采用全氟癸基三甲氧基硅烷对纳米TiO₂进行改性,有效改善了纳米粒子的团聚性能。利用两步法分别制备相同浓度范围的改性前/后TiO₂纳米流体,考察了2组纳米流体的热导率、静态接触角对核沸腾传热特性的影响。结果表明,在质量分数为0.05%时,未改性纳米流体沸腾传热系数较去离子水最大提高16.3%,改性纳米流体传热系数可提高28.57%,且改性纳米流体临界热通量较未改性纳米流体降低11.68%。热导率和接触角是影响不同润湿性纳米流体具有不同沸腾传热特性的主要因素,润湿性较差纳米流体易提前起沸和形成核化点,但随热通量的增加会造成气泡合并、恶化传热。

Nano TiO₂ is modified by perfluorodecyltrimethoxysilane to effectively enhance the aggregation properties of nanoparticles.TiO₂ nanofluids with the same concentration range before and after modification are prepared by a two-step method,and the effects of thermal conductivity and static contact angle of the two groups of nanofluids on the nuclear boiling heat transfer characteristics are investigated.The results demonstrate that at a mass fraction of 0.05%,the boiling heat transfer coefficient of unmodified TiO₂ nanofluid is up to 16.3% higher than that of deionized water,but that of modified TiO₂ nanofluid is 28.57% higher than that of deionized water.Furthermore,the critical heat flux of modified TiO₂ nanofluid is 11.68% lower than that of unmodified TiO₂ nanofluid.Thermal conductivity and contact angle are the main factors affecting the boiling heat transfer characteristics of nanofluids with different wettability.The nanofluids with poor wettability tend to start boiling in advance and form nucleation points,but the increase in heat flux causes bubbles to merge and deteriorate heat transfer.

张泽玉(1999-),女,硕士研究生,研究方向为纳米流体传热,2467778155@qq.com。