نتایج جستجو برای: variable thermal conductivity

تعداد نتایج: 505932  

The intent of this analysis is to explore the influence of thermal radiation paired with variable thermal conductivity on MHD micropolar fluid flow over an upper surface. The novelty of the present model is to consider the fluid flow along an upper horizontal surface of a paraboloid of revolution (uhspr) with the porous medium.  This physical phenomenon is described by a set of coupled...

Mahdi Sahebi Mohammad-Reza Ebrahimnataj

Constructal design is used to study heat removal from a square heated body with a tree shaped high thermal conductivity pathways embedded in the body. The objective is to minimize the defined maximum dimensionless temperature difference for the body. The thermal conductivity of the body is low, and there is a uniform heat generation on it. The volume of the body is fixed. The amount of high con...

Journal: :transport phenomena in nano and micro scales 2014
s. akbarzadeh m. farhadi k. sedighi m. ebrahimi

in this paper, the measurement of the viscosity of zno in ethylene glycol, propylene glycol, mixture of ethylene glycol and water (60:40 by weight), and a mixture of propylene glycol and water (60:40 by weight) and the thermal conductivity in ethylene glycol and propylene glycol as base fluids in the range of temperature from 25 ºc to 60 ºc are investigated. the results indicate that as the tem...

Journal: :Advanced materials 2015
Hyejin Jang Joshua D Wood Christopher R Ryder Mark C Hersam David G Cahill

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...

2017
Jaeho Lee Woochul Lee Geoff Wehmeyer Scott Dhuey Deirdre L. Olynick Stefano Cabrini Chris Dames Jeffrey J. Urban Peidong Yang

Phonons can display both wave-like and particle-like behaviour during thermal transport. While thermal transport in silicon nanomeshes has been previously interpreted by phonon wave effects due to interference with periodic structures, as well as phonon particle effects including backscattering, the dominant mechanism responsible for thermal conductivity reductions below classical predictions s...

Journal: :Advanced materials 2015
Annie Weathers Zia Ullah Khan Robert Brooke Drew Evans Michael T Pettes Jens Wenzel Andreasen Xavier Crispin Li Shi

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 ...

2014
Jung J Kim Kwang-Soo Youm Mahmoud M Reda Taha

A numerical method to identify thermal conductivity from time history of one-dimensional temperature variations in thermal unsteady-state is proposed. The numerical method considers the change of specific heat and thermal conductivity with respect to temperature. Fire test of reinforced concrete (RC) columns was conducted using a standard fire to obtain time history of temperature variations in...

2014
Sivasankaran Harish Mitsuru Tabara Yoshifumi Ikoma Zenji Horita Yasuyuki Takata David G Cahill Masamichi Kohno

We report a dramatic and irreversible reduction in the lattice thermal conductivity of bulk crystalline silicon when subjected to intense plastic strain under a pressure of 24 GPa using high-pressure torsion (HPT). Thermal conductivity of the HPT-processed samples were measured using picosecond time domain thermoreflectance. Thermal conductivity measurements show that the HPT-processed samples ...

Journal: :The journal of physical chemistry letters 2014
Andrea Pisoni Jaćim Jaćimović Osor S Barišić Massimo Spina Richard Gaál László Forró Endre Horváth

We report on the temperature dependence of thermal conductivity of single crystalline and polycrystalline organometallic perovskite CH3NH3PbI3. The comparable absolute values and temperature dependence of the two samples' morphologies indicate the minor role of the grain boundaries on the heat transport. Theoretical modeling demonstrates the importance of the resonant scattering in both specime...

Journal: :The Review of scientific instruments 2013
Jun Liu Jie Zhu Miao Tian Xiaokun Gu Aaron Schmidt Ronggui Yang

The increasing interest in the extraordinary thermal properties of nanostructures has led to the development of various measurement techniques. Transient thermoreflectance method has emerged as a reliable measurement technique for thermal conductivity of thin films. In this method, the determination of thermal conductivity usually relies much on the accuracy of heat capacity input. For new nano...

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