bluuebunny/crossref_metadata_2025_split huggingface dataset:
Bubble Breakup and Coalescence in a Plunging Liquid Jet Bubble Column
Authors: Atkinson Bruce W. , Jameson Graeme J. , Nguyen Anh V. , Evans Geoffrey M. , Machniewski Piotr M. 
Published: July 2010

AbstractIn this study the bubble size distribution and energy dissipation rate are measured in a plunging liquid jet bubble column. The maximum stable bubble diameter in the mixing zone was successfully predicted based on Weber number analysis. A Pareto analysis indicated that the coalescence of bubbles principally occurred as a binary process. The bubble number flux was modeled based on the bubble number concentration, collision frequency of two bubbles of the same diameter, and the probability of coalescence taking place. In general, the predictions were in good agreement with the measurements for both the mixing and pipe flow zones.
Bubble Column Bioreactors: Comparison with Stirred Fermenters Based on Local Gas Hold‐up Distribution
Authors: Vlaev Serafim D. , Fialova Marie 
Published: July 2010

AbstractLocal gas hold‐up in viscous aerated batches in bubble column and impeller gas dispersion devices was studied. Unlike the former analyses valid for water, the emphasis of this study was on gas hold‐up in relatively viscous and shear‐thinning liquids mimicking physically nutrient solutions from industrial fermentation practice. Gas hold‐up is correlated with viscosity, plasticity and shear‐inducing velocities. Vessels with ID 0.2‐0.4 m were studied. The prevailing parabolic type of radial profile specific for water was shown to change to a flat saddle type one with incidental peaks. Comparison with stirred vessels with two different impeller designs showed opposite effects. Possible control of gas dispersion efficiency by appropriate selection of gas dispersion devices is discussed.
Effect of Dispersion on Particle Segregation Due to Sparged Air in a Hydrocyclone
Authors: Liu Shijie , Zhu Zhengxiang , Masliyah Jacob H. 
Published: July 2010

AbstractFractionation of kraft wood pulp fibres was carried out in a hydrocyclone. Long fibres tend to migrate to the low shear region and report to the overflow stream. Excellent fractionation was found at high pulp slurry feed rates with a split ratio between 0.07 and 0.3. However, when air bubbles are sparged, all the fibres are more uniformly distributed inside the hydrocyclone. When increasingly more bubbles are present, on the other hand, long fibres drain down slower because of rapidly rising air bubbles. Thus, more long fibres report to the overflow stream at extremely high air injection rates.
Solid‐Liquid Mass Transfer and Hydrodynamics in the Hydrogenation of 4‐Nitrobenzoic Acid
Authors: Winterbottom Mike , Fishwick Rob , Stitt Hugh 
Published: July 2010

AbstractSolid‐liquid mass transfer coefficients were determined in a stirred reactor for the hydrogenation of 4‐nitrobenzoic acid. The effects of the catalyst particle physical properties were investigated and the findings compared to the model system of aqueous dissolution of salicylic acid. In an attempt to explain these mass transfer observations the technique of positron emission particle tracking (PEPT) has been used to study the effect of different operating conditions on the liquid flow patterns and, in particular, the particle‐liquid slip velocities. Time‐averaged slip velocities were determined, thereby revealing information about particle‐liquid behaviour and zones of poor mass transfer in agitated reactors.
Quality of Mixedness Profiles Based on Spatial Distribution of Local Mass Transfer Coefficients in a Bubble Column
Authors: Nedeltchev Stoyan , Ookawara Shinichi , Ogawa Kohei 
Published: July 2010

AbstractLocalkLameasurements were performed during physical absorption of carbon dioxide into deionized water in a 0.289 m diameter bubble column equipped with a perforated plate gas distributor (31 holes × ø 0.002 m, free plate area 0.15 %). Three superficial gas velocities (ug) were examined (0.018, 0.031 and 0.038 m/s) under clear liquid height of 0.56 m. The spatialkLadistributions were treated by the quality of mixedness (QM) algorithm. It was found that at the regime transition velocity (Utrans= 0.034 m/s) to churn‐turbulent flow regime both lower and upper column zones are characterized with the same QM indices.
Liquid Dispersion and Gas‐Liquid Mass Transfer in Three‐Phase Inverse Fluidized Beds
Authors: Kim Sang Woo , Kim Hyun Tae , Song Pyung Seob , Kang Yong , Kim Sang Don 
Published: July 2010

