Momentum transfer in climbing film flow in annular duct

Kim, D. H.; Knudsen, James G.

doi:10.1002/aic.690130224

Cited by 5 publications

(1 citation statement)

References 5 publications

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“…Values of T~ were also calculated from Equations (7) and ( and radii of maximum air velocity obtained by Kim (13,14) were used with pressure gradients from the present work. These results are also presented in Figure 9 and are within 25 to 60% of those obtained by using data.…”

Section: Shear Stress At the Inner Wallmentioning

confidence: 99%

Mass transfer at the solid-liquid interface for climbing film flow in an annular duct

Sutey¹,

Knudsen²

1968

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A method utilizing a diffusion controlled electrochemical reaction was used to measure average and instantaneous mass transfer coefficients a t the solid-liquid interface in upward gasliquid climbing film flow in a vertical annular duct. These measurements give some indication of the mechanics of flow of the film, the extent of turbulence a t the inner wall, and the effect of film thickness and wove motion on the mass transfer process a t the inner wall. Predictions of incipient downflow of the film, shear stress a t the inner wall, and interfacial shear stress were obtained from these measurements. Fluctuations in the velocity gradient a t the inner wall were also studied. Results of this study are in good agreement with previous work and with theoretical predictions based on simplified momentum balance concepts.Climbing film flow is but one of the various regimes of upward two-phase (gas-liquid) flow. In climbing film flow the liquid moves upward as a film on the surface of the duct as the faster moving gas stream flows upward adjacent to the liquid film. Due to the momentum transfer at the gas-liquid interface, the liquid film is transported upward at the expense of the pressure energy of the gas stream. As a result, the liquid film is characterized by complex wave and entrainment phenomena. This type of flow is of particular interest since it exists over a rather wide range of gas and liquid flow rates and is commonly encountered in process equipment.

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Section: Shear Stress At the Inner Wallmentioning

confidence: 99%

Mass transfer at the solid-liquid interface for climbing film flow in an annular duct

Sutey¹,

Knudsen²

1968

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Mass transfer at the solid‐liquid interface for climbing film flow in an annular duct

Sutey

Knudsen

1969

AIChE Journal

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A method utilizing a diffusion controlled electrochemical reaction was used to measure average and instantaneous mass transfer coefficients at the solid‐liquid interface in upward gasliquid climbing film flow in a vertical annular duct. These measurements give some indication of the mechanics of flow of the film, the extent of turbulence at the inner wall, and the effect of film thickness and wave motion on the mass transfer process at the inner wall. Predictions of incipient downflow of the film, shear stress at the inner wall, and interfacial shear stress were obtained from these measurements. Fluctuations in the velocity gradient at the inner wall were also studied. Results of this study are in good agreement with previous work and with theoretical predictions based on simplified momentum balance concepts.

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Dispersion in laminar flowing liquid films involving heat transfer and interfacial shear

Shair

1971

AIChE Journal

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the 3.94 obtained for the ethyl acetate-water system, considering the accuracy of the measurements, that rounding them all off to 3.9 seems most reasonable:( 3 ) Figure 9 shows the comparison of the new data as well as the earlier data (11) from baffled vessels with those computed from Equation ( 3 ) . I t is not now possible to recover the information needed to include the earlier data from unbaffled vessels, unfortunately. Most of the data are represented by Equation ( 3 ) within 20%. Considering the great number of measurements represented by each plotted point, the scatter is not considered excessive, and the applicability of the proposed mechanism seems reasonably well confirmed. More reliable coalescence data are obviously urgently needed. Chemical reactors utilizing downward flowing liquid films have certain advantages when the reaction temperature must be carefully controlled ( 1 ) . When the reaction is highly exothermic, the wall is cooled and the film is kept thin. Generally, the gas-phase reactant is diluted, and the flows are concurrent to avoid flooding. Chien (2) has correlated the static pressure gradient and superficial friction factor with the superficial gas and liquid Reynolds numbers. Stainthorp and Batt (21 ) have investigated the wave properties in a downward concurrent two-phase system. Although many investigations have been performed with falling films (for example see references 4 to 6 ) , much less Correspondence concerning this article should be addressed to Prof.F. H. Shair. Page 920July, 1971is known about the flow within thin liquid films which are influenced by shear at the gas-liquid interface and by heat transfer. In order to predict the behavior of a chemical reactor, a residence time distribution function must be known ( 7 , 8 ) . Tracer studies are often used to determine the validity of a fluid mechanical model. For reasons of economy these studies usually involve the rapid injection of a small amount of tracer at the reactor entrance, and monitoring the fluid at the reactor exit, Since the F diagram, the internal age distribution function, and the exit age distribution function are interrelated in a simple manner, knowledge of any one function allows the determination of the other two functions. As pointed out by Danckwerts ( 7 ) , the F diagram (or F function) is easy to obtain, and permits certain calculations to be made concerning thc performance of the system when used, for instance, as a Consequently, the solution to the problem under consideration will be presented in terms of the F diagram 01 F function. It is noted that the F function is simply that integral of the exit age distribution function E .G. I. Taylor (9) established the analytical foundation concerning the treatment of dispersion in which both convcction and diffusion are important. Although several significant extensions have been made to the theory of such dispersions (10 to 1 3 ) , the laminar Newtonian flow in a film when influenced by both heat transfer and interfacial shear has not been available pr...

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Momentum transfer in climbing film flow in annular duct

Cited by 5 publications

References 5 publications

Mass transfer at the solid-liquid interface for climbing film flow in an annular duct

Mass transfer at the solid-liquid interface for climbing film flow in an annular duct

Mass transfer at the solid‐liquid interface for climbing film flow in an annular duct

Dispersion in laminar flowing liquid films involving heat transfer and interfacial shear

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