Cu-水纳米流体的分散行为及导热性能研究

通过测定Cu-水纳米悬浮液的Zeta电位和吸光度,采用Hotdisk热物性分析仪测量了其导热系数,探讨了不同pH值和分散剂浓度对Cu-水纳米悬浮液分散稳定性和导热性能的影响.结果表明,pH值和分散剂加入量是影响Cu-水纳米悬浮液分散稳定和导热系数的重要因素.最优化的pH值和分散剂加入量能显著提高水溶液中Cu表面Zeta电位绝对值,增大了颗粒间静电排斥力,悬浮液分散稳定性较好,导热系数较高.从分散稳定和导热系数提高两个方面来考虑,pH=9.5左右被选为最优化值,在0.1%Cu-H2O纳米流体中,0.07%SDBS被选为最优化浓度.另外,Cu-水纳米流体的导热系数随纳米粒子质量分数的增大而增大,呈非线性关系,且比现有理论(Hamilton-Crosser模型)预测值大.

Study on dispersion behavior and thermal conductivity of Cu-H2O nanofluids

Dispersion and stability of Cu nanoparticles in water were studied under different pH values, different dispersant concentration by the method of zeta potential and absorbency. The thermal conductivity was measured by a Hot Disk Thermal Constants Anlyser. The results show that the pH condition and the addition of dispersant can significantly influence the stability and the thermal conductivity of Cu-HzO nanofluids. Optimizing pH value and dispersant concentration of the nanofluids result in higher zeta potential, which can lead to better dispersion behavior and higher thermal conductivity of nanofluids. Taking into account the combined effect of dispersion behavior and thermal conductivity, pH 9.5 can be selected as an operating pH, and the 0.07% SDBS can be selected as an optimizing concentration for the 0.1% Cu-H2O nanofluids. The thermal conductivity of Cu-H2O nanofluid is enhanced approximately nonlinearly with the weight fraction of the copper nanoparticle, which are greater than those calculated from Hamilton-crosser model.