A synthesis of tortuosity and dispersion in effective thermal conductivity of porous media

Abstract:Recent advances in manufacturing methods open the possibility for broader use of metal foams and metal matrix composites (MMCs) for heat exchangers, and these materials can have tailored material properties. Metal foams in particular combine a number of interesting properties from a heat exchanger's point of view. In this paper, the material properties of metal foams and MMCs are surveyed, and the current state of the art is reviewed for heat exchanger applications. Four different applications are considered: liquid-liquid, liquid-gas and gas-gas heat exchangers and heat sinks. Manufacturing and implementation issues are identified and discussed, and it is concluded that these materials hold promise both for heat exchangers and heat sinks, but that some key issues still need to be solved before broad scale

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“…Recently, Yang and Nakayama [100] provided a more in-depth study of the thermal dispersion phenomena in porous media.…”

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confidence: 99%

A Review of Metal Foam and Metal Matrix Composites for Heat Exchangers and Heat Sinks

Han

Wang

Park³

et al. 2012

Heat Transfer Engineering

219

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“…This integral is solved by midpoint rule -as explained by [26] -to give û which is required for solving Eq. (14). We solve for a modified dimensionless temperature defined as Nu θ ψ = to uncouple Eqns.…”

Section: Numerical Solution Proceduresmentioning

confidence: 99%

“…Numerical simulations have been exclusively used in the literature for such non-Darcy flow problems [11][12][13][14]. Hunt and Tien [15] experimentally studied non-Darcian forced convection flow and heat transfer in high-porosity fibrous media.…”

Section: Introductionmentioning

confidence: 99%

Thermal dispersion effects on forced convection in a porous-saturated pipe

Hooman

Dahari

2017

Thermal Science and Engineering Progress

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Thermal dispersion effects on fully developed forced convection inside a porous-saturated pipe are investigated. The pipe wall is assumed to be kept at a uniform and constant heat flux. Having the fully developed velocity field furnished by an arbitrary power series function, the energy equation is solved using asymptotic techniques for the limiting case when thermal conductivity, as a result of thermal dispersion, weakly changes with the Péclet number. A numerical solution, valid for the entire range of thermal dispersion conductivity, is also presented. This latter solution is presented to check the accuracy of the former. The two solutions are then cross-validated in the limits. Besides, results are found to be in good agreement with those previously reported in the literature.

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“…Since the values of thermal conductivity of solid and fluid phases are close to each other (k s /k f ¼ 2), the term of thermal tortuosity can be neglected [15]. Then, the RHS of Eq.…”

Section: The Microscopic and Macroscopic Governing Equationsmentioning

confidence: 99%

Effect of pore to throat size ratio on thermal dispersion in porous media

Özgümüş

Mobedi

2016

International Journal of Thermal Sciences

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a b s t r a c tIn this study, the effects of pore to throat size ratio on thermal dispersion of periodic porous media consisting of inline array of rectangular rods are investigated, numerically. The continuity, momentum and energy equations are solved for representative elementary volumes (REVs) of the porous media to obtain microscopic velocities in the voids between the rods and temperature distribution for entire of the REVs. Volume averaging method is employed to compute the macroscopic velocity and temperature values. There are velocity and temperature deviations between the macroscopic and microscopic values. These deviations are computed numerically and thermal dispersion coefficients of the porous media are determined. The aim of this study is to analyze the effects of pore to throat size ratio on the longitudinal and transverse thermal dispersion in the porous media. The study is performed for pore to throat size ratios between 1.63 and 7.46, porosities from 0.7 to 0.9, and pore level Reynolds numbers between 1 and 100. It is found that in addition to the porosity and Reynolds number, the parameter of pore to throat size ratio plays an important role on thermal dispersion in a porous medium. It is found that there is an optimum value of pore to throat size ratio for maximum longitudinal thermal dispersion coefficient; however, the transverse thermal dispersion increases with the increasing of values of pore to throat size ratio.

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A synthesis of tortuosity and dispersion in effective thermal conductivity of porous media

Cited by 110 publications

References 28 publications

A Review of Metal Foam and Metal Matrix Composites for Heat Exchangers and Heat Sinks

A Review of Metal Foam and Metal Matrix Composites for Heat Exchangers and Heat Sinks

Thermal dispersion effects on forced convection in a porous-saturated pipe

Effect of pore to throat size ratio on thermal dispersion in porous media

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