This study determined the optimal dispersion conditions of nanofluids by orthogonal experiments. Stable graphene/propylene glycol nanofluids are successfully prepared by a "two-step method" using a 60 wt % propylene glycol deionized water solution as the base fluid, and its thermal conductivity and viscosity are evaluated. Additionally, the effects of the graphene mass concentration and nanofluid temperature on thermal conductivity and viscosity are expounded, and a model for the prediction of thermophysical properties is established. The combined effect of thermal conductivity and viscosity on the heat transfer enhancement of nanofluids is analyzed theoretically, and the optimum mass concentration of graphene is determined. The results show that the thermal conductivity of nanofluids increases with the increase of the graphene concentration and nanofluid temperature. Also, the viscosity of nanofluid increases with the increase of the graphene concentration and decreases significantly with the increase of the nanofluid temperature. When the mass concentration of graphene is higher than 0.2 wt %, the increase in thermal conductivity caused by the increase of the graphene mass concentration decreases significantly, while the increase of viscosity increases significantly, and the effect of the heat transfer enhancement is almost not improved.

本研究通过正交实验确定了纳米流体的最佳分散条件。以60重量％的丙二醇去离子水溶液为基础液，通过“两步法”成功地制备了稳定的石墨烯/丙二醇纳米流体。此外，阐述了石墨烯质量浓度和纳米流体温度对热导率和粘度的影响，并建立了预测热物理性质的模型。从理论上分析了导热系数和黏度对纳米流体传热增强的综合作用，并确定了石墨烯的最佳质量浓度。结果表明，随着石墨烯浓度和纳米流体温度的升高，纳米流体的热导率增加。而且，纳米流体的粘度随着石墨烯浓度的增加而增加，并且随着纳米流体温度的增加而显着降低。当石墨烯的质量浓度高于0.2wt％时，由石墨烯质量浓度的增加引起的导热率的增加显着降低，而粘度的增加显着增加，并且几乎没有改善传热增强的效果。 。