Phase Change Physics
Theoretically understand and experimentally characterize interfacial heat and mass transfer
A Unified Relationship for Evaporation Kinetics
We experimentally realized and elucidated kinetically limited evaporation where the molecular gas dynamics close to the liquid-vapor interface dominate the overall transport. This process fundamentally dictates the performance of various evaporative systems and has received significant theoretical interest. However, experimental studies have been limited due to the difficulty of isolating the interfacial thermal resistance. Here, (…)
Modeling Evaporation from Nanopores
Evaporation from nanopores is of fundamental interest in nature and various industrial applications. We present a theoretical framework to elucidate evaporation and transport within nanopores by incorporating non-equilibrium effects due to the deviation from classical kinetic theory. Additionally, we include the non-local effects arising from phase-change in nanoporous geometries, and the self-regulation of the shape (…)
Liquid-Gas Interface
Manipulate liquid-gas interface behavior with surface engineering to promote/suppress transport phenomena
Traditionally Nonwetting Surface Made to Wet Mercury
We present a surface-engineering approach that turns all liquids highly wetting, including ultra-high surface tension fluids such as mercury. Previously, highly wetting behavior was only possible for intrinsically wetting liquid/material combinations. Here, we show that roughness made of reentrant structures allows for a metastable hemiwicking state even for nonwetting liquids as predicted by our surface (…)
Transport-Based Modeling of Nucleation on Electrodes
Bubble nucleation is ubiquitous in gas evolving reactions which are instrumental for a variety of electrochemical systems. Fundamental understanding of the nucleation process, which is critical to system optimization, remains limited as prior works generally focused on the thermodynamics and have not considered the coupling between surface geometries and different forms of transport in the (…)
Coexistence of Contact Line Pinning and Depinning
Textured surfaces are instrumental in water repellency or fluid wicking applications, where the pinning and depinning of the liquid–gas interface plays an important role. We demonstrate that a contact line can exhibit nonuniform behavior even without varying the local energy barrier. Around a cylindrical pillar, an interface can reside in an intermediate state where segments (…)
High-Performance Cooling
Leverage phase change together with novel materials and advanced fabrication to create efficient cooling solutions for buildings, food produce, and electronics
Insulated Cooling with Evaporation and Radiation (ICER)
Passive cooling relying on evaporation and radiation, while offering great energy-saving opportunities, faces challenges with low ambient cooling powers, environmental heating, high water usage, and climate condition constraints. To overcome these shortcomings, here, we present insulated cooling with evaporation and radiation (ICER), which utilizes a solar-reflecting layer, an infrared-emitting evaporative layer, and an infrared-transparent, solar-reflecting, (…)
Passive Subambient Cooling with Evaporation-Insulation Bilayer
Passive thermal management strategies show promise to alleviate the ever-increasing global energy demand for cooling which is projected to triple in 2050. Passive cooling also provides viable pathways to distribution and storage of food and pharmaceuticals in underdeveloped areas, given that >10% of the world’s population still have no access to electricity. Due to the (…)
Hierarchical High Flux Evaporative Cooling
High power density electronics are severely limited by current thermal management solutions which are unable to dissipate the necessary heat flux while maintaining safe junction temperatures for reliable operation. Further, a wide range of industrial systems requires using low surface tension liquids where heat transfer enhancement has proved challenging for boiling and evaporation. Here, we enable (…)