bluuebunny/crossref_metadata_2025_split huggingface dataset:
A Mathematic Model for Direct Causticization of Na2CO3 with TiO2 in a Semi‐batch Reactor
Authors: Zeng Le , Van Heiningen Adriaan R. P. 
Published: July 2010

AbstractA mathematic model was developed for direct causticization of sodium carbonate with titanium dioxide in a semi‐batch reactor. The model predictions of the titanate yield and pentatitanate yield showed a reasonable agreement with the experimental data from a pilot‐scale fluidized bed operating in semi‐batch mode. The rate constant of the present model was generally consistent with those obtained from the small‐scale batch experiments in the literature. A new rate constant considering carbonate conversion to pentatitanate was introduced. All the results provided support that the solid‐state direct causticization of sodium carbonate with titanium dioxide in a semi‐batch fluidized bed follows the shrinking‐core diffusion model.
On the Characteristic Drying Rate Approach to Correlating Experimental Results of the Drying of Moist Porous Materials
Authors: Chen Xiao Dong 
Published: July 2010

AbstractSchlunder's model of a surface, is the only fundamental attempt to explain the constant drying rate phenomena, for materials with pore sizes of a few microns. Here, a direct comparison between this approach and the conventional mass transfer (CMT) theory has been made, by extending the approach to incorporate cell sizes of food, plant materials and to low water contents. Contrast to CMT, the extended Schlunder's model analysis suggests that the boundary layer thickness have an effect on the relative drying rate. Some new experimental results are also presented to support one viewpoint regarding the characteristic drying rate method.
Compatibilization of Polymer Blends
Authors: Utracki Leszek A. 
Published: July 2010

AbstractMost polymer blends are immiscible and need to be compatibilized. The compatibilization must accomplish: (i) optimization of the interfacial tension; (ii) stabilize the morphology against high stresses during forming; and (iii) enhance adhesion between the phases in the solid state. Compatibilization is accomplished either by addition of a compatibilizer or by reactive processing. This review will focus on the three aspects: description of the interphase, compatibilization by addition and reactive compatibilization.
Morphology in Immiscible Polymer Blends During Solidification of an Amorphous Dispersed Phase under Shearing
Authors: Deyrail Yves , Michel Alain , Cassagnau Philippe 
Published: July 2010

AbstractSolidification under shear of dispersed polycarbonate (PC) fibers in copolymer polyethylene‐methyl acrylate matrix (EMA) was investigated using a hot optical shear device. First, the deformation of PC droplets and its modeling under isothermal conditions were studied for comprehension purposes. Overall agreement with literature models was found and the main influence of the viscosity ratio has been stressed. Second, the morphology control through dynamic quenching was experimented. It consists of solidifying the amorphous PC dispersed phase under shear flow. Break‐up times of PC fibers were taken into account. Shear rate and quenching‐time balance was demonstrated. Thus, during dynamic solidification, a fibrillar morphology could be obtained through rapid quenching. Long quenching times allow nodular morphology, whose size depends on the shear rate used. PC rods can be obtained by adjusting the shear rate during dynamic quenching.
Dependence of the Morphology Development on the Kinetics of Reactive Melt Blending of Immiscible Polymers
Authors: Yin Z , Koulic C , Pagnoulle C , Jérôme R 
Published: July 2010

AbstractPoly(methyl methacrylate) (PMMA) containing 50 wt% of anthracene (anth) labeled reactive PMMA chains [thus end‐capped by an anhydride (anh) or an isocyanate (NCO)] has been melt blended with polystyrene containing 33 wt% of chains end‐capped by an aliphatic amine (PS‐NH2) at 180°C. Conversion of anth‐PMMA‐anh and anth‐PMMA‐NCO into PMMA‐b‐PS copolymers has been determined by SEC with a UV detector. The interfacial reaction mainly occurs in the initial mixing stage (⩽1.0 min), although at a rate which depends on the reactive groups attached to PMMA. Moreover, this interfacial reaction rate controls how the phase morphology is developed.
Synthesis of Oligoester α,ω‐diols by Alcoholysis of PET through the Reactive Extrusion Process
Authors: Michel Alain , Cassagnau Philippe , Dannoux Morgane 
Published: July 2010

