bluuebunny/crossref_metadata_2025_split huggingface dataset:
Numerical simulation of short‐dwell coaters: Steady state flow patterns and pressure distributions
Authors: Cao Zhenlei , Esmail M. Nabil 
Published: July 2010

AbstractThe steady state flow in a short‐dwell coater has been simulated by solving the two‐dimensional Navier‐Stokes equations in the primary pressure and velocity variables for substrate Reynolds numbers up to 1000. The small opening under the blade has very little effect on the flow patterns in the coating pond. However, it does have a significant effect on the pressure field in the pond. The pressure on the substrate surface, which controls liquid penetration during application, has a maximum value under the blade, near its tip. Low coating weights and high coating speeds lead to higher maximum pressure on the substrate. The operating pressure which must be applied to the blade can be predicted for a given coating weight and substrate velocity. For high substrate speeds and low coating weights, higher operating pressures are needed to keep the blade in position.
The maximum‐power test for gross errors in the original constraints in data reconciliation
Authors: Crowe Cameron M. 
Published: July 2010

AbstractThe detection of gross errors in the reconciliation of process measurement data is an important step in removing their distorting effects on the corrected data. Tests of maximum power (MP), based on the normal distribution, are known for the detection of gross errors in the measurements and for the constraints, but only for those remaining after the removal of unmeasured flows. Here, the MP tests are derived for the original constraints, which allows the direct detection of gross errors in species balances around individual process units. It is shown that the square of the MP test statistic is precisely equal to the reduction in the weighted sum of squares of the adjustments which results from the deletion of that constraint. The test is illustrated with two examples.
Prediction of Gas‐Phase Adsorption Isotherms Using Neural Nets
Authors: Basu Sukanta , Henshaw Paul F. , Biswas Nihar , Kwan Hon K. 
Published: July 2010

AbstractThis study investigated a number of models (the modified Sips', Dubinin‐Astakhov's, VSM theory, the generalized Khan et al.'s model and a simple artificial neural network (ANN)) to predict the effect of temperature on equilibrium adsorption of hydrocarbon gases and vapors on activated carbon. Published data on the adsorption of methane, ethane and propane on activated carbon at 311 K to 505 K were used to estimate the parameters of the conventional models and train the network. Then, the conventional models and the ANN were used to predict the isotherm at a single temperature for each adsorbate, and these results were compared with experimental data. It was found that the ANN model had a lower mean relative error than the conventional models.
CFD Simulations of Three‐dimensional Wall Jets in a Stirred Tank
Authors: Bhattacharya Sujit , Kresta Suzanne M. 
Published: July 2010

AbstractThe flow near the tank wall in a stirred tank driven by a 45° pitched‐blade turbine is simulated with Multiple Reference Frames, the k‐e turbulence model and standard wall functions. The results are compared to the three‐dimensional wall jet identified in a previous paper. The self‐similar velocity profiles in the jet are predicted satisfactorily, but the decay of the local maximum velocity and jet expansion are underpredicted. The underlying physical reasons for this failure are investigated. The effect of impeller size and position on the impingement point of the impeller discharge and the jet core velocity are well predicted by the simulations. The results provide a benchmark for CFD/MRF in the bulk of a stirred tank, identifying where CFD over‐ or underpredicts performance.
Simple Model to Evaluate Loading/Flooding Transition in Aerated Vessels Stirred by Rushton Disc Turbines
Authors: Paglianti Alessandro 
Published: July 2010

AbstractPrediction of the flooding/loading transition in an aerated stirred tank is crucial for the correct design of aerated stirred tank reactors. Despite the importance of this problem, only semiempirical equations are available at the moment. This work provides a simple mechanistic model for predicting the flooding/ loading transition in stirred tank reactors equipped with Rushton turbines. This model could be a useful one, since it allows the user to scale‐up agitated vessels easily. It has only been tested for Rushton turbines, but because the model is based simply on mass balances, energy balances and continuity equations, it could also be used with other impellers after a few modifications.
Critical Impeller Speed for Suspending Solids in Aerated Agitation Tanks
Authors: Zhu Yonggang , Wu Jie 
Published: July 2010

