UNS: Experimental and Theoretical Investigation of Thin Film Evaporation in Superhydrophobic-Superhydrophilic Hybrid Micro\Nanotextures

因为液体蒸发会带走表面的大量热量，所以需要快速蒸发。研究小组将制造新型表面，这种表面上的液体薄膜可以比典型的沸腾过程蒸发得更快。因此，这些表面能够在许多工业应用中要求的非常高的速率去除热量。不仅是研究生，来自达拉斯地区的K-12学生也将参与这个项目。与有核沸腾相比，薄膜蒸发在毛细管排芯结构中可能产生更高的传热速率。为了进一步增强薄膜蒸发传热，PI提出探索一种新的途径，利用电介质上的电润湿（EWOD）来启动和维持在热点表面装饰的微/纳米多孔双芯结构中的薄膜蒸发。PI将首先开发具有微纳米结构的多尺度纹理表面，并对其进行超疏水或超亲水性处理。EWOD流体操作将用于在表面产生精确控制的液体体积。该项目将集中于检测流体半月板分布和润湿流动动力学，在不同的表面结构上使用微piv（粒子成像测速）来确定在高热流通量存在下，表面纹理对排芯动力学和薄膜厚度的相互依赖性以及表面纹理对传热速率的影响。

Because liquid evaporation takes away a large amount of heat from a surface, rapid evaporation is desirable. The research team will fabricate new types of surfaces from which thin liquid films can evaporate faster than in a typical boiling process. As a consequence, these surfaces enable removing heat at very high rates which is demanded in many industrial applications. Not only graduate students but also K-12 students from the Dallas area will be involved in this project.Thin film evaporation in capillary wicking structures can potentially yield higher heat transfer rates as compared to those of nucleate boiling. To further enhance the film evaporation heat transfer, the PI proposes to explore a novel avenue with the help of electro-wetting on dielectric (EWOD) to initiate and sustain thin film evaporation in micro/nano porous bi-wick structures decorated on hot spot surfaces. The PI will first develop multi-scale textured surfaces with micro- and nano-scale structures with treatments to make them super-hydrophobic or super-hydrophilic. The EWOD fluidic operations will be used to generate precisely controlled liquid volume on the surface. The project will be concentrated on detecting fluid meniscus distributions and wetting flow dynamics, using micro-PIV (particle imaging velocimetry) on different surface structures to determine the interdependency of the surface texturing on the wicking dynamics and thin film thickness in the presence of high heat fluxes and the effect of surface texturing on heat transfer rates.