Cao Qun, Cui Zheng, Shao Wei
Institute of Thermal Science and Technology, Shandong University, 17923 Jingshi Road, 250061 Jinan, China.
Shandong Institute of Advanced Technology, 250100 Jinan, China.
Langmuir. 2020 Mar 24;36(11):2802-2815. doi: 10.1021/acs.langmuir.9b03989. Epub 2020 Mar 10.
Rough nanostructured surfaces can enhance evaporation heat transfer. Most studies artificially optimized the geometry and size during the design of nanostructured surfaces. Instead of the empirical design of nanostructured surfaces, this paper proposes a mathematical optimization method of the grooved nanostructured surface design. This method is inspired by the molecular dynamics simulations of grooved nanostructured surfaces. The results show that the heat transfer performance exhibits a positive correlation with the defined sectional area of the grooved nanostructured surface; thus, this method is developed to convert the maximum heat transfer and evaporation rate to a mathematical conditional extremum solution. The mathematical description of the optimization method is to solve the surface structure with the maximum sectional area when the heat transfer area is constant. Comparing the molecular dynamics (MD) simulation results of the optimal surface and the existing ones under the same simulation conditions indicates that the optimal surface has the best heat transfer performance compared with the other ones. Additionally, discussions on the types of grooved nanostructured surfaces, the materials of solid and liquid, and the wettability of grooved surfaces verify the generality of the calculation results and the optimization method. The explanation of the method is that different nanostructured surfaces have a similar potential energy per liquid atom, which affects the latent heat of the evaporation process. However, the maximum sectional area corresponds to the minimum interfacial thermal resistance and the maximum interaction energy per unit area, which will enhance the heat transfer at the solid-liquid interface. Moreover, a nanostructured surface with the maximum sectional area also obtains the maximum area of the liquid-vapor interface and thus enhances the evaporation heat transfer process.
粗糙的纳米结构表面可以增强蒸发传热。大多数研究在纳米结构表面设计过程中人工优化其几何形状和尺寸。本文提出了一种带槽纳米结构表面设计的数学优化方法，而不是对纳米结构表面进行经验设计。该方法受到带槽纳米结构表面分子动力学模拟的启发。结果表明，传热性能与所定义的带槽纳米结构表面截面积呈正相关；因此，该方法旨在将最大传热和蒸发速率转化为数学条件极值解。该优化方法的数学描述是在传热面积恒定的情况下求解具有最大截面积的表面结构。在相同模拟条件下比较最优表面与现有表面的分子动力学（MD）模拟结果表明，与其他表面相比，最优表面具有最佳的传热性能。此外，对带槽纳米结构表面的类型、固体和液体的材料以及带槽表面的润湿性的讨论验证了计算结果和优化方法的通用性。该方法的解释是，不同的纳米结构表面每个液体原子具有相似的势能，这会影响蒸发过程的潜热。然而，最大截面积对应于最小界面热阻和最大单位面积相互作用能，这将增强固液界面处的传热。此外，具有最大截面积的纳米结构表面还获得了最大的液 - 气界面面积，从而增强了蒸发传热过程。
