Topic
Mass transfer coefficient
About: Mass transfer coefficient is a research topic. Over the lifetime, 7827 publications have been published within this topic receiving 168354 citations.
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TL;DR: In this article, the average mass transfer liquid film coefficient (kL) in an aerated tank stirred by two Rushton turbines on common shaft was measured by the dynamic pressure method with pure oxygen absorption.
Abstract: Experimental data on the average mass transfer liquid film coefficient (kL) in an aerated tank stirred by two Rushton turbines on common shaft are presented. Liquid media used were distilled water and 0.5 M sodium sulphate solution. Volumetric mass transfer coefficient (kLa) was measured by the dynamic pressure method with pure oxygen absorption. Specific interfacial area a was taken from Alves et al. [Chem. Eng. Proc., in press] who measured data on local gas hold-up and local average bubble diameter in the same apparatus and batches. Values of kL are quantitatively interpreted in terms of correlations based on idealized eddy structures of turbulence in the bubble vicinity, namely by “eddy” model by Lamont and Scott [AIChE J. 16 (1970) 513] in the form of kL=0.523(eν/ρ)0.25(D/ν)1/2, which fits the data with the mean deviation of 4.7%. It is shown that the decisive quantity to correlate kL in the stirred tank is power dissipated in the liquid phase rather than the bubble diameter and the slip velocity as assumed by Alves et al.
103 citations
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TL;DR: In this article, the authors analyzed the hydrogen and oxygen stable isotope distribution in liquid and water vapor, and the effect of molecular mass transfer is directly obtained without having to perform difficult measurements in the air in the immediate vicinity of the water surface.
Abstract: The calculation of the evaporation flux is based on certain assumptions concerning processes in the vicinity of the air-water interface. Most of the recently proposed evaporation theories differ mainly in the estimated contributions of molecular and turbulent mass transfer in the vapor phase just above the liquid surface. This paper will show that, by analyzing the hydrogen and oxygen stable isotope distribution in liquid and water vapor, the processes taking place on a very small scale near the liquid can be investigated. The effect of molecular mass transfer is directly obtained without having to perform difficult measurements in the air in the immediate vicinity of the water surface. Experiments are carried out in the Institut de Mecanique Statistique de la Turbulence air-water tunnel specially designed for the simulation of ocean-atmosphere energy exchanges. The wind velocities vary from 0.7 to 7 m/s. The experimental results obtained do not support the classical Reynolds analogy between momentum and mass transfer down to the interface and the theory proposed by Sheppard, but they are in agreement with Sverdrup's, Kitaigorodskiy and Volkov's, and Brutsaert's theories, all of which involve a layer just above the air-water interface through which mass transfer is dominated by molecular diffusion. The thickness of this layer in the two first theories is shown to decrease with increasing wind velocity. Direct application of Brutsaert's theory for roughness Reynolds numbers smaller than 1 is in good agreement with our experimental data.
103 citations
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TL;DR: The applicability of Kolmogoroff's theory of local isotropic turbulence to problems involving particle-liquid mass transfer in turbulent flow is critically examined in this paper, which leads to the conclusion that the hydrodynamics of mass transfer can be accounted for by a single parameter; the power input per unit mass.
103 citations
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TL;DR: In this paper, an open sun and greenhouse drying of onion flakes has been performed to study the effect of mass on convective mass transfer coefficient for open as well as greenhouse drying.
102 citations
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TL;DR: In this article, commercially available zeolites (CBV28014, CBV901) with a high Si/Al ratio were tested as adsorbents to recover 1-butanol from aqueous solutions such as acetone butanol-ethanol fermentation broth.
102 citations