scholarly journals A Review on Gas-Liquid Mass Transfer Coefficients in Packed-Bed Columns

2021 ◽  
Vol 5 (3) ◽  
pp. 43
Author(s):  
Domenico Flagiello ◽  
Arianna Parisi ◽  
Amedeo Lancia ◽  
Francesco Di Natale
Keyword(s):  
Mass Transfer ◽  
Fluid Dynamic ◽  
Mass Transfer Rate ◽  
Model Fitting ◽  
Interfacial Area ◽  
Packed Bed ◽  
Original Form ◽  
Transfer Coefficients ◽  
Unit Surface ◽  
Packed Bed Columns

This review provides a thorough analysis of the most famous mass transfer models for random and structured packed-bed columns used in absorption/stripping and distillation processes, providing a detailed description of the equations to calculate the mass transfer parameters, i.e., gas-side coefficient per unit surface ky [kmol·m−2·s−1], liquid-side coefficient per unit surface kx [kmol·m−2·s−1], interfacial packing area ae [m2·m−3], which constitute the ingredients to assess the mass transfer rate of packed-bed columns. The models have been reported in the original form provided by the authors together with the geometric and model fitting parameters published in several papers to allow their adaptation to packings different from those covered in the original papers. Although the work is focused on a collection of carefully described and ready-to-use equations, we have tried to underline the criticalities behind these models, which mostly rely on the assessment of fluid-dynamics parameters such as liquid film thickness, liquid hold-up and interfacial area, or the real liquid paths or any mal-distributions flow. To this end, the paper reviewed novel experimental and simulation approaches aimed to better describe the gas-liquid multiphase flow dynamics in packed-bed column, e.g., by using optical technologies (tomography) or CFD simulations. While the results of these studies may not be easily extended to full-scale columns, the improved estimation of the main fluid-dynamic parameters will provide a more accurate modelling correlation of liquid-gas mass transfer phenomena in packed columns.

STUDY OF EXTERNAL MASS TRANSFER DURING DRYING OF BERRY RAW MATERIALS TAKING INTO THE SHRINKAGE PHENOMENON

2019 ◽  
Author(s):  
А.В. АКУЛИЧ ◽  
Л.А. ГОСТИНЩИКОВА
Keyword(s):  
Mass Transfer ◽  
Energy Supply ◽  
Raw Materials ◽  
Mass Transfer Rate ◽  
Experimental Studies ◽  
Volume Shrinkage ◽  
External Mass Transfer ◽  
Transfer Coefficients ◽  
Ir Radiation ◽  
Criterial Equations

Исследованы закономерности внешнего массообмена при сушке ягодного сырья для различных способов энергоподвода. Установлено, что ягоды при сушке подвержены значительной объемной (72–81%) и линейной (35–43%) усадке, которую необходимо учитывать при расчете коэффициентов массоотдачи. Объекты исследования – ягоды черники, красной и черной смородины. Проведены экспериментальные исследования по сушке ягодного сырья при конвективном и конвективном с ИК-излучением способах энергоподвода. Исследования проведены при скорости сушильного агента хса1,2 м/с и температуре tса 70°С. Получены критериальные уравнения внешнего массоообмена при сушке ягод для периода постоянной скорости, учитывающие объемную усадку. Определено, что при сушке с конвективным энергоподводом объемная усадка при одном и том же значении критерия Рейнольдса оказывает на 12–20% большее влияние на интенсивность массоообмена для красной смородины по сравнению с черникой и черной смородиной. При сушке с конвективным энергоподводом, ИК-излучением и предварительным прокалыванием объемная усадка наиболее существенно влияет на массообмен для черной смородины, протекающий в 1,5–1,8 раза интенсивнее по сравнению с черникой и красной смородиной. Полученные критериальные уравнения могут быть использованы при расчете и проектировании установок для сушки ягодного сырья. The laws of external mass transfer during drying of berry raw materials for various methods of energy supply are investigated. It is established that the berries during drying are subject to significant volumetric (72–81%) and surface (35–43%) shrinkage, which must be taken into account when calculating the mass transfer coefficients. The objects of the study were various berries: blueberries, red and black currants. Experimental studies have been carried out on the drying of selected berries both in the case of convective and convective methods with IR radiation. Investigations were carried out at a drying agent velocity хса1,2 m/s and its temperature tca70°С. The criterion equations of external mass transfer during drying of berries for a period of constant speed, taking into account the volume shrinkage, are obtained. It was determined that during drying with convective energy supply, volume shrinkage with the same value of the Reynolds criterion on 12–20% has a greater effect on the mass transfer rate for red currants. When drying with convective energy supply, IR radiation and preliminary piercing, the volume shrinkage most significantly affects the mass transfer for black currants, which is 1,5–1,8 times more intense than blueberries and red currants. The obtained criterial equations can be used in the calculation and design of berries dryers.

