Heat Conduction in Multilayered Rectangular Domains

2007 ◽  
Vol 129 (4) ◽  
pp. 440-451 ◽  
Author(s):  
James Geer ◽  
Anand Desai ◽  
Bahgat Sammakia

This paper presents the results of an analytical study of steady state heat conduction in multiple rectangular domains. Any finite number of domains that are equally sized (in plane) may be considered in the current analysis. The thermal conductivity and thickness of these domains may be different. The entire geometry composed of these connected domains is considered as adiabatic on the lateral surfaces and can be subjected to a wide range of thermal boundary conditions at the top and bottom. For example, the bottom of the stack may be adiabatic, while the top of the stack may be exposed to a uniform heat transfer coefficient. Spatially varying heat generation rates can be applied in each of the domains. The solutions are found to be in agreement with known solutions for simpler geometries. The analytical solution presented here is very general in that it takes into account the interface resistances between the layers. One application of this analytical study relates to the thermal management of three-dimensional stacks of computer devices and interconnect layers. The devices would have spatially nonuniform power dissipation within them, and the interconnect layers would have a significantly lower thermal conductivity than the devices. Interfacial defects, such as delamination or air voids, between the devices and the interconnect layers may be included in the model. Another possible application is to the study of hot spots in a chip stack with nonuniform heat generation. Many other potential applications may also be simulated.

Author(s):  
Anand Desai ◽  
James Geer ◽  
Bahgat Sammakia

This paper presents the results of an analytical study of steady state heat conduction in multiple rectangular domains. Any finite number of such domains may be considered in the current study. The thermal conductivity and thickness of these domains may be different. The entire geometry composed of these connected domains is considered as adiabatic on the lateral surfaces and can be subjected to uniform convective cooling at one end. The other end of the geometry may be adiabatic and a specified, spatially varying heat generation rate can be applied in each of the domains. The solutions are found to be in agreement with known solutions for simpler geometries. The analytical solution presented here is very general in that it takes into account the interface resistances between the layers. One application of this analytical study relates to the thermal management of a 3-D stack of devices and interconnect layers. Another possible application is to the study of hotspots in a chip stack with non uniform heat generation. Many other potential applications may also be simulated.


Author(s):  
Bo Dan ◽  
James F. Geer ◽  
Bahgat G. Sammakia

The current paper presents the results of an analytical study of steady state heat conduction in a rectangular tube with eccentric hot spots on both the top and the bottom surfaces. The rectangular domain is assumed to be adiabatic on the lateral surfaces and a single or multiple eccentric hot spots can be applied on the top and bottom surfaces. Isothermal, heat flux or convection boundary conditions can be applied on the hot spots. Because the hot spots are eccentric, the spreading resistance becomes a dominant factor in heat conduction in the tube. The multiple hot spots, multiple layer and combination problems are also studied in the current paper. The solutions can be applied to the thermal management of three-dimensional stacks of electronic devices, the interconnect layers and the thermoelectric devices.


1968 ◽  
Vol 90 (1) ◽  
pp. 103-108 ◽  
Author(s):  
E. M. Sparrow ◽  
A. Haji-Sheikh

A method of analysis is described which yields closed-form solutions for two-dimensional heat conduction problems for bodies of arbitrary shape. Three-dimensional problems can also be treated without basic conceptual changes. The method accommodates rather general thermal boundary conditions including arbitrary spatial variations in surface temperature or in surface heat flux, or a convective (or linearized radiative) exchange with a fluid having spatially varying temperature and heat transfer coefficient. For transient problems, the initial temperature may be arbitrarily distributed. Once the solution method has been developed, its practical realization is rather direct, being facilitated by the use of widely available computer routines. A numerical example to illustrate the method is worked out.


Author(s):  
Bo Dan ◽  
James F. Geer ◽  
Bahgat G. Sammakia

The current paper presents the results of an analytical study of steady state heat conduction in a rectangular tube with eccentric hot spots on both the top and the bottom surfaces. The rectangular domain is assumed to be adiabatic on the lateral surfaces and a single or multiple eccentric hot spots can be applied on the top and bottom surfaces. Isothermal, heat flux, or convection boundary conditions can be applied on the hot spots. Because the hot spots are eccentric, the spreading resistance becomes a dominant factor in heat conduction in the tube. The multiple hot spots, multiple layers and combination problems are also studied in the current paper. The solutions can be applied to the thermal management of three-dimensional stacks of electronic devices, the interconnect layers and the thermoelectric devices.


Author(s):  
Najib Hdhiri ◽  
Brahim Ben Beya

Purpose The purpose of this study is to investigate the effects of heat generation or absorption on heat transfer and fluid flow within two- and three-dimensional enclosure for homogeneous medium filled with different metal liquid. Numerical results are presented and analyzed in terms of fluid flow, thermal field structures, as well as average Nusselt number profiles over a wide range of dimensionless quantities, Grashof number (Gr) (104 and 105), SQ (varied between −500 to 500) and Prandtl number (Pr = 0.015, 0.024 and 0.0321). The results indicate that when the conductive regime is established for a Grashof number Gr = 104, the 2D model is valid and predicts all three-dimensional results with negligible difference. This was not the case in the convective regime (Gr = 105) where the effect of the third direction becomes important, where a 2D-3D difference was seen with about 37 per cent. Also, in most cases, the authors find that the heat absorption phenomena have the opposite effect with respect to the heat generation. Design/methodology/approach Numerical results are presented and analyzed in terms of fluid flow, thermal field structures, as well as average Nusselt number profiles over a wide range of dimensionless quantities. Findings Grashof number (Gr) (104 and 105), SQ (varied between −500 to 500) and Prandtl number (Pr = 0.015, 0.024 and 0.0321). Originality/value The results indicate that when the conductive regime is established for a Grashof number Gr = 104, the 2D model is valid and predicts all three-dimensional results with negligible difference.


