A Numerical Study of Thermal Dispersion in Porous Media

Kuwahara, Fujio; Nakayama, A.; Koyama, Hitoshi

doi:10.1115/1.2822696

Cited by 139 publications

(62 citation statements)

References 17 publications

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“…It was also observed that for low Peclet numbers, the total thermal diffusivity is almost equal to the stagnant thermal conductivity of the porous medium and the thermal dispersion is negligible. Kuwahara et al [5] studied periodical square rods in inline arrangement to determine transverse thermal dispersion and tortuosity. Two correlations for the determination of thermal dispersion, for high and low Peclet numbers, in terms of porosity, Peclet number and fluid thermal conductivity were suggested.…”

Section: Introductionmentioning

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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Section: Introductionmentioning

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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“…where is porosity; is area porosity tensor; is the effective viscosity, is a sheet or a turbulent viscosity; the last term in this equation represents the viscous and inertial drag forces imposed by the pore walls on the fluid [15].…”

Section: Porous Media Modelmentioning

confidence: 99%

Numerical Study and Structural Optimization of a Top Combustion Hot Blast Stove

Liu

Yao

et al. 2014

Advances in Mechanical Engineering

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The hot blast stove is one of the most important equipment devices in the blast furnace iron making process. The temperature and duration of hot air are the crucial parameters to assess the performance of the hot blast stove. In order to sustain the desired high temperature air, it requires rapid completed combustion reaction, stable flue gas flow structure, and uniform temperature distribution throughout the regenerator. In the present work, a 3D numerical model with all essential turbulence, heat transfer, and combustion considerations has been developed to assess the performance of a typical hot air stove. The flow field of the whole domain and temperature distribution within the regenerator were simulated using the model. The predicted results show that the velocity at each nozzle varies substantially due to the uneven pressure distribution in cavity of the traditional hot blast stove, generating the eccentric vortex that leads to nonuniform temperature distribution in the regenerator. In order to solve this problem, a new structure design of top combustion regenerative hot blast stove is proposed. Numerical simulations were then carried out to compare based on the performance of the new hot blast stove design against the traditional hot blast stove.

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“…where K eff,f and K eff,s are the effective conductivity tensors for the fluid and solid phases, respectively, given by Kuwahara and Nakayama (1996) [42] and Quintard et al (1997) [10], this can be accomplished for the thermal dispersion and local conduction tensors, K disp and K f,s , by making use of a unit cell subjected to periodic boundary conditions for the flow together with an imposed linear temperature gradient on the porous medium. The dispersion and conduction tensors are then obtained directly from the distributed results within the unit cell by making use of Eqs.…”

Section: Macroscopic Two-energy Equation Modelingmentioning

confidence: 99%

“…If time fluctuations of the flow properties are also considered, in addition to spatial deviations, there are two possible methodologies to follow in order to obtain macroscopic equations: (a) application of time-average operator followed by volumeaveraging [41][42][43][44][45][46], or (b) use of volume-averaging before time-averaging is applied [47][48][49]. However, both sets of macroscopic mass transport equations are equivalent when examined under the recently established double decomposition concept [17][18][19][20][21][22].…”

Section: Decomposition Of Flow Variables In Space and Timementioning

confidence: 99%

Interfacial Heat Transport in Highly Permeable Media: A Finite Volume Approach

Lemos

Saito

2008

Cellular and Porous Materials

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The transport of heat inside highly permeable media has attracted the attention of scientists and engineers due to its many engineering applications. Such applications can be found in solar energy receiver devices, heat exchangers, porous combustors, grain drying equipment, heat sink units, energy recovery systems, etc. In many of these modern engineering systems the use of cellular and metallic porous foams brings the advantages of having large specific heat transfer areas, or the interfacial transport area per unit volume is large when compared with other heat-capturing devices. More realistic modeling of transport processes in such media is then essential for the reliable design and analysis of high-efficiency engineering systems.Motivated by the wide spectrum of practical engineering applications, macroscopic transport modeling of incompressible flows in porous media has been developed over the last few decades, mostly based on the volume-average methodology for either heat [1] or mass transfer [2,3]. Classic books by Bear (1972) [4], Nield and Bejan (1992) [5] and Ingham and Pop (1998) [6], to mention a few, also document forced convection and related models for heat transport in porous media.From the point of view of energy transfer between phases, namely the cellular material phase and the working fluid, there are basically two different models commonly found in the literature: (a) a local thermal equilibrium model and (b) a two-energy equation or thermal nonequilibrium model. The first one assumes that the bulk solid temperature does not differ much from the average value of the fluid temperature; thus local thermal equilibrium between the fluid and the solid phase is assumed. This model greatly simplifies theoretical and numerical research but the assumption of local thermal equilibrium between the fluid and the solid is inadequate for a number of practical problems [7][8][9]. As a result, in recent years more attention has been paid to the local thermal nonequilibrium model, both theoretically and numerically [10,11].

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A Numerical Study of Thermal Dispersion in Porous Media

Cited by 139 publications

References 17 publications

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

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

Numerical Study and Structural Optimization of a Top Combustion Hot Blast Stove

Interfacial Heat Transport in Highly Permeable Media: A Finite Volume Approach

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