Kruse Corey, Lucis Mike, Shield Jeff E, Anderson Troy, Zuhlke Craig, Alexander Dennis, Gogos George, Ndao Sidy
Department of Mechanical and Materials Engineering, University of Nebraska-Lincoln, Lincoln, NE 68588.
Department of Electrical Engineering, University of Nebraska-Lincoln, Lincoln, NE 68588.
J Therm Sci Eng Appl. 2018 Jun;10(3). doi: 10.1115/1.4038763. Epub 2018 Mar 28.
An experimental investigation of the effects of layers of nanoparticles formed during femtosecond laser surface processing (FLSP) on pool boiling heat transfer performance has been conducted. Five different stainless steel 304 samples with slightly different surface features were fabricated through FLSP, and pool boiling heat transfer experiments were carried out to study the heat transfer characteristics of each surface. The experiments showed that the layer(s) of nanoparticles developed during the FLSP processes, which overlay FLSP self-organized microstructures, can either improve or degrade boiling heat transfer coefficients (HTC) depending on the overall thickness of the layer(s). This nanoparticle layer thickness is an indirect result of the type of microstructure created. The HTCs were found to decrease with increasing nanoparticle layer thickness. This trend has been attributed to added thermal resistance. Using a focused ion beam milling process and transmission electron microscopy (TEM), the physical and chemical properties of the nanoparticle layers were characterized and used to explain the observed heat transfer results. Results suggest that there is an optimal nanoparticle layer thickness and material composition such that both the HTCs and critical heat flux (CHF) are enhanced.
对飞秒激光表面处理（FLSP）过程中形成的纳米颗粒层对池沸腾传热性能的影响进行了实验研究。通过飞秒激光表面处理制备了五个表面特征略有不同的不锈钢304样品，并进行了池沸腾传热实验，以研究每个表面的传热特性。实验表明，飞秒激光表面处理过程中形成的纳米颗粒层覆盖在飞秒激光自组织微结构上，根据该层的总厚度，其既可以提高也可以降低沸腾传热系数（HTC）。这种纳米颗粒层厚度是所创建微观结构类型的间接结果。发现传热系数随纳米颗粒层厚度的增加而降低。这种趋势归因于增加的热阻。使用聚焦离子束铣削工艺和透射电子显微镜（TEM）对纳米颗粒层的物理和化学性质进行了表征，并用于解释观察到的传热结果。结果表明，存在一个最佳的纳米颗粒层厚度和材料组成，使得传热系数和临界热流密度（CHF）都得到提高。
