Nanoscale Heat Transfer
The transport processes of mass, momentum, and heat in nanoscale systems are dominated by the large surface-to-volume ratio inherent at this length scale. To understand these processes we have to extend our macroscale models to include the effect of the micro structure eg.: surface chemistry, atomic scale corrugation, and fluid- and and solid impurities. In this rearch we study nanoscale heat transfer and we apply tempeture gradients to drive solid and fluid nanoparticles.
Thermophoretic Motion of Gold and Water Nanodroplets Confined inside Carbon Nanotubes
We study the thermophoretic motion of solid gold nanoparticles and water nanodroplets confined inside carbon nanotubes using molecular dynamics simulations. The nanodroplet moves in the direction opposite to the imposed thermal gradient with a terminal velocity that is linearly proportional to the gradient. We find that the motion along the axial is associated with a solid body rotation of the water nanodroplet that follows the helical symmetry of the carbon nanotube.
Schematic of the water nanodroplet confined inside a carbon nanotube. A thermal gradient is imposed by heating the end sections (in red) of the carbon nanotube.
Thermophoretic motion of a solid gold nanoparticle confined inside a carbon nanotube.
Thermal Conductivity of Carbon Nanotubes in Aqueous Solutions
Carbon nanotube (CNT) suspensions in alpha-alkene liquids have exhibited marked increases in thermal conductivity, leading to interest in these systems for heat management applications. Pristine CNTs have large thermal conductivity in the axial direction, but small values have been observed in the radial direction between CNTs and surrounding media. The objective of our study is to determine the characteristics of the solution that can maximize this radial heat transfer.
Hexanamine mediates the thermal properties of solvated CNTs.
Hexanamine mediates the thermal properties of solvated CNTs. Hexanamine (CH3-(CH2)5-NH2) is added to the system to study the thermal resinstance of solvated CNTs. The results obtained from the NEMD simulations of the pristine carbon nanotube-water system reveal a significant jump in the water temperature at the interface.
Collaborators: Professor Chriostofer Hierold (ETHZ), Dr. Richard Jaffe (NASA Ames), Professor Eftimios Kaxiras (Harvard), Harvey Zambrano (Technical University of Denmark)
- Schoen, P.A.E., Walther, J.H. Poulikakos, D. and Koumoutsakos P., Phonon assisted thermophoretic motion of gold nanoparticles inside carbon nanotubes, Applied Physics Letters , 90, 253116, 2007 (Abstract) (pdf)
- Schoen, P.A.E., Walther, J.H., Arcidiacono, S. , Poulikakos, D. and Koumoutsakos P., Nanoparticle Traffic on Helical Tracks: Thermophoretc Mass Transport through Carbon Nanotubes, Nano Letters, 6(8), 1910-1917, 2006 (Abstract) (pdf)