Effect of fluid dispersion coefficients on particle-to-fluid heat transfer coefficients in packed beds

Wakao, Noriaki; Funazkri, T.

doi:10.1016/0009-2509(79)85064-2

Cited by 762 publications

(266 citation statements)

References 48 publications

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“…In the first instance this has important implications for the interpretation of measurements made on packed beds since such measurements would be used, for example, to infer heat transfer coefficients. In this respect, data for Nusselt numbers given in [12] derived from packed bed tests show significant spread, typically encompassing a factor of about 4. This uncertainty has implications for the prediction of thermodynamic losses.…”

Section: Discussionmentioning

confidence: 99%

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Wave propagation and thermodynamic losses in packed-bed thermal reservoirs for energy storage

2014

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This paper presents a numerical and theoretical analysis of thermal wave propagation in packed bed thermal reservoirs for energy storage applications. In such reservoirs, the range of temperatures encountered is usually such that the solid storage medium will exhibit significant changes in specific heat capacity. This in turn results in non--linear wave propagation and may lead to the formation of shock--like thermal fronts. Such effects have an impact on the exergetic losses due to irreversible heat transfer, and should be taken into account during the design and optimisation of the reservoirs. In the present paper, the emphasis is on thermal losses due to irreversible heat transfer. Frictional (pressure) losses and heat leakage between the storage medium and the environment are also important but are not considered here. The implications of the results for storage material, and particle size are discussed briefly in the context of loss minimisation. Keywords: energy storage, irreversible heat transfer, thermal reservoirs, exergetic loss. NOMENCLATURE

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Section: Discussionmentioning

confidence: 99%

“…[12]. Wave propagation based on the model equations (5a) and (6a) is investigated below but numerical results are also presented for comparison and for the purpose of evaluating losses where an analytical solution is not tractable.…”

Section: Governing Equationsmentioning

confidence: 99%

Wave propagation and thermodynamic losses in packed-bed thermal reservoirs for energy storage

2014

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“…As correlation for the heat transfer coefficient the empirical one proposed by Wakao et al [39,40] is applied. This correlation can be used up to a particle Re of 8500:…”

Section: Governing Equationsmentioning

confidence: 99%

Modelling heat transfer during flow through a random packed bed of spheres

et al. 2017

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Heat transfer in a random packed bed of monosized iron ore pellets is modelled with both a discrete three-dimensional system of spheres and a continuous Computational Fluid Dynamics (CFD) model. Results show a good agreement between the two models for average values over a cross section of the bed for an even temperature profiles at the inlet. The advantage with the discrete model is that it captures local effects such as decreased heat transfer in sections with low speed. The disadvantage is that it is computationally heavy for larger systems of pellets. If averaged values are sufficient, the CFD model is an attractive alternative that is easy to couple to the physics up-and downstream the packed bed. The good agreement between the discrete and continuous model furthermore indicates that the discrete model may be used also on non-Stokian flow in the transitional region between laminar and turbulent flow, as turbulent effects show little influence of the overall heat transfer rates in the continuous model.

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“…In order to obtain a correlation for h i in the turbulent regime, all curves were first collapsed after plotting them in terms of Re D /f, as shown in Figure 1.15. Next, the least squares technique was applied in order to determine the best correlation, which led to a minimum comparison is presented in Figure 1.16, which also shows computations using correlations given by Zhukauskas (1972) [57] and Wakao et al (1979) [56], Eqs. (1.49) and (1.50), respectively.…”

Section: Correlations For Laminar and Turbulent Flowsmentioning

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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Effect of fluid dispersion coefficients on particle-to-fluid heat transfer coefficients in packed beds

Cited by 762 publications

References 48 publications

Wave propagation and thermodynamic losses in packed-bed thermal reservoirs for energy storage

Wave propagation and thermodynamic losses in packed-bed thermal reservoirs for energy storage

Modelling heat transfer during flow through a random packed bed of spheres

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

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