CAREER: Uncover contact line dynamics during thin film evaporation on micro/nano-engineered surfaces with combined velocimetry, thermometry, and interferometry

功率密度不断增加的计算机和电子产品已经成为我们日常生活中不可或缺的一部分，以支持我们的学习、通信、驾驶和其他应用。有效的热管理技术对于将这些设备冷却到安全温度以保持其高性能至关重要。薄膜蒸发是一种基于液体冷却剂连续蒸发的冷却策略，具有设计简单、制冷量大、稳定性高等优点，是一种很有发展前途的冷却策略。通过引入微柱和纳米孔等微纳米结构，近年来薄膜蒸发的冷却能力有了很大的提高，但由于缺乏对微观和纳米尺度下的详细流动和热特性的基本了解，仍然远远低于理论预测。这个职业项目致力于通过精确测量通常厚度为几微米的薄冷却剂膜内的流动速度、膜形状和温度，来研究蒸发界面上的流体流动和热传输过程。将通过在蒙大拿州立大学建立一个热流体教学实验室，将所获得的知识纳入教育和外联活动，并编写针对普通公众和学童的教材，特别强调农村社区和代表性不足群体的教材。该项目的总体目标是通过创新的实验和建模工作，通过量化三维速度场、界面温度和界面轮廓，促进对蒸发界面上的流动、热传输和接触线动力学的基本理解。具体地说，项目团队将(I)采用散光粒子跟踪测速、荧光测温和干涉显微镜相结合的方法对微结构表面进行测量，(Ii)使用纳米级量子点温度计和环境扫描电子显微镜来量化纳米孔内的薄膜温度和半月面动力学，(Iii)通过引入Marangoni流来开发微尺度薄膜蒸发模型，提高了模型的精度。这项研究将以高空间和时间分辨率表征蒸发薄膜的芯吸动力学、汽液界面温度、曲率和半月面动力学，这将允许精确确定容纳系数和量化Marangoni效应，从而填补当前的知识空白，并为下一代预测工具提供信息。该项目由热传输过程计划和既定的刺激竞争研究计划(EPSCoR)联合资助。该奖项反映了NSF的法定使命，并通过使用基金会的智力优势和更广泛的影响审查标准进行评估，被认为值得支持。

Computers and electronics with ever-increasing power densities have become an indispensable part of our daily life to support our learning, communication, driving, and other applications. Effective thermal management technologies are essential to cool these devices to a safe temperature to sustain their high performance. Thin film evaporation, based on continuous evaporation of very thin films of liquid coolant, is a promising cooling strategy due to its simple design, high cooling capacity, and high stability. By incorporating micro/nano-structures such as micro-pillars and nano-pores, the cooling capacity of thin film evaporation has been significantly improved in recent years but is still much lower than theory predictions, due to the lack of fundamental understanding, especially the detailed flow and thermal characteristics at microscopic and nanoscopic scales. This CAREER project seeks to study fluid flow and thermal transport processes at evaporating interfaces by accurately measuring the flow speed, film shape and temperature within thin coolant films that are typically a few micrometers thick. The knowledge gained will be integrated into educational and outreach activities by establishing a thermal-fluid instructional laboratory at Montana State University and creating educational materials targeting the general public and school children with a special emphasis on those from rural communities and underrepresented groups. The overarching goal of this project is to advance the fundamental understanding of the flow, thermal transport, and contact line dynamics at evaporating interfaces via quantifying 3D velocity fields, interface temperature, and interface profile, enabled by innovative experiments and modeling efforts. Specifically, the project team will (i) employ combined astigmatism particle tracking velocimetry, fluorescence thermometry and interference microscopy to perform measurements on micro-structured surfaces, (ii) quantify film temperature and meniscus dynamics within nanopores using nanoscale quantum dot thermometers and environmental scanning electron microscopy, and (iii) develop a microscale model for thin film evaporation on micro-structured surfaces with improved accuracy by incorporating Marangoni flows. The research will characterize the wicking dynamics, liquid-vapor interface temperature, curvature and meniscus dynamics of thin evaporating films with high spatial and temporal resolutions, which will allow precise determination of the accommodation coefficient and the quantification of Marangoni effects, thus filling in current knowledge gaps and informing the next generation of predictive tools.This project is jointly funded by the Thermal Transport Processes Program and the Established Program to Stimulate Competitive Research (EPSCoR).This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.