Longitudinal dispersion mechanisms in packed beds

Babcock, R. E.; Green, D. W.; Perry, R. H.

doi:10.1002/aic.690120516

Cited by 49 publications

(15 citation statements)

References 15 publications

(4 reference statements)

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“…Rosen presented a solution for the case, what he called it a general problem of the transient behavior of a linear fixed-bed system where the rate of adsorption is determined by the combined effect of a liquid film and solid diffusion into spherical particles [6]. Babcock, Green and Perry made a theoretical study about the longitudinal dispersion mechanism during the steady flow of a fluid through unconsolidated spherical beads [7]. Rasmuson In the current study, hydrogen fluoride (HF) adsorption onto the sodium fluoride pellets is modeled.…”

Section: Introductionmentioning

confidence: 99%

Modeling hydrogen fluoride adsorption by sodium fluoride

Afzal

Rahimi

Ehsani

et al. 2010

Journal of Industrial and Engineering Chemistry

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Section: Introductionmentioning

confidence: 99%

Modeling hydrogen fluoride adsorption by sodium fluoride

Afzal

Rahimi

Ehsani

et al. 2010

Journal of Industrial and Engineering Chemistry

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“…It has also been necessary to examine critically the conditions proposed earlier by Handley and Heggs (9) and by Babcock and co-workers (2,3 ) .…”

Section: Applicability Of Single Parameter Modelsmentioning

confidence: 99%

“…An alternative parameter known as the bed length parameter, yx has been used by Rosen and Babcock et al (2,3) as a measure of the relative importance of internal particle conduction. This parameter, also known as the "effective bed length," is simply the ratio of the transfer parameter Y to the particle Biot number Handley and Heggs (9) have suggested that internal particle conduction effects may be ignored when the value of the bed length parameter is greater than 60.…”

Section: Effects Of Internal Particle Conductivitymentioning

confidence: 99%

Prediction of breakthrough curves in packed beds: I. Applicability of single parameter models

Jeffreson

1972

AIChE Journal

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Applicability of Single Parameter ModelsConditions under which simplified, single parameter models may be used to predict breakthrough curves in linear, packed bed adsorbers and thermal regenerators are examined with reference, in particular, to earlier conditions proposed by Handley and Heggs and by Babcock and co-workers. I t is found that for high values of heat capacity ratio the Schumann model provides a satisfactory description of packed bed dynamics where fluids axial dispersion and solids conduction effects are lumped into a single parameter the curve spread parameter u*.For low values of heat capocity ratio, the equivalent conductivity model of Babcock and co-workers should provide a more accurate description. The value of the Biot number Bi was found to provide the sole criterion for estimating the relative importance of the internal solids conduction. Empirical correlations are presented which allow rapid estimates of breakthrough curves to be mode from the curve spread parameter and which facilitate analysis of experimental data from breakthrough curve experiments.The prediction of breakthrough curves in linear, packedbed adsorbers and thermal regenerators has been the subject of many theoretical and experimental investigations since Schumann's work (19) in 1929. This interest arises fundamentally because of the economic importance of fixed bed-fluid transfer processes and because of the resultant need to rapidly and accurately design related equipment.Design procedures for well insulated thermal regenerators or adsorbers in which particle internal conductivities may be regarded as infinite have been well developed and were summarized by McAdams (21 ) . Such procedures depend on the Schumann model which makes the assumption amongst others that axial conduction or dispersion in the fluid phase is of negligible importance. The addition of a term for fluid phase axial dispersion (5, 7 ) to the Schumann equation greatly complicates the mathematical solution of the equations and raises the question of whether it is necessary to devise a completely new set of design procedures.In this paper the conditions under which the Schumann solution may be extended to cover the cases of finite particle conductivity and axial fluids dispersion are considered. It has also been necessary to examine critically the conditions proposed earlier by Handley and Heggs (9) and by Babcock and co-workers (2, 3 ) .It is shown that for most cases of practical importance the well-established design procedures referred to above may continue to be used, subject to the satisfaction of a number of simple criteria. At the same time, one of the objects of this paper is to make the task of the design engineer easier by presenting empirical correlations of points on a breakthrough curve against nondimensional groups commonly used in chemical engineering. The use of these groups simplifies the tasks of design and analysis and facilitates translation of the results from heat to mass transfer.The application of complex mathematical "models" to...

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“…Moench [12], in his study of doubly-porous groundwater reservoirs, incorporated the effects of a thin layer of low permeable material or fracture skin which may be present at fracture-block interfaces. Babcock et al [2] developed a model for longitudinal dispersion mechanisms during steady flow of a fluid through unconsolidated spherical beads which include a stagnant fluid film surrounding the particle. Skopp and Warrick [14] studied miscible displacement by considering there to be a mobile phase and a stationary phase, whereby solute transfer occurs through the mobile phase via convection, and through the stationary phase via diffusion.…”

Section: Literature Reviewmentioning

confidence: 99%

A two-stage heat transfer model for the peripheral layers of a grain store

Antic

Hill

2003

Journal of Applied Mathematics and Decision Sciences

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Abstract. An understanding of the flow of heat in grain store structures, in particular, within the peripheral layer, is important from many industrial perspectives. To analyse the heat transfer within such regions a mathematical model known as the two-stage heat transfer model is proposed. This model makes a distinction between the air and grain within the grain bulk, and thus takes into consideration the fact that the rate of heat transfer through the grain is different to that through the interstitial air surrounding the grain. Such a model lends itself to a solution via Laplace transforms and approximate analytical results are obtained for small and large times. In addition, the Stehfest numerical algorithm is used for the inversions and very good agreement is obtained between the two approaches. The present model is compared to a previously developed double-diffusivity heat transfer model by the authors, and good agreement is obtained. At present, no experimental data is available to validate the model as it is very difficult to measure the air and grain temperatures separately, particularly in the peripheral layer. The proposed model provides insight into the potential difference existing between the air and grain temperatures.

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Longitudinal dispersion mechanisms in packed beds

Cited by 49 publications

References 15 publications

Modeling hydrogen fluoride adsorption by sodium fluoride

Modeling hydrogen fluoride adsorption by sodium fluoride

Prediction of breakthrough curves in packed beds: I. Applicability of single parameter models

A two-stage heat transfer model for the peripheral layers of a grain store

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