Heat or Mass Transfer in Laminar Flow in Conduits With Constriction

Chow, J. C. F.; Soda, Kunihisa

doi:10.1115/1.3450063

Cited by 8 publications

(2 citation statements)

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“…As was found by Chow and Soda (1973), who solved a regular perturbation problem for small values of ?A, the Sherwood number increases with amplitude. However, for larger values of rA, this trend reverses itself.…”

Section: Resultsmentioning

confidence: 58%

Entrance region (Lévêquelike) mass transfer coefficients in packed bed reactors

Fedkiw

Newman

1979

AIChE Journal

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respectively asThe Peclet number for a tube and for a sphere are defined Hence they may be related by Introducing c2 into Equation (A-2) one obtainsThe overall mass transfer rate may be expressed asHere, de is the equivalent diameter and A, the total transfer area. Equation (A-4) for a sphere, becomes D QS = Shs-AsAc = ShsD(?rds)Ac ( A-5 ds while for a tube it reads D dT QT = ShT-ATAc = S~T D ( T L T ) A C (A-6) A mass transfer balance is now performed on a volume of the granular bed of dimensions ( 1 x 1 x h ) , where h = cpdc. The number of pores, np, in such a volume is np = N p czdc -1 * 1 ( A-7 1 whereas the number of spheres in the same volume is czdc * 1 * 1 * ( Ie) n , = ( A-8 1 ads3 -6 Using Equations (A-5 to A-8), the balance yields QT np = Qsns ( A-9 )and finally, after some algebraic manipulations, one obtains Calculations for the high Peclet number, entrance region (L&$quelike) packed bed, mass transfer coefficient using a sinusoidal periodically constricted tube model for the void structure of the bed are presented. An inverse cube root dependence of the mass transfer coefficient on the bed depth is predicted. This length dependence is anticipated only at very low Reynolds numbers. Calculations which assume a mixing region between successive periods are also presented. No bed length dependence is anticipated in these coefficients.The periodically constricted tube model for porous permeability of a nonconsolidated packed bed. They enmedia constitutes a useful model for mass transfer in two-visioned the bed as cell styctures made of segments of phase, packed-bed reactors. This model was developed by parabolic periodically constricted tubes. A sinusoidal peri-Pavatakes and co-workers (1973. 1977) to medict the odically constricted tube (PCT) is used in this work to model'the void structure in a bed in order to predict the mass transfer coefficient. The fluid is assumed to be in the viscous flow regime, and the reactant conversion is assumed to be controlled by mass transfer from the Peter Fedkiw is with the

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Section: Resultsmentioning

confidence: 58%

Entrance region (Lévêquelike) mass transfer coefficients in packed bed reactors

Fedkiw

Newman

1979

AIChE Journal

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“…The applied electric potential was held constant at 800mV, which provided the diffusional controlled condition. The Sherwood number is related to the difFusional current by Sh = idHJzFCbA@ (2) The physical properties of the electrolyte presented by Mackley5) were used in these experiments.…”

Section: Discussionmentioning

confidence: 99%

Mass transfer characteristics in a channel with symmetric wavy wall for steady flow.

Nishimura

Ohori

Kajimoto

et al. 1985

J. Chem. Eng. Japan

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Mass transfer characteristics in a channel with symmetric wavy wall were investigated by the Leveque theory and the electrochemical method. The channel used has a geometry similar to that of the Oxford membrane blood oxygenator. The flow regime covered ranged from laminar to turbulent flow. The local Sherwood number distributions indicate that the reversed-flow region significantly differs from the forward-flow region in mass transfer characteristics. For laminar flow, mass transfer enhancementof the wavy channel is scarcely expected as compared with the corresponding straight channel, but is found to be remarkable for turbulent flow.

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