Numerical Analysis of Conduction in a Foam

2002 ◽  
Author(s):  
A. M. Druma ◽  
M. K. Alam ◽  
C. Druma
Keyword(s):  
Thermal Conductivity ◽  
Porous Medium ◽  
Numerical Models ◽  
High Porosity ◽  
Material Microstructure ◽  
Element Analysis ◽  
Empirical Parameter ◽  
Bulk Properties ◽  
Heat Spreaders ◽  
Homogeneous Models

Porous organic materials are being developed for use as insulation, heat spreaders, and compact heat exchanger cores. The bulk properties of such a porous medium are difficult to determine analytically, particularly for the case of high porosity or when the porous material is not isotropic or homogeneous. Models that predict thermal conductivity of foams often use an empirical parameter to account for the effect of pore shape and material microstructure on the conduction process. A finite element analysis has been developed to calculate the thermal conductivity of a porous medium containing micropores. The effective thermal conductivity and the empirical conduction parameter are evaluated by comparing the results of the analytical and numerical models.

Model of Multiscale Transport in Carbon Foams

2003 ◽  
Author(s):  
C. Druma ◽  
M. K. Alam ◽  
A. M. Druma
Keyword(s):  
Thermal Conductivity ◽  
Numerical Models ◽  
Carbon Foam ◽  
Compact Heat Exchanger ◽  
High Concentration ◽  
Element Analysis ◽  
Bulk Properties ◽  
Heat Spreaders ◽  
Carbon Foams ◽  
Different Shapes

A number of carbon foam products are being developed for use as insulation, heat spreaders, and compact heat exchanger cores. Such foams have voids that are typically of the order 100 microns, and pore walls are about 10 microns. Within the walls of the pores, the graphene planes are arranged anisotropically so that the thermal transport is highly dependent on the orientation of the bulk foam. This results in bulk conductivities that range from 1 W/mK to 200 W/mK. The bulk properties of such a porous medium are difficult to determine analytically, particularly for the case of high concentration of non-spherical pores, or when the porous material is anisotropic or non-homogeneous. A finite element analysis has been developed to calculate the bulk thermal conductivity of carbon foams containing micropores of different shapes. The effective thermal conductivity is then evaluated by comparing the results of the analytical and numerical models.

Study of Miniaturization of a Silicon Vapor Chamber for Compact 3D Microelectronics, via a Hybrid Analytical and Finite Element Method

2019 ◽  
Vol 6 (5) ◽  
pp. 01-18
Author(s):  
Ma Yue ◽  
Shirazy Mahmoud ◽  
Coudrain Perceval ◽  
Colonna Jean-Phulippe ◽  
Souifi Abdelkader ◽  
...  
Keyword(s):  
Thermal Conductivity ◽  
Numerical Models ◽  
Computational Cost ◽  
Vapor Chamber ◽  
Cooling Systems ◽  
Heat Spreaders ◽  
Operating Limits ◽  
Silicon Vapor ◽  
Core Height ◽  
Low Computational Cost

The interest in silicon vapor chambers (SVCs) has increased in the recent years as they have been identified as efficient cooling systems for microelectronics. They present the advantage of higher thermal conductivity and smaller form factor compared to conventional heat spreaders. This work aims to investigate the potential miniaturization of these devices, preliminary to integration on the backside of mobile device chips, located as close as possible to hotspots. While detailed numerical models of vapor chamber operation are developed, an easy modeling with low computational cost is needed for an effective parametric study.  Based on the study of the operating limits, this paper shows the thinning potential of a water filled micropillar for a device operating below 10 W and identify the corresponding vapour core height, and wick thickness.

scholarly journals Study of Miniaturization of a Silicon Vapor Chamber for Compact 3D Microelectronics, via a Hybrid Analytical and Finite Element Method

2019 ◽  
Vol 7 (6) ◽  
pp. 1-16
Author(s):  
Yue MA ◽  
M. R. S. Shirazy ◽  
Q. Struss ◽  
P. Coudrain ◽  
J.P. Colonna ◽  
...  
Keyword(s):  
Thermal Conductivity ◽  
Numerical Models ◽  
Computational Cost ◽  
Vapor Chamber ◽  
Cooling Systems ◽  
Heat Spreaders ◽  
Operating Limits ◽  
Silicon Vapor ◽  
Core Height ◽  
Low Computational Cost

The interest in silicon vapor chambers (SVCs) has increased in the recent years as they have been identified as efficient cooling systems for microelectronics. They present the advantage of higher thermal conductivity and smaller form factor compared to conventional heat spreaders. This work aims to investigate the potential miniaturization of these devices, preliminary to integration on the backside of mobile device chips, located as close as possible to hotspots. While detailed numerical models of vapor chamber operation are developed, an easy modeling with low computational cost is needed for an effective parametric study.  Based on the study of the operating limits, this paper shows the thinning potential of a water filled micropillar for a device operating below 10 W and identify the corresponding vapour core height, and wick thickness.