AbstractThe alcoholysis of PET with diols in the presence of dibutyltinoxide was carried out in a twin‐screw extruder with residence times of 1 min and without solvent. The reaction led to scissions of PET chains and to the synthesis of oligoester α,ω‐diols with average number molecular weights of about 1000 g·mol—1 characterised by conventional techniques such as NMR, SEC and MALDI‐TOF. The alcoholysis kinetics was studied with a rheological tool under selected conditions, and it was shown that this reaction is quite compatible with the residence times in an extruder. This study clearly shows that the oligoesters synthesised by reactive extrusion have characteristics similar to the oligoesters synthesised by batch processes over many hours. Furthermore, the melting temperature of these oligoesters can be controlled between room temperature and 220°C by using diols with different structures for the alcoholysis.
Polymer‐Clay Nanocomposites Based on Blends of Polyamide‐6 and Polyethylene
Authors: Mehrabzadeh Mahmood , Kamal Musa R. 
Published: July 2010

AbstractThe preparation of polyamide‐6/clay, high‐density polyethylene/clay, and high‐density polyethylene/ polyamide‐6/clay nanocomposites is considered. X‐ray diffraction (XRD), differential scanning calorimetry (DSC), and Fourier Transform Infrared (FTIR) measurements show that the clay enhances the crystallization of the γ‐form of polyamide‐6. The clay also acts as a nucleation agent and causes a reduction of spherulitte size. Scanning electron microscopy (SEM) analysis of fracture surfaces shows that the clay reduces the PA‐6 particle size in the HDPE/PA‐6/clay nanocomposites and changes the morphology. Mechanical properties and the effect of maleated polyethylene are also reported.
Quantitative Analysis of Mixer‐Type Rheometers using the Couette Analogy
Authors: Aït‐Kadi Abdellatif , Marchal Philippe , Choplin Lionel , Chrissemant Anne‐Sophie , Bousmina Mosto 
Published: July 2010

AbstractA procedure based on a Couette analogy, to quantitatively analyze torque/rotor speed data in order to extract viscosity/shear‐rate curves using non‐conventional geometries is presented. It is first validated using a relatively simple geometry for which the equivalent internal radius used in the analogy can be analytically obtained. The results showed that the equivalent internal radius depends only slightly on the nature of the fluid and that there is an optimal radial position r* in the analog Couette gap where the calculations can be easily performed for computing the viscosity/shear‐rate data from torque/rotational speed data. The experimental results with complex geometries and complex fluids are found to coincide, within experimental errors, with those obtained using standard geometries over a wide range of shear rates. The approach is also found to be very useful to evaluate shear‐rate and viscosity data in Couette viscometers when large gaps are used with non‐Newtonian fluids.
Diffusion of One‐ and Two‐Component Fluids into Polymeric Membranes
Authors: Afif Ali E. L. , Grmela Miroslav 
Published: July 2010

AbstractThe starting point of this paper is a model of the non‐Fickian diffusion of a simple fluid into a polymeric medium that has been introduced in El Afif and Grmela (2002). The model is extended to a mixture consisting of two simple fluids and one polymeric medium. The effects of the polymeric medium on diffusion are included in the formulations through the use of relative momenta playing the role of internal variables. In ternary mixtures, new phenomena arise due to cross‐coupling effects. As a consequence, the single diffusion Deborah number in binary mixtures becomes a 2 × 2 matrix in ternary mixtures. Two specific examples for which experimental data are available are investigated in detail.
Peculiarities of the Thermodynamics of Electrolyte Solutions: A Critical Discussion
Authors: Wilczek‐Vera Grazyna , Vera Juan H. 
Published: July 2010

AbstractDifferences in the thermodynamic treatment of electrolyte and nonelectrolyte solutions are highlighted. The relations between expressions for concentrations are stated and the need to consider the presence of ions is emphasized. Examples are presented to show that the activity coefficient of a particular ion depends on the nature of the other ions in the solution. An overview is given of the state of development — and shortcomings — of methods to measure the activity coefficient of individual ions. Pitfalls in the use of polynomials to evaluate the mean ionic activity from measurements of the activity of the solvent are emphasized and solutions proposed. The interpretation of the mean ionic activity coefficient of weak electrolytes is discussed. The relation between the excess Gibbs energy and the activity coefficients of the species in solutions is reviewed and the relation between the McMillan‐Mayer and Lewis‐Randall frameworks is commented. An abstract of the basic equations for electrolyte solution thermodynamics is appended.
Thermodynamics and Stoichiometry of Reactions between Hydrogen Sulfide and Concentrated Sulfuric Acid
Authors: Wang Hui , Dalla Ivo G. , Chuang Lana , Chuang Karl T. 
Published: July 2010

