Thermal Conductivity Modeling of Compacted Nanocomposites Using Phonon Boltzmann Model Equation
Date Issued
2008
Date
2008
Author(s)
Hsu, Jen-Chieh
Abstract
The equation of phonon radiative transfer (EPRT) is a nonlinear, integral, differential equation with many variables. It is difficult for us to solve the equation directly. If we simplify the relaxation time of collision term by Bhatnagar- -Gross-Krook Equation. The equation will become easily to cope with. In this paper, we deal with phase space where the discrete ordinate method is used for angular discretization; and using upwind scheme the deal with spatial discretization.anocomposites in superlattices are observed that may realize a similar thermal conductivity reduction and thermoelectric efficiency enhancements. So it provides us a way to increase the benefits of the nanoscale effects to thermoelectric materials in bulk form. If there are two species of nanocomposites, one is a material in the form of nanowires embedded in another host matrix material; the other is a discrete mixture of two different kinds of nanowires that are compacted. At the same stoichiometry, a nanocomposite in the form of discrete mixtures of nanowires does not have a continuous phase of material, so its thermal conductivity is lower than composites with nanowires embedded in a host material. n this paper, using EPRT with the discrete ordinate method to investigate simulation about the density of interface of one dimension superlattice, nanocomposites of nanowires embedded in another host matrix material, and nanocomposites of compacted silicon and germanium nanowire mixtures nanocompacted.esults show that the thermal conductivity of composites in the form of compacted silicon and germanium nanowire mixtures is lower than the composites with silicon nanowires embedded in a germanium matrix at the same atomic composition and characteristic size of the nanowires.inally, we will take our data to compare with the other study which simulation by Direct Monte Carlo Method.
Subjects
Equation of Phonon Radiative Transport
Discrete Ordinate Method
nanowire
nanocompacted
Type
thesis
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