bluuebunny/crossref_metadata_2025_split huggingface dataset:
A Method for Calculation of Final Film Thickness in Free Coating of Viscoelastic Fluids onto a Vertical Surface
Authors: Savarmand Saeid , Azizmohammadi Siroos , Bahrami Ali , Golkar‐Narenji Mohammad‐Reza 
Published: July 2010

AbstractA method for the calculation of the final film thickness in free coating of a viscoelastic fluid onto a vertical surface withdrawn from its vessel is developed. The method is based on the definition of an objective function, the minimization of which guarantees that the kinematic as well as the dynamic conditions at the lower boundary of the dynamic meniscus region are simultaneously satisfied. A systematic approach is provided in order to localize the optimum value of the final film thickness within the optimization interval. It was observed that there was a clear relationship between the estimated final film thickness and the value of a parameter A. The closeness of this parameter to zero corresponds to the dynamic constraint being fulfilled at the lower boundary of the dynamic meniscus region. This relationship is used as an objective means of determining the direction to update the interval of optimization to obtain the final thickness of the film. The results of the proposed method are compared to the previous works on the free coating of viscoelastic fluids, which are based on a trial‐and‐error method. The performance of the previously applied rheological models to the formulation of the free coating process, mainly the modified Oldroyd models, is also compared by introducing the present method.
Strategies for Starting Up Azeotropic Distillation Columns with Multiple Steady States
Authors: Benz Sonia J. , Francesconi Javier A. , Scenna Nicolás J. 
Published: July 2010

AbstractThe operability of azeotropic distillation columns with multiplicity is analysed during start‐up by dynamic simulation. Different steady states can be reached by applying different start‐up configurations and/or policies. The well‐known benzene‐heptane‐acetone (BHA) system is studied. The process by which the column reaches these steady states can be seen through the examination of profile evolutions corresponding to the given start‐up policies. Indeed, a clear partition of the start‐up policies space yielding different solutions is achieved. Some properties of this space are explained and start‐up critical values can be identified. Finally, some guidelines for start‐up supervision are outlined for the study case.
Kinetics and Combustion Characteristics of Deinking Sludge in a Thermobalance and an Internally Circulating Fluidized Bed
Authors: Namkung Won , Roh Seon A. H. , Guy Christophe , Kim Sang Done 
Published: July 2010

AbstractThe kinetic parameters (activation energy, pre‐exponential factor and reaction order) of volatile and char of deinking sludge are determined by thermo‐gravimetric analysis. From the Arrhenius plot, the activation energy and the pre‐exponential factor of char are determined. The reaction order is found to be 0.7 with respect to oxygen partial pressures of 507 – 3040 Pa. The effects of riser gas velocity, solid feeding rate and annulus air on combustion efficiency have been determined in an internally circulating fluidized bed (ICFB). The combustion efficiency decreases with increasing riser gas velocity and solid feeding rate, while it increases with increasing annulus air. High combustion efficiency is obtained when the annulus air is injected.
Simulation de la distillation catalytique par un nouveau modèle de transfert &&num;0150; Application à la production d'acétate de méthyle
Authors: Druart Florence , Reneaume Jean‐Michel , Meyer Michel , Rouzineau David 
Published: July 2010

AbstractNous présentons un modéle de transfert pour la distillation catalytique utilisant les équations de Maxwell‐Stefan et incluant la diffusion effective dans le catalyseur poreux. L'écriture et la résolution de ce modéle ont été adaptées à son inclusion dans un simulateur commercial. Il est donc robuste et souple. Nous étudions l'influence des caractéristiques du catalyseur, de la configuration de la colonne, de la non‐idéalité du mélange et de la qualité de l'échange liquide/vapeur. La conclusion principale de ces essais est l'existence d'un optimum de fonctionnement notamment pour le taux de reflux et l'emplacement du catalyseur.
A Modular Mixed‐Integer Non‐Linear Programming Algorithm for Synthesis of Chemical Processes
Authors: Li Hehua , Qian Yu , Zheng Shiqing , Cheng Huanong 
Published: July 2010

AbstractA modular approach to the formulation and a solution of mixed‐integer non‐linear programming (MINLP) problems are presented, which reduce the size of MINLP and the computational expenses effectively. The method decomposes the synthesis task into three hierarchical levels—the superstructure, the structure, and the modules, with the layer of modules being the most critical to the problem solution. The strategy has been implemented in a simulation environment in which the variables of interest are defined as implicit functions of the optimization variables. The implicit relationships are handled using a data‐oriented process simulation technique (DOPS) that significantly simplify the simulation. The method has been effectively applied to two case studies, one from literature for the synthesis of hydrodesalkylation, and another from industrial process manufacturing methylene diphenylene diisocyanates.
Holdup Profile in Multistage Stirred‐Cell Liquid‐Liquid Extraction Column Using Population Balance Model
Authors: Ismail Ashraf S. 
Published: July 2010

AbstractThe drop exit frequency model developed in the literature is modified and simplified to suit the practical situations. An adjusting factor is inserted in the exit frequency model to account for the simplification of the hydrodynamic pattern used in the analysis and the incorrect constants used in the rise velocity model. The holdup profiles calculated in the present analysis are compared with experimental and theoretical results in the literature to evaluate the model. The comparison shows good agreement between the present model and the experimental data. Even for the cases of poor agreement, the breakage and coalescence rates are adjusted, and the stages of quasi‐equilibrium state are determined to improve the results.
The Bed Expansion and Particle Velocity Analysis in the Swirling Fluidized Bed Combustor (SFBC) Cold Model
Authors: Lee S. W. , Liu Y 
Published: July 2010

AbstractFlow visualization and analysis was extensively conducted in a bench‐scale swirling fluidized bed combustor (SFBC) cold model. An advanced laser‐based particle image velocimetry (PIV) system was used to visualize the gas‐particle flow in SFBC cold model. The robust experiment design method was applied to study the bed expansion in the SFBC cold model in relationship with secondary airflow ratio. It was found that the secondary airflow ratio did not affect the bed expansion in the SFBC cold model. Based on the PIV velocity profiles analysis, it was observed that particle velocities increased when secondary airflow ratio is increased. The secondary air was definitely generating the high tangential particle velocity.
Power‐Law Fluid Flow Over a Sphere: Average Shear Rate and Drag Coefficient
Authors: Renaud Maurice , Mauret Evelyne , Chhabra Rajendra P. 
Published: July 2010

AbstractBased on the consideration of the rate of mechanical energy dissipation, an expression for the average shear rate for a sphere falling in a power‐law fluid in the creeping flow regime has been deduced. The average shear rate in a power‐law fluid (n<1) appears to be higher than that in an equivalent Newtonian fluid. This in turn has been combined with the numerical predictions of drag coefficient (up to Reynolds number of 100) of a sphere to develop a generalized drag correlation for power‐law liquids encompassing both n > 1 and n < 1 which appears to apply up to much higher values of the Reynolds number. The available experimental data have been used to demonstrate the reliability and accuracy of the new correlation for shearthinning liquids. Also, in the limit of n = 1, this expression reproduces the standard drag curve with a very high accuracy.
Wood Pulp as Model Fluid to Mimic the Oxygen Mass Transfer in Aspergillus Niger Fermentation
Authors: Patel Nilesh , Goudreault Julie , Bagchee Shohini , Thibault Jules 
Published: July 2010

AbstractTo characterize the oxygen mass transfer in a fermentation system and to study the efficiency of mixing devices, model fluids are often used so that experimental conditions can be better controlled. In this study, wood pulp suspensions were used in an attempt to mimic the rheological properties of fermentation broths of Aspergillus niger. Two different types of bioreactor were used: a reciprocating plate bioreactor and a stirred (Rushton) bioreactor. The oxygen mass transfer coefficient (KLa) was measured for various mixing intensities, airflow rates and wood pulp concentrations, and a correlation of KLa as a function of the power input per unit volume and the superficial gas velocity was derived for each bioreactor and each pulp concentration. KLa was found to increase with agitation and air flow rate, and was adversely affected by an increase in pulp concentration in the case of the reciprocating plate bioreactor.
A Novel Photometric Technique to Detect the Onset of Asphaltene Precipitation at Low Concentrations: The Effect of Maltenes and Water
Authors: Horvath‐Szabo Geza , Masliyah Jacob H. , Czarnecki Jan 
Published: July 2010

AbstractA photometer was utilized to measure the intensity of scattered light in toluene / heptane / asphaltenes mixtures. On the scattering‐intensity versus heptane‐to‐toluene ratio functions, two linear regions can be observed. The intersection of these regions determines the heptane‐to‐toluene ratio at which the precipitation of asphaltenes starts. The onset of asphaltene precipitation was determined as a function of asphaltene concentration in the presence and in the absence of maltenes as well as water. The onset is dependent on the asphaltene concentration. The presence of water promoted while the presence of maltenes inhibited the precipitation of asphaltenes.
Generalized Mathematical Modeling of Fluid‐Solid Non‐Catalytic Reactions Using Finite Volume Method: Multiple Reactions
Authors: Gupta Parthapratim , Saha Ranjit Kumar 
Published: July 2010

AbstractMultiple Fluid Solid Non‐Catalytic (FSNC) reactions have been analyzed in a single particle based on sharp interface model (SIM) using Finite Volume Method (FVM), which is shown to be a suitable technique for solving moving boundary problems involving multiple chemical reactions and diffusion. The effect of various model parameters, like the order of reaction, Thiele modulus, thermicity and Arrhenius parameters, c20/c10, are found to have significant effects on independent, parallel and consecutive reactions.
Periodic Operation of Three — Phase Catalytic Reactors
Authors: Silveston Peter L. , Hanika Jiri 
Published: July 2010

AbstractPeriodic operation of three phase reactors has been explored for more than two decades. This type of forcing changes selectivity and can increase either conversion or throughput. Experiments and simulation demonstrate periodic flow interruption or variation enhances reaction rates for concurrent trickle beds provided reactants are in the gas phase or can be volatilized under bed operating conditions. Temperature excursions in trickle beds can be controlled by either flow variation or switching the feed between an inert and a reactant. Several approaches to increasing rate through faster mass transfer using flow pulsing have been studied. Pulsing flow can be induced by low amplitude modulation. Periodic switching of flow direction in airlift reactors increases gas hold up and thereby the mass transfer rate. Periodic operation of three phase reactors, thus, appears to be a fertile area for engineering research.
Applications of Markov Chains in Particulate Process Engineering: A Review
Authors: Berthiaux Henri , Mizonov Vadim 
Published: July 2010

AbstractProcesses involving particles, are known to exhibit extremely unpredictable behaviour, mainly due to the mesoscopic nature of granular media. Understanding particulate processes, not only for intellectual satisfaction, but also for process design and operation, basically requires a systems approach in modelling. Because they combine simplicity and flexibility, the stochastic models based on the Markov chain theory are very valuable mathematical tools to this respect. However, they are still largely ignored by the whole core of chemical engineering researchers. This motivates the existence of this review paper, in which we examine the three traditional issues: mixing and transport, separation and transformation.
Theoretical Analysis of the Onset of Gas Entrainment from a Stratified Region through a Single Side‐Oriented Branch at Moderate Froude Numbers
Authors: Ahmed Mahmoud , Hassan Ibrahim , Esmail Nabil 
Published: July 2010

AbstractA theoretical investigation has been conducted for the prediction of the critical height at the onset of gas entrainment during single discharge from a stratified, two‐phase region, through a branch installed on an inclined flat wall. The predicted critical height at the onset of gas entrainment was proven to be a function of Froude number (Fr) and density ratio of the interface fluids. Three different experimental data sets at wall inclination angles of zero, 45 and 90 degrees (i.e. side, inclined and bottom branches) were used for comparisons. A good concurrence was illustrated between the experimental and theoretical values.
Experimental Study and CFD Simulation of Hydrodynamic Behaviours in an External Loop Airlift Slurry Reactor
Authors: Wang Tiefeng , Wang Jinfu , Jin Yong 
Published: July 2010

AbstractThe local hydrodynamic behaviours in an external loop airlift slurry reactor, including the gas holdup, bubble rise velocity, bubble size, were measured with a fibre optic probe. The liquid circulation velocity was measured with an ultrasound Doppler velocimetry. Two‐dimensional simulations were carried out in the framework of Two‐Fluid formulation coupled with a k‐ϵ turbulence model. The lateral forces and interphase turbulence were taken into account and good agreement between the experimental and simulation results was obtained. The simulations show that the lateral forces and interphase turbulence have noticeable influence and should be included in the CFD model.
Modelling of Inclusion Re‐entrainment During Filtration
Authors: Kocaefe Duygu , Murray‐Chiasson Audrey , Kocaefe YaşAr , Waite Peter 
Published: July 2010

AbstractDuring filtration, the release of deposited inclusions back to the main flow under certain conditions is called re‐entrainment. In this study, re‐entrainment was investigated experimentally in a pilot scale filter under continuous flow as well as interrupted flow conditions. Also, one‐dimensional mathematical model simulating the global behaviour of filter bed was developed and validated by comparing its predictions with the experimental results. This model solves the mass conservation equations for the inclusions. A deposition/re‐entrainment sub‐model was incorporated into the filter model. The model predictions were in good agreement with the experimental data.
Single‐stage Treatment in Selective Hydrogenation of Acetylene over CDS Type of Pd‐Ag/Al2O3 Catalyst
Authors: Chen Wen‐Shing , Wei Kuo‐Ming 
Published: July 2010

AbstractThe (computer designed shape) CDS type of Pd‐Ag/Al2O3 catalyst in single‐stage reactor provides superior catalytic activity and selectivity of ethylene in comparison with those of existed two‐stage reactors packed with G‐58B catalyst under industrial operating conditions. In this research, the contents of palladium and silver of catalysts were analyzed by inductive coupling plasma (ICP). The X‐ray photoelectron spectroscopy (XPS) showed that Pd‐Ag alloy has been formed. Higher yield of ethylene may be interpreted by both geometric and electronic effect induced from silver metal. By means of Pyrolysis/GC/MS analysis of used catalysts, the components of carbonaceous deposits were found to be n‐alkenes, including n‐C8 ∼ n‐C16 or n‐C18, which may result from oligomerization of acetylene.
Distributions of Crystal Size from DSC Melting Traces for Polyethylenes
Authors: Feng Lijun , Kamal Musa R. 
Published: July 2010

AbstractMelting curves, obtained by differential scanning calorimetry, are used to estimate crystal size distributions. The proposed theoretical analysis is applied to different types of polyethylene, including high‐density polyethylene (HDPE), metallocene catalyzed linear low‐density polyethylenes (m‐LLDPE), blends of m‐LLDPEs, and Ziegler‐Natta catalyzed LLDPEs (ZN‐LLDPE). Theoretical predictions are in agreement with experimental results. A generalized melting temperature equation successfully predicts the melting temperatures of all the LLDPEs, although it was initially proposed for homogeneous copolymers with excluded comonomers. A new definition of the heat of fusion for pure crystals is proposed. This heat of fusion can be calculated from the average crystal size or the crystal size number distribution.
A Comparative Study of Combined Feedforward/Feedback Model Predictive Control for Nonlinear Systems
Authors: Chu Ji‐Zheng , Jang Shi‐Shang , Chen Yu‐Nan 
Published: July 2010

AbstractModel predictive control (MPC) provides a natural framework to realize feedforward and feedback control for nonlinear systems where the effect of disturbances (DVs) cannot be separated from that of manipulated variables (MVs). This study examines the performance of MPC with measured DVs as partial inputs of the model used, which is termed as combined feedforward/feedback MPC (CMPC) in contrast to conventional MPC using a model without input of any measured DV. In the simulation of a pH process, we demonstrate the clear superiority of CMPC over MPC. In the experiment with a bench‐scale ethanol and water distillation column, CMPC and MPC using artificial neural network (ANN) models are applied to the dual temperature control problem. External recurrent neural networks (ERNs) with and without a measured DV (feed rate of the column) as their partial input are built and employed in the experiment, with a result that inclusion of the measured DV in the model makes CMPC perform significantly better than MPC. To strengthen practical experience in applying ANN‐based MPC, a detailed procedure of the experiment is also documented.
Gas Hold‐up and Liquid Circulation Velocity in Gas‐Liquid‐Solid Airlift Reactors
Authors: Popović Milan K. , Kiefner Andreas W. , Bajpai Rakesh K. 
Published: July 2010

AbstractSimple empirical correlations for gas hold‐up and liquid circulation velocity in two‐ and three‐phase airlift reactors are presented in this paper and their applicability has been demonstrated. The empirical correlations are good alternatives to the semi‐theoretical drift‐flux approach to predictions of gas hold‐ups and liquid circulation velocities in airlift reactors.
Decolorization of RR‐120 Dye Using Ozone and Ozone/UV in a Semi‐Batch Reactor
Authors: Kazemi Mohammad , Mohammadzadeh Jafar S. Soltan , Khoshfetrat Ali B. , Kaynejad Mohammad A. 
Published: July 2010

AbstractTreatability of RR‐120 aqueous dye solutions using O3 and O3/UV was studied in a bench scale set‐up. Reduction in colour and chemical oxygen demand (COD) under various pH and initial dye concentrations were investigated. Pseudo first order reaction rate was satisfactorily used for kinetic interpretations in destruction of the dye. The results showed that decolorization with O3 was faster at neutral pH values. While use of UV had a small effect on ozonation at low pH values, UV radiation had a considerable effect at pH values of 7 and above. It was found that ozone utilization efficiency of higher than 95% could be attained in the experimental set up.
The Yield Stress of Gas/Liquid/Fibre Suspensions
Authors: Pettersson Johan , Rasmuson Anders 
Published: July 2010

AbstractYield stress measurements of gas/liquid/fibre suspensions, were conducted to examine the effect of gas concentration as well as fibre concentration. Obtaining a well mixed stable pulp suspension with gas was difficult. A transparent model system consisting of glass fibres submersed in refractive index matched liquid gave stable suspensions and had the additional advantage of allowing visual observations. The measurements were performed in a baffled shear tester and concentrations were in the range of 0–12.5% vol. gas and 8–14% wt. fibres. Results show that yield stress decreases with increasing gas fraction for constant fibre concentrations. Since the fibre concentration is defined in the liquid phase, the amount of fibres decreases with increasing gas concentration. This fact alone partly explains the decrease in yield stress, but the gas also has a direct impact on the decrease in yield stress. Further, as expected, the yield stress increases with increasing fibre concentrations when the gas fraction is kept constant.
A Review of Recent Technological Advances in the Brightening of High‐Yield Pulps
Authors: Ni Yonghao 
Published: July 2010

AbstractPeroxide brightening/bleaching is an important unit operation for pulp and paper mills producing value‐added paper grades containing bleached mechanical pulps. In this paper, a number of process innovations have been discussed. They include:

hydrosulphite assisted chelation process, the so‐called Qy process;
DTPA spray;
PN2process;
PMprocess;
Mg(OH)2‐based peroxide process.
It will be shown that these processes can improve the peroxide brightening/bleaching processes in terms of (1) decreasing the production cost, (2) improving the product quality, and (3) decreasing the environmental impact.
Hydrodynamic Characteristics of a Powder‐Particle Spouted Bed with Powder Entrained in Spouting Gas
Authors: Zhu Qunyi , Lim C. Jim , Epstein Norman , Bi Hsiaotao T. 
Published: July 2010

AbstractSpouting of 3.7 mm polyvinyl chloride particles in a cone‐based cylindrical column is subjected to entrainment of FCC powder in the spouting air. It is found that the powder entrainment reduces the minimum spouting velocity, increases the bed pressure drop and reduces the maximum spoutable bed height. At any given bed height and value of U/Ums, there is a critical value of powder loading ratio above which spouting gives way to slugging.
Écoulement de Taylor‐Couette en géométrie finie et à surface libre
Authors: Ammar Mahamdia , Ahcène Bouabdallah , Eddine Skali Salah 
Published: July 2010

AbstractLes réacteurs de type de Taylor‐Couette sont une application relativement récente dans le domaine du génie des procédés. La stabilité et la structure de l'écoulement dans ce dispositif sont examinées sous les effets combinés de la surface libre et de la hauteur de fluide dans l'espace annulaire. L'exploration des régimes d'écoulement est réalisée en fonction du nombre de Taylor Ta pour différentes valeurs du rapport d'aspect Γ. Au moyen de la vélocimétrie ultrasonore (UVP) on détermine le profil moyen de vitesse axiale et la longueur d'onde axiale. On procède également à l'analyse spectrale par transformée rapide de Fourier des fluctuations associées aux valeurs moyennes de la vitesse en vue d'analyser la structure de l'écoulement. On vise particulièrement à vérifier, selon la hauteur de remplissage et la vitesse de rotation imposée, la présence ou l'absence de l'onde azimutale. On met en évidence les effets de la surface libre et du rapport d'aspect sur les conditions d'apparition de la deuxième instabilité. L'analyse des fluctuations montre que l'apparition du régime d'ondes azimutales (wavy mode) est retardé quand le rapport d'aspect diminue. En dessous d'une valeur critique notée Γc = 10, le régime d'ondes azimutales n'est plus observé.