AbstractA thermodynamic analysis of the possible reactions between hydrogen sulfide and concentrated sulfuric acid shows that four reactions are feasible. However, only two of these reactions apparently occur in experiments at 1 atm and 0°C to 150°C. Hydrogen sulfide is first oxidized by molecular sulfuric acid, forming SO2, sulfur and water, and then the H2S may react with the dissolved product, SO2, to generate sulfur and water. The stoichiometry of the consecutive reactions and their dependence on acid concentration were determined experimentally using mass balance measurements. The results of this study suggest a possible alternative method for sulfur removal and recovery that has more advantages.
Free Convective Mass Transfer Behaviour of Inclined Cylinders with Active Ends
Authors: Nirdosh Inderjit , Sedahmed Gomma 
Published: July 2010

AbstractRates of mass transfer at inclined cylinders with active ends were determined under natural convection conditions by measuring the limiting current of copper deposition from acidified copper sulphate. Physical properties of the solution, cylinder dimensions and inclination were varied to produce a ScGr range of 1.53 × 109 to 7 × 1010. Under these conditions the data for different orientations were correlated by Sh = 1.075 (ScGr)0.242. The characteristic length used in obtaining Sh and Gr was calculated by dividing the cylinder surface area by the cylinder perimeter projected onto the horizontal plane. At high CuSO4 concentrations a reasonable agreement was found between the experimental rate of mass transfer and that calculated by summing the rate of mass transfer at individual surfaces of the cylinder. Deviations were observed at low CuSO4 concentrations, and the possible causes of the deviations were explained.
Propylene Solubility in Toluene and Isododecane
Authors: Dariva Cláudio , Lovisi Humberto , Mariac Luis C. Santa , Coutinho Fernanda M. B. , Oliveira José Vladimir , Pinto José Carlos 
Published: July 2010

AbstractPropylene solubility in toluene and isododecane (2,2,4,6,6‐Pentamethylheptane, CA Registry# 13475‐82‐6) was measured at different temperatures and pressures, similar to the ones normally used to carry out propylene polymerizations through metallocene and Ziegler‐Natta catalysts. Experimental data were obtained with a gravimetric method, where experimental liquid phase compositions are measured at known temperature and pressure conditions. The experimental data were modeled with two different models: the Wilson excess Gibbs free energy model and an empirical model. Both modeling approaches may be recommended for analysis of kinetic data obtained for slurry propylene polymerizations in toluene and isododecane.
Mixing Time in a Short Bubble Column
Authors: Ravinath M , Kasat Gopal R. , Pandit Aniruddha B. 
Published: July 2010

AbstractMixing time measurements have been carried out in a 0.2m I.D. short bubble column (Hc/D ⩽ 5) with different spargers and for different clear liquid height to diameter (HC/D) ratios. Superficial gas velocity has been varied in the range of 0.01m/s to 0.1m/s. Effect of bulk fluid viscosity on the mixing time has also been studied. The circulation cell model, with two fitted parameters viz. number of circulation cells, S and the inter‐cell exchange velocity, Ve, has been used to predict and explain the variation in mixing time and the flow pattern in the short bubble column for different types of spargers.
Interfacial Area and Liquid‐Side Volumetric Mass Transfer Coefficient in a Downflow Bubble Column
Authors: Mandal Ajay , Kundu Gautam , Mukherjee Dibyendu 
Published: July 2010

AbstractAn experimental investigation was made to measure interfacial area, a, and liquid‐side volumetric mass transfer coefficient, kLa, in a downflow bubble column by chemical methods viz., absorbing CO2 in aqueous sodium hydroxide and sodium carbonate/bicarbonate buffer solution respectively. The effect of gas and liquid flowrate and nozzle sizes on a and kLa were investigated. The experimental data obtained in the present system were analyzed and correlations were developed to predict a and kLa in terms of superficial gas velocity. The variation of a and kLa with specific power input were shown in graphical plot and compared with other gas‐liquid systems.
Ultrasonic Measurement for Two/Three‐Phase Flow Detection
Authors: Zheng Ying 
Published: July 2010

