Showing papers on "Mass transfer coefficient published in 2014"
TL;DR: In this paper, a chart is presented to make the required decisions and to enable the reader to characterise and confine a given extraction system regarding fluid dynamics and mass transfer, especially addressing the behaviour of systems dominated by Marangoni instabilities.
135 citations
TL;DR: In this article, the performance of hollow fiber membrane biofilm reactor (HFM-BR) as a reactor configuration for syngas fermentation was evaluated at abiotic conditions within a wide range.
130 citations
TL;DR: In this article, a liquid-liquid mass transfer between immiscible liquids using the system 1-butanol and water, with succinic acid as the mass transfer component, is presented.
123 citations
TL;DR: In this article, an experimental study regarding transport of phenol through a supported liquid membrane (SLM) using tributyl phosphate (TBP) and sesame oil as liquid membrane was performed.
Abstract: Phenols pose a risk to the environment and to human health. Phenol and its derivatives are toxic pollutants, frequently found in surface and tap waters, and in aqueous effluents from various manufacturing processes. In this paper, an experimental study regarding transport of phenol through a supported liquid membrane (SLM) using tributyl phosphate (TBP) and sesame oil as liquid membrane (LM) was performed. Factors affecting permeation of phenol such as initial phenol concentration, carrier concentration, feed phase pH and stripping phase concentration were analyzed using Taguchi method. Optimal experimental condition of phenol transport was obtained using analysis of variance (ANOVA) after 7 h extraction (feed concentration: 200 mg/L; carrier concentration (%TBP): 40%; feed pH: 2; strip phase concentration: 1.1 M). Mass transfer coefficient for this system was evaluated, and compared with similar works, and it was shown that it has the highest mass transfer rate. In addition to transport study, stability of the membrane was investigated by examination of stripping phase concentration, carrier concentration and salt concentration effects.
108 citations
TL;DR: In this paper, a unit cell model is proposed to study the absorption of CO2 bubbles under slug flow in a T-junction microchannel, and the amount of gas absorbed during the bubble formation process has been measured to be about 2-10% of the inlet gas phase.
106 citations
TL;DR: In this paper, the mass transfer characteristics during CO 2 bubble absorption and diffusion processes in nanofluid with Al 2 O 3 nanoparticles were analyzed and the effect of the nanoparticles on mass transfer enhancement was measured.
101 citations
TL;DR: In this paper, a liquid-liquid mass transfer mechanism with slug flow in microreactor is investigated by means of experiments in square microchannels of 0.2 and 0.3 mm width.
94 citations
TL;DR: In this article, two analytical solutions are derived to model the heated flow-through experiments for granite fractures in the literature, and they show that water temperature increases non-linearly along fracture plane.
92 citations
TL;DR: In this paper, the adsorption kinetics of erythrosine B and indigo carmine on chitosan films were studied by a diffusional mass transfer model.
Abstract: The adsorption kinetics of erythrosine B and indigo carmine on chitosan films was studied by a diffusional mass transfer model The experimental curves were obtained in batch system under different conditions of stirring rate (80–200 rpm) and initial dye concentration (20–100 mg L −1 ) For the model development, external mass transfer and intraparticle diffusion steps were considered and the specific simplifications were based on the system characteristics The proposed diffusional mass transfer model agreed very well with the experimental curves, indicating that the surface diffusion was the rate limiting step The external mass transfer coefficient ( k f ) was dependent of the operating conditions and ranged from 132 × 10 −4 to 217 × 10 −4 m s −1 The values of surface diffusion coefficient ( D s ) increased with the initial dye concentration and were in the range from 041 × 10 −14 to 2290 × 10 −14 m 2 s −1 The Biot number ranged from 170 to 4785, confirming that the intraparticle diffusion due to surface diffusion was the rate limiting step in the adsorption of erythrosine B and indigo carmine on chitosan films
82 citations
TL;DR: In this paper, the performance of a monolithic biofilm reactor (MBR) as a novel reactor configuration for syngas fermentation was evaluated in abiotic conditions within a wide range of gas flow rates and liquid flow rates.
79 citations
TL;DR: In this article, an experimental investigation of the fluid flow and mass transfer characteristics during reactive gas-liquid absorption in a minichannel reactor was studied in a channel having hydraulic diameter of 762μm and a circular cross-sectional geometry.
