改性SiO_2纳米颗粒沸腾沉积层的形成原理及其沸腾换热  

Deposition mechanisms and boiling heat transfer of modified SiO_2 nanoparticles deposition layer in boiling experiments

作　　者：王东民 董丽宁[2] 全晓军[1] WANG Dongmin;DONG Lining;QUAN Xiaojun(School of Mechanical Engineering,Shanghai Jiao Tong University,Shanghai 200240,China;Shanghai Institute of Satellite Engineering,Shanghai 200240,China)

机构地区：[1]上海交通大学机械与动力工程学院,上海200240 [2]上海卫星工程研究所,上海200240

出　　处：《化工学报》2018年第10期4200-4205,共6页CIESC Journal

基　　金：国家自然科学基金项目(51406122)~~

摘　　要：实验研究了改性SiO_2纳米流体液滴蒸发后的沉积图案,以及改性SiO_2纳米颗粒沸腾沉积层对沸腾换热的影响。液滴蒸发实验研究表明:改性官能团会影响改性SiO_2纳米颗粒是否吸附在液-气界面,从而推断出在沸腾过程中改性官能团对纳米颗粒沉积方式的影响。沸腾实验研究结果表明:用聚乙二醇基团改性的SiO_2纳米颗粒沸腾沉积层使加热面的平均粗糙度从160 nm大幅增长到977 nm,且能增强纯水的沸腾传热系数;而用磺酸基团改性的SiO_2纳米颗粒沸腾沉积层对加热面的平均粗糙度的改变不明显,只使其增大了60 nm,且恶化了纯水的沸腾传热系数。通过沸腾换热实验结果较好地验证了通过液滴蒸发实验推断出的沸腾过程中改性官能团对纳米颗粒沉积方式的影响。Different drying patterns of modified SiO2 nanofluid droplets have been observed and the effects of modified SiO2 nanoparticle deposition layer formed in boiling on pure water boiling heat transfer have also been investigated experimentally.The different drying patterns of nanofluid droplets show that modified function groups can affect whether SiO2 nanoparticles can be adsorbed to the liquid-air interface,and based on this result a conjecture has been made about the effects of modified functional groups on the way of nanoparticle deposition during boiling of nanofluids.From boiling experiments,it is found that polyethylene glycol(PEG)groups modified SiO2 nanoparticles deposition layer on a heater surface can increase average roughness of the heater surface a lot from 160 nm to 977 nm,and it can also increase pure water boiling heat transfer coefficient.However,the sulfonic acid groups modified SiO2 nanoparticles deposition layer on a heater surface affect average roughness of the heater surface a little(increased 60 nm),and it deteriorates the pure water boiling heat transfer coefficient.The effects of modified functional groups on the deposition of nanoparticles during the boiling process inferred by droplet evaporation experiments were verified by boiling heat transfer experiments.

关 键 词：二氧化硅 纳米粒子 蒸发 沉积物 沸腾换热 

分 类 号：TK124[动力工程及工程热物理—工程热物理]