AbstractAxial dispersion of continuous liquid phase and gas‐liquid mass transfer characteristics were investigated in a three‐phase inverse fluidized bed with viscous liquid medium. The axial dispersion coefficient of liquid phase(Dz) increased with increasing gas(UG) or liquid velocity(UL), but decreased with an increase in the viscosity of continuous liquid medium(µL). The volumetric gas‐liquid mass transfer coefficient(kLa) increased with increasing UG but decreased with increasing µL, while it did not change considerably with increasing UL : The effects of UG were dominant in three phase inverse fluidized beds. In the beds of polyethylene particle(relatively heavier particle), the values of Dz and kLa exhibited higher values than those in the beds of polypropylene particles(lighter particle). The values of Dz and kLa were well correlated in terms of operating variables.
Gas Holdup and Mass Transfer in a Three‐Phase Reversed Flow Jet Loop Slurry Reactor with Non‐Newtonian Fluids
Authors: Li Yongxiang , Wu Wei , Min Enze 
Published: July 2010

AbstractExperiments were carried out to study the total gas holdup and mass transfer coefficient in a three‐phase reversed flow jet loop slurry reactor, with air, carboxymethyl cellulose (CMC) aqueous solution and resin as gas, liquid, and solid phases respectively. The distinct feature of this study is that the liquid employed was non‐Newtonian. The influences of reactor geometry, solid holdup, and operation parameters were studied and the optimum values of draft tube to reactor diameter ratio, solid holdup, and distance between the lower edge of the draft tube and the bottom plate, were found to be 0.45, 0.03 and 0.08 m, respectively. Empirical corrections for the total gas holdup and mass transfer coefficient were developed.
Using CFD to Describe the Hydrodynamics of Internal Air‐lift Reactors
Authors: Van Baten Jasper M. , Ellenberger Jürg , Krishna Rajamani 
Published: July 2010

AbstractThe hydrodynamics of three configurations of internal airlift reactors, two with riser diameters of 0.1 m and one with a riser diameter of 0.24 m, operating with air—water system, have been experimentally investigated for a range of superficial gas velocities. The experimental results are compared with a model using computational fluid dynamics (CFD) with Eulerian descriptions of the gas and liquid phases. Interactions between the bubbles and the liquid are taken into account by means of a momentum exchange, or drag coefficient based on a literature correlation. The turbulence in the liquid phase is described using the k‐ϵ model. The CFD model shows good agreement with the measured data on gas holdup, liquid velocity in the downcomer and in the riser for all three configurations. The developed CFD model has the potential of being applied as a tool for scaling up.
CFD Simulation of Residence Time Distribution and Mixing in Bubble Column Reactors
Authors: Ekambara Kalekudithi , Joshi Jyeshtharaj B. 
Published: July 2010

AbstractA three‐dimensional CFD model has been developed to predict liquid phase velocities in bubble columns. An agreement was observed between the predicted and the experimental data available in the published literature. The validated CFD model has been extended for the simulation of macro‐mixing and hence the prediction of mixing time, RTD and dispersion coefficient. Liquid phase mixing time was measured in 0.2 and 0.4 m i.d. columns over a wide range of superficial gas velocity (0.07 to 0.295 m/s) and height‐to‐diameter ratio (2 to10). An agreement was observed between the CFD predictions and the experimental values of the mixing time as well as all the experimental data on dispersion coefficient published in the literature.
Oxidation of Tetrachloroethylene in a Bubble Column Photochemical Reactor Applying the UV/H2O2 Technique
Authors: Alibegic Dzevo , Tsuneda Satoshi , Hirata Akira 
Published: July 2010

AbstractMass transfer of tetrachloroethylene (PCE) gas, followed by a free‐OH radical reaction in the liquid phase, was studied in a bubble column reactor equipped with a UV light source and containing aqueous H2O2 as the reacting medium. Degradation of PCE in the liquid phase was found to follow pseudo‐first‐order kinetics, and the optimal ratio of H2O2/PCE leading to the highest oxidation rate could be successfully obtained from the analysis of the steady‐state OH radical concentration. Absorption of PCE gas was in the kinetic slow regime and could be predicted based on the ratio of the apparent rate constant of PCE liquid degradation to the volumetric mass transfer coefficient (kapp/KLa). The presence of small amounts of PCE in the liquid bulk had positive effect on the mass transfer over the range studied and need to be taken into account.
Comparison, Combination and Validation of Measuring Techniques for Local Flow and Turbulence Analysis in Bubble Columns and Airlift Reactors
Authors: Vial Christophe , Bendjaballah‐Lalaoui Nadia , Poncin Souhila , Wild Gabriel , Midoux Noël 
Published: July 2010

