CAREER: Understanding thermal transport across phase-change interfaces via in situ micro-Raman thermography

汽液相变包括蒸发、沸腾和冷凝，用于发电、微电子设备的冷却和建筑物的热控。在过去的十年中，纳米技术的进步使纳米工程设备具有优异的传热性能。虽然可以在宏观尺度上测量系统的热性能，但在微观尺度上了解相变边界发生了什么，对于设计下一代热器件是必要的。本研究的总体目标是开发一种可以直接探测相变区的温度测量技术，并进一步了解纳米结构存在下的液-汽相变热输运的微观机理。拟议的研究将通过将实践项目纳入高中和本科教学、接待本科研究人员和开发新的研究生课程，纳入教育和指导活动。此外，该项目计划扩大热流体工程的真实影响，从热质传递的角度研究传染病通过呼吸道飞沫的传播。拟议的研究旨在开发一种新的平台，基于与热流体室接口的显微拉曼光谱，以前所未有的精度和空间分辨率在线测量固-液-蒸汽接触线附近的温度。该平台使人们能够(I)研究表面微纳米结构在促进相变界面热传递中的作用，(Ii)开发多长度尺度结构来同时最大化热传递系数和临界热流密度，以及(Iii)通过详细的温度映射来了解与高温度梯度相关的相变过程。这项研究将在宏观热表征和微观精确热测量之间架起一座桥梁。通过这项工作获得的基本见解将导致高效的相变装置。此外，现场局部温度测量方法将成为研究包括冷凝、结霜和沸腾在内的相变过程的通用平台，为相变热传递的发展做出广泛贡献。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。

Liquid-vapor phase change including evaporation, boiling and condensation are utilized in power generation, cooling of micro-electronics, and thermal control of buildings. The advancement of nanotechnology over the last decade has enabled nanoengineered devices with superior heat transfer performance. Although the thermal performance at the macroscale system level can be measured, understanding what happens at the phase change boundary at the microscale is necessary to design the next-generation thermal devices. The overarching goal of this research is to develop a temperature measurement technique that can directly probe phase change region, and to further understand the microscopic mechanisms of liquid-vapor phase-change thermal transport in the presence of nanostructures. The proposed research will be integrated into education and mentoring activities by incorporating hands-on projects into high school and undergraduate teaching, hosting undergraduate researchers and developing new graduate courses. Furthermore, the project plans to broaden the real-world impact of thermo-fluids engineering by studying the transmission of infectious diseases through respiratory droplets from the perspective of heat and mass transfer.The proposed research aims to develop a novel platform, based on micro-Raman spectroscopy interfaced with a thermofluidic chamber, for in-situ measurement of temperature near the solid-liquid-vapor contact line with unprecedented accuracy and spatial resolution. This platform allows one to (i) investigate the role of surface micro and nanostructures in promoting the thermal transport across phase-change interfaces, (ii) develop multi-length-scale structures to maximize the heat transfer coefficient and the critical heat flux simultaneously, and (iii) understand phase change processes associated with high temperature gradients by detailed temperature mapping. The proposed research will bridge the gap between macroscopic thermal characterization and precise thermal measurement at the microscale. The fundamental insights gained through this work will lead to highly effective phase change devices. In addition, the in situ, local temperature measurement method will be a general platform to investigate phase change processes including condensation, frosting, and boiling, contributing broadly to the advancement of phase change heat transfer.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.