Flow and heat transfer behaviour of nanofluids in microchannels
Flow and heat transfer behaviour of nanofluids in microchannels
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DOI：
10.1016/j.pnsc.2018.03.005
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发表时间：
2018-04-01
影响因子：
4.7
通讯作者：
Ding, Yulong
中科院分区：
文献类型：
--
作者：
Bowers, James;Cao, Hui;Ding, Yulong
实验研究了水基二氧化硅和氧化铝纳米流体在微通道中的流动和传热。在低雷诺数下，特别是在高纳米颗粒浓度下，测量的摩擦系数高于传统模型的预测。摩擦系数随雷诺数的增加而减小，这可能是由于流体剪切引起纳米颗粒聚集形状的增大以及局部纳米颗粒浓度和纳米流体粘度的改变。由于颗粒可能形成核/壳结构，流体剪切对二氧化硅纳米颗粒形貌的增强也可能影响摩擦系数。测量的二氧化硅纳米流体的热导率与麦克斯韦-克罗斯模型大致一致，而氧化铝纳米流体仅显示出轻微的增强。在低颗粒浓度下，观察到两种纳米流体相对于其基础流体（水）的对流换热增强。随着雷诺数的增加和微通道水力直径的增大，传热增强作用增强。然而，大多数实验表明，相对于传热的增强，泵送功率需求会增加，这可能会阻碍纳米流体的工业吸收，特别是在受限环境中，如微机电系统（MEMS）。
Flow and heat transfer of aqueous based silica and alumina nanofluids in microchannels were experimentally investigated. The measured friction factors were higher than conventional model predictions at low Reynolds numbers particularly with high nanoparticle concentrations. A decrease in the friction factor was observed with increasing Reynolds number, possibly due to the augmentation of nanoparticle aggregate shape arising from fluid shear and alteration of local nanoparticle concentration and nanofluid viscosity. Augmentation of the silica nanoparticle morphology by fluid shear may also have affected the friction factor due to possible formation of a core/shell structure of the particles. Measured thermal conductivities of the silica nanofluids were in approximate agreement with the Maxwell-Crosser model, whereas the alumina nanofluids only showed slight enhancements. Enhanced convective heat transfer was observed for both nanofluids, relative to their base fluids (water), at low particle concentrations. Heat transfer enhancement increased with increasing Reynolds number and microchannel hydraulic diameter. However, the majority of experiments showed a larger increase in pumping power requirements relative to heat transfer enhancements, which may hinder the industrial uptake of the nanofluids, particularly in confined environments, such as Micro Electro-Mechanical Systems (MEMS).