Gas–liquid mass transfer in a falling film microreactor: Effect of reactor orientation on liquid-side mass transfer coefficient

2016 ◽  
Vol 155 ◽  
pp. 38-44 ◽  
Author(s):  
David Lokhat ◽  
Ashveer Krishen Domah ◽  
Kuveshan Padayachee ◽  
Aman Baboolal ◽  
Deresh Ramjugernath
Keyword(s):  
Mass Transfer ◽  
Transfer Coefficient ◽  
Mass Transfer Coefficient ◽  
Falling Film ◽  
Liquid Mass ◽  
Liquid Mass Transfer

Effect of bubble contamination on gas–liquid mass transfer coefficient on CO2 absorption in amine solutions

2008 ◽  
Vol 137 (2) ◽  
pp. 422-427 ◽  
Author(s):  
Rocío Maceiras ◽  
Sebastião S. Alves ◽  
M. Ángeles Cancela ◽  
Estrella Álvarez
Keyword(s):  
Mass Transfer ◽  
Transfer Coefficient ◽  
Mass Transfer Coefficient ◽  
Co2 Absorption ◽  
Liquid Mass ◽  
Liquid Mass Transfer ◽  
Amine Solutions

scholarly journals Numerical study of the hydrodynamics and mass transfer in the external loop airlift reactor

2021 ◽  
pp. 34-34
Author(s):  
Predrag Kojic ◽  
Jovana Kojic ◽  
Milada Pezo ◽  
Jelena Krulj ◽  
Lato Pezo ◽  
...  
Keyword(s):  
Mass Transfer ◽  
Transfer Coefficient ◽  
Mass Transfer Coefficient ◽  
Airlift Reactor ◽  
Volumetric Mass Transfer Coefficient ◽  
Cfd Model ◽  
Gas Velocity ◽  
Liquid Mass ◽  
External Loop ◽  
Liquid Mass Transfer

The objective of this study was to investigate the hydrodynamics and the gas-liquid mass transfer coefficient of an external-loop airlift reactor (ELAR). The ELAR was operated in three cases: different inlet velocities of fluids, different alcohols solutions (water, 0.5% methanol, 0.5% ethanol, 0.5% propanol and 0.5% butanol) and different concentration of methanol in solutions (0%, 0.5%, 1%, 2% and 5%). The influence of superficial gas velocity and various diluted alcohol solutions on hydrodynamics and gas-liquid mass transfer coefficient of the ELAR was studied. Experimentally, the gas hold-up, liquid velocities and volumetric mass transfer coefficient values in the riser and the downcomer were obtained from the literature source. A computational fluid dynamics (CFD) model was developed, based on two-phase flow, investigating different liquids regarding surface tension, assuming the ideal gas flow, applying the finite volume method and Eulerian-Eulerian model. The volumetric mass transfer coefficient was determined using CFD model, as well as artificial neural network model. The effects of liquid parameters and gas velocity on the characteristics of the gas-liquid mass transfer were simulated. These models were compared with appropriate experimental results. CFD model successfully succeed to simulate the influence of different alcohols regarding the number of C-atoms on hydrodynamics and mass transfer.

The effect of microbubbles on gas-liquid mass transfer coefficient and degradation rate of COD in wastewater treatment

2016 ◽  
Vol 73 (8) ◽  
pp. 1969-1977 ◽  
Author(s):  
Kangning Yao ◽  
Yong Chi ◽  
Fei Wang ◽  
Jianhua Yan ◽  
Mingjiang Ni ◽  
...  
Keyword(s):  
Mass Transfer ◽  
Wastewater Treatment ◽  
Activated Sludge ◽  
Transfer Coefficient ◽  
Mass Transfer Coefficient ◽  
Degradation Rate ◽  
Mass Transfer Rate ◽  
Cod Removal ◽  
Liquid Mass ◽  
Liquid Mass Transfer

A commonly used aeration device at present has the disadvantages of low mass transfer rate because the generated bubbles are several millimeters in diameter which are much bigger than microbubbles. Therefore, the effect of a microbubble on gas-liquid mass transfer and wastewater treatment process was investigated. To evaluate the effect of each bubble type, the volumetric mass transfer coefficients for microbubbles and conventional bubbles were determined. The volumetric mass transfer coefficient was 0.02905 s−1 and 0.02191 s−1 at a gas flow rate of 0.67 L min−1 in tap water for microbubbles and conventional bubbles, respectively. The degradation rate of simulated municipal wastewater was also investigated, using aerobic activated sludge and ozone. Compared with the conventional bubble generator, the chemical oxygen demand (COD) removal rate was 2.04, 5.9, 3.26 times higher than those of the conventional bubble contactor at the same initial COD concentration of COD 200 mg L−1, 400 mg L−1, and 600 mg L−1, while aerobic activated sludge was used. For the ozonation process, the rate of COD removal using microbubble generator was 2.38, 2.51, 2.89 times of those of the conventional bubble generator. Based on the results, the effect of initial COD concentration on the specific COD degradation rate were discussed in different systems. Thus, the results revealed that microbubbles could enhance mass transfer in wastewater treatment and be an effective method to improve the degradation of wastewater.

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