CAREER: Ultrafast Localized Plasmas in Dense Fluids: From Fundamental Phase-Change Phenomena and Diagnostics to Efficient Heat and Mass Transport

Energy and water are the interconnected foundations of our global society. Central to most thermo-electric energy conversion and water purification technologies are liquid-vapor phase-change processes such as boiling, evaporation and condensation. To improve these technologies that convert thermal energy to electrical energy or provide clean water, phase-change phenomena must be both efficient and controllable.

The goal of this CAREER project is to integrate research and education around the use of ultrafast (20-100 nanoseconds) and fast (0.1-10 microseconds) pulsed plasma discharges in liquids and vapors to probe, manipulate or tune and enhance heat and mass transfer processes during liquid-vapor phase change encountered in boiling and desalination processes. Plasma, one of the four fundamental states of matter, is an ionized and highly energetic state of matter with unique physical and optical properties (consider, for example, lightning).

By controlling the duration of a plasma in a dense fluid, such as liquid water, losses via heat transfer and electrolysis may be minimized, and the impact of the plasma on the fluid may be controlled. In this project, the plasma will be tailored to the applications. Ultrafast or non-thermal pulsed plasmas will be sued to measure temperature and species or locally perturb a fluid during boiling, and fast or thermal pulsed plasmas will be used to locally alter the state of the fluid in desalination processes.

The project will also leverage this cross-disciplinary approach to convey the importance of efficient energy conversion and water resource utilization to a diverse group of students, ranging from grades K-8 to the university level, in the Bryan-College Station area of Texas. The goals of these efforts are to engage, encourage, and support the pursuit of science-related higher education and to train informed, current/future consumers of our energy and water resources.

The intellectual focus of this project is the interaction between extremely short timescale pulsed non-thermal and thermal plasma discharges in dense fluids and the thermodynamic phase transitions that result from rapid energy deposition in the fluid. These plasma-fluid interactions will be experimentally characterized to fundamentally study highly transient liquid-vapor-solid phase-change and the physicochemical processes resulting from the controlled energy/timescale of pulsed plasma discharges in fluids.

The fundamental studies will be leveraged to develop novel optical diagnostic techniques to measure species concentration and vapor phase temperature in situ during phase-change heat transfer using a non-thermal plasma as the probe. The findings will also be used to tune and enhance heat/mass transfer processes during boiling heat transfer and water purification through on-demand and localized bubble nucleation via a non-thermal plasma and salt-water separations through a thermal plasma.

The plasma-fluid interaction framework will be leveraged as a novel vehicle to engage and introduce a diverse group of early-age students to energy conversion and clean water technologies and to spark their interest in science and engineering higher-education. The knowledge resulting from these research activities will also be actively integrated into thermal-fluid sciences curricula at the undergraduate and graduate levels to introduce and train students in state-of-the-art energy conversion and water purification technologies.

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.