Abstract

In this work, a series of Al₂O₃–SiO₂/water hybrid nanofluid with different volume fractions and surfactant types were prepared. The Al₂O₃ and SiO₂ were synthesized using the sol-gel method, and ultrasonic vibration was used to disperse the powders into the DI water to form nanofluids. The effects of anionic (SDS), cationic (CTAB) and nonionic (PVP) surfactants toward the stability, electrical conductivity, and viscosity of the nanofluid were then investigated. Zeta potential analysis, spectral analysis method, sedimentation method, and centrifugation method were used to compare the stability of the nanofluids. The obtained results indicated that the surfactant played an important role in dispersing the nanoparticles (NPs) and forming stable nanofluids. Nanofluids with low concentration of Al₂O₃ showed good dispersion in water, but it tended to aggregate when the amount used was higher. The viscosity of nanofluids increased slightly when the surfactant was added due to the increase of solid-phase concentration in the nanofluids. SDS positively affected the dispersion and stability of the nanofluids, and the best ratio of Al₂O₃:SiO₂ was at 30:70. The electrical conductivity increased with temperature, and nanofluid containing CTAB and SDS had a higher increment in conductivity.

摘要

在这项工作中，制备了一系列具有不同体积分数和表面活性剂类型的Al ₂ O ₃ -SiO ₂ /水杂化纳米流体。Al ₂ O ₃和 SiO ₂使用溶胶-凝胶法合成，并使用超声振动将粉末分散到去离子水中形成纳米流体。然后研究了阴离子 (SDS)、阳离子 (CTAB) 和非离子 (PVP) 表面活性剂对纳米流体的稳定性、导电性和粘度的影响。Zeta电位分析法、光谱分析法、沉降法和离心法被用来比较纳米流体的稳定性。所得结果表明，表面活性剂在分散纳米颗粒（NPs）和形成稳定的纳米流体方面起着重要作用。具有低浓度 Al ₂ O _{3 的}纳米流体在水中表现出良好的分散性，但当用量较高时，它倾向于聚集。由于纳米流体中固相浓度的增加，当加入表面活性剂时，纳米流体的粘度略有增加。SDS对纳米流体的分散性和稳定性有积极影响，Al ₂ O ₃ :SiO ₂的最佳比例为30:70。电导率随温度升高而增加，含有 CTAB 和 SDS 的纳米流体具有更高的电导率增量。