Papers by Keyword: Mass Transfer Coefficient

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Authors: Yong Dan Li, Su Min Lu, Qin Peng Guan
Abstract: Three-phase slurry bubble column reactor owns a wide application area. This review focuses on the hydrodynamics of the reactor from the findings of published studies, which includes the flow regimes, gas holdup, bubble size and distribution and mass transfer coefficients. The factors affecting each parameter and the status of the research are discussed, and the development of slurry bubble column reactor has also been prospected. At present, the experimental data that can be used in the industrial application is not accurate, an enlargement of the reactor is still a difficult problem, it remains to be further exploring in close to real environment.
2404
Authors: Olga Karabelchtchikova, Richard D. Sisson
Abstract: Initiated by the need of industry for gas carburizing process control and optimization, this paper focuses on understanding the effect of the time, temperature and carbon potential on the mass transfer coefficient and carbon diffusivity in Austenite. A method for direct flux integration has previously been proposed to calculate these kinetic parameters from the experimental carbon concentration profiles. AISI 8620 steel discs were gas carburized at different levels of atmosphere carburizing potential for selected austenizing temperatures. Analyses of the carburized parts included experimental measurement of weight gain, surface carbon concentration and carbon concentration profiles. The time-dependent weight gain and surface carbon content measurements allowed calculation of the time average mass transfer coefficient, while carbon concentration profiles were used to calculate the concentration dependent carbon diffusivity for selected process parameters. Excellent agreement was found between the calculated mass transfer coefficient and carbon diffusivity values and those reported in the literature. The calculated values served as input in the previously developed carburizing model validating the predicted results by comparison with the experimental concentration profiles.
171
Authors: Hesham S. Bamufleh, S. A. Nosier, M. A. Daous
Abstract: The solid-liquid mass transfer rate at a stack of circular fin surfaces in a bubble column was investigated. A diffusion-controlled dissolution technique of copper in an acidified chromate solution was employed. Variables studied included the number of actively exposed fins ranging from 5 to 20, pertinent physical properties of the solution, and air superficial velocity. Experimental data showed that the rate of the diffusion-controlled mass transfer increases with increasing superficial air velocity and decreases with increasing chromate solution acid concentration. Moreover, at relatively low superficial air velocity, increasing the number of actively exposed fins results into a continuous increase in the mass transfer coefficient. At relatively higher superficial air velocity, however, the mass transfer coefficient decreases in the 5 to 10 range of actively exposed fins and then reverts to increase in the 15 to 20 range.
647
Authors: Mohd Sharizan Md Sarip, Noor Azian Morad
Abstract: Subcritical water extraction (SWE) is introduced in the extraction of ginger bioactive compounds, namely 6-gingerol and 6-shagoal. The extraction mechanism is identified using mass transfer coefficient model. The overall mass transfer coefficient, k or driving force for each compound is measured through experimental determination. Compound identification and analysis iss conducted using High Performance Liquid Chromatography (HPLC). The k value for 6-gingerol and 6-shagoal under optimized condition (130°C, 3.5MPa) of 28:3 (ml:g) solvent to sample ratio are 0.02849 cm/min and 0.04873 cm/min, respectively.
1900
Authors: Rocío Maceiras, Xosé R. Nóvoa, Angeles Cancela, Estrella Álvarez
Abstract: The mass transfer coefficients at different axial positions in a bubble column have been measured using a conductivity method. Measurements of CO2 absorption in methyldiethanolamine solutions were carried out in a prismatic column 0.06 m side and 1.03 m height. Five electrode pairs were placed at various axial positions in the column. Measurements were conducted at different gas flow rates and amine concentration. It was found that the local mass transfer varied in the axial direction. An experimental model was developed to obtain the absorption rate values using the electrochemical method data. The model agrees quite well with the experimental obtained data.
87
Authors: Yang Lin Li
Abstract: In order to improve the efficiency of ozone mass transfer in liquid phase, the method enhanced by electric field was put forward. The effect on ozone mass transfer was investigated from voltage, electrode spacing and gas flow rate. The result showed that ozone concentration in water and the total mass transfer coefficient increased correspondingly with the increase of the voltage, and ozone concentration in water and the total mass transfer coefficient increased correspondingly with increase of the electrode spacing in the range from 1 to 3 cm, and ozone concentration in water increased correspondingly with increase of the gas flow rate, but the total mass transfer coefficient reduced correspondingly.
2139
Authors: Dai Yong Jia, Lu Yan Sui, Ming Lai He
Abstract: In this study, an experiment platform was built up to determine the key parameter, mass transfer coefficient, of the ventilation and dehumidification process in main cable of suspension bridge. On the basis of experimental studies, an empirical formula of the mass transfer coefficient was obtained, which can greatly contribute to control the content of moisture in the main cable of suspension bridges.
151
Authors: Fei Wu, Jie Wu, Mei Jin, Fang Wang, Ping Lu
Abstract: Based on acetone-H2O system, the influence of the gas-liquid distribution inducer on the mass transfer coefficient in the rotating packed bed with the stainless steel packing was investigated. Furthermore, the absorption performance was also obtained under the experimental condition of the rotational speed of 630 rpm, the gas flow rate of 2 m3/h and the liquid flow rate of 100 L/h in the rotating packed bed with different types and different installation ways of the distribution inducer. The experimental results showed that the volumetric mass transfer coefficient Kyα per unit contact length of gas-liquid was increased by 8.6% for the forward-curved fixed blade, by 19.8% for the backward-curved rotor blade and by 33.2% with the combination of the straight radial rotor blade and the backward-curved fixed blade, respectively. Furthermore, when the gas flow rate was 2.5 m3/h, Kyα per unit contact length of gas-liquid was increased by 2.9% for the forward-curved fixed blade, by 25.3% for the backward-curved rotor blade, by 42.7% for the combination of the straight radial rotor blade and the backward-curved fixed blade, respectively. The results indicated that the distribution inducer play an important role on the improvement of the mass transfer coefficient in acetone-H2O system.
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