AbstractThe applicability of velocimetry techniques based on the Doppler effect — such as laser and ultrasound Doppler velocimetry — for investigating local hydrodynamics in bubble columns and airlift reactors have been extended to non‐coalescing media. Their limitations are highlighted, especially as a function of gas sparger and reactor type. The ultrasound technique was shown to be able to measure either bubble or liquid velocity. Differences in local hydrodynamics due to coalescence behaviour were used to support the analysis. Data validation was carried out both by mass balance and by comparison with other techniques, such as electrochemical probes, Pavlov tubes and optical probes.
Gas/Liquid Two‐phase Flow in a Flat Sheet Filtration Module: Measurement of Local Wall Shear Stresses
Authors: Ducom Gaëlle , Puech François‐Pierre , Cabassud Corinne 
Published: July 2010

AbstractAir sparging in membrane filtration consists in generating an intermittent gas/liquid flow by injecting air in the concentrate compartment together with the feed. This process is very efficient for flux enhancement for different membrane processes. In order to understand the influence of wall shear stresses generated by the two‐phase flow on the flux enhancement, this work aimed to characterize local wall shear stresses generated by the two‐phase flow during filtration operated at a low permeate flux. Local wall shear stresses were measured using an electrochemical method in different points of a flat sheet nanofiltration module and for several operating conditions.
Two‐Phase Flow in Porous Media Under Spatially Uniform Magnetic‐Field Gradients
Authors: Iliuta Ion , Larachi Faïçal 
Published: July 2010

AbstractExternal inhomogeneous magnetic fields exert a body force on electrically nonconducting, magnetically permeable fluids, and this force can be used to compensate or to amplify the gravitational body force. The ability to influence two‐phase flow by the application of external inhomogeneous magnetic field is of potential interest in the operation of trickle‐bed reactors from the point of view of catalytic process intensification. An exhaustive modeling framework was developed to illustrate how external inhomogeneous magnetic fields are able to influence both trickle bed hydrodynamics and reaction performance. The model was based on the volume‐average mass and momentum balance equations and volume‐average species balance equations under a spatially uniform magnetic‐field gradient, µ20H(dh/dz). The catalytic wet air oxidation of phenol in the presence of a catalyst consisting of a mixture of CuO, ZnO and CoO was considered as a case study.
Modelling of Trickle Bed Reactor for the Catalytic Wet Air Oxidation of Phenol
Authors: Eftaxias Athanasios , Larachi Faiçal , Stüber Frank 
Published: July 2010

AbstractA non‐isothermal trickle‐bed transport‐reaction model has been developed and tested for the catalytic wet air oxidation of phenol over CuO/γ‐Al2O3. Isothermal simulations confirmed that partial catalyst wetting, and the resulting gas‐solid mass transfer, leads to higher phenol conversions, when oxygen is the limiting reactant. Non‐isothermal simulations evidenced that phenol conversion and adiabatic temperature rise may be overestimated if water evaporation is neglected. When accounting for the latter, the temperature rise exhibited a maximum at gas velocities slightly above the stoichiometric demand for complete mineralisation. It was further observed that under the conditions studied, the temperature rise levels off with increasing inlet phenol concentration, while with increasing inlet temperature it reaches a maximum and then drops.
Experimental Validation of a Two‐Phase Flow Model for Pressure Drop and Liquid Hold‐up in Downflow Packed Bed Bubble Reactors
Authors: Boyer Christophe , Ferschneider Gilles 
Published: July 2010

AbstractA new model has been developed in order to predict pressure drop and gas fraction of industrial fixed bed reactor operated in downward bubbly flow. The mechanistic approach proposed by Attou and Ferschneider (1999) has been followed. In this approach, mass and momentum balances are solved for gas‐liquid mixture. To solve the system equation, closure laws are needed for the interfacial force between liquid and solid FLS and for the gas fraction expression. These closure laws have been determined by measuring both pressure drop and gas fraction with downward air‐water bubbly flows through a 40 cm diameter fixed bed of glass beads. The averaged gas fraction is measured by using a gamma scanning system that perform attenuation measurements along 64 chords across a section. Finally, a new bubble flow model is proposed to interpret the results.
Hydrodynamic Behavior of a Three‐Phase Spouted Bed with Very Large Particles
Authors: Wang Jinfu , Wang Tiefeng , Liu Lizao , Chen He 
Published: July 2010