AbstractSystematic measurements have been carried out in agitated gas‐liquid‐solids systems to determine the just off‐bottom suspension speed. A variety of solids sizes, solids concentrations, impeller sizes and tank sizes are used. The difference between the just off‐bottom suspension speeds with and without gas sparging does not show a linear relationship with the gassing rate and the relation is system‐dependent. The relative just off‐bottom suspension speed RJSS = Njsg / Njs is found to be dependent only on the just suspension aeration number Najs = Qg / NjsD3 and, for DT6 impellers, the relation is RJSS = 1 + mNanjs with the values of 2.6 and 0.7 for m and n, respectively. The relation is independent of the impeller size, solids size, solids loading and tank size, and can be used to scale up laboratory data to full‐scale mixing vessels. Data from different studies support the present findings.
Power Consumption in the Turbulent Regime for a Coaxial Mixer
Authors: Tanguy Philippe A. , Thibault Francis 
Published: July 2010

AbstractThe power consumption of a new coaxial mixer composed of an anchor impeller and a pitched‐blade turbine impeller, and a series of rods operated in a contra‐rotating mode has been characterized experimentally in the turbulent regime. It is shown that both the power curve and the turbulent power number vary significantly with the speed ratio between the impellers. Likewise with single impeller mixers, the transition regime starts at a Reynolds number above 100 and the turbulent regime between 103 and 104 irrespective of the definition of the Reynolds number used.
Morphology Development in Kenics Static Mixers (Application of the Extended Mapping Method)
Authors: Galaktionov Oleksiy S. , Anderson Patrick D. , Peters Gerrit W. M. , Meijer Han E. H. 
Published: July 2010

AbstractThis paper addresses the interfacial area generation in Kenics static mixers using a new method. A statistical description of the microstructure development is obtained using the extended mapping method, which is restricted to systems with negligible interfacial tension. However, the layered structures created in a Kenics are a good example where interfacial tension does not play an important role (the layered structure is retained). The extended mapping method is adopted to the special flow conditions in spatially periodic flows. The efficiency of the interface generation for different mixer layouts is compared and additional attention is given to the distribution of the interfacial area across the mixer. It is shown that the extended mapping method enables us to find the blade configuration that optimizes the mixing performance, in accordance to the standard mapping method, but now including much more details concerning the microstructure development in this chaotic flow.
Pressure Drop and Mass Transfer Study in Static Mixers with Gas Continuous Phase
Authors: Couvert Annabelle , Péculier Marie‐France , Laplanche Alain 
Published: July 2010

AbstractThe aim of this work was to characterize both the influence of the gas and the liquid flow rates on the pressure drop generated by static mixers type Sülzer, and on the mass transfer performances of these gas‐liquid contactors. The originality of this work rests on the use of the static mixers with a gas continuous phase. Several configurations were studied: vertical upward flow, vertical downward flow, and horizontal positions, with one to five mixing elements. It was concluded that the pressure drop is mainly generated by the gas phase, whatever the configuration chosen. Moreover, the volumetric mass transfer coefficients kLa found were lower than those obtained with the same static mixers used in classic conditions (that is with a liquid continuous phase), but greater than values obtained with classic reactors like bubble columns or packed columns. The efficiency of these gas‐liquid reactors was found high, as well as the energy dissipated, unfortunately.
Gas—Liquid Mass Transfer Coefficient in Stirred Tank Reactors
Authors: Yawalkar Archis A. , Heesink Albertus B. M. , Versteeg Geert F. , Pangarkar Vishwas G. 
Published: July 2010

AbstractVolumetric gas—liquid mass transfer coefficient (kLa) data available in the literature for larger tanks (T = 0.39 m to 2.7 m) have been analyzed on the basis of relative dispersion parameter, N/Ncd. It was observed that at a given superficial gas velocity (VG), kLa values were approximately the same irrespective of geometric configuration (size of the tank, type and size of the impellers, type of the sparger, etc.) at a particular N/Ncd. A single correlation based on N/Ncd is presented which shows satisfactory agreement with the kLa data of different workers.
Preparation and Kinetic Considerations for the Dissolution of Cr‐substituted Iron Oxides in Reductive‐complexing Formulations
Authors: Manjanna Jayappa , Venkateswaran Gopala 
Published: July 2010

