含油纳米制冷剂沸腾中气相与液相之间球形纳米颗粒的迁移特性

Migration Characteristic of Spherical Nanoparticles from Liquid to Vapor Phase during Refrigerant/Nanolubricant Mixture Boiling

为了评估纳米制冷剂的沸腾传热效果以及球形纳米颗粒在制冷系统中的循环能力,采用称重法实验研究了纳米制冷剂沸腾中气/液相间球形纳米颗粒的迁移特性,重点考察球形纳米颗粒种类和粒径、制冷剂种类、润滑油浓度、热流密度和初始液位高度对球形纳米颗粒迁移特性的影响.结果表明:球形纳米颗粒迁移率随球形纳米颗粒密度或粒径的减小而增大;制冷剂的动力学黏度越小、密度越大,其在完全蒸发时的球形纳米颗粒的迁移率越大;球形纳米颗粒的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.

In order to evaluate the heat transfer characteristics of nanorefrigerant and the cycle behavior of nanoparticles in the refrigeration system, the migration of nanoparticles during pool boiling was investigated experimentally. Weigh method is used in the present study. The research focuses on the influence of nanoparticle type and size, refrigerant type, mass fraction of lubricating oil, heat flux and initial liquid-lev- el height on the migration of nanoparticles during pool boiling. The experimental results show that the migration ratio of nanoparticles during the pool boiling of refrigerant-based nanofluid increases with the decrease of nanoparticle density, nanoparticle size, dynamic viscosity of refrigerant, mass fraction of lubricating oil or heat flux; while increases with the increase of liquid-phase density of refrigerant or initial liquid- level height.