采用两步法，以聚乙烯吡咯烷酮（PVP）为表面活性剂，制备了不同种类的纳米冷冻机油并对其分散稳定性进行了实验研究。采用Hot Disk热常数分析仪，测量了40℃下纳米冷冻机油（纳米材料为TiO2、Al2O3、Fe2O3、石墨和碳纳米管，体积分数为0.05%、0.1%、0.2%、0.5%、1%和2%）的热导率，分析研究了颗粒体积分数、粒径、材质以及表面活性剂等因素的影响。结果表明：纳米冷冻机油的热导率随着颗粒体积分数的提高而增大；相同体积分数下随着颗粒粒径的增大而减小，而相同粒径下又随着颗粒材质热导率的提高而增大；同时分散稳定性优的纳米冷冻机油热导率较高。基于纳米粒子的体积分数、粒径、团聚理论和布朗运动开发了纳米冷冻机油热导率预测模型，并与实验数据进行比较，发现预测值与90%的实验数据偏差在±3%以内，平均偏差1.6%。%Naphthenic nano-refrigeration-oils (NROs) with different types of nanoparticles were prepared by two-step method with polyvinyl pyrrolidone (PVP) as surfactant. The dispersion stability and the thermal conductivity of the NROs were investigated experimentally by Shimadzu UV-Vis and Hot Disk thermal constant analyzer,respectively. The NROs with various nanparticles (including TiO2、Al2O3、Fe2O3、graphite and CNT) with volume fractions of 0.05%,0.1%,0.2%,0.5%,1% and 2% were tested at 40℃. And the influence of volume fraction,particle size,material and surfactant was analyzed. The results show that the thermal conductivity of NROs increases with the increase of nanoparticle volume fractions. The thermal conductivity of NROs shows a downward trend when the particle size increases at the same volume fraction. While at same particle size it improves with the thermal conductivity of particle material. Besides,the NROs with better dispersion stability have higher thermal conductivity. A model for predicting the thermal conductivity of NROs was developed based on volume fraction,particles,aggregation theory and Brownian movement of nanoparticles. The predictions of the model agree with 90% of experimental data within the deviation of ±3%,and the mean deviation of 1.6%.
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