AbstractThe dissolution rate coefficients of Cr‐substituted (0‐20 at.% Cr) iron oxides viz. hematite and magnetite were determined by using an inverse cubic rate (ICR) law applicable for spherical particles as well as by a general kinetic equation (GKE) applicable for polydispersed particles. An attempt is made to compare both the treatments for different kinds of dissolution profiles obtained by employing oxides with narrow particle size distribution in V(II)‐EDTA and citric acid‐EDTA‐ascorbic acid formulations at 353±5K. The dissolution profiles could be classified into three types based on the nature of oxide and formulations. It is observed that both ICR and GKE treat the dissolution course as a function of decrease in fraction of undissolved mass, m/m0. The dissolution rate coefficients determined by ICR and GKE have shown the similar trend of decrease with increasing Cr content of the oxides and was ascribed to lattice stabilization.
Prediction of High‐Pressure Phase Equilibria using Cubic EOS: What Can Be Learned?
Authors: Polishuk Ilya , Stateva Roumiana P. , Wisniak Jaime , Segura Hugo 
Published: July 2010

AbstractModern semi‐empirical cubic EOSs are usually attached by complex functionalities, such as Huron‐Vidal (HV)‐type mixing rules. Although this practice improves the flexibility of the models, it also complicates consideration of an overall picture of phase behavior. As a result, GE‐based equations are usually adjusted to the experimental data by way of a local fit. The latter approach tends to ignore that different regions of the thermodynamic phase space are closely inter‐related. The present study demonstrates that the contribution of (HV)‐type mixing rules to predicting high‐pressure phase equilibria can be quite modest and that in addition they may generate non‐realistic phase diagrams.
Predicting the Distribution Constants of Butane Extraction of Organic Pollutants from Aqueous Solubility
Authors: Teo Khay‐Chuan , Yang Chun , Xu Yan‐Rong 
Published: July 2010

AbstractThe n‐butane/water distribution constant is one of the key parameters in determining the extraction efficiency. Experimental results on 34 organic compounds illustrated that a fundamental linear relationship exists between the distribution constant and the aqueous solubility of the solute. The relationship can be broadly applied to many different classes of chemical compounds as well as to many different solvent extraction systems. The linear equation obtained by a regression method allows one to estimate the distribution constant and predict the result of butane extraction if the aqueous solubility of certain solute is available.
Integrated Scheme of Natural Gas Usage with Minimum Production of Entropy
Authors: Granovskii Michael S. , Safonov Mikhail S. , Pozharskii Sergey B. 
Published: July 2010

AbstractThree schemes of the gas turbine cycle have been analyzed from the point of view of the second law of thermodynamics: the conventional gas turbine cycle, where natural gas (methane) is oxidized by air; a closed gas turbine cycle, in which methane is oxidized by oxygen; and a proposed gas turbine cycle, in which the methane is first converted to synthesis gas (a mixture of carbon oxide and hydrogen), then part of the synthesis gas is oxidized by oxygen for electric energy generation while the rest is withdrawn from the power cycle for production of methanol, ether, synthetic fuel, etc. It has been shown that the third integrated scheme of natural gas usage provides minimum entropy increase as well as suppression of toxic nitrogen oxides generation in combustion products. Therefore, it could be considered as a prospective energy‐saving technology.
Linear Viscoelastic Properties of Suspensions of Rigid Hairy Particles in a Polymeric Matrix
Authors: Dagréou Sylvie , Kasseh Abdeslam , Allal Ahmed , Marin Gérard , Aït‐Kadi Abdellatif 
Published: July 2010

AbstractThe aim of this work is to use a recently developed statistical model of dispersions with non‐hydrodynamic interactions (Dagréou et al., 2002) to describe the linear viscoelastic properties of suspensions of rigid hairy particles in a polymeric matrix. We first present numerical simulations of our model applied to this system; we demonstrate that taking physical interactions into account allows one to predict the complex relaxation behaviour of filled polymers. We then compare the statistical model to experimental results on suspensions of grafted silica particles in a polystyrene matrix and show that they are in reasonable agreement up to volume fractions close to percolation.
Molecular Weight Polydispersity Effects on Diffusion at Polymer/Polymer Interfaces
Authors: Qiu Hua , Bousmina Mosto 
Published: July 2010