2021 ◽  
Vol 2021 ◽  
pp. 1-20 ◽  
Author(s):  
Dhinakaran Veeman ◽  
M. Swapna Sai ◽  
P. Sureshkumar ◽  
T. Jagadeesha ◽  
L. Natrayan ◽  
...  

As a technique of producing fabric engineering scaffolds, three-dimensional (3D) printing has tremendous possibilities. 3D printing applications are restricted to a wide range of biomaterials in the field of regenerative medicine and tissue engineering. Due to their biocompatibility, bioactiveness, and biodegradability, biopolymers such as collagen, alginate, silk fibroin, chitosan, alginate, cellulose, and starch are used in a variety of fields, including the food, biomedical, regeneration, agriculture, packaging, and pharmaceutical industries. The benefits of producing 3D-printed scaffolds are many, including the capacity to produce complicated geometries, porosity, and multicell coculture and to take growth factors into account. In particular, the additional production of biopolymers offers new options to produce 3D structures and materials with specialised patterns and properties. In the realm of tissue engineering and regenerative medicine (TERM), important progress has been accomplished; now, several state-of-the-art techniques are used to produce porous scaffolds for organ or tissue regeneration to be suited for tissue technology. Natural biopolymeric materials are often better suited for designing and manufacturing healing equipment than temporary implants and tissue regeneration materials owing to its appropriate properties and biocompatibility. The review focuses on the additive manufacturing of biopolymers with significant changes, advancements, trends, and developments in regenerative medicine and tissue engineering with potential applications.


Author(s):  
Jayangani I. Ranasinghe ◽  
Ericmoore Jossou ◽  
Linu Malakkal ◽  
Barbara Szpunar ◽  
Jerzy A. Szpunar

The understanding of the radial distribution of temperature in a fuel pellet, under normal operation and accident conditions, is important for a safe operation of a nuclear reactor. Therefore, in this study, we have solved the steady-state heat conduction equation, to analyze the temperature profiles of a 12 mm diameter cylindrical dispersed nuclear fuels of U3O8-Al, U3Si2-Al, and UN-Al operating at 597 °C. Moreover, we have also derived the thermal conductivity correlations as a function of temperature for U3Si2, uranium mononitride (UN), and Al. To evaluate the thermal conductivity correlations of U3Si2, UN, and Al, we have used density functional theory (DFT) as incorporated in the Quantum ESPRESSO (QE) along with other codes such as Phonopy, ShengBTE, EPW (electron-phonon coupling adopting Wannier functions), and BoltzTraP (Boltzmann transport properties). However, for U3O8, we utilized the thermal conductivity correlation proposed by Pillai et al. Furthermore, the effective thermal conductivity of dispersed fuels with 5, 10, 15, 30, and 50 vol %, respectively of dispersed fuel particle densities over the temperature range of 27–627 °C was evaluated by Bruggman model. Additionally, the temperature profiles and temperature gradient profiles of the dispersed fuels were evaluated by solving the steady-state heat conduction equation by using Maple code. This study not only predicts a reduction in the centerline temperature and temperature gradient in dispersed fuels but also reveals the maximum concentration of fissile material (U3O8, U3Si2, and UN) that can be incorporated in the Al matrix without the centerline melting. Furthermore, these predictions enable the experimental scientists in selecting an appropriate dispersion fuel with a lower risk of fuel melting and fuel cracking.


2019 ◽  
Vol 9 (17) ◽  
pp. 3540 ◽  
Author(s):  
Ferdows Afghah ◽  
Caner Dikyol ◽  
Mine Altunbek ◽  
Bahattin Koc

Melt electrospinning writing has been emerged as a promising technique in the field of tissue engineering, with the capability of fabricating controllable and highly ordered complex three-dimensional geometries from a wide range of polymers. This three-dimensional (3D) printing method can be used to fabricate scaffolds biomimicking extracellular matrix of replaced tissue with the required mechanical properties. However, controlled and homogeneous cell attachment on melt electrospun fibers is a challenge. The combination of melt electrospinning writing with other tissue engineering approaches, called hybrid biomanufacturing, has introduced new perspectives and increased its potential applications in tissue engineering. In this review, principles and key parameters, challenges, and opportunities of melt electrospinning writing, and particularly, recent approaches and materials in this field are introduced. Subsequently, hybrid biomanufacturing strategies are presented for improved biological and mechanical properties of the manufactured porous structures. An overview of the possible hybrid setups and applications, future perspective of hybrid processes, guidelines, and opportunities in different areas of tissue/organ engineering are also highlighted.


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