TL;DR: In this paper, the effects of O/A ratio and residence time on overall volumetric mass transfer coefficient have been studied and an attempt has been made to explain the experimental trends with the help of liquid-liquid flow patterns observed by using a high speed image acquisition system.
TL;DR: In this article, the influence of nanoparticles on the mass transfer behavior of drops inside a pulsed liquid-liquid extraction column (PLLEC) was investigated, and a new predictive correlation was proposed to calculate the effective diffusivity and mass transfer coefficient in terms of the nanoparticle volume fraction.
Abstract: Mass transfer in gas–liquid systems has been significantly enhanced by recent developments in nanotechnology. However, the influence of nanoparticles in liquid–liquid systems has received much less attention. In the present study, both experimental and theoretical works were performed to investigate the influence of nanoparticles on the mass transfer behaviour of drops inside a pulsed liquid–liquid extraction column (PLLEC). The chemical system of kerosene–acetic acid–water was used, and the drops were organic nanofluids containing hydrophobic SiO2 nanoparticles at concentrations of 0.01, 0.05, and 0.1 vol%. The experimental results indicate that the addition of 0.1 vol% nanoparticles to the base fluid improves the mass transfer performance by up to 60%. The increase in mass transfer with increased nanoparticle content was more apparent for lower pulsation intensities (0.3–1.3 cm/s). At high pulsation intensities, the Sauter mean diameter (d32) decreased to smaller sizes (1.1–2.2 mm), leading to decreased Brownian motion in the nanoparticles. Using an analogy for heat and mass transfer, an approach for determining the mass diffusion coefficient was suggested. A new predictive correlation was proposed to calculate the effective diffusivity and mass transfer coefficient in terms of the nanoparticle volume fraction, Reynolds number, and Schmidt number. Finally, model predictions were directly compared with the experimental results for different nanofluids. The absolute average relative error (%AARE) of the proposed correlation for the mass transfer coefficient and effective diffusivity were 5.3% and 5.4%, respectively.
TL;DR: In this article, a new method for enhancing the mass transfer coefficient in the gas absorption process was reported, which was carried out in a wetted-wall column using different aqueous nanofluids as the solvent.
Abstract: A new method for enhancing the mass transfer coefficient in the gas absorption process is reported. CO2 absorption experiments were carried out in a wetted-wall column using different aqueous nanofluids as the solvent. The mass transfer characteristics were found to increase by applying Al2O3/water nanofluid. The mass transfer coefficient decreased with TiO2/water nanofluid. In the case of Fe3O4/water nanofluid, the mass transfer rate was enhanced by increasing the nanoparticle volume fraction, but the mass transfer coefficient was lower than that obtained with water for all experimental conditions studied. Finally, applying a downward magnetic field resulted in higher mass flux and mass transfer coefficient in comparison with experiments without a magnetic field.
TL;DR: An intelligent correlation model was developed in this work to predict the mass transfer coefficient more accurately for CO2 capture with NaOH solution in different type rotating packed beds and had superior performance on prediction accuracy and generalization ability.
TL;DR: In this paper, the adsorption of Basic Magenta II onto H 2 SO 4 activated immature Gossypium hirsutum seeds was analyzed using Ho, modified Freundlich, Sobkowsk-Czerwi, Blanchard, Elovich, Avrami, and modified Ritchie kinetic models by nonlinear regression-sum of normalized errors analysis.
TL;DR: In this paper, a 3D-printed helically micro-structured spacers in comparison to state-of-the-art net spacers was investigated for ultrafiltration.
TL;DR: In this paper, the influence of impeller geometry on mass transfer performance and power demand of an unbaffled stirred vessel operating both in sub-critical conditions (the free surface vortex has not yet reached the impeller) and in supercritical conditions, where a gas phase is ingested and dispersed inside the reactor, is presented.
TL;DR: In this paper, a two-dimensional analysis of transport phenomena occurring during drying of a rectangular object is performed employing analytical method and the external flow is predicted numerically and then the convective heat transfer coefficient is determined during convective drying.
TL;DR: In this paper, the mass transfer of CO2 chemical absorption into monoethanol amine (MEA) aqueous solutions under Taylor flow in a T-junction microchannel was investigated experimentally using a high speed camera and two pressure sensors.
TL;DR: A submerged hollow fibre membrane bioreactor system capable of achieving high carbon monoxide (CO) mass transfer for applications in microbial synthesis gas conversion systems was proposed and practicality of HFMBR to support microbial growth and organic product formation was assessed.
