A Hybrid Phonon Gas Model for Transient Ballistic-Diffusive Heat Transport

2013 ◽  
Vol 135 (4) ◽  
Author(s):  
Yanbao Ma
Keyword(s):  
Heat Conduction ◽  
Heat Transport ◽  
Heat Pulse ◽  
Heat Energy ◽  
New Model ◽  
Conduction Mechanisms ◽  
Transverse Phonon ◽  
Numerical Tools ◽  
Thermal Pulses

We present a continuum hybrid phonon gas model to describe transient ballistic-diffusive heat transport. In this model, heat energy is carried by a mixture of longitudinal and transverse phonon gases so that the distinction between longitudinal and transverse phonon excitations is taken into account. This new model is validated by the successful reconstruction of benchmark cases of heat-pulse experiments in NaF, which have never been completely reconstructed before. It is elucidated how thermal pulses are transmitted by longitudinal and transverse phonon gases. This model not only helps us yield new insight in transient ballistic-diffusive heat conduction mechanisms but also provides numerical tools to study transient ballistic-diffusive heat conduction in nanoelectronic and modern optoelectronics.

Heat Pulse Propagation Along Silicon Nanofilms

2012 ◽  
Author(s):  
Yanbao Ma
Keyword(s):  
Thin Film ◽  
Heat Conduction ◽  
Numerical Model ◽  
Knudsen Number ◽  
Pulse Propagation ◽  
Heat Pulse ◽  
Phonon Transport ◽  
Similarity Parameter ◽  
Ballistic Phonons ◽  
Thermal Pulses

Recent advances in nanotechnology create a demand for greater scientific understanding of the transient ballistic phonon transport at the nanoscale. It is believed that ballistic phonons may travel for long distances without destruction, but it is unclear how far they can travel. Here, a numerical model is developed to study phonon transport in silicon nanofilms. It is elucidated how thermal pulses are transmitted in silicon nanofilms by longitudinal, ballistic transverse and dispersive transverse phonons. It is found that both ballistic longitudinal and ballistic transverse phonons are highly dissipative so they can only travel for short distances, while dispersive transverse phonons at lower frequencies are less dissipative and can travel for longer distances. There exists a similarity parameter (Knudsen number) in thin-film heat conduction with different thicknesses.

scholarly journals A new viewpoint on theory of the scaling-law heat conduction process

2021 ◽  
Vol 25 (6 Part B) ◽  
pp. 4505-4513
Author(s):  
Xiao-Jun Yang ◽  
Ping Cui ◽  
Jian-Gen Liu
Keyword(s):  
Heat Conduction ◽  
Heat Transport ◽  
Transport System ◽  
Heat Conduction Problem ◽  
Scaling Law ◽  
Linear Scaling ◽  
New Model ◽  
Conduction Process ◽  
Vector Calculus ◽  
Heat Conduction Process

In this article, we suggest a new model for the heat-conduction problem by us?ing the scaling-law vector calculus with Mandelbrot scaling law. The linear and non-linear scaling-law heat conduction equations are considered as analogues to the work of Fourier, Laplace, and Burgers. The obtained results are considered as typical examples to deal with the Mandelbrots scaling-law phenomena in heat transport system.

scholarly journals Theories and heat pulse experiments of non-Fourier heat conduction

2016 ◽  
Vol 7 (2) ◽  
pp. 150-166 ◽  
Author(s):  
Péter Ván
Keyword(s):  
Heat Conduction ◽  
Heat Pulse ◽  
Theoretical Background ◽  
Point Of View ◽  
Experimental Basis ◽  
Equilibrium Thermodynamics ◽  
Fourier Heat Conduction ◽  
Non Equilibrium

Abstract The experimental basis and theoretical background of non-Fourier heat conduction is shortly reviewed from the point of view of non-equilibrium thermodynamics. The performance of different theories is compared in case of heat pulse experiments.

