Challenges in Microscale Conductive and Radiative Heat Transfer

1994 ◽  
Vol 116 (4) ◽  
pp. 799-807 ◽  
Author(s):  
C. L. Tien ◽  
G. Chen
Keyword(s):  
Heat Transfer ◽  
Radiative Heat ◽  
Energy Transport ◽  
Optoelectronic Devices ◽  
Transport Processes ◽  
Future Research ◽  
Conductive Heat ◽  
Microscale Heat Transfer ◽  
Definition Of ◽  
Thermal Energy Transport

This work addresses challenges in the emerging field of microlength scale radiative and conductive heat transfer in solids and recommends specific directions of future research. Microlength scale heat transfer involves thermal energy transport processes in which heat carrier characteristic lengths become comparable to each other or the characteristic device dimension. Identification of these characteristic lengths leads to the definition of different microscale heat transfer regimes. A review of the theoretical bases describing heat transfer in each regime is followed by a discussion of the obstacles confronted in current research. Engineering challenges are illustrated with the applications of microscale heat transfer in cryogenic systems, material processing, and electronic, optical, and optoelectronic devices. The experimental difficulties discussed have hampered the development of microscale heat transfer research and deserve great efforts to overcome them.

Introduction

1978 ◽  
Vol 288 (1355) ◽  
pp. 385-386
Keyword(s):  
Heat Transfer ◽  
Lower Mantle ◽  
Large Scale ◽  
Radiative Heat ◽  
Reasonable Doubt ◽  
Mantle Flow ◽  
Conductive Heat ◽  
Mantle Material ◽  
Radiative Processes ◽  
The Earth

During the last fifteen years, three major developments have influenced thinking on temperature distributions within the Earth and on the origin of magmas. Perhaps the most important was the recognition that large scale plate movements which have occurred at the Earth’s surface require large scale counterflow of mantle material in the solid state. The thermal diffusivity of mantle rocks and the scale of mantle flow are such that even if the flow velocity is as low as 1 mm/a, the temperature distribution within the Earth is governed by convective, rather than conductive, transfer of heat. This has meant that the majority of thermal models of the Earth’s interior have had to be discarded as irrelevant; nearly all were based on assumptions of conductive heat transfer with a transition downwards to radiative processes. It was a feature of these models that they all gave rather high temperatures in the lower mantle; indeed, in order to keep the lower mantle below its melting temperature it was commonly necessary both to invoke radiative heat transfer and to postulate concentration of nearly all the radioactive heat production in the upper few hundred kilometres. Today the approach is very different. Conductive calculations are thought to be appropriate for only the outermost part of the mantle — that part which is incorporated in the surface plates; below the plates and at their margins, which are zones of localized up welling or downward motion, temperatures are related to the circulating motions within the mantle. It is not clear at present how deep these motions extend; beyond reasonable doubt to 700 km, but possibly over the full depth of the mantle. Remaining constraints on the distribution of heat-producing elements are largely chemical rather than physical.

The Role of Radiative Heat Transfer With Participating Gases on the Temperature Distribution in Solid Oxide Fuel Cells

2004 ◽  
Author(s):  
J. D. J. VanderSteen ◽  
J. G. Pharoah
Keyword(s):  
Heat Transfer ◽  
Fuel Cells ◽  
Temperature Distribution ◽  
Solid Oxide Fuel Cells ◽  
Radiative Heat Transfer ◽  
Radiative Heat ◽  
Transport Processes ◽  
Solid Oxide ◽  
Oxide Fuel ◽  
Participating Media

Solid oxide fuel cell (SOFC) technology has been shown to be viable, but its profitability has not yet been seen. To achieve a high net efficiency at a low net cost, a detailed understanding of the transport processes both inside and outside of the SOFC stack is required. Of particular significance is an accurate determination of the temperature distribution because material properties, chemical kinetics and transport properties depend heavily on the temperature. Effective utilization of the heat can lead to a substantial increase in overall system efficiency and decrease in operating cost. Despite the extreme importance in accurately predicting temperature, the majority of SOFC modeling work ignores radiative heat transfer. SOFCs operate at temperatures around or above 1200 K, where radiation effects can be significant. In order to correctly predict the radiation heat transfer, participating gases must also be included. Water vapour and carbon dioxide can absorb, emit, and scatter radiation, and are present at the anode in high concentrations. This paper presents a thermal transport model for analyzing heat transfer and improving thermal management within planar SOFCs. The model was implemented using a commercial computational fluid dynamic (CFD) code and includes conduction, convection, and radiation in a participating media. It is clear from this study that radiation must be considered when modelling solid oxide fuel cells. The effect of participating media radiation was shown to be minimal in this geometry, but it is likely to be more important in tubular geometries.

