We describe an optical beam deflection technique for measurements of the thermal diffusivity of fluid mixtures and suspensions of nanoparticles with a precision of better than 1%. Our approach is tested using the thermal conductivity of ethanol-water mixtures; in nearly pure ethanol, the increase in thermal conductivity with water concentration is a factor of 2 larger than predicted by effectiv...

Anomalous large thermal conductivity has been observed numerically and experimentally in one- and two-dimensional systems. There is an open debate about the role of conservation of momentum. We introduce a model whose thermal conductivity diverges in dimensions 1 and 2 if momentum is conserved, while it remains finite in dimension d > or = 3. We consider a system of harmonic oscillators perturb...

One of the most important physical factors related to the thermal conductivity of composites filled with graphene nanoplatelets (GNPs) is the dimensions of the GNPs, that is, their lateral size and thickness. In this study, we reveal the relationship between the thermal conductivity of polymer composites and the realistic size of GNP fillers within the polymer composites (measured using three-d...

We present a systematic study on the effect of surface chemistry on thermal transport in colloidal nanocrystal (NC) solids. Using PbS NCs as a model system, we vary ligand binding group (thiol, amine, and atomic halides), ligand length (ethanedithiol, butanedithiol, hexanedithiol, and octanedithiol), and NC diameter (3.3-8.2 nm). Our experiments reveal several findings: (i) The ligand choice ca...

Thermal and electrical transport in a new class of nanocomposites composed of random isotropic two-dimensional ensembles of nanotubes or nanowires in a substrate (host matrix) is considered for use in the channel region of thin-film transistors (TFTs). The random ensemble of nanotubes is generated numerically and each nanotube is discretized using a finite volume scheme. To simulate transport i...

Kurdistan Rasa grape is beautiful, delicious and black in color. It has some vitamins such as E, C and some protectors such as antioxidant. In order to design equipments and facilities for the drying, preservation and processing of Rasa grape, it is necessary to know about the specific heat and thermal conductivity. Therefore, the objectives of this study were to determine the specific heat and...

The anisotropic thermal conductivity of passivated black phosphorus (BP), a reactive two-dimensional material with strong in-plane anisotropy, is ascertained. The room-temperature thermal conductivity for three crystalline axes of exfoliated BP is measured by time-domain thermo-reflectance. The thermal conductivity along the zigzag direction is ≈2.5 times higher than that of the armchair direct...

In recent years many experimentalists have reported an anomalously enhanced thermal conductivity in liquid suspensions of nanoparticles. Despite the importance of this effect for heat transfer applications, no agreement has emerged about the mechanism of this phenomenon, or even about the experimentally observed magnitude of the enhancement. To address these issues, this paper presents a combin...

Suspended microdevices are employed to measure the in-plane electrical conductivity, thermal conductivity, and Seebeck coefficient of suspended poly(3,4-ethylenedioxythiophene) (PEDOT) thin films. The measured thermal conductivity is higher than previously reported for PEDOT and generally increases with the electrical conductivity. The increase exceeds that predicted by the Wiedemann-Franz law ...

Thermal rectification is a phenomenon in which thermal transport is preferred in one direction over the opposite. Though observations of thermal rectification have been elusive, it could be useful in many applications such as thermal management problems at the micro/nano scale for electronics cooling. The current work explores the possibility of thermal rectifying devices with the use of interf...