AbstractThe hydrodynamic behavior of a three‐phase spouted bed with large particles of diameter 10.5, 12 and 16mm was studied. Liquid circulation was used to spout the large particles. Experiments were carried out to study the influence of the superficial gas velocity, liquid circulation velocity, particle diameter and settled particle bed height on the minimum liquid spouting velocity, pressure drop and gas holdup. In the spouted regime, liquid circulation and the movement of the large particles enhance bubble breakup and increase the gas holdup. The frequent collision of these large particles with the reactor wall and nozzles are helpful in preventing fouling. This indicates a potential application in gas‐liquid systems in which fouling occurs due to deposition and adhesion.
Expanded Bed Column Bioreactor Performance and Hydrodynamics
Authors: Abdul‐Rahman R , Ozaki H , Zainola N 
Published: July 2010

AbstractStudies on the removal of nitrogen constituents by a dual media expanded bed bioreactor showed substantial removals of about 85% COD and 80% total‐N. Kinetic parameters obtained were: for growth, YH = 0.23mg/mg, µH = 0.278day—1, KH = 461mg/L and bH = 0.0151day—1 and for denitrification, YHD = 0.670mg/mg, µHD = 0.205day—1, KHD = 0.54mg/L and bHD = 0.0300day—1. Hydrodynamics studies gave Ut (terminal settling velocity) and Umf (minimum fluidization velocity) for bare GAC as 0.637m/s and 0.005m/s respectively. For GAC with biofilm, Ut was at 0.426‐0.083m/s, with almost double the increase in buoyancy for particles carrying biofilm. This in turn reduced the Umf for GAC with biofilm, which was at 0.0062‐0.0009m/s.
3D‐ECT Velocimetry for Flow Structure Quantification of Gas‐Liquid‐Solid Fluidized Beds
Authors: Warsito W , Fan Liang‐Shih 
Published: July 2010

AbstractThe electrical capacitance tomography (ECT) velocimetry techniques, namely tomography tracking velocimetry (TTV) and tomography image velocimetry (TIV) are proposed in this study to quantify the flow structure of gas‐liquid‐solid fluidized beds based on the ECT images. The tomography images of the bubbles in the three‐phase system are obtained from image reconstruction using the neural network multi‐criteria optimization image reconstruction technique (NN‐MOIRT), developed earlier by the authors. The TTV is based on an auto‐correlation of tomography images in a single plane sensor to track the three‐dimensional position of a bubble swarm. The TIV is based on a cross‐correlation of tomography images in two plane sensors to calculate the three‐dimensional velocity components of the bubble swarm. The bubble spiral motions, the fluctuations of the three‐dimensional bubble swarm velocity components and fluxes in three‐dimensional space are discussed along with the effect of gas superficial velocity, the presence of solid particles and the column height.
Modeling of an Airlift Reactor with Floating Solids for Wastewater Treatment
Authors: Merchuk José C. , Shechter Ronen 
Published: July 2010

AbstractThis paper presents a three‐phase reactor fluid dynamic model that is used in the development of a generic process for upgrading existing wastewater treatment plants. The core of the process consists of an attached growth airlift reactor (AGAR) in which a biomass carrier is used. Mixing is provided in the aerobic stages by partitions that create an airlift effect. The combination of the organized flow pattern and the low density of the media enables prevention of carrier migration between different process stages, without need of screens. Measurements of liquid velocity in a demonstration plant confirm the predicted values with reasonable accuracy.
The Effect of Bed Temperature on Mass Transfer between the Bubble and Emulsion Phases in a Fluidized Bed
Authors: Wu Wenyuan , Agarwal Pradeep K. 
Published: July 2010