TL;DR: In this paper, the axial impellers combination (3WHu) provides more effective homogenization performance than the impellers with combined radial and axial flow (HBT+2WHu, HBT+ 2WHd, HBLT+2Wu, and 3WHu), while the radial impeller combination is the worst.
Abstract: Global and local gas–liquid characteristics (gas hold-up, volumetric mass transfer coefficient), and flow field, mixing time of the liquid phase are investigated for various triple-impeller configurations. Four types of impellers (Rushton turbine (RT), hollow blade turbine (HBT), wide-blade hydrofoil impeller pumping down (WHd), and pumping up (WHu)) were used to form four combinations (3RT, HBT+2WHd, HBT+2WHu, and 3WHu). The results show that the axial impellers combination (3WHu) provides more effective homogenization performance than the impellers with combined radial and axial flow (HBT+2WHu, HBT+2WHd), while the radial impellers combination (3RT) is the worst. When the gas superficial velocity is 1.625 mm s–1, 3WHu produces a 53% higher mass transfer coefficient than HBT+2WHd, HBT+2WHu, and 3RT lie between them. When the gas superficial velocity reaches up to 8.124 mm s–1, however, all of the tested configurations give almost similar mass transfer coefficients under equivalent power input. For 3RT, t...
TL;DR: In this paper, a numerical model for mass transfer across the fluid interface of falling films is presented, where the influence of wave regimes and flow patterns on local Sherwood numbers and distinct mass transfer enhancement mechanisms taking effect in specific wave regimes.
TL;DR: In this paper, a theoretical control-volume-based model is developed based on the assumptions of smooth interface between the annular liquid film and vapor core, and uniform film thickness around the channel's circumference.
TL;DR: In this paper, a cocurrent rotating packed bed (CO-RPB) with a novel SiC structured packing was employed as a process intensification candidate to upgrade existing desulfurization systems.
Abstract: The emission of SO2 leads to serious environmental problems, which has attracted increasing attention. In this work, a cocurrent rotating packed bed (CO-RPB) with a novel SiC structured packing was employed as a process intensification candidate to upgrade existing desulfurization systems. The effects of rotating speed, gas flow rate, liquid flow rate, SO2 inlet concentration, total salt concentration, and alkalinity on the SO2 removal efficiency were investigated by adopting the ammonia-based solution as the absorbent. The experimental results showed that the SO2 concentration at the RPB outlet can meet the new Chinese emission standard very well. In addition, the gas-side volumetric overall mass transfer coefficient (Kya) was deduced based on the mass balance equation, and its correlation was also proposed. The predicted Kya calculated by the correlation was in good agreement with the experimental data, and the deviation was within the range of ±8%.
TL;DR: The results showed that the model that considered internal resistance with a variable mass transfer coefficient was more flexible than the other ones and this model described the dynamics of the adsorption process of the dye in the fixed-bed column better.
Abstract: Reactive blue 5G dye removal in a fixed-bed column packed with Dowex Optipore SD-2 adsorbent was modelled. Three mathematical models were tested in order to determine the limiting step of the mass transfer of the dye adsorption process onto the adsorbent. The mass transfer resistance was considered to be a criterion for the determination of the difference between models. The models contained information about the external, internal, or surface adsorption limiting step. In the model development procedure, two hypotheses were applied to describe the internal mass transfer resistance. First, the mass transfer coefficient constant was considered. Second, the mass transfer coefficient was considered as a function of the dye concentration in the adsorbent. The experimental breakthrough curves were obtained for different particle diameters of the adsorbent, flow rates, and feed dye concentrations in order to evaluate the predictive power of the models. The values of the mass transfer parameters of the mathematic...
TL;DR: In this article, a set of non-charged similar molecules is chosen as solutes to minimize other interactions apart of those related to size. André et al. used the hydrodynamic model to characterize the behavior of the membrane to uncharged solutes, assuming that membrane pores are straight and cylindrical.
TL;DR: In this article, power consumption, local and average volumetric mass transfer coefficient (k L a ) were compared for six impeller combinations in a 50L perspex tank with xanthan gum solutions.
TL;DR: In this paper, a kinetic study of the biosorption of lead ions by olive stone was analyzed according to six different kinetic models (pseudo first, pseudo second, pseudo n-order, Elovich, solid diffusion and double exponential models).
TL;DR: It is found the coupled blowing effects due to mass transfer can have significant influences on velocity profiles, drag, heat flux, as well as temperature and concentration profiles.