AbstractUltrasonic technique offers a good potential for phase holdup measurements in multiphase systems. Experiments were performed in an expanded fluidized bed consisting of water, air bubbles and/or glass beads. In this research note, the instantaneous signals of ultrasound were, for the first time, analyzed for the purpose of phase holdup determination. The results show that the fluctuations of the speed and attenuation of ultrasound are a well‐defined function of solid and gas holdups in a multiphase system.
Recovery of Tritium from Wastewater Generated by Decommissioning of Gas Cooled Reactors (GCR)
Authors: Takeshita Kenji , Nnakano Yoshio , Shimizu Masami 
Published: July 2010

AbstractThe recovery of tritium from wastewater generated by the decommissioning of a 166‐MWe GCR, Tokai‐1, nuclear reactor was evaluated. The dimensions of two tritium separation columns, water distillation process and hydrogen‐isotope exchange with hydrophobic Pt‐catalyst, were evaluated numerically under the assumptions that the recovery of tritium from the wastewater would be completed in five years and the wastewater after the recovery of tritium would be suitable for release into the environment. It was found that, in addition to lower steam, the column was smaller than that for the water distillation process. The hydrogen‐isotope exchange process was suitable for the treatment of wastewater, not only for a process design point of view but also for a reduction of energy consumption.
Flow Regime Identification in a Bubble Column Based on both Kolmogorov Entropy and Quality of Mixedness Derived from CAERPT Data
Authors: Nedeltchev Stoyan , Kumar Sailesh B. , Dudukovic Milorad P. 
Published: July 2010

AbstractComputer‐automated radioactive particle tracking (CARPT) data obtained in a 0.162 m air‐water bubble column operated at ambient pressure have been analysed. The superficial gas velocity (Ug) has been varied in the range 0.02‐0.12 m/s under constant liquid height 1.04 m. A perforated plate (82 holes ø 0.4 mm, free plate area 0.05 %) distributor has been used. The Kolmogorov entropy (KE) vs.Ugallows identification of the transition velocity (Utrans= 0.064 m/s) between bubbly and transition regimes. KE models for both regimes have been also developed. The quality of mixedness (QM) concept shows that QM(upper zone) ⊕ QM(lower zone) atUtrans= 0.064 m/s.
Bubble Dynamics Measurements Using Four‐Point Optical Probe
Authors: Xue Junli , Al‐Dahhan Muthanna , Dudukovic M. P. , Mudde R. F. 
Published: July 2010

AbstractBy conducting an analysis of the measurement errors it was found that bubble dynamics obtained by two‐point probes can be highly inaccurate. A four‐point optical probe with appropriate data processing algorithm has been developed so that the bubble velocity vector can be obtained. This probe provides directly the value of specific gas‐liquid interfacial area. However, for obtaining accurate values of bubble velocity and size, the four‐point probe must be calibrated by a CCD camera at the same conditions. Calibration columns have been developed for this purpose where the bubble size and velocity can be varied to calibrate the measurements by the four‐point optical probe against a CCD camera.
Dynamics of a Bubble Column: Influence of Gas Distribution on Coherent Structures
Authors: Harteveld Wouter K. , Mudde Robert F. , Van Den Akker Harrie E. A. 
Published: July 2010

AbstractThe influence of the pattern of gas distribution on the dynamics of a bubble column is studied. LDA and glass fiber probe measurements were performed in a 15 cm column, aerated in well‐controlled patterns using a special distributor. Superficial gas velocities of 0.015 m/s to 0.023 m/s were investigated. Uniform aeration gives very uniform gas distribution. The familiar large‐scale circulation and structures are absent. Non‐uniform gas‐injection introduces dynamic structures in the entrance region. Large‐scale structures are absent in the flow above the entrance region, independent of the gas injection pattern.
Gas Holdup in a Fiber Suspension
Authors: Su Xuefeng , Heindel Theodore J. 
Published: July 2010

AbstractThis paper investigates the effects of fiber mass fraction and length on gas holdup and flow regime transition. The experiments are performed using three different Rayon fiber lengths (3, 6, and 12 mm) over a range of superficial gas velocities (Ug ⩽ 18 cm/s) and a range of fiber mass fractions (0 ⩽ C ⩽ 1.8%) in a 15.24 cm diameter bubble column, in which air is continuously bubbled through a fixed volume of a fiber suspension. Experimental results show that increasing the fiber mass fraction tends to decrease the overall gas holdup when the fiber mass fraction is less than a certain value, which depends on fiber length. Fiber length influences the gas holdup when C ⩽ 1.4%, and increasing fiber length reduces the overall gas holdup. Homogeneous, transitional, and heterogeneous flow conditions are observed at low fiber mass fractions, but when C ⩽ 0.6%, purely heterogeneous flow conditions are observed. The flow regime transition is not significantly affected by fiber length.
A Method for the Detection of Defluidized Zones in Slurry Bubble Columns
Authors: Emami Ahad , Briens Cedric 
Published: July 2010

