Abstract:

Pool boiling heat transfer characteristics of CeO₂ nanofluids on the smooth surface were conducted at the atmospheric pressure. The pool boiling heat transfer performance of boiling heat transfer coefficient (HTC) as a function of heat flux and mass fraction of CeO₂/water-based nanofluids have been measured and discussed. In addition, the thermal conductivities, static contact angle of different concentrations of CeO₂ were determined. The surface deposition of different concentrations of CeO₂ nanofluids after boiling was observed, and the contact angle of deionized water on the deposition surface was measured. From the pool boiling experimental results, it was indicated that CeO₂ nanofluids enhanced the boiling HTC. The optimal mass fraction of nanofluids is 0.05%, and the boiling heat transfer coefficient is 36% higher than that of deionized water. The thermal conductivity and the static contact angle increase with the increase of the mass fraction of the nanofluids. In the experimental range, the thermal conductivity increases by 1% at the maximum, while the contact angle of the nanofluid increases from 50.5° to 92.9°. The surface deposition phenomenon increases with the mass fraction of nanofluids, and the contact angle of deionized water on the deposition surface changes greatly (51.4°~134.4°). The influence of the thermal conductivity of the nanofluid can be negligible. The contact angle and the particle deposition on the boiling surface have a greater effect on the enhanced heat transfer of the nanofluid.

Key words: CeO₂, nanomaterials, sol-gel method, nanofluids, enhanced heat transfer, boiling heat transfer

摘要：

对CeO₂纳米流体进行了池沸腾传热特性研究，考察了CeO₂/水基纳米流体的热导率，静态接触角以及沸腾后表面沉积情况对沸腾传热的影响。结果表明，CeO₂纳米流体可提高沸腾传热系数，且纳米流体最佳质量分数为0.05％，其沸腾传热系数较去离子水提高36%。热导率以及接触角随纳米流体质量分数的增加而增加，在本实验范围内，热导率最大增加1%；而纳米流体接触角从50.5°增加到92.9°；表面沉积随纳米流体的质量分数增加越来越明显，去离子水在沉积表面的接触角发生较大变化（51.4°~134.4°）。纳米流体的热导率影响可忽略不计；而接触角和沸腾表面颗粒沉积对纳米流体的强化传热作用影响较大。

关键词: 二氧化铈, 纳米材料, 溶胶凝胶法, 纳米流体, 强化传热, 沸腾传热