HEAT TRANSFER AND THERMAL ENERGY TRANSPORT

2013 ◽  
pp. 35-48
Author(s):  
J.L. PEUBE ◽  
G.F. HEWITT ◽  
E.R.G. EcKERT ◽  
A.C. GRINGARTEN ◽  
E. HAHNE ◽  
...  
Keyword(s):  
Heat Transfer ◽  
Thermal Energy ◽  
Energy Transport ◽  
Thermal Energy Transport

Review of Microscale Heat Transfer

1994 ◽  
Vol 47 (9) ◽  
pp. 397-428 ◽  
Author(s):  
A. B. Duncan ◽  
G. P. Peterson
Keyword(s):  
Heat Transfer ◽  
Final Section ◽  
Radiative Heat ◽  
Heat Pipes ◽  
Liquid Films ◽  
Thin Liquid Films ◽  
Review Of The Literature ◽  
Conduction Heat Transfer ◽  
Microscale Heat Transfer ◽  
Micro Heat Pipes

A review of the literature in the area of microscale heat transfer is presented to provide a concise overview of the recent advances in this field of study. The review is divided into three major sections with each subdivided into subsections. The first section deals with the effects of size reductions in conduction heat transfer, and includes subsections on laser induced heating on the microscale and conduction in thin films. The second section addresses microscale forced convection and includes subsections on micro heat pipes, microscale boiling, and thin liquid films near the contact line. The final section examines the effects of small length scales on radiative heat transfer. The three major sections are followed by a summary that identifies, consolidates, and summarizes the most important advances in each of these three areas.

Adsorption-Based Thermal Rectifier

2015 ◽  
Author(s):  
Tadeh Avanessian ◽  
Gisuk Hwang
Keyword(s):  
Heat Transfer ◽  
Heat Transfer Rate ◽  
Thermal Energy ◽  
Transfer Rate ◽  
Energy Transport ◽  
Accommodation Coefficient ◽  
Thermal Rectification ◽  
Thermal Accommodation ◽  
Thermal Accommodation Coefficient ◽  
Thermal Energy Transport

Controlling thermal energy transport (thermal diode) for the desired direction is crucial to improve the efficiency of thermal energy transport, conversion, and storage systems as electrical diodes significantly impact on modern electronic systems. The degree of thermal rectification is measured by the difference between the heat transfer rate in favorable and unfavorable directions to the heat transfer rate in the unfavorable direction. A gas-filled, nano-gap structure with two different surface coatings is considered to design the thermal rectifier. In such a structure where the characteristic length scale is similar to the order of the mean free path of the fluid particles (Knudsen flow regime), the effective thermal conductivity is dominantly controlled by the gas-surface interaction, i.e., thermal accommodation coefficient. For the thermal rectification, the adsorption-based, nonlinear thermal accommodation coefficient change is a key design parameter. Here, these are examined using the kinetic theory for various pressure and temperature ranges. Optimal material selections are also discussed.

A Reduced Dimension Finite Volume Method for Radiative Heat Transfer in Axisymmetrical Cylinders

Volume 4 ◽  
2004 ◽  
Author(s):  
Weixue Tian ◽  
Wilson K. S. Chiu
Keyword(s):  
Heat Transfer ◽  
Finite Volume Method ◽  
Finite Volume ◽  
Radiative Heat Transfer ◽  
Radiative Heat ◽  
Control Volume ◽  
Heat Transfer Analysis ◽  
Radiative Energy ◽  
Conductive Heat ◽  
Volume Method

This paper presents a modified scheme to analyze the radiative heat transfer in axisymmetrical enclosures using the finite volume method. The modified scheme is derived from the conservation of radiative energy in an infinitely thin slice of an axisymmetrical cylinder. Therefore, the final discretized equations are based on a two-dimensional mesh in the spatial domain, and similar to meshes used for convective and conductive heat transfer analysis. The control angle overlap problem caused by misalignment of solid angles with control volume faces in the angular direction is eliminated. Error caused by the control volume face curvature is also eliminated. Comparison of results for several demonstration cases with literature yields satisfactory results.

scholarly journals Thermal analysis on natural convection coupled with radiative heat transfer in a saturated porous cavity

2021 ◽  
pp. 256-256
Author(s):  
Yuanyuan Chen ◽  
Yiwei Chen ◽  
Xuecheng Xu
Keyword(s):  
Heat Transfer ◽  
Radiative Heat Transfer ◽  
Radiative Heat ◽  
Energy Transport ◽  
Local Thermal Equilibrium ◽  
Radiative Energy ◽  
Transfer Coefficients ◽  
Interphase Heat Transfer ◽  
Porous Cavity ◽  
Rayleigh Numbers

