ERI: Ultrafast Transiently Nucleated Laser Bubbles for Realistic Phenomenological Boiling Studies

ERI：用于现实唯象沸腾研究的超快瞬态成核激光气泡

• 批准号: 2301782
• 负责人: Navdeep Dhillon
• 金额: $ 20万
• 依托单位: California State University-Long Beach Foundation
• 依托单位国家: 美国
• 项目类别: Standard Grant
• 财政年份: 2023
• 资助国家: 美国
• 起止时间: 2023-05-01 至 2025-04-30
• 项目状态: 未结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=2301782&HistoricalAwards=false
• 关键词: ERI; Ultrafast; Transiently; Nucleated; Laser

Nucleate boiling is a phenomenon of utmost importance in major industries such as power generation, desalination, chemical processing, and thermal management. However, it remains poorly understood due to its inherent physical complexity and the random nature of vapor bubble formation on hot surfaces, preventing meaningful performance enhancements. Advanced high-speed optical and infrared imaging techniques have recently become available to experimentally study the dynamic and thermal behavior of growing bubbles. The problem, however, is the experimental difficulty in focusing on an individual bubble growth event amidst a huge mass of randomly forming and mutually interacting bubbles. By studying the physics of ultra-fast microscale liquid-vapor transitions, this project seeks to develop a novel laser-based technique to generate a controlled vapor bubble that is identical in its thermal and growth characteristics to randomly forming bubbles in nucleate boiling. This will enable ground-breaking parametric and phenomenological studies in boiling, potentially leading to large scale energy efficiency and throughput improvements in many thermal systems critical for the nation’s defense, infrastructure, and energy security. The project also encompasses significant educational and outreach activities, including research training of diverse undergraduate and graduate students at CSULB, development of a web-based engineering applications platform to promote scientific computational and programming skills, and outreach to local high school and community college students.The goal of this research study is to develop and characterize a novel laser-based controlled bubble generation technique and to illuminate the physics underlying laser pulse-induced homogeneous nucleation at a solid-liquid interface. The mechanism of this ultra-fast non-equilibrium nucleation, which acts as an artificial nucleation site for the controlled bubble, has largely been unexplored, both experimentally and theoretically. This project undertakes rigorous experimental studies and theoretical/CFD analysis to implement the laser-based phenomenological-boiling-studies platform and fill significant scientific gaps in the understanding of near-wall non-equilibrium homogeneous nucleation in two specific aims: (i) Demonstrate laser-induced artificial bubble generation and characterize the key laser parameters and (ii) Identify the critical near-wall homogeneous bubble nucleation temperature using parametric nucleation experiments and modeling. On the experimental side, optical high-speed imaging studies will be performed using a focused-laser setup and an advanced pool boiling facility. Theoretical analysis and CFD simulations will be used to model the thermal evolution of the laser hotspot in nucleation. Results of this study will lay the groundwork for a new theory on near-wall non-equilibrium homogeneous vapor nucleation.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.

核沸腾是发电、海水淡化、化学加工、热管理等主要行业中的一种非常重要的现象。然而，由于其固有的物理复杂性和热表面上蒸汽气泡形成的随机性质，人们对它的了解仍然很少，从而阻碍了有意义的性能改进。先进的高速光学和红外成像技术最近已经可以用来实验研究不断增长的气泡的动态和热行为。然而，问题在于，在大量随机形成并相互作用的气泡中，关注单个气泡增长事件的实验难度很大。通过研究超快速微尺度气液相变的物理学，该项目试图开发一种新的基于激光的技术来产生受控汽泡，该气泡在热和生长特性上与核态沸腾中随机形成的气泡相同。这将使开创性的沸腾参数和现象学研究成为可能，可能导致对国家国防、基础设施和能源安全至关重要的许多热力系统的大规模能效和吞吐量改进。该项目还包括重要的教育和推广活动，包括在CSULB对不同的本科生和研究生进行研究培训，开发基于网络的工程应用平台以促进科学计算和编程技能，以及向当地高中和社区大学学生推广。这项研究的目标是开发和表征一种新的基于激光的可控气泡产生技术，并阐明激光脉冲诱导固-液界面均质成核的物理基础。这种超快非平衡成核的机制，作为受控气泡的人工成核点，在很大程度上还没有从实验和理论上得到探索。该项目开展了严格的实验研究和理论/CFD分析，以实现基于激光的唯象沸腾研究平台，并填补了在理解近壁非平衡均匀成核方面的重大科学空白，具体目的有两个：(I)演示激光诱导的人工气泡的产生并表征关键的激光参数；(Ii)通过参数成核实验和建模确定临界近壁均匀气泡成核温度。在实验方面，将使用聚焦激光装置和先进的池沸腾设备进行光学高速成像研究。采用理论分析和CFD模拟相结合的方法，对激光成核热点的热演化过程进行了模拟。这项研究的结果将为近壁非平衡均匀蒸汽成核的新理论奠定基础。这一奖项反映了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。