High-temp lightweight spacecraft radiators are critical to thermal control of nuclear-powered space missions. 3D-printed titanium loop heat pipes (LHPs) and titanium-encapsulated pyrolytic graphite fins will be demonstrated to simultaneously improve thermal performance and mechanical robustness for sustainable heat dissipation. LHPs will significantly simplify and enable flexible designs of the pumped flow loop, heat pipes, and radiator integration with single, connected structures, minimizing joints and improving reliability. The all-Ti LHP evaporator assembly will be 3D printed to minimize interfacial thermal resistances and CTE mismatch. Learn more about this NASA Early Stage Innovation project here. 

Flow boiling and condensation are crucial to the efficient and safe operation of electronics cooling, power generation, refrigeration, water purification, chemical processing, and among others. Two-phase flows are also subject to a wide range of interfacial instabilities which can lead to significant performance degradation. This project aims to probe liquid-vapor interfacial instabilities in flow boiling and condensation using wideband acoustic sensing, with a focus on both the critical heat flux and the flow regime transitions. Microgravity experiments will be performed using NASA's flow boiling and condensation experiment facility on the International Space Station. Learn more about this NSA/CASIS project here. 

Liquid-infused surfaces possess super slippery properties and potential benefits in self-cleaning and anti-fouling applications. We examine the drop impact dynamics on lubricated and liquid-infused surfaces, with a focus on probing the role of the entrained air layer prior to drop-film contact and during drop-film interactions. By integrating the total internal reflection microscopy, reflection interference microscopy, and high-speed imaging, the air film evolution and post-rupture liquid-liquid contact dynamics are directly visualized for different impact conditions and drop/film/substrate properties with nanometer spatial and microsecond temporal resolution. Learn more about this NSF project here. 

Li-air battery, with its usable energy density close to 1,700Wh/kg, has captured worldwide attention but suffers from low round-trip efficiency and rate capacity. The cathode microstructure and the Li2O2 formation can have a significant influence on the performance of non-aqueous Li-air batteries. We examine the effect of electrode microstructure and Li2O2 growth morphology on Li-air cell performance via combined multi-scale modeling and experiments. Our integrated program includes novel electrode fabrication, high fidelity multi-scale modeling, post-mortem and in-situ characterization, electrochemical testing, and high performance computing to probe the effects of electrode microstructure and Li2O2 growth morphology on cell performance. Learn more about this NSF project here. 

Understanding bubble dynamics during boiling is challenging due to the drastic changes in system parameters, such as nucleation, bubble morphology, temperature, and pressure. Principal component analysis, an unsupervised dimensionality reduction algorithm, is used to extract new physical descriptors of boiling heat transfer from pool boiling experimental images without labeling and training.