含油纳米制冷剂沸腾中纳米颗粒相间迁移机制

Migration Mechanism of Nanoparticles From Liquid Phase to Vapor Phase in the Boiling of Nanorefrigerant-Oil Mixture

含油纳米制冷剂沸腾中纳米颗粒相间迁移机制,是评估纳米制冷剂沸腾传热效果和制冷系统中纳米颗粒循环能力的基础。本文基于颗粒捕集理论和气浮理论,提出了各因素对纳米颗粒相间迁移的影响机制;即纳米颗粒迁移率随其密度或粒径的减小而增大,制冷剂动力学黏度越小、密度越大,其完全蒸发时纳米颗粒迁移率越大,纳米颗粒迁移率随润滑油浓度的增大而减小,随热流密度的增大而减小,随初始液位高度的增加而增大。同时通过实验验证了理论分析。

Migration mechanism of nanoparticles from liquid phase to vapor phase in the boiling of nanorefrigerant-oil mixture is fundamental to the evaluation of nanorefrigerant boiling heat transfer and nanoparticles circulation in refrigeration systems. Based on the particles trapping theory and flotation theory, the influence mechanism of different factors on the migration of nanoparticles is proposed. The results showed that the migration ratio of nanopaticles increases with the decrease of the density or size of nanoparticles. When the refrigerant is completely evaporated, the smaller dynamic viscosity or larger density of refrigerant causes the larger migration ratio of nanoparticles. The migration ratio of nanoparticles decreases with the increase of lubricating oil concentration or heat flux, while increases with the increase of initial liquid-level height. The accuracy of the theoretical analysis results is verified by the experimental results.