GOALI: Local thermoreflectance measurement of evaporative heat transfer in the thin film region of a dynamic meniscus

目标：动态弯月面薄膜区域蒸发传热的局部热反射测量

• 批准号: 1804752
• 负责人: Jonathan Malen
• 金额: $ 33.3万
• 依托单位: Carnegie-Mellon University
• 依托单位国家: 美国
• 项目类别: Standard Grant
• 财政年份: 2018
• 资助国家: 美国
• 起止时间: 2018-09-01 至 2022-01-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=1804752&HistoricalAwards=false
• 关键词: GOALI; Local; thermoreflectance; measurement; evaporative

Cooling by evaporation is used in a wide range of important industrial and power-generation processes. Improved understanding of evaporative heat transfer will lead to more energy-efficient equipment designs for the thermal management industry. The objective of this project is to measure local evaporative heat transfer in the thin film region of menisci with unprecedented spatial resolution. Theory suggests that heat flux will spike in the thin evaporating region of the meniscus, yet prior experiments cannot adequately resolve this key feature. Thermal management technologies exploit this region using micro/nanostructured surfaces that expand the meniscus. New experiments that measure local evaporation are critical to improve such nanostructure designs for the thermal management industry but are also of fundamental value to meniscus driven processes like boiling and desalination. The educational activities will expose students to industry-driven academic research through curriculum development, guest seminars, and internships. Through collaboration with a local non-profit, regular outreach opportunities will be formalized with underrepresented middle school students. Evaporative heat fluxes will be measured using frequency domain thermoreflectance (FDTR) and simultaneous measurements of meniscus thickness will be made using interferometry. The microscale extent of the thin film region (100-102 ?gm in-plane, 100-103 nm thick) and sub-Kelvin liquid-vapor temperature differences (superheats) challenge conventional thermometry, while parasitic conduction into the underlying substrate obfuscates actual evaporative heat fluxes. As a result, prior measurements effectively integrate evaporation rates over large swaths of liquid-vapor interface, permitting a range of satisfactory theoretical interpretations. Thermoreflectance approaches, which have revolutionized heat conduction research, will help to overcome these barriers in thin film evaporation metrology. These accurate measurements of the evaporative heat flux (?b10%) will uniquely discern the role of surface attractive forces and accommodation coefficients on thin film evaporation.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.

蒸发冷却广泛应用于重要的工业和发电过程。 对蒸发传热的更好理解将为热管理行业带来更节能的设备设计。 本项目的目的是测量局部蒸发传热的薄膜区域的Rupci前所未有的空间分辨率。 理论表明，热通量将在弯月面的薄蒸发区域中达到峰值，然而先前的实验不能充分解决这个关键特征。 热管理技术利用微/纳米结构表面扩展弯月面来利用该区域。测量局部蒸发的新实验对于改善热管理行业的这种纳米结构设计至关重要，但对于像沸腾和脱盐这样的弯月面驱动过程也具有根本价值。教育活动将通过课程开发，客座研讨会和实习让学生接触行业驱动的学术研究。 通过与当地非营利组织合作，将与代表性不足的中学生正式确定定期外联机会。 蒸发热通量将使用频域热反射（FDTR）和弯月面厚度的同时测量将使用干涉测量。薄膜区域的微尺度范围（100-102？面内100-103 nm厚）和低于开尔文的液体-蒸汽温差（过热）挑战了传统的温度测量法，而进入下面的衬底的寄生传导使实际的蒸发热通量模糊。因此，先前的测量有效地整合了大片的液体-蒸汽界面的蒸发速率，允许一系列令人满意的理论解释。 热反射法是热传导研究的一个革命性的方法，它将有助于克服薄膜蒸发计量中的这些障碍。这些蒸发热通量的精确测量（？b10%）将独特地辨别表面吸引力和调节系数对薄膜蒸发的作用。该奖项反映了NSF的法定使命，并通过使用基金会的知识价值和更广泛的影响审查标准进行评估，被认为值得支持。

项目成果

Hot-spot thermal management by phase change materials enhanced by spatially graded metal meshes

• DOI: 10.1016/j.ijheatmasstransfer.2019.119153
• 发表时间: 2020-04
• 期刊: International Journal of Heat and Mass Transfer
• 影响因子: 5.2
• 作者: L. Wei;J. Malen

Assessing the impact of disjoining pressure on thin-film evaporation with atomistic simulation and kinetic theory

• DOI: 10.1063/5.0010467
• 发表时间: 2020-05
• 期刊: Applied Physics Letters
• 影响因子: 4
• 作者: Xiaoman Wang;Yang Li;J. Malen;A. McGaughey