scholarly journals Gas-solid and gas-liquid mass transfer: Effect of turbulent Schmidt number

2007 ◽  
Vol 13 (3) ◽  
pp. 167-168 ◽  
Author(s):  
Aleksandar Dudukovic ◽  
Rada Pjanovic
Keyword(s):  
Mass Transfer ◽  
Eddy Viscosity ◽  
Schmidt Number ◽  
Mass Transfer Rate ◽  
Transfer Effect ◽  
Transfer Coefficients ◽  
Mass Transfer Effect ◽  
Liquid Mass ◽  
Turbulent Schmidt Number ◽  
Liquid Mass Transfer

The scope of this paper is to explain effect of eddy viscosity and turbulent Schmidt number on mass transfer rate. New, theoretically based correlation for gas-liquid mass transfer coefficients are proposed.

Distribution of Mass Transfer Rate and Wall Shear Stress Behind Simple Rectangular Stenosis in Pulsating Flow

1989 ◽  
Vol 111 (1) ◽  
pp. 47-54 ◽  
Author(s):  
R. Yamaguchi
Keyword(s):  
Mass Transfer ◽  
Shear Stress ◽  
Wall Shear Stress ◽  
Transfer Rate ◽  
Schmidt Number ◽  
Fluid Dynamic ◽  
Mass Transfer Rate ◽  
Pulsating Flow ◽  
Flow Through ◽  
Wall Shear

The distributions of mass transfer rate and wall shear stress in sinusoidal laminar pulsating flow through a two-dimensional asymmetric stenosed channel have been studied experimentally and numerically. The distributions are measured by the electrochemical method. The measurement is conducted at a Reynolds number of about 150, a Schmidt number of about 1000, a nondimensional pulsating frequency of 3.40, and a nondimensional flow amplitude of 0.3. It is suggested that the deterioration of an arterial wall distal to stenosis may be greatly enhanced by fluid dynamic effects.

Liquid-liquid mass transfer studies in various stirred vessel designs

2015 ◽  
Vol 31 (4) ◽  
Author(s):  
Reza Afshar Ghotli ◽  
Abdul Raman Abdul Aziz ◽  
Shaliza Ibrahim
Keyword(s):  
Mass Transfer ◽  
Transfer Coefficient ◽  
Mass Transfer Coefficient ◽  
Interfacial Area ◽  
Operating Conditions ◽  
Experimental Results ◽  
Dispersed Phase ◽  
Transfer Coefficients ◽  
Mass Transfer Coefficients ◽  
Wide Range

AbstractA general review on correlations to evaluate mass transfer coefficients in liquid-liquid was conducted in this work. The mass transfer models can be classified into continuous and dispersed phase coefficients. The effects of drop size and interfacial area on mass transfer coefficient were investigated briefly. Published experimental results for both continuous and dispersed phase mass transfer coefficients through different hydrodynamic conditions were considered and the results were compared. The suitability and drawbacks of these correlations depend on the operating conditions and hydrodynamics. Although the results of these models are reasonably acceptable, they could not properly predict the experimental results over a wide range of designs and operating conditions. Therefore, proper understanding of various factors affecting mass transfer coefficient needs to be further extended.

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