Electro-chemical measurements of mass transfer in semi-cylindrical hollows

Aggarwal, J. K.; Talbot, L.

doi:10.1016/0017-9310(79)90099-1

Cited by 22 publications

(12 citation statements)

References 6 publications

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“…The present finding that the mass transfer coefficient inside the cavity is less than the flat surface mass transfer coefficient is consistent with the finding of Aggarwal and Talbot [8] who used large semi-cylindrical cavities. They found that local Sh at the wall of the channel in laminar steady flow was reduced by about 25% due to the presence of the semi-cylindrical hollow irrespective of the hollow diameter.…”

Section: Resultssupporting

confidence: 94%

“…These plots show that the mass transfer data of the cavities fall below the flat surface data; the deeper the cavity, the higher the deviation from the flat plate value. The low mass transfer coefficient inside the cavity compared to that of the flat plate is attributed to the formation of a slow recirculating eddy (secondary flow) inside the cavity under forced convection [7][8][9][10][11][12][13][14][15]. This eddy prevents effective communication between the external flow and the inside of the cavity; the deeper the cavity the larger the diameter of the slow recirculating eddy and the larger the resistance to the rate of mass transfer between the cavity wall and the fluid outside the cavity.…”

Section: Resultsmentioning

confidence: 99%

“…The present work may also be of a value to heat and mass transfer at rough surfaces [7]. Aggarwal and Talbot [8] used the limiting current electrochemical technique to obtain local mass transfer coefficients in large semi-cylindrical cavities (i.e., mass transfer distribution inside the cavity) with the aim of developing a compact artificial lung of high surface area and high mass transfer coefficient. Alkire et al [9][10][11] and Shin & Econmou [12] studied the effect of fluid flow on the rate of mass transfer at the bottom of small rectangular cavities in relation to etching of masked surfaces which is used in printed circuit fabrication.…”

Section: Introductionmentioning

confidence: 99%

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Forced Convection Mass Transfer Inside Large Hemispherical Cavities Under Laminar Flow Conditions

Zaki

Nirdosh

Sedahmed

1997

Chemical Engineering Communications

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Rates of mass transfer at hemispherical cavities machined in the wall of a vertical rectangular duct were measured by an electrochemical technique which involved measuring the limiting current of the cathodic reduction of K 3 Fe(CN), . Variables studied were solution flow rate, physical properties of the solution and cavity diameter. The mass transfer coefficient inside the cavity was found to be less than the flat surfaoe value (the duct wall), and decreased with an increase in the cavity diameter. Mass transfer data inside the cavity were correlated by the equation: ( d )0.33 Sh, = 0.89 SC'Re'w here Sh" and Sc and Re are Sherwood, Schmidt and Reynolds numbers, respectively; and d. and d are the duct equivalent diameter and cavity diameter, respectively. Practical implications of the present results in mass transfer limited processes such as diffusion controlled corrosion, electrochemical machining, electroplating and etching have been highlighted.

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Section: Resultssupporting

confidence: 94%

Section: Resultsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Forced Convection Mass Transfer Inside Large Hemispherical Cavities Under Laminar Flow Conditions

Zaki

Nirdosh

Sedahmed

1997

Chemical Engineering Communications

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“…A similar finding was reported by previous studies on different cavity geometry. Aggarwal and Talbot[6] who used semicylindrical cavities reported 25 To decrease in the rate of mass transfer below the flat surface value, while Zaki et al 1151 who used hemispherical cavities reported 52% decrease below the flat surface value. The difference in the percent reduction in the mass transfer coefficient below the flat surface value reported by different authors underlines the importance of cavity geometry in determining the rate of mass transfer inside the cavity.…”

mentioning

confidence: 98%

Effect of laminar flow on the rate of mass transfer inside cubical cavities

1997

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An electrochemical technique which involved measuring the limiting current of the cathodic reduction of potassium ferricyanide was used to study the rate of mass transfer inside a cubical cavity machined in the wall of a vertical rectangular duct. Variables studied were side length, physical properties of the solution and flow rate of the solution. The mass transfer coefficient was found to decrease with increasing cavity size; in all cases, the mass transfer coefficient inside the cavity was less than that at the duct wall. Mass transfer data inside the cavity were correlated by the equation Sh, = 0.525 (Sc Re d,/L)0.33. Comparison of the present results with the results obtained using other cavity geometries shows that cavity geometry plays an important role in determining the rate of mass transfer inside the cavity.

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“…and ⌽* ϭ 0 [23] on the top boundary. Condition 23 corresponds to the situation where it was assumed that the top of the calculation domain was an equipotential line, a choice justified by refining the placement of the top boundary until the results were not affected.…”

Section: Methodsmentioning

confidence: 99%

Local Mass Transport in Two-Dimensional Cavities in Laminar Shear Flow

Γεωργιαδου

Mohr

Alkire

2000

J. Electrochem. Soc.

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The local mass-transfer rate was investigated along the bottom wall of two-dimensional cavities of nominally rectangular shape, 100 m wide, and aspect ratio (depth/width) 0.5. Experimental measurements were made by an electrochemical limiting current technique based on reduction of K 3 Fe(CN) 6 at gold ultramicroelectrodes, each 10 m wide and spaced 1 m apart. Experiments were carried out in the presence of laminar fluid flow in the range between Stokes flow and turbulent flow (0.068 < Re < 2400). Numerical computations of two-dimensional, laminar, convective diffusion were carried out with use of (a) a research grade finitedifference code (ERMES) and (b) a commercial grade finite-element program (FIDAP). In addition, ERMES was implemented for numerical computations of two-dimensional, multispecies transport by convection, diffusion, and migration under laminar flow. The simulations carried out for both rectangular (ERMES) and undercut (FIDAP) cavity shapes indicated that the hydrodynamic profiles consisted of a major recirculating vortex in the cavity and a pair of relatively small eddies inside the two corners at all flow rates studied. The simulations indicated that above an aspect ratio of 0.33 the hydrodynamic flow pattern for a rectangular cavity changed from a major single eddy to isolated corner eddies. In the convective regime, experimental and theoretical results agreed in average mass-transport rates to the surface and in the local flux distributions but differed in predicting the location of the maximum.

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Electro-chemical measurements of mass transfer in semi-cylindrical hollows

Cited by 22 publications

References 6 publications

Forced Convection Mass Transfer Inside Large Hemispherical Cavities Under Laminar Flow Conditions

Forced Convection Mass Transfer Inside Large Hemispherical Cavities Under Laminar Flow Conditions

Effect of laminar flow on the rate of mass transfer inside cubical cavities

Local Mass Transport in Two-Dimensional Cavities in Laminar Shear Flow

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