AbstractThe effect of molecular weight distribution (MWD) on diffusion at symmetric polymer/polymer interfaces is investigated by rheological tools. A new model allowing the determination of a self‐diffusion coefficient of polydisperse polymer systems is presented. The model is based on the double reptation theory and Doi and Edwards' molecular dynamics applied to A/A polymers brought into intimate contact in the molten state. The material parameters for the model are obtained from linear oscillatory shear experiments, in which the dynamic shear modulus is measured in parallel plate geometry under a small amplitude of deformation as a function of time and frequency for a sandwich‐like assembly. The experiments were conducted on polystyrene (PS) blends with constant weight average molecular weight (Mw) but with variable number average molecular weights (Mn). The measured self‐diffusion coefficients showed that the presence of short molecules in the blend increases the mean value of the self‐diffusion coefficient and the magnitude of such increase can be quantitatively evaluated by the proposed model.
Hydrophobic Interactions in Silane‐Treated Silica Suspensions and Bitumen Emulsions
Authors: Sanders R Sean , Chow Ross S. , Masliyah Jacob H. 
Published: July 2010

AbstractIn the extraction of bitumen from Canada's oil sands reserves, bitumen droplet coalescence is an important factor in determining the efficacy of the separation process. In a simplified analysis of bitumen droplet interactions, the relative contributions of classical DLVO and non‐DLVO forces occurring between a bitumen droplet and surface‐treated planar collector were evaluated using the impinging jet cell technique. Initial experiments were conducted using a system consisting of silane‐treated silica particles and a hydrophobic collector. This system is known to exhibit attractive non‐DLVO interactions as was clearly demonstrated by the present study. The attachment of bitumen droplets onto two different hydrophobic collectors was then examined. Results of these experiments indicate that bitumen droplet interactions involve an additional repulsive force that may be attributable to the heterogeneous nature of the droplet surface.
Model and Simulation of a Ported Kiln for Iron Oxide Pellet Induration
Authors: Davis Richard A. , Englund David J. 
Published: July 2010

AbstractA mathematical model of a ported kiln for iron oxide pelletizing was developed to simulate the effects of under‐bed air injection on kiln fuel requirements and magnetite oxidation. A tanks‐in‐series model was used to set up material and energy balance equations for countercurrent flow of solids and gas through the kiln. The diffusion‐limited, shrinking core model was used for the magnetite oxidation reaction kinetics. The port air distribution in the model was adjusted by global optimization to minimize the fuel requirement. The simulation results show that magnetite oxidation may be completed in the kiln with significant fuel savings.
Modelling of Hydrothermal‐Mechanical Expression of Brown Coal
Authors: Guo Jian , Tiu Carlos , Uhlherr Peter H. T. 
Published: July 2010

AbstractThe large water content of brown coal can be reduced by hydrothermal‐mechanical expression (HME). The HME process combines the advantages of hydrothermal dewatering and mechanical dewatering and consequently, with low input of energy, produces dry, dense and hydrophobic coal. The mechanism of the HME process is analysed using the theory of one‐dimensional consolidation. A Terzaghi‐Voigt combined model is used to model the HME process operated at high temperature and pressure. The temperature‐related behaviours of some important model coefficients including the consolidation coefficient and the creep constant are identified. The model prediction for moisture reduction during expression agrees well with experimental data.
Measurement of Solid Circulation Patterns in Liquid—Solid and Gas—Liquid—Solid Fluidized Beds
Authors: Barghi Shahzad , Briens Cedric L. , Bergougnou Maurice A. 
Published: July 2010

AbstractSolid circulation patterns were determined by measuring collisions between tracer particles and cylindrical probes in liquid—solid and gas—liquid—solid fluidized beds. Special probes were used to obtain two‐ and three‐dimensional views of particle motion. Circulation patterns for 3 and 5 mm glass beads were studied. Mixing cells, which had been formed at low liquid velocities, grew in size and eventually merged as the liquid velocity increased. The flow patterns of smaller particles having the same density as bed particles and particles lighter than bed particles (graphite particles) with the same size were also measured.
Decreasing the Sampling Time Interval in Radioactive Particle Tracking
Authors: Mostoufi Navid , Kennedy Gregory , Chaouki Jamal 
Published: July 2010