AbstractThe rate of interphase mass transfer between the bubble and emulsion phases of a bubbling fluidized bed is of primary importance in all models for fluidized bed reactors. Many experimental studies have been reported, however, all these investigations have been carried out in fluidized beds operated at room temperature. In this work, the effect of the bed temperature on the interphase mass transfer is reported. Single bubbles containing argon – used as a tracer – were injected into an incipiently fluidized bed maintained at the required temperature. The change in argon concentration in the bubble was measured using a suction probe connected to a mass spectrometer. The effects of bed particle type and size, bubble size, and bed temperature on the mass transfer coefficient were examined experimentally. The interphase mass transfer coefficient was found to decrease with the increase in bed temperature and bubble size, and increase slightly with increase in particle size. Experimental data obtained in this study were compared with some frequently used correlations for estimation of the mass transfer coefficient.
Bitumen Recovery with Oily Air Bubbles
Authors: Wallwork Vince , Xu Zhenghe , Masliyah Jacob 
Published: July 2010

AbstractAir‐kerosene bubbles were used in a novel laboratory scale pipeline loop to assess the extraction performance of poor processing oil sand ores. The addition of kerosene to air, whereby producing oily bubbles, substantially enhanced bitumen recovery from poor processing oil sand ores. The oily bubbles were added in a pipeline loop during bitumen liberation from the sand grains. The bitumen recovery from poor processing ores with the addition of the oily bubbles to the conditioning slurry becomes comparable to that of good processing ores. The present findings can be of substantial benefit to the oil sands industry.
Enhanced Production of Podophyllotoxin by Fed‐batch Cultivation of Podophyllum hexandrum
Authors: Chattopadhyay Saurabh , Bisaria Virendra S. , Bhojwani Sant S. , Srivastava Ashok Kumar 
Published: July 2010

AbstractPodophyllum hexandrum (Indian May Apple) was successfully cultivated in a 3 L stirred tank bioreactor under low shear conditions in batch and fed‐batch modes of operation. A statistically optimized culture medium was used for the batch cultivation of Podophyllum hexandrum. Under optimum culture conditions of P. hexandrum, the batch culture showed a growth‐associated product formation with a maximum biomass of 21.4 g/L dry cell weight (DCW) basis and a podophyllotoxin production of 13.8 mg/L in 26 d. A mathematical model was developed to design the nutrient feeding strategies for a fed‐batch cultivation to prolong the productive log phase of cultivation. The fed‐batch cultivation was able to enhance the biomass and podophyllotoxin accumulation to 48 g/L (DCW basis) and 43.2 mg/L, respectively, in 60 d. The volumetric productivity of podophyllotoxin in fed‐batch cultivation was found to be 0.72 mg/(L. d) as opposed to 0.53 mg/(L. d) in batch cultivation under optimized culture conditions.
Extended Linear QDMC of a Gibbsite Crystalliser: A Simulation Study
Authors: Tadayon Abdolsamad , Tadé Moses O. , Ang H. M. 
Published: July 2010

AbstractAn extended linear quadratic dynamic matrix control (EQDMC) of a gibbsite crystallisation system is presented. The process model of the crystalliser is based on the conservation principles of mass and population balances, and kinetic relations including nucleation, growth, and agglomeration correlations. It is shown that the process is non‐linear with constraints and possesses interaction among its process variables. Practical concerns in crysallisation plants such as low flow rates and high magma densities that may lead to solids deposition and eventual line blocking are considered as the system's constraints. The controller is developed by combining extended linear dynamic matrix control (EDMC) and quadratic dynamic matrix control (QDMC) algorithms. Two types of control outputs are considered: controlled and associated variables. The capability of the controller in bringing the controlled variables to their setpoints while maintaining all process constraints within their limits is demonstrated via simulation. It is shown that increasing prediction horizon improves the control performance.
The Tank Drainage Problem Revisited: Do These Equations Actually Work?
Authors: Joye Donald D. , Barrett Branden C. 
Published: July 2010

AbstractThe tank drainage problem with pipeline attached is studied in this work. Laminar and turbulent formulations of this unsteady‐state flow problem are derived and evaluated by experimental data. Additional literature models are also evaluated for comparison. Several experimental configurations were used including a small tank with a vertical tube, the same with various‐ sized orifices, a large tank with a horizontal pipe, and a large tank including a piping system with elbows, vertical drop and horizontal extension. Not all the models performed well under all conditions. Limitations of the models are discussed. The model derived by Loiacono and the model we derived (an exact equivalent) showed the best for both laminar and turbulent flow, predicting drainage times to better than ± 8%, on average.