Vertical single-wall carbon nanotube forests as plasmonic heat pipes

Enhanced Phase-Change Heat Transfer by Surface Wettability Control

The phase-change heat-transfer coefficient can be improved by several orders of magnitude through the design of micro-nanostructures on typical surfaces. However, with the rapid development of intelligent and integrated devices, there is an increasing desire to regulate the heat exchange form of the surface to adapt to various environmental requirements. This study concerns the design of a carbon nanotube array-based phase-change heat-transfer surface, which can switch its wettability between superhydrophobicity and superhydrophilicity. By installing this surface on a device that integrates boiling heat transfer and condensation heat transfer, the device can independently adjust the surface wettability for different heat-transfer requirements. As a result, this surface can enhance condensation heat-transfer coefficient over 90 % in the superhydrophobic state and enhance the boiling heat-transfer coefficient over 41 % in the superhydrophilic state. Surfaces with controllable wettability can aid development of a new generation of smart control technologies to actively regulate system and device temperatures.

Crumpled graphene ball-based broadband solar absorbers

Sheet-like graphene tends to stack with each other in thin films, resulting in relatively smooth microstructures with increased reflection as the thickness increases. In contrast, when the sheets are crumpled into a shape like paper balls, reflection is greatly reduced. In this work, crumpled graphene balls are found to be strong light absorbers in the visible and near-infrared regions. Average absorption of thin films made of crumpled graphene balls can reach up to 97.4% in the wavelength region of 350-2500 nm. When crumpled graphene balls are used as the solar absorber for the interfacial evaporation system, an evaporation efficiency of 84.6% was obtained under one sun at ambient pressure. Enhanced solar absorption of crumpled graphene balls, coupled with their aggregation-resistance and universal solution processability, makes them promising candidates for solar heating/distillation applications.

Li-ion battery cooling system integrates in nano-fluid environment

In this design challenge by the Texas Space Grant Consortium, the researchers design a cooling system for a lithium-ion battery. Lithium-ion batteries are an effective and reliable source of energy for small, portable devices. However, similar to other existing sources of energy, there is always a problem with overheating. The objective is to design a cooling system for lithium-ion batteries that will work in a zero gravity environment for orbital and interplanetary space systems. The system is to serve as a backup battery and a signal booster that can be incorporated into a spacesuit. The design must be able to effectively cool the batteries without the use of an atmosphere to carry away heat but also be a lightweight and reliable design. The design incorporates carbon nanotubes suspended in distilled water creating a nano-fluid environment. This design must include a failsafe in the event of thermal runaway, a problem common to lithium-ion batteries. This failsafe will completely shut off the system if the batteries reach a certain temperature. A cooling system that incorporates nano-fluids will achieve a lightweight and efficient way of cooling batteries.

Ultrafast thermal charging of inorganic nano-phase change material composites for solar thermal energy storage

Ultrafast charging of NG–PCM and CNT–PCM nanocomposites has been demonstrated using a conventional heating approach and direct solar illumination experimental setups.

Radiative Exchange between Graphitic Nanostructures: A Microscopic Perspective

Electromagnetic radiative heat exchange involving graphene nanostrucrures is studied using an atomistic approach based on the coupled dipole method modified by the fluctuation dissipation theorem. This method includes taking into account many-particle electromagnetic contributions and enables treating two or more nanostructures with nontrivial boundary conditions at different temperatures. We present a microscopic picture of the heat exchange process in graphene nanostructured based systems in terms of a transmission coefficient, characteristic temperature function, and atomic morphology. Our studies provide general pathways of near-field radiation control at the nanoscale.