Abstract

The quest for effective and efficient heat exchange systems has been a subject of recent research. Nanofluids are high performance ultra-modern heat transfer fluids with superior properties compared to those of regular heat transfer fluids. Therefore, studies on the viscosity of nanofluids are essential owing to its effect on the pumping requirements of thermal systems. This article investigates the influence of concentration and temperature on the dynamic viscosity of AlN and SiC nanofluids. Nanofluids with a volume concentration of 0.5–5% were prepared by dispersing AlN nanoparticles in ethylene glycol (EG), SiC in ethylene glycol, and SiC in distilled water (DW) using the two-step method. The experimental investigation on the viscosity of these nanofluids was performed at the temperature range of 28–60 °C using an Ostwald viscometer. It was observed that the measured nanofluids exhibited an increase in the viscosity with an increase in the volume concentration of nanoparticles. Specifically, for SiC/DW nanofluids at 0.5 and 5% volume concentration, the viscosity ratio was 1.023 and 1.435 times that of the base fluid. Moreover, the viscosity of nanofluids is reduced by increasing the temperature relative to that of their base fluids. The experimental values were compared with existing theoretical model, and their predictions are below the experimental results; therefore, correlation was derived on the basis of the experimental data. The margin of deviation of these models in predicting the viscosity of the studied nanofluids varied between −15 and 23% for AlN/EG; −7 and 21% for SiC/EG, and −11 and 4% for SiC/DW nanofluid.

摘要

寻求有效和高效的热交换系统一直是最近研究的主题。纳米流体是高性能的超现代传热流体，与常规传热流体相比具有更优越的性能。因此，由于其对热系统的泵送要求的影响，因此对纳米流体的粘度进行研究是必不可少的。本文研究了浓度和温度对 AlN 和 SiC 纳米流体动态粘度的影响。使用两步法将 AlN 纳米颗粒分散在乙二醇 (EG) 中、将 SiC 分散在乙二醇中、将 SiC 分散在蒸馏水 (DW) 中，制备了体积浓度为 0.5-5% 的纳米流体。使用 Ostwald 粘度计在 28-60°C 的温度范围内对这些纳米流体的粘度进行了实验研究。观察到测量的纳米流体的粘度随着纳米颗粒体积浓度的增加而增加。具体而言，对于体积浓度为 0.5% 和 5% 的 SiC/DW 纳米流体，其粘度比是基础液的 1.023 和 1.435 倍。此外，纳米流体的粘度通过提高相对于其基础流体的温度而降低。将实验值与现有理论模型进行比较，其预测值低于实验结果；因此，相关性是根据实验数据得出的。对于 AlN/EG，这些模型在预测所研究的纳米流体粘度方面的偏差幅度在 -15 和 23% 之间变化；SiC/EG 为 -7 和 21%，SiC/DW 纳米流体为 -11 和 4%。