纳米流体具有很好的导热性能,引起了广泛的关注和研究。采用改进的Hummers法制备了氧化石墨烯(GO)。采用超声振荡法把不同质量的GO分散于去离子水和去离子水加乙二醇的混合液中,制得分散效果较好的质量分数为0.05%、0.1%、0.025%和0.075%的GO-水纳米流体和分散效果较好的质量分数为0.05%、0.1%的GO-(水+乙二醇)纳米流体。采用X射线衍射仪和拉曼光谱仪对石墨和GO进行结构、形貌表征,结果表明石墨的结构已经被破坏,形成了新的晶体结构。采用黏度计测试剪切压力,得出了各浓度的GO-水纳米流体和GO-(水+乙二醇)纳米流体的剪切压力在一定温度下随剪切速率的增大而增大;各浓度的GO-水纳米流体在不同温度下的剪切应力和剪切速率之间不是严格的线性关系,表现为非牛顿行为,表明GO-水纳米流体的非牛顿行为强烈依赖于温度;各浓度的GO-(水+乙二醇)纳米流体在较低温度范围下表现为牛顿行为,在较高温度范围下表现为非牛顿行为,表明GO-(水+乙二醇)纳米流体的牛顿或非牛顿行为强烈依赖于温度。黏度测试结果表明:两种纳米流体的黏度随着流体温度的升高而降低,随着颗粒质量分数增加而增加。用自制实验装置进行了纳米流体的热性能测试,从而得出强制对流传热系数与雷诺数的关系。
Nanofluids have attracted extensive attention and research because of their good thermal conductivity.Graphene oxide (GO) was prepared by modified Hummers method.GO with different mass were dispersed in the mixture of deionized water and deionized water plus ethylene glycol by ultrasonic oscillation method.GO water nanofluids with 0.05%,0.1%,0.025% and 0.075% of GO and good dispersion effect were prepared.And GO-(water+ethylene glycol) nanofluids with 0.05%、0.1% of GO and good dispersion effect were prepared.The structure and morphology of graphite and GO were characterized by XRD and raman spectroscopy.The results shown that the structure of graphite was destroyed and formed new crystal structure.The shear pressure of GO water Nanofluids and GO-(water+glycol) nanofluids with different concentrations were measured by viscometer.The shear pressure increased with the increase of shear rate at a certain temperature.The shear stress and shear rate of GO water nanofluids with different concentrations at different temperatures were not strictly linear,showing non-newtonian behavior,indicating that the non-newtonian behavior of GO water nanofluids strongly depended on temperature;GO-(water+glycol) nanofluids of various concentrations exhibited newtonian behavior in the lower temperature range and non-newtonian behavior in the higher temperature range,indicating that the newtonian or non-newtonian behavior of GO-(water+glycol) nanofluids was strongly dependent on temperature.The viscosities of the two nanofluids were measured by viscometer.It was found that the viscosities of the two nanofluids decreased with the increase of fluid temperature,and the viscosities of GO water Nanofluids and GO-(water+glycol) nanofluids increased with the increase of particle mass concentration.The thermal performance of nanofluids was tested with a self-made experimental device,and the relationship between forced convection heat transfer coefficient and Reynolds number was obtained.
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基金资助
油气田应用化学四川省重点实验室开放基金项目(YQKF202122)
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