The Structure and Dynamics of Thin Film Liquid-Vapor Systems in Microgeometries

一个为期三年的项目将用于研究微米尺度系统中蒸发的结构和动力学。我们计划探索在0.1 - 20微米的典型尺度下，液-气系统在受限几何中的行为方式，其中大块半月板和被吸附的液膜之间的过渡区起主导作用。特别感兴趣的将是描述导致散装液相的薄液体过渡膜的作用，并已被证明对小型系统中的整体传热和传质有重要贡献。流体和表面化学、几何以及流体添加剂的影响将被系统地探讨。新的实验技术将用于测量液-固界面附近200nm的速度和温度，以及直接测量固体衬底上的薄液膜的厚度。将测量流体速度和蒸发速率，并与类似系统的理论和数值预测进行比较。智力优势：微观几何中两相系统的行为，特别是光滑表面上的薄液膜的特征仍然是一个至关重要的问题，并且在传热和流体力学文献中存在积极的争论。随着微工程继续向更小尺度推进，这些热输运问题的物理表征和建模变得更加相关和具有挑战性。高质量的实验数据对于指导该领域的模型和数值实验至关重要。更广泛的影响：在这项研究中获得的结果将有助于指导设计和分析大量微米尺度的传热系统（热管，毛细管泵送循环等），这些系统可用于多种应用，如芯片冷却，微系统中的热控制，空间电源应用等。该项目将支持培训一名研究生与PI密切合作。该项目还将涉及一名本科生。我们还将继续建立在我们招募弱势群体的成功历史上（通过领导力联盟），并将利用和参与布朗大学MRSEC外展项目，例如通过与K-12教师培训项目和高中生研究体验项目合作。最后，我们将继续与媒体制作方（如新星和探索频道）合作，为广大观众开发科学节目。

CBET-0854148Breuer A three year program will be conducted to study the structure and dynamics of evaporation in micron-scale systems. We plan to explore the manner in which liquid-vapor systems behave in confined geometries with typical scales of 0.1 - 20 microns where the role of the transitional zone between the bulk meniscus and the adsorbed liquid film becomes dominant. Of particular interest will be the description of the role of the thin liquid transition film that leads the bulk liquid phase and has been demonstrated to contribute significantly to the overall heat and mass transfer in small systems. The effects of fluid and surface chemistry, geometry, and the presence of fluid additives will be systematically explored. Novel experimental techniques will be used to measure velocities and temperatures in the 200 nm near the liquid-solid interface, as well as to directly measure the thickness of the thin liquid film on the solid substrate as it evolves. Measurements of fluid velocities and evaporation rates will be taken and compared with theoretical and numerical predictions for similar systems.Intellectual Merit: The behavior of two-phase systems in microgeometries, and in particular, the character of the thin liquid film on a smooth surface continues to be a problem of critical importance and one in which there is active debate in the heat transfer and fluid mechanics literature. As microengineering continues to push towards smaller scales, the characterization and modeling of the physics of these thermal transport problems becomes more relevant and challenging. High-quality experimental data are critical in providing guidance to models and numerical experiments in this field. Broader Impacts: The results obtained during this research will help guide design and analysis for a wealth of micron-scale heat transfer systems (heat pipes, capillary pumped loops, etc.) that can be used in a multitude of applications such as chip cooling, thermal control in micro-systems, space power applications, etc. The project will support the training of one graduate student to work closely with the PI. The project will also involve an undergraduate student. We will also continue to build on our successful history of recruiting under-represented groups (through the Leadership Alliance), and will leverage and participate with the Brown University MRSEC outreach program, for example by working with the K-12 Teacher Training Program and high school student Research Experience Program. Lastly, we will continue to work with media producers (such as NOVA and Discovery Channel) in the development of science programming for a wide audience.