Heat conduction mechanisms in hot pressed ZrB2 and ZrB2–SiC composites

2013 ◽  
Vol 33 (10) ◽  
pp. 1615-1624 ◽  
Author(s):  
Manish Patel ◽  
V.V. Bhanu Prasad ◽  
Vikram Jayaram
Keyword(s):  
Heat Conduction ◽  
Conduction Mechanisms ◽  
Sic Composites

Anomalous Heat Conduction, Diffusion and Heat Rectification in Nanoscale Structures

2009 ◽  
Author(s):  
Gang Zhang ◽  
Nuo Yang ◽  
Gang Wu ◽  
Baowen Li
Keyword(s):  
Thermal Conductivity ◽  
Heat Conduction ◽  
Heat Transport ◽  
Nano Materials ◽  
Fourier Law ◽  
Nanoscale Structures ◽  
Recent Developments ◽  
Theoretical Results ◽  
Good Agreement ◽  
Anomalous Heat

In this paper, we report the recent developments in the study of heat transport in nano materials. First of all, we show that phonon transports in nanotube super-diffusively which leads to a length dependence thermal conductivity, thus breaks down the Fourier law. Then we discuss how the introduction of isotope doping can reduce the thermal conductivity efficiently. The theoretical results are in good agreement with experimental ones. Finally, we will demonstrate that nanoscale structures are promising candidates for heat rectification.

Thermal Conductivity and Phonon Engineering in Low-Dimensional Structures

1998 ◽  
Vol 545 ◽  
Author(s):  
G. Chen ◽  
S. G. Volz ◽  
T. Borca-Tasciuc ◽  
T. Zeng ◽  
D. Song ◽  
...  
Keyword(s):  
Thermal Conductivity ◽  
Heat Conduction ◽  
Transport Equation ◽  
Boltzmann Transport Equation ◽  
Dynamics Simulation ◽  
Boltzmann Transport ◽  
Model Based ◽  
Conduction Mechanisms ◽  
Interface Scattering ◽  
Low Dimensional

AbstractUnderstanding phonon heat conduction mechanisms in low-dimensional structures is of critical importance for low-dimensional thermoelectricity. In this paper, we discuss heat conduction mechanisms in two-dimensional (2D) and one-dimensional (1D) structures. Models based on both the phonon wave picture and particle picture are developed for heat conduction in 2D superlattices. The phonon wave model, based on the acoustic wave equations, includes the effects of phonon interference and tunneling, while the particle model, based on the Boltzmann transport equation, treats the internal as well interface scattering of phonons. For 1D systems, both the Boltzmann transport equation and molecular dynamics simulation approaches are employed. Comparing the modeling results with experimental data suggest that the interface scattering of phonons plays a crucial role in the thermal conductivity of low-dimensional structures. We also discuss the minimum thermal conductivity of low-dimensional structures based on a generalized thermal conductivity integral, and suggest that the minimum thermal conductivities of low-dimensional systems may differ from those of their corresponding bulk materials. The discussion leads to alternative ways to reduce thermal conductivity based on the propagating phonon modes.

scholarly journals Nonlinear Heat Transport in Superlattices with Mobile Defects

Entropy ◽  
2019 ◽  
Vol 21 (12) ◽  
pp. 1200 ◽  
Author(s):  
David Jou ◽  
Liliana Restuccia
Keyword(s):  
Thermal Conductivity ◽  
Heat Flux ◽  
Heat Conduction ◽  
Thermal Resistance ◽  
Heat Transport ◽  
Concentration Dependence ◽  
Transport Coefficients ◽  
Nonlinear Behavior ◽  
Strongly Nonlinear

We consider heat conduction in a superlattice with mobile defects, which reduce the thermal conductivity of the material. If the defects may be dragged by the heat flux, and if they are stopped at the interfaces of the superlattice, it is seen that the effective thermal resistance of the layers will depend on the heat flux. Thus, the concentration dependence of the transport coefficients plus the mobility of the defects lead to a strongly nonlinear behavior of heat transport, which may be used in some cases as a basis for thermal transistors.

scholarly journals Heat-pulse propagation along nonequilibrium nanowires in thermomass theory

2016 ◽  
Vol 7 (2) ◽  
pp. 39-55
Author(s):  
Antonio Sellitto ◽  
Patrizia Rogolino ◽  
Isabella Carlomagno
Keyword(s):  
Temperature Gradient ◽  
Transport Equation ◽  
Heat Transport ◽  
Pulse Propagation ◽  
Heat Pulse ◽  
Average Temperature ◽  
Temperature Ranges ◽  
Heat Transport Equation ◽  
Heat Pulses ◽  
Theoretical Proposal

AbstractWe analyze the consequences of the nonlinear terms in the heat-transport equation of the thermomass theory on heat pulses propagating in a nanowire in nonequilibrium situations. As a consequence of the temperature dependence of the speeds of propagation, in temperature ranges wherein the specific heat shows negligible variations, heat pulses will shrink (or extend) spatially, and will increase (or decrease) their average temperature when propagating along a temperature gradient. A comparison with the results predicted by a different theoretical proposal on the shape of a propagating heat pulse is made, too.

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