Final Report: Thermal Conductance of Solid-Liquid Interfaces

Cahil, David, G. ; Braun, Paul, V.

The Board of Trustees of the University of Illinois, Champaign, IL

关键词: Modifications;    Nanoscale Composite Materials;    Thermal Conductivity;    Nanofluids;    Nanoscale Thermal Transport;   

DOI  :  10.2172/885425
RP-ID  :  DOE/ER/45938-FR.UIUC.A8525
RP-ID  :  FG02-01ER45938
RP-ID  :  885425

美国|英语

来源: UNT Digital Library

【 摘 要 】

Research supported by this grant has significantly advanced fundamental understanding of the thermal conductance of solid-liquid interfaces, and the thermal conductivity of nanofluids and nanoscale composite materials. • The thermal conductance of interfaces between carbon nanotubes and a surrounding matrix of organic molecules is exceptionally small and this small value of the interface conductance limits the enhancement in thermal conductivity that can be achieved by loading a fluid or a polymer with nanotubes. • The thermal conductance of interfaces between metal nanoparticles coated with hydrophilic surfactants and water is relatively high and surprisingly independent of the details of the chemical structure of the surfactant. • We extended our experimental methods to enable studies of planar interfaces between surfactant-coated metals and water where the chemical functionalization can be varied between strongly hydrophobic and strongly hydrophilic. The thermal conductance of hydrophobic interfaces establishes an upper-limit of 0.25 nm on the thickness of the vapor-layer that is often proposed to exist at hydrophobic interfaces. • Our high-precision measurements of fluid suspensions show that the thermal conductivity of fluids is not significantly enhanced by loading with a small volume fraction of spherical nanoparticles. These experimental results directly contradict some of the anomalous results in the recent literature and also rule-out proposed mechanisms for the enhanced thermal conductivity of nanofluids that are based on modification of the fluid thermal conductivity by the coupling of fluid motion and the Brownian motion of the nanoparticles.