Phase-change phenomena including boiling, evaporation, condensation and icing are key processes in numerous engineering applications such as thermal management of electronics, power generation, building HVAC and desalination. 

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We will develop metrological methods with high spatial and temporal resolution to probe thermal transport near the three-phase contact region. Such capabilities will aid us in discovering avenues to approach theoretical thermal transport limits. We will also develop novel and scalable materials and structures across various length scales to achieve high heat transfer performance. Current effort includes the development of a micro-Raman thermometry platform to probe evaporation near the solid-liquid-vapor three-phase contact region, suppressing flow boiling instability using micro and nanoengineered structures, and high-speed IR imaging to resolve transient heat transfer. 

Multiphase fluid systems, including combinations of gases, liquids, and solids, are fundamental to various engineering applications such as thermal management, power generation, desalination, and advanced manufacturing.

Understanding and controlling the behavior of these systems can lead to significant advancements in efficiency and functionality.
We aim to develop innovative methods for manipulating multiphase fluid motion using photo-responsive surfactants. These surfactants alter their molecular structure in response to light, resulting in changes in interfacial tension. This phenomenon, known as the photo-Marangoni effect, can dynamically influence the movement of bubbles and droplets within the fluid.

Future generation of high-energy-density and fast-charging batteries promises to enable renewable energy technologies and zero-emission electric vehicles. One of the central challenges, besides material innovation, is the increasing heat generation and temperature heterogeneity, which accelerates capacity fade and poses safety concerns. 

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We aim to systematically study thermal processes in energy storage systems, from microscopic thermal characterization for mechanistic understanding to device level electrochemical-thermal co-engineering. We will investigate the effects of heterogeneous and extreme temperature environments on battery safety, storage and operation, develop platforms for battery internal temperature mapping, in-operando thermal diagnostic tools, and advanced battery thermal management. Current effort includes characterizing lithium-ion batteries hibernating through freeze-thaw processes using in situ optical and acoustic spectroscopy. These efforts will aid the development of future generation batteries with high performance and safe operation.

Water and energy are among the greatest challenges of the 21st century, yet current state-of-the-art desalination technologies including reverse osmosis and multi-stage flash distillation are still energy-intensive.

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We are developing a highly energy-efficient desalination system using solar or waste thermal energy and multi-stage thin-film phase change. We will enhance the thermal transport processes to more efficiently utilize energy, which can significantly reduce energy consumption compared to existing industrial desalination processes.

Temperature has been shown to be a critical factor impacting Additive Manufacturing (AM). During selective laser melting (SLM), the fast-scanning laser causes rapid heating, melting, followed by drastic shrinkage and circulation of the molten metal driven by temperature gradients. The resulting heat transfer and fluid flow affect the melt pool and the cooling rate, which in turn affect grain growth and the microstructure of the printed part. Previous efforts to optimize thermal processes in AM have mostly relied on trial and error and on tuning laser parameters such as power and scan rate, but a more detailed quantitative understanding of temperature effects in AM is still lacking.

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We perform detailed operando temperature measurement during metal AM and establish a quantitative understanding of how extreme thermal fields affect the microstructure of additively manufactured (AM) metals, which will enable real-time quality control and optimization of AM processes by tuning thermal parameters. Furthermore, we import 2D temperature measurement into a 3D numerical model to predict the temperature gradient, cooling rate, and solidification velocity at the liquid-solid boundary to gain insights into thermal-microstructure relationship.