bluuebunny/crossref_metadata_2025_split huggingface dataset:
Rheology of Glaze Suspensions
Authors: Savarmand Saeid , Golkar‐Narenji Mohammad‐Reza , Saedi Kourosh 
Published: July 2010

AbstractRheological properties of suspensions and ceramic glaze slurries under steady flow conditions have been considered. Colloidal forces play an important role in the rheology of such ceramic slurries. Since the potential function characterizes the rheology of colloidal systems, a new dimensionless group, viz. potential number, is introduced within a dimensional analysis representing the relative significance of the potential to the Brownian energy. In order to relate the relative viscosity to other dimensionless groups, a new model is proposed by the inclusion of an extra term in addition to that of the hard‐sphere theory owing to the fact that the presence of colloidal forces always increases the fluid viscosity with respect to that predicted by the hard‐sphere. Steady viscosity measurements have been carried out on ceramic glaze suspensions at different volume fractions, particle diameters, and shear rates. Experimental results have been used to modify the model relating the relative viscosity to the Péclet number, potential number, volume fraction, and maximum packing fraction.
Gypsum Scale Formation in White Water of a Closed‐Cycled Paper Mill
Authors: Choi Sang‐June , Kim Hae‐Young , Kim Young‐Hun , Park Hyeon , Englezos Peter 
Published: July 2010

AbstractThe accumulation of calcium and sulfate ions in a process stream of a closed papermaking system may cause calcium sulfate scale formation. This study presents measurements of calcium sulfate precipitation conditions and a thermodynamics‐based model for the prediction of such precipitation conditions in the papermaking white water at 50°C. The precipitates were found to have the structure of gypsum (CaSO4·2H2O). The model calculations were compared with experimental data and found to be in good agreement.
Energy Efficiency of an Indirect Thermally Coupled Distillation Sequence
Authors: Hernández Salvador , Pereira‐Pech Salvador , Jiménez Arturo , Rico‐Ramírez Vicente 
Published: July 2010

AbstractSeveral thermally coupled distillation sequences have been proposed to improve the thermal inefficiency of conventional distillation sequences. Particularly, