bluuebunny/crossref_metadata_2025_split huggingface dataset:
Layer Inversion and Bed Contraction in Down‐Flow Binary‐Solid Liquid‐Fluidized Beds
Authors: Escudié R. , Epstein N. , Grace J. R. , Bi H. T. 
Published: July 2010

AbstractExperiments were carried out on downward‐flow water‐fluidized binary mixture of spheres selected for possible layer inversion. With the two binaries tested (relatively high‐density large particles mixed with lower‐density smaller particles), only one of the five possible steps of the layer inversion progression was clearly identified for the higher liquid velocities, a mixed layer being observed at the top of the column close to the distributor. This layer manifested a bed contraction so large that its bulk density was lower than those of its constituent mono‐components at the same liquid velocity, which determined its location within the column. The voidage of the mixed layer could be predicted with good accuracy (<0.7%) by regression of the Westman packed bed equation with one adjustable parameter.
Measuring Flow Velocity and Uniformity in a Model Batch Digester Using Electrical Resistance Tomography
Authors: Lee Q. F. , Bennington C. P. J. 
Published: July 2010

AbstractThe literature shows that the extent of delignification in batch digesters varies as a function of chip location in the vessel. This non‐uniformity may be exacerbated by a number of factors but is commonly attributed to poor and/or non‐uniform liquor flow through the reactor (which causes poor chemical and heat distribution to the chip mass during the cook). Electrical resistance tomography (ERT) was used to evaluate the uniformity of liquor flow in a laboratory model digester under scaled industrial conditions (a 1:15 geometrically scaled vessel, a vessel to particle diameter ratio of 93:1 to minimize wall effects, and close approximation of liquor superficial velocity and pore Reynolds number). Local interstitial flow velocities were measured using pixel‐pixel cross correlation techniques. It was possible to create uniform zones in the digester, but a stagnation point was observed in the centre of the vessel at the screen level. This point coincides with the location of highest kappa numbers (lowest degree of cooking) reported in industrial tests.
Production of 4‐Hydroxybutyl Acrylate and Its Reaction Kinetics over Amberlyst 15 Catalyst
Authors: Yang Jung‐Il , Cho Soon‐Haeng , Kim Hak‐Joo , Joo Hyunku , Jung Heon , Lee Kwan‐Young 
Published: July 2010

AbstractEsterification of acrylic acid (AA) with 1,4‐butanediol (BD) was carried out over a solid acid catalyst to produce 4‐hydroxybutyl acrylate (HBA), an environmentally benign coating agent. The Amberlyst 15 catalyst was more active for the reaction than other ion exchanged resin catalysts such as Amberlyst 35 and DOWEX HCR‐S(E). The quasi‐homogeneous model was chosen to express the esterification reaction kinetics over Amberlyst 15. The stirring speed was changed from 300 rpm to 750 rpm and the reaction rate showed no influence of external mass transfer. The reaction temperature was varied from 100°C to 120°C to calculate activation energies of the reactions. The calculated activation energies were 58.3 kJ/mol and 86.7 kJ/mol for HBA and BDA (1,4‐butanediol diacrylate, by‐product) productions, respectively. The catalyst concentration was also changed from 0.0043 g/ml to 0.0171 g/ml to find its effect on the rate constant. The complete kinetic equation of esterification to produce HBA over the Amberlyst 15 catalyst based on the quasi‐homogeneous model was developed.
Hydrogen Yield from Low Temperature Steam Reforming of Ethanol
Authors: Das Nikhil K. , Dalai Ajay K. , Ranganathan R. 
Published: July 2010

AbstractLow temperature steam reforming of ethanol in the temperature range of 200–360°C was studied to maximize the production of H2. The optimum reaction conditions in presence of a suitable catalyst can produce mainly the desired products H2and CO2. Cu/Al2O3catalysts with six different concentrations ranging from 0 to 10 wt.% Mn, were prepared, characterized and studied for the ethanol‐steam reforming reaction. Maximum ethanol conversion of 60.7% and hydrogen yield of 3.74 (mol H2/ mol ethanol converted) were observed at 360°C for catalyst with 2.5 wt.% Mn loading.
An Improved LES on Dense Particle‐Liquid Turbulent Flows Using Integrated Boltzmann Equations
Authors: Tang Xuelin , Wu Jing 
Published: July 2010

AbstractAn improved large eddy simulation (LES) using a dynamic second‐order subgrid stress (SGS) model has been developed for simulating dense particle‐liquid two‐phase turbulent flows. The governing equations of each phase are obtained from a microscopic point of view, using the kinetic theory of molecular gas. They are derived by multiplying the Boltzmann equation of each phase by property parameters and integrating over the velocity space. An inter‐particle collision term is included in the governing equation of the particle phase. Assuming a Maxwellian distribution of the velocity for particle‐phase, an inter‐particle collision term is derived.
Entrainment Rate of Coarse Particles at Different Temperatures in Gas Fluidized Beds
Authors: Choi Jeong‐Hoo , Kim Sang Done , Grace John R. 
Published: July 2010

AbstractBased on available experimental data, an empirical relationship is developed for the entrainment rate of coarse particles at the exit of gas‐fluidized beds, including the effects of fine particles in the bed, temperature, gas velocity, particle size and density, and column size. It predicts well the influence of fine particles on the entrainment rate of coarse particles, taking into account the momentum of the fine particles and the effect of superficial gas velocity. It also accounts well for the influence of temperature at different solid densities and gas velocities.
Modèles Hydrodynamiques pour la Séparation des Courants dans un Décanteur Pilote
Authors: Berthiaux Henri , Lavin Antonio Guttierrez , De Las Heras Julio Bueno , Alvarez Marisol Muñiz 
Published: July 2010

AbstractMalgré son emploi généralisé dans l'industrie, la décantation est une opération qui n'a pas encore révélé toutes ses facettes. En particulier, les aspects hydrodynamiques sont par nature complexes du fait de la dépendance des volumes identifiables aux conditions opératoires, ce qui a une conséquence indéniable sur le comportement de l'équipement en régime transitoire.
Sulphation Characteristics of Paper Sludge Ash
Authors: Roh Seon Ah , Kim Sang Don 
Published: July 2010

AbstractThe effects of SO2 concentration and particle size on sulphation of paper sludge ash were determined in a thermobalance reactor. The activation energy and pre‐exponential factor of sulphation reaction of sludge ash were determined based on the uniform‐reaction model. From the X‐ray diffraction analysis, only CaSO4 formation is observed without any other sulphation compounds. The outer pore of the sludge ash is not blocked by CaSO4 and the sulphation occurs uniformly throughout the ash. The uniform distributions of CaO and other inert minerals in the ash provide uniform sulphation with good penetration of SO2 into pores of the sludge ash without pore blocking during sulphation of CaO.
Soret Diffusion and Non‐Ideal Dufour Conduction in Macroporous Catalysts with Exothermic Chemical Reaction at Large Intrapellet Damköhler Numbers
Authors: Belfiore Laurence A. 
Published: July 2010

AbstractThe adiabatic temperature rise in catalytic pellets is predicted from a modified version of the Prater equation. Onsager reciprocal relations for coupled heat and mass transfer are violated in an analysis of thermal diffusion in macroporous catalysts with exothermic chemical reaction when Dufour conduction (i.e., the diffusion‐thermo effect) is neglected. In this contribution, Dufour conduction is analyzed for both ideal and non‐ideal pseudo‐binary gas mixtures that simulate the production of methanol from carbon monoxide and hydrogen. In the diffusion‐controlled regime at large intrapellet Damköhler numbers where intermolecular collisions provide the dominant resistance to mass transfer within the catalytic pores, temperatures in the catalytic core could be much greater than predictions based on the original Prater equation when the Prater number exceeds 0.30. The molecular flux of thermal energy includes Fourier's law, the interdiffusional flux, and Dufour conduction. Diffusional mass flux includes Fick's law and the Soret effect. All physicochemical properties of the reactive gas mixture exhibit temperature dependence. There is essentially no difference between maximum intrapellet temperature predictions that include or neglect ideal Dufour conduction when external catalytic surface temperatures range from 300‐400 K and thermal diffusion enhances the flux of “smaller” reactants toward the centre of the catalyst. For “large‐molecule reactants” that participate in exothermic reactions, thermal diffusion opposes Fick's law and Dufour conduction opposes Fourier's law. Under these conditions, it is demonstrated that core temperatures are overestimated by neglecting both off‐diagonal coupling mechanisms (i.e., Soret diffusion and Dufour conduction). Prater numbers greater than unity and unrealistically high gas pressures are required to distinguish between maximum intrapellet temperatures for ideal and real gas simulations, where the latter consider two‐body interactions for Lennard‐Jones molecules in the virial equation of state.
Simulations of Bubble Column Reactors Using a Volume of Fluid Approach: Effect of Air Distributor
Authors: Akhtar M. Abid , Tadé Moses , Pareek Vishnu 
Published: July 2010

AbstractTwo‐ and three‐dimensional numerical simulations have been performed on a laboratory scale bubble column reactor using a volume‐of‐fluid approach. The effect of hole‐size and superficial gas velocity on the bubble size distribution and their trajectories has been investigated on a 20 cm diameter and 1 m high cylindrical reactor. All simulations were performed in a transient manner using a FLUENT solver. Surface tension between two phases has been modelled as a body force with a constant value. Turbulence was modelled using the k‐ϵ turbulence approach. A comparison between simulation predictions and the reported experimental studies has shown a good agreement.
A Quasi‐Steady State Shell and Shrinking Core Approach to the Drying of Porous Particles and an Example of Parameter Identification
Authors: Manganaro James L. 
Published: July 2010

AbstractA quasi‐steady state shell and shrinking core approach which recognizes heat and mass transfer resistances in both the gas and particle phases for drying of a porous particle is proposed. A mean field model (constant properties) using this approach was embedded in a spreadsheet combined with a genetic algorithm for parameter identification to provide an easy means of characterizing the drying process from drying data. In drying, assuming a mean field, four major parameters are typically unknown: two related to the process (heat and mass transfer coefficients) and two which incorporate porous particle properties (shell thermal conductivity and vapour diffusivity). It is shown how these four parameters may be determined from experimental drying data. The model was applied to data for spouted bed drying of rice. For the particular case studied, external heat transfer was found to be the controlling mode, although resistance to moisture diffusion within the particle is important. The approach presented admits of future refinements to improve its scope and utility.
Butyl Acrylate/Vinyl Acetate Emulsion‐Based Pressure‐Sensitive Adhesives: Empirical Modelling of Final Properties
Authors: Jovanovic Renata , Dubé Marc A. 
Published: July 2010

AbstractThe influence of the amounts of acrylic acid, chain transfer agent and anionic stabilizer on polymer microstructural properties and final adhesive performance of BA/VAc emulsion‐based PSAs on stainless‐steel and high‐density polyethylene substrates was investigated using a Box‐Behnken experimental design for 15 runs. The resulting data were empirically modelled. For each final adhesive property (i.e., loop tack, shear and peel strength), different models were found to fit the data. Similar models for loop tack and peel strength were found to be adequate for different PSA thicknesses on the same substrate. AA and SDS had significant effects on loop tack as did the AA‐SDS and CTA‐SDS two‐factor interactions. Quadratic peel strength models were found to adequately describe the data for SS substrate cases with a noticeable absence of any interaction parameters. The shear strength models were similar regardless of the substrate or thickness of the adhesive (e.g. in all models, AA and CTA, as well as their second‐order interactions, were the significant factors).
Modelling Carbon Dioxide Corrosion with Film Crystallization and Erosion
Authors: Kennell Glyn F. , Heppner Kevin L. , Evitts Richard W. 
Published: July 2010

AbstractThis paper presents a model of carbon dioxide corrosion in a steel straight pipe under turbulent flow, which includes protective iron carbonate film formation, film undermining, and film erosion. The flow field was discretized using a finite volume technique, with mass transport of dissolved species accounted for with an infinitely dilute solution model. The experimental results of Nesic and Lee, Corrosion 59, 616–628 (2003) were accurately predicted and transient corrosion trends for several temperatures and carbon dioxide partial pressures were determined. The model calculates thinner but denser films at higher fluid flow rates, which corresponds to the experimental trend obtained by Schmitt and Mueller, NACE International, Paper 44 (1999).
Design and Techno‐Economic Analysis of a Process for Transforming Pig Manure into a Value‐Added Product
Authors: Fugère Mylène , Farand Patrice , Chabot Rock , Stuart Paul 
Published: July 2010

AbstractThis study involves the design and techno‐economic analysis of a process that couples biodrying and conventional drying to increase the economic value of liquid pig manure sludge, by transforming it into a stable organic fertilizer. The process has significant environmental benefits compared to other disposal methods, especially considering recent legislative changes restricting the spreading of liquid pig manure, and at the same time provides a return on investment. It was found that the rate of return for the process was 14%, but could reach 25% if the price of the fertilizer product increases as expected.
Identification of Multivariable Delay Processes in Presence of Nonzero Initial Conditions and Disturbances
Authors: Wang Qing‐Guo , Hang Chang Chieh , Liu Min , Tang Wei 
Published: July 2010

AbstractIn this paper, a robust identification method is proposed for multiple‐input and multiple‐output (MIMO) continuous‐time processes with multiple time delays. Suitable multiple integrations are constructed and regression equations linear in the aggregate parameters are derived with the use of the test responses and their multiple integrals. The multiple time delays are estimated by solving some algebraic equations without iteration and the other process model parameters are then recovered. Its effectiveness is demonstrated through simulation and real‐time testing.
Integration of Design and Control: A Robust Control Approach Using MPC
Authors: Chawankul N. , Sandoval La Ricardez , Budman H. , Douglas P. L. 
Published: July 2010

AbstractThis paper presents a new method to integrate process control with process design. The process design is based on steady‐state costs, .i.e., capital and operating costs. Control is incorporated into the design in terms of a variability cost. This term is calculated based on the non‐linear process model, represented here as a nominal linear model supplemented with model parameter uncertainty. Robust control tools are then used within the approach to assess closed‐loop robust stability and to calculate closed‐loop variability. The integrated method results in a non‐linear constrained optimization problem with an objective function that consists of the sum of the steady costs and the variability cost. Optimization using the traditional sequential approach and the new integrated method was applied to design a multi‐component distillation column using a Model Predictive Control (MPC) algorithm. The optimization results show that the integrated method can lead to significant cost savings when compared to the traditional sequential approach. In addition, an RGA analysis was performed to study the effects of process interactions on the optimization results.
Reference Trajectory Optimization Under Constrained Predictive Control
Authors: Lam David K. , Baker Rhoda , Le Swartz Christopher 
Published: July 2010

AbstractChemical process systems often need to respond to frequently changing product demands. This motivates the determination of optimal transitions, subject to specification and operational constraints. However, direct implementation of optimal input trajectories would, in general, result in offset in the presence of disturbances and plant/model mismatch. This paper considers reference trajectory optimization of processes controlled by constrained model predictive control (MPC). Consideration of the closed‐loop dynamics of the MPC‐controlled process in the reference trajectory optimization results in a multi‐level optimization problem. A solution strategy is applied in which the MPC quadratic programming subproblems are replaced by their Karush‐Kuhn‐Tucker optimality conditions, resulting in a single‐level mathematical program with complementarity constraints (MPCC). The performance of the method is illustrated through application to two case studies, the second of which considers economically optimal grade transitions in a polymerization process.
Fault Detection of Non‐Linear Processes Using Kernel Independent Component Analysis
Authors: Lee Jong‐Min , Qin S. Joe , Lee In‐Beum 
Published: July 2010

AbstractIn this paper, a new non‐linear process monitoring method based on kernel independent component analysis (KICA) is developed. Its basic idea is to use KICA to extract some dominant independent components capturing non‐linearity from normal operating process data and to combine them with statistical process monitoring techniques. The proposed method is applied to the fault detection in the Tennessee Eastman process and is compared with PCA, modified ICA, and KPCA. The proposed approach effectively captures the non‐linear relationship in the process variables and showed superior fault detectability compared to other methods while attaining comparable false alarm rates.
Role of Collective Interactions in Self‐Assembly of Charged Particles at Liquid Interfaces
Authors: Wu Stanley , Nikolov Alex , Wasan Darsh 
Published: July 2010

AbstractCharged nano‐colloidal particles self‐assemble and display ordered arrays or other structures at liquid interfaces. We used Monte Carlo (MC) simulations to examine the effect of long‐range repulsive collective inter‐particle interactions on structural—transitions from liquid‐like to crystal‐like. We used the asymptotic pair interaction potential proposed by Hurd (J. Phys. A. Math Gen 18, L1055 (1985)), which includes both the screened Coulombic contribution and the dipole‐dipole interaction. The effects of the collective inter‐particle interactions on the interfacial 2‐D colloid structure formation were quantified by the radial distribution function and the potential of the mean force. The MC simulations agreed with the experimentally observed particle structural transitions at both the air‐water and oil‐water interfaces. The effects of the particle charge and interfacial coverage on the 2‐D structure formation were analyzed. The significance of the results lies in their potential applications in inducing 2‐D structural transitions in interfacial colloids to form ordered structures; this controls the emulsion and foam stability, and aids in the fabrication of patterned materials with desirable properties.
Initial Deposition of Colloidal Particles on a Rough Nanofiltration Membrane
Authors: Rizwan Tania , Bhattacharjee Subir 
Published: July 2010

AbstractThe initial rate of colloid deposition onto semi‐permeable membranes is largely controlled by the coupled influence of permeation drag and particle‐membrane colloidal interactions. Recent studies show that the particle‐membrane interactions are subject to immense local variations due to the inherent morphological heterogeneity (roughness) of reverse osmosis (RO) and nanofiltration (NF) membranes. This experimental investigation reports the effect of membrane roughness on the initial deposition of polystyrene latex particles on a rough NF membrane during cross flow membrane filtration under different operating pressures and solution chemistries. Atomic force microscopy was used to characterize the roughness of the membrane and observe the structure of particle deposits. At the initial stages of fouling, the AFM images show that more particles preferentially accumulate near the “peaks” than in the “valleys” of the rough NF membrane surface.
Asymmetric Polymer Bridging Between Starch‐Coated Colloidal Particles and Pulp Fibres by Cationic Polyacrylamide
Authors: Poraj‐Kozminski Agatha , Hill Reghan J. , van de Ven Theo G. M. 
Published: July 2010

AbstractInternal sizing agents are commonly used as additives in papermaking to impart hydrophobicity to paper. They are commonly added in the form of colloidal particles, stabilized by cationic starch. As an example we studied the deposition of micron‐sized Alkyl Ketene Dimer (AKD) particles on pulp fibres by cationic polyacrylamide (cPAM), a common flocculent. It was found that cPAM did not adsorb on AKD particles stabilized by cationic starch. Despite this inability to adsorb, cPAM was found to drastically improve the deposition of AKD particles on pulp fibres. This deposition was ascribed to asymmetric polymer bridging, a phenomenon observed by us before, while studying clay deposition on fibres by polyethylene oxide. In asymmetric polymer bridging between two types of particles, the bridging polymer first adsorbs on one type of particle, since it is unable to adsorb on the second type. Asymmetric polymer bridging occurs when the enthalpy gain on both surfaces exceeds the entropy loss. The kinetics of AKD deposition on fibres was found to agree with the predictions of the asymmetric bridging theory. In addition, an increase in bond strength with time was found, due to starch and cPAM reconfiguration. The increase in AKD retention by cPAM is also observed in experiments on a laboratory twin‐wire sheet former. Asymmetric polymer bridging by cPAM between starch‐coated AKD particles and fibres is compared with classical polymer bridging by cPAM between fibres and AKD particles coated by carboxymethylcellulose.
Probing of Thin Slipping Films by Persistent External Disturbances
Authors: Alleborn N. , Sharma A. , Delgado A. 
Published: July 2010

AbstractThis paper investigates the propagation of thickness disturbances on the free surface of a thin viscous liquid film on a solid substrate. On the free surface of the film the disturbances are induced by moving local external pressure perturbations acting on the surface. The analysis is performed by the Fourier‐Laplace transform applied to the linearized perturbation equations for small amplitudes. The amplitude of the interface deflection caused by the disturbance, is reconstructed by the inverse Fourier‐Laplace transform and numerically evaluated in the long time limit in long wave approximation. The proposed technique appears promising for probing the slip length of a thin film by recording its free surface response to a moving perturbation.