AbstractThe study of the movement of solids in multiphase reactors using radioactive particle tracking is currently limited to fairly modest particle velocities because of count‐rate limitations of the detection system. In this work, this restriction was overcome by increasing the activity of the radioactive tracer, by decreasing the sampling time interval and by modifying the particle tracking software to recognize which detectors were saturated and to use only the data from the remaining unsaturated detectors. Higher tracer activity resulted in lower standard deviation of the calculated tracer coordinates.
Two‐Phase Bubbly Flow Structure in Large‐Diameter Vertical Pipes
Authors: Shoukri Mamdouh , Hassan Ibrahim , Gerges Ihab 
Published: July 2010

AbstractThe two‐phase flow structure of an air‐water, bubbly, upward flow in a 20 cm diameter pipe is presented with particular emphasis on the local interfacial area concentration. The radial distribution of void fraction, bubble velocity, bubble size, bubble frequency, and interfacial area concentration were measured using a local dual‐optical probe. The experimental results showed that the saddle‐type distribution of void fraction and interfacial area concentration, which are common for bubbly flow in small diameter pipes, only appeared in the present experiments under conditions of very low area‐averaged void fraction (<ϵ> < 0.04). The values for the interfacial area concentration were higher in large diameter pipes when compared with data obtained under the same flow conditions in small pipes. The area‐averaged void fraction data were correlated using the drift‐flux model.
Kinetic Modeling of Liquid Phase Oxidation of Cyclohexane
Authors: Bhattacharya Arijit , Mungikar Amol 
Published: July 2010

AbstractA kinetic model for the liquid phase oxidation (LPO) of cyclohexane has been derived using a reaction network based on a consistent free radical mechanism. It was demonstrated that on embedding this rate model within the overall model of a semi‐batch gas‐liquid reactor (SBR) one can predict the time variation of the dissolved oxygen concentration and the rate of oxygen absorption which compare fairly closely with some well regarded published experimental data. The model is distinguished by easy extendibility and modularity whereby it could be tailored to predict, in the context of a SBR, cyclohexane conversion and ketone‐alcohol (K‐A) product selectivity levels as observed in commercial plants and in the published data on pilot plant experimentation. The model is expected to be of use in the design and scale‐up of LPO reactors.
Energy Dissipation at the Slug Nose and the Modeling of Solids Transport in Intermittent Flow
Authors: Stevenson Paul , Thorpe Rex B. 
Published: July 2010

AbstractIt is shown, by means of Lagrangian momentum and power balances across the slug nose in slug flow, that the power dissipated due to sudden expansion of the fluid in the film immediately downstream of the slug nose is greater than the power lost due to viscous action at the pipe wall but that it may not be large enough to materially aid particle transport. This has the implication that sand transport in intermittent flow may be considered as transport in a hybrid flow of hydraulic conveying and stratified flow when the length of the mixing section at the slug nose is short compared to the length of the slug body.
Natural Convection in Heat Generating Oval Porous Enclosures: A Non‐Darcian Model
Authors: Das Subrat , Sahoo Ranjit Kumar , Morsi Yos S. 
Published: July 2010

AbstractThis paper presents a series of numerical simulations dealing with the problem of natural convection flows and associated heat transfer in an enclosure filled with a fluid‐saturated porous medium. The analysis is based on the finite element technique and incorporates the Brinkman‐extended Darcy model for an oval enclosure. The numerical results obtained for a modified Rayleigh number, Ra, Darcy number, Da, offset, E, and eccentricity, e, are presented and discussed. The numerical predictions for a square enclosure compared well with published data. It is found that any increase in Da or Ra results in a higher fluid velocity that is responsible for shifting the core of the flow. Moreover, at higher ovality (E = 0.5), asymmetric flow is observed even at the lower range of Rayleigh number (Ra ⩽ 20), which may be attributed to the effect of curved isothermal wall.