Thermal conductivity measurements of nanofluids
Thermal conductivity measurements of nanofluids
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DOI：
10.1016/j.ijheatmasstransfer.2016.09.080
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发表时间：
2017-01-01
影响因子：
5.2
通讯作者：
Guzei, D. V.
中科院分区：
文献类型：
--
作者：
Pryazhnikov, M. I.;Minakov, A. V.;Guzei, D. V.
本文介绍了室温下纳米流体导热系数的系统测量结果。总共研究了50多种基于水、乙二醇和机油的纳米流体，其中含有SiO2、Al2O3、TiO2、ZrO2、CuO和金刚石颗粒。纳米颗粒体积浓度为0.25 ~ 8%，粒径为10 ~ 150nm。研究表明，纳米流体的热导率不能用经典理论（麦克斯韦等）来描述。纳米流体导热系数是一个复杂的函数，不仅与颗粒浓度有关，还与颗粒大小、颗粒材料和基液类型有关。测量的导热系数几乎总是超过麦克斯韦公式计算的值，尽管具有足够小颗粒的纳米流体的导热系数可能比麦克斯韦理论预测的还要低。然而，在所有情况下，纳米流体的导热系数随粒径的增大而增大。研究结果令人信服地表明，纳米颗粒材料的热导率与含纳米颗粒的纳米流体的热导率之间没有直接的相关性。基液对纳米流体的有效导热系数也有显著影响。实验证实，基液的导热系数越低，纳米流体的相对导热系数越高。(C) 2016 Elsevier Ltd.版权所有。
The paper presents the results of systematic measurements of the thermal conductivity coefficient of nanofluids at room temperature. In total, more than fifty various nanofluids based on water, ethylene glycol, and engine oil containing particles of SiO2, Al2O3, TiO2, ZrO2, CuO, and diamond were studied. The nanoparticles volume concentration ranged from 0.25 to 8% and the particles size ranged from 10 to 150 nm. It is shown that the thermal conductivity of nanofluids is not described by the classical theories (Maxwell's and so forth). The nanofluid thermal conductivity coefficient is a complicated function not only of the particle concentration, but also the particles size, their material, and type of base fluid. Measured thermal conductivity coefficients almost always exceed the values calculated by the Maxwell's formula, though nanofluids with sufficiently small particles may have thermal conductivity coefficients even lower than those predicted by the Maxwell theory. However, in all cases, the nanofluid thermal conductivity coefficient enhances with increasing particle size. It is convincingly shown that there is no direct correlation between the thermal conductivity of the nanoparticle material and the thermal conductivity of nanofluid containing these particles. The base liquid also significantly influences the effective thermal conductivity of the nanofluid. It has been confirmed that the lower the thermal conductivity of the base fluid, the higher the relative thermal conductivity coefficient of the nanofluid. (C) 2016 Elsevier Ltd. All rights reserved.