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通过两步法制备了不同体积浓度的γ-Al_2O_3纳米流体,并添加不同质量分数的十二烷基苯磺酸钠(SDS)和聚乙烯吡咯烷酮(PVP)作为分散剂。分析了温度以及两种表面活性剂对γ-Al_2O_3纳米流体稳定性和导热系数的影响。试验结果表明,非离子型表面活性剂PVP比阴离子表面活性剂SDS具有更好的分散效果。随着表面活性剂浓度的增加,纳米流体的导热系数呈先增加后减小的趋势,适当的粒子浓度与活性剂浓度比例有利于提高纳米流体的导热系数。
Different concentrations of γ-Al 2 O 3 nanofluids were prepared by two-step method. Sodium dodecyl benzene sulfonate (SDS) and polyvinylpyrrolidone (PVP) with different mass fractions were added as dispersants. The effects of temperature and the two surfactants on the stability and thermal conductivity of γ-Al 2 O 3 nanofluids were analyzed. The experimental results show that the nonionic surfactant PVP has better dispersing effect than the anionic surfactant SDS. With the increase of surfactant concentration, the thermal conductivity of nanofluids tends to increase at first and then decrease. The proper ratio of particle concentration and active agent concentration is helpful to improve the thermal conductivity of nanofluids.