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

California State University-Long Beach Foundation, Long Beach CA

Investigators

Abstract

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.