AbstractThe formation of defluidized zones was studied in a laboratory slurry bubble column equipped with heat transfer probes. The probes were small thermistors 2.4 mm in diameter. Dionized water and air were used as a liquid and gas phase, respectively. Solids were fine ceramic particles with mean size of 19.2 μm and density of 2244 kg/m3. The effects of solids holdup (up to 30 wt% on gas free basis), gas superficial velocity (0.01‐0.09 m/s), sparger height (0.01‐0.09 m) on defluidized zones formation was studied. Cycle analysis of the local heat transfer fluctuations reliably detected the local formation of defluidized zones for each condition.
The Mechanisms of Bubble Coalescence in a Non‐Newtonian Fluid
Authors: Lin Tsao‐Jen , Lin Gen‐Ming 
Published: July 2010

AbstractThe coalescing mechanism of two in‐line oblate‐cusped bubbles rising in a non‐Newtonian fluid has been qualitatively and quantitatively studied by using particle image analyzer. Through effects of the shear thinning and viscoelasticity on the flow structure, the acceleration of the trailing bubble to the leading bubble is evident. While two bubbles are getting closer, the drained liquid is circulated to the back of the trailing bubble. To encounter these dynamic flow structures, the bubble shape evolution for the leading bubble in each stage is from oblate‐cusped to elongated oblate‐cusped, to invert pentagonal, and to oblate. Suppressed by the trailing bubble and the flow structure, the shape of leading bubble changes from oblate‐cusped to oblate, to flattened oblate, and to flattened oblate with concave surface.
Bubble Motion in Non‐Newtonian Fluids and Suspensions
Authors: Frank Xavier , Li Huai Z. , Funfschilling Denis , Burdin Florence , Ma Youguang 
Published: July 2010

AbstractThe present paper reports a study of the motion of air bubbles in both non‐Newtonian fluids and fluid‐solid (laponite) suspensions. Quantitative information concerning the bubble rise velocity was obtained. In particular, the acceleration mechanism of the rise velocity in fluids was investigated by both a modern technique — Particle Image Velocimetry and a classical method — birefringence visualization. An analytical modeling is proposed to compute the rise velocity of a bubble train with the memory effects. Finally, the visualization demonstrates that the bubble shape and rise velocity in a suspension are very complicated due to the displacement of solid particles by bubbles.
Dynamic Gas Disengagement in a High‐Pressure Bubble Column
Authors: Jordan Uwe , Saxena Alok K. , Schumpe Adrian 
Published: July 2010

AbstractBubble disengagement after stopping the gas supply is analyzed based on the concept of constant slip velocity; it is compared with the approaches used by previous investigators. The technique has been applied to study the gas density effect (0.17 to 46.6 kg·m—3) on the gas hold‐up structure in a bubble column with organic liquids (toluene, ethanol, 1‐butanol, decalin) and tap water. With increasing gas density, the large bubble rise velocity decreases; this indicates smaller bubble size. The small bubble hold‐up is correlated with the gas and the liquid properties whereas the large bubble hold‐up is hardly affected.
Euler/Lagrange Calculations of Bubbly Flows with Consideration of Bubble Coalescence
Authors: Sommerfeld Martin , Bourloutski Evgueni , Bröder Dirk 
Published: July 2010

AbstractA bubble coalescence model was developed on the basis of the Lagrangian approach, where bubbles are followed through the turbulent flow field along their trajectories. The collision process was described using a stochastic inter‐particle collision model. Coalescence occurred if the contact time became larger than the film drainage time. The film drainage time was determined by a simple formulation according to classical approaches, whereas the contact time resulted directly from the collision model. The performance of the model was analyzed for bubble rise in a prescribed homogeneous isotropic turbulence field. Moreover, numerical calculations by the coupled Euler/Lagrange approach were performed and compared with measurements in a bubble driven loop facility. The comparison showed reasonably good agreement for liquid and bubble velocities.