The effect of diffusivities and surface films on rates of gas absorption

Davies, J.; Kilner, A.A.; Ratcliff, G. A.

doi:10.1016/0009-2509(64)85049-1

Cited by 61 publications

(18 citation statements)

References 8 publications

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“…The relationship reported by Versteeg et al (1987) between the liquid phase mass transfer rate and the stirrer speed was similar to the observations presented by Davies et al (1964), Kozinski and King (1966), Linek et al (1970), and Al-Ghawas (1988). So far, for stirred cell reactors with a smooth horizontal gas-liquid interface physical absorption experiments in only aqueous solutions seem to have been reported.…”

Section: Many Authorssupporting

confidence: 85%

Physical absorption into non-aqueous solutions in a stirred cell reactor

Littel

Versteeg

Swaaij

1991

Chemical Engineering Science

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Section: Many Authorssupporting

confidence: 85%

Physical absorption into non-aqueous solutions in a stirred cell reactor

Littel

Versteeg

Swaaij

1991

Chemical Engineering Science

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“…This indicates that n = 3 and that their values of r are high. As stated before, the value oft is dependent on a, t (brought about by changes in, for instance, the viscosity, density or stirrer speed, geometrical factors) and D, and although the experimental set-up looks similar, T could be relatively high (Hikita and Ishikawa, 1969;Machon and Linek, 1974) or low (Davies et al, 1964;Kozinsky and King, 1966;Linek et al, 1970) depending on the experimental conditions and geometrical factors. In the present work, however, an important variation in T was obtained (see Fig.…”

Section: Measurements Of the Liquid-phase Mass-transjkr Coe#icientmentioning

confidence: 94%

“…12 the limits and the solution according to the King model are also presented. Davies et al (1964), Kozinsky and King (1966) and Linek et al (1970) found that the dependence on diffusivity was proportional to fiat a constant stirrer speed (constant hydrodynamic conditions). In terms of the King model this indicates that the values of r must be small.…”

Section: Measurements Of the Liquid-phase Mass-transjkr Coe#icientmentioning

confidence: 99%

The effect of diffusivity on gas-liquid mass transfer in stirred vessels. Experiments at atmospheric and elevated pressures

Versteeg

Blauwhoff

Swaaij

1987

Chemical Engineering Science

122

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Abstract-Mass transfer has been studied in gas-liquid stirred vessels with horizontal interfaces which appeared to the eye to be completely smooth. Special attention has been paid to the influence of the coefficient of molecular diffusion. The results are compared with those published before. The simplifying assumptions of identical hydrodynamical conditions at the same stirrer speed in one particular geometry, which have been made in some previous investigations, is shown to be wrong and may-lead to incorrect conclusions on the influence of the diffusion coefficient. For the gas phase the mass transfer can be described by the penetration theory (Higbie, R.

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“…The batch absorption technique presents three main drawbacks: Under conditions of high agitation the liquid tends to approach saturation very quickly, within 10 sec. in one case (5) and within 1 min. in another (21), thus reducing the time available for measurements.…”

mentioning

confidence: 94%

“…Knowledge of the effect of diffusivity on k, is a key factor in the evaluation of various theoretical approaches, but there is little agreement within the available data. For the case of liquid phase resistance to gas absorption in a stirred vessel, Hutchinson and Sherwood (17), Dobbins (8,9) and Davies, Kilner, and RatcIiff (5) have reported values of m lying between 0.25 and 0.9. Kishinevsky and Serebryansky (21) find that k, is compIetely independent of diffisivity for a high level of agitation.…”

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confidence: 96%

The influence of diffusivity on liquid phase mass transfer to the free interface in a stirred vessel

Kozinski

King

1966

AIChE Journal

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primary viscosity distributioii viscosity disturbance primary viscosity distribution ( J p o ) , dimensionless kinematic viscosity density primary density distribution density disturbance disturbance growth factor defined by Equation (12) amplitude of pressure disturbance divided by mean density primary angular velocity distribution primary angular velocity distribution (n/n,.), dimensionless dummy radial position variable 3. -, Proc. Roy. SOC., 246A, 301 (1958). 4. 5.6. 7. 8. 9.10. 11.12. 13.Kirchgassncr, K., ZAMP, 12, 14 (1981).Walowit, J. A,, S. Tsao, and R. C. DiPrima, 1. Appl. Mech., 31,585 (1964).Lewis, J. W., Proc. Roy. SOC., 117A, 388 ( 1928 Liquid phase mass transfer coefficients were measured in a continuous flow, stirred vessel containing a gas and a liquid phase. Helium, hydrogen, oxygen, argon, and carbon dioxide were desorbed from distilled water into nitrogen a t seven different levels of agitation. A t low stirring speeds the system was stratified and mass transfer coefficients were proportional to diffusivity raised to a power between 0.5 and 0.6. A t higher stirring speeds the interface was broken and corrections for desorption into the entrained bubbles indicated that the mass transfer coefficient at the main free interface was proportional to a higher power of diffusivity. The results are interpreted in the light of a general model considering eddy diffusion and surface renewal effects.Many industrial processes involve mass transfer between a gas and a liquid. Often the interface between the two phases is relatively free to move about in space and Each approach predicts a different degree of dependence of the liquid phase mass transfer coefficient upon diftusivity. A general analysis of liquid phase mass transfer at a free surface in turbulent systems has been put forward by one of the present authors (19), and involves concepts of molecular diffusion, small-scale eddy diffusion, and large-scale surface renewals. From this analysis it follows that the exponent on diffusivity in a correlation for the li uid phase mass transfer coefficient depends upon upon the surface age. If surface tension causes the eddy diffusivity in the liquid to damp out continuously to zero at the interface, the exponent m in the be 1 avior of the eddy diffusivity near the interface and k L -D"' will be 0.5 for low ages of a surface element under consideration. It is convenient to denote this damping by postulating that the eddy diffusivity is proportional to y", where y is distance normal to the interface. If n > 2, increasing surface ages will cause m to rise continuously from 0.5 to an upper limiting value of 1 -I/n. If n = 2, m will be 0.5 for all ages, and if n lies between 0 and 2 the exponent upon D will continually decrease as surface age increases, reaching a nonzero limiting value only if n > 1.If the small eddies causing the eddy diffusivity are somehow not damped out at the interface by surface tension, the exponent on diffusivity will be reduced. A limiting case of m = 0, corresponding to kL being completel...

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The effect of diffusivities and surface films on rates of gas absorption

Cited by 61 publications

References 8 publications

Physical absorption into non-aqueous solutions in a stirred cell reactor

Physical absorption into non-aqueous solutions in a stirred cell reactor

The effect of diffusivity on gas-liquid mass transfer in stirred vessels. Experiments at atmospheric and elevated pressures

The influence of diffusivity on liquid phase mass transfer to the free interface in a stirred vessel

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