Enhanced mass transfer in air oscillating in a channel with periodically varying radius

Козлов, В. Г.; Polezhaev, Denis

doi:10.1016/j.ijheatmasstransfer.2020.120818

Cited by 3 publications

(4 citation statements)

References 19 publications

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“…Recently, Kozlov and Polezhaev experimentally studied the effect of air oscillations on the diffusion rate of vapor in air in a channel of variable radius [10] . They discovered a novel phenomenon associated with the significant enhancement of longitudinal mass transfer due to steady vortical flows.…”

Section: Methods Detailedmentioning

confidence: 99%

“…As the fluid evaporates through the channel of variable radius or porous medium, its free surface descends at a constant velocity dh f / dt . Recently, Kozlov and Polezhaev [10] stated that knowledge of this velocity is essential to calculate the molecular diffusion coefficient in a channel of variable radius:

…”

Section: Methods Detailedmentioning

confidence: 99%

“…2 Evolution of the free surface position due to evaporation (without oscillation) in the experiments with the channel of variable radius ( a ) and porous medium consisting of randomly packed hard spheres ( b ). Data in the left graph were first published in [10] ; Data in the right graph were first published in [11] . …”

Section: Methods Detailedmentioning

confidence: 99%

“…In the absence of air oscillations, the technique allows measuring the coefficient of molecular diffusion of vapor in air. Perhaps an even more significant result is that a new approach can be used to measure the coefficient of enhanced vapor diffusion in oscillating air which was first discovered in very recent research [10] . Another useful side effect of the new technique is that it makes it possible to calculate the diffusive tortuosity of porous media.…”

Section: Methods Detailedmentioning

confidence: 99%

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Measure method of effective diffusion in gas oscillating in channels of variable radius or porous medium

2021

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The paper discusses a new technique for measuring the diffusion coefficient of vapor of a volatile fluid in air in long straight channels or porous media. The proposed experimental technique is universal and allows a) determining the coefficient of molecular diffusion of vapor of a volatile liquid in air; b) calculating the coefficient of effective diffusion of vapor in oscillating air. The proposed technique was tested in the study of the diffusion of 2-propanol vapor in air at rest and oscillating air in a channel of variable radius and a porous medium consisting of randomly packed hard spheres of equal diameter and was found to be relevant. Initial experiments with a porous medium show that the proposed experimental technique can also be used to estimate the diffusive tortuosity of porous media. The results of studies, finished and planned, are useful for understanding the physical processes taking place in various technical operations including wood and food drying, drug delivery, etc. The new experimental technique provides accurate measurement of the molecular diffusion coefficient of vapor of a volatile fluid in air. The experimental setup allows measuring the enhanced mass transfer of vapor of a volatile fluid in oscillating air in a straight channel of constant/variable radius and a porous medium. The additional advantage of the present technique is that it enables the estimation of the diffusive tortuosity of a porous medium.

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Section: Methods Detailedmentioning

confidence: 99%

…”

Section: Methods Detailedmentioning

confidence: 99%

Section: Methods Detailedmentioning

confidence: 99%

Section: Methods Detailedmentioning

confidence: 99%

See 2 more Smart Citations

Measure method of effective diffusion in gas oscillating in channels of variable radius or porous medium

2021

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Gas injection into a tilted rotating cylinder

Lefranc

Detournay²,

Meunier

2023

Physics of Fluids

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The flux of CO2 diffusing inside a new type of bioreactors has been measured experimentally. This geoinspired bioreactor consists of a partially filled cylinder rotating around its axis tilted vertically, thus mimicking the precession motion of the Earth. The height of fluid is chosen equal to two radii in order for the first Kelvin mode to be resonant. The CO2 diffuses through a membrane located at the bottom of the liquid. The partial pressure of CO2 above the free surface is measured as a function of time. This temporal evolution is modeled by the presence of diffusive layers with no advection at the top and the bottom of the liquid. This basic model leads to an experimental value for the flux of CO2 at the membrane, which is found to be proportional to the inverse square root of the Ekman number. This is in agreement with the presence of Ekman layers of thickness proportional to the square root of the Ekman number. At a given Ekman number, the flux weakly depends on the tilt angle α with a scaling as α1/4.

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Mass transfer of solute in an oscillating flow in a two-dimensional channel

Bushueva,

Polezhaev

2024

Physics of Fluids

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The effective diffusion of a solute in a rectangular two-dimensional channel is experimentally studied. We experimentally examine the effective diffusion of Rhodamine B dissolved in water oscillating in a rectangular Hele–Shaw cell. The concentration of Rhodamine B in water is measured by the intensity of its fluorescence emission. In particular, we consider two problems: (i) effective diffusion of solute in water oscillating in a two-dimensional rectangular channel (Hele–Shaw cell) and (ii) effective diffusion of solute in pores between monosized hard spheres randomly packed in a rectangular Hele–Shaw cell. It is revealed that the rate of solute mass transfer exceeds the molecular diffusion rate in both cases. It has been demonstrated that when water oscillates between parallel walls, diffusion is accelerated by Taylor dispersion with the effective diffusion coefficient Deff exceeding the molecular diffusion coefficient Dm by 1–2 orders of magnitude. The effective diffusion coefficient Deff depends only on the relative amplitude but not on the frequency of the fluid oscillations in the studied range of frequencies and amplitudes. When the fluid oscillates in the pores of the porous medium, solute transport is faster than in the case of Taylor dispersion. Here, the effective diffusion coefficient depends on both the frequency and amplitude of oscillations. The analysis shows that the experimental data obtained at various frequencies and amplitudes of oscillations are consistent with the relation Deff/Dm∼Pe2 (Pe is the Peclet number). We suggest that the enhanced solute mass transfer is associated with the time-averaged fluid flows that arise due to spatial heterogeneity of the amplitude of water oscillations in the pores between randomly packed hard spheres.

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Enhanced mass transfer in air oscillating in a channel with periodically varying radius

Cited by 3 publications

References 19 publications

Measure method of effective diffusion in gas oscillating in channels of variable radius or porous medium

Measure method of effective diffusion in gas oscillating in channels of variable radius or porous medium

Gas injection into a tilted rotating cylinder

Mass transfer of solute in an oscillating flow in a two-dimensional channel

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