米流体
团聚体
气泡成核
固液作用力
传热速率
nanofluid
agglomeration
bubble nucleation
solid-liquid interaction force
heat transfer rate