Porous foam is an ideal material for enhancing radiative heat transfer in numerous thermal equipment. The solid skeletons of porous foams can absorb/ release radiative energy and transfer convective energy with the surrounding fluid in the pores. In this paper, the conduction-convection-radiation coupling heat transfer in a porous cavity is investigated. A local thermal nonequilibrium model is used to represent the energy transport during the solid and fluid phases. The heat flux caused by thermal radiation is obtained by solving the radiation transfer equation. The thermal and fluid fields are studied to discern various parameters, including the Planck numbers Pl , the modified Rayleigh numbers Ra , and the interphase heat transfer coefficients H . Our study indicates the following: (1) the effect of radiation can be neglected when Pl > 20; (2) the modified Rayleigh numbers have little influence on the solid temperature when the radiative heat transfer is dominant and the convective heat transfer between the two phases is weak; and (3) the local thermal-equilibrium can be formed when H exhibits high values.

Heat transfer and thermal energy transport

Energy ◽  
1977 ◽  
Vol 2 (1) ◽  
pp. 76-85
Author(s):  
J.L. Peube ◽  
C.F. Hewitt ◽  
E.R.G. Eckert ◽  
A.C. Gringarten ◽  
E. Hanne ◽  
...  
Keyword(s):  
Heat Transfer ◽  
Thermal Energy ◽  
Energy Transport ◽  
Thermal Energy Transport

scholarly journals Recent Advances in Thermal Metamaterials and Their Future Applications for Electronics Packaging

2020 ◽  
Vol 143 (1) ◽  
Author(s):  
Jae Choon Kim ◽  
Zongqing Ren ◽  
Anil Yuksel ◽  
Ercan M. Dede ◽  
Prabhakar R. Bandaru ◽  
...  
Keyword(s):  
Heat Transfer ◽  
Thermal Management ◽  
High Performance ◽  
State Of The Art ◽  
Electronics Packaging ◽  
The State ◽  
Future Research ◽  
Conductive Heat ◽  
Recent Advances ◽  
Conventional Cooling

Abstract Thermal metamaterials exhibit thermal properties that do not exist in nature but can be rationally designed to offer unique capabilities of controlling heat transfer. Recent advances have demonstrated successful manipulation of conductive heat transfer and led to novel heat guiding structures such as thermal cloaks, concentrators, etc. These advances imply new opportunities to guide heat transfer in complex systems and new packaging approaches as related to thermal management of electronics. Such aspects are important, as trends of electronics packaging toward higher power, higher density, and 2.5D/3D integration are making thermal management even more challenging. While conventional cooling solutions based on large thermal-conductivity materials as well as heat pipes and heat exchangers may dissipate the heat from a source to a sink in a uniform manner, thermal metamaterials could help dissipate the heat in a deterministic manner and avoid thermal crosstalk and local hot spots. This paper reviews recent advances of thermal metamaterials that are potentially relevant to electronics packaging. While providing an overview of the state-of-the-art and critical 2.5D/3D-integrated packaging challenges, this paper also discusses the implications of thermal metamaterials for the future of electronic packaging thermal management. Thermal metamaterials could provide a solution to nontrivial thermal management challenges. Future research will need to take on the new challenges in implementing the thermal metamaterial designs in high-performance heterogeneous packages to continue to advance the state-of-the-art in electronics packaging.

A Discussion of Nano-Length Scale Heat Conduction by Comparing the Ballistic-Diffusive Equation and Molecular Dynamics Simulation

2002 ◽  
Author(s):  
Pezhman Akbari ◽  
Boon-Keat Chui ◽  
Lisa Oravecz-Simpkins ◽  
John R. Lloyd
Keyword(s):  
Heat Transfer ◽  
Molecular Dynamics ◽  
Heat Conduction ◽  
Molecular Dynamics Simulation ◽  
Energy Transport ◽  
Dynamics Simulation ◽  
Length Scale ◽  
Conductive Heat ◽  
Using Data ◽  
Length Analysis

A discussion of two methods, the Ballistic-Diffusive, Chen [1,2], and Molecular Dynamics simulation, for solving heat conduction in the nano-length regime is presented. Using data from Chen [1,2], a solution to the Ballistic Diffusive equation is rescaled and compared with the Fourier solution. Results imply that care must be taken when rescaling and comparing equations used in the different length scale regimes because physical definitions (i.e. temperature) are not identical in the two regions (nano and macro length). Analysis of the molecular dynamics simulation shows its inadequacy to describe conductive heat transfer in the nanoscale. Based on the discussion, a modified energy transport map is devised.

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