Thermal Performance of Natural Graphite Heat Spreaders With Embedded Thermal Vias

2007 ◽  
Author(s):  
Martin Smalc ◽  
Prathib Skandakumaran ◽  
Julian Norley
Keyword(s):  
Thermal Conductivity ◽  
Heat Flux ◽  
Thermal Performance ◽  
Numerical Models ◽  
Accelerated Aging ◽  
High Heat ◽  
High Heat Flux ◽  
Natural Graphite ◽  
Heat Spreaders ◽  
Graphite Heat

Natural graphite heat spreaders are in use in electronic cooling applications where heat flux density is low. Natural graphite is an anisotropic material, with a high thermal conductivity in the plane of the spreader combined with a much lower thermal conductivity through its thickness. This low through-thickness thermal conductivity poses a problem when attempting to cool heat sources with relatively high heat flux densities. This problem can be overcome by embedding a thermal via in the graphite material. This via is made from an isotropic material with a thermal conductivity significantly higher than the through-thickness graphite conductivity. This paper examines the thermal performance of a natural graphite heat spreader with an embedded thermal via. The work is primarily experimental although numerical models were used to guide the experiments. The thermal performance of these spreaders is compared to that of spreaders made from conventional isotropic materials. The effect of accelerated aging tests on the performance of these graphite spreaders is reviewed. Finally, two applications are examined; first cooling an ASIC module and second, cooling an FB-DIMM memory card.

Thermal Performance of Natural Graphite Heat Spreaders

2005 ◽  
Author(s):  
Martin Smalc ◽  
Gary Shives ◽  
Gary Chen ◽  
Shrishail Guggari ◽  
Julian Norley ◽  
...  
Keyword(s):  
Thermal Conductivity ◽  
Thermal Management ◽  
Numerical Models ◽  
Laptop Computer ◽  
Natural Graphite ◽  
Heat Spreader ◽  
Graphite Sheet ◽  
Cooling Fan ◽  
Heat Spreaders ◽  
Graphite Heat

Heat spreaders can be made from natural graphite sheet materials. These spreaders take advantage of the anisotropic thermal properties of natural graphite. Natural graphite exhibits a high thermal conductivity in the plane of the sheet combined with a much lower thermal conductivity through the thickness of the sheet. As a result, a natural graphite sheet can function as both a heat spreader and an insulator and can be used to eliminate localized hot spots in electronic components. In some cases, a natural graphite heat spreader can replace a conventional thermal management system consisting of a heat sink and cooling fan. This paper examines the properties of natural graphite heat spreaders and the application of these spreaders to thermal management problems in laptop computers. The thermal and mechanical properties of natural graphite heat spreaders are presented along with a discussion of how those properties are measured. The use of a natural graphite heat spreader to reduce the touch temperature in a laptop computer is presented. Both experimental techniques and numerical models are used to examine performance of the heat spreader in this application.

Melting of ice in a porous medium saturated with ice and gas while injecting warm water

2019 ◽  
Vol 13 (4) ◽  
pp. 112-117 ◽  
Author(s):  
V.Sh. Shagapov ◽  
M.N. Zapivakhina
Keyword(s):  
Mass Transfer ◽  
Porous Medium ◽  
Low Temperature ◽  
Numerical Models ◽  
Warm Water ◽  
Temperature Fields ◽  
Initial State ◽  
Simplified Models ◽  
Frozen Soils ◽  
Porous Formation

The numerical models for the injection of warm water (in the temperature range from 300 to 340 K) into a cold porous formation are considered. Simplified models describing the processes of heat and mass transfer are proposed. The influence of the parameters determining the initial state of the porous medium, the boundary pressure, temperature and moisture content on the rate of propagation of hydrodynamic and temperature fields in the porous medium is investigated. It has been established that it is economically feasible to melt frozen soils saturated with ice and gas (air) at a sufficiently low temperature of the injected water (about 300 K).

scholarly journals The Equivalent Thermal Conductivity of the Micro/Nano Scaled Periodic Cubic Frame Silver and Its Thermal Radiation Mechanism Analysis

Energies ◽  
2021 ◽  
Vol 14 (14) ◽  
pp. 4158
Author(s):  
Haiyan Yu ◽  
Haochun Zhang ◽  
Heming Wang ◽  
Dong Zhang
Keyword(s):  
Thermal Conductivity ◽  
Thermal Radiation ◽  
Cell Size ◽  
Near Infrared ◽  
High Porosity ◽  
Mechanism Analysis ◽  
Infrared Band ◽  
Spectral Radiation ◽  
Radiation Mechanism ◽  
Equivalent Thermal Conductivity

Currently, there are few studies on the influence of microscale thermal radiation on the equivalent thermal conductivity of microscale porous metal. Therefore, this paper calculated the equivalent thermal conductivity of high-porosity periodic cubic silver frame structures with cell size from 100 nm to 100 µm by using the microscale radiation method. Then, the media radiation characteristics, absorptivity, reflectivity and transmissivity were discussed to explain the phenomenon of the radiative thermal conductivity changes. Furthermore, combined with spectral radiation properties at the different cross-sections and wavelength, the radiative transmission mechanism inside high-porosity periodic cubic frame silver structures was obtained. The results showed that the smaller the cell size, the greater radiative contribution in total equivalent thermal conductivity. Periodic cubic silver frames fluctuate more in the visible band and have better thermal radiation modulation properties in the near infrared band, which is formed by the Surface Plasmon Polariton and Magnetic Polaritons resonance jointly. This work provides design guidance for the application of this kind of periodic microporous metal in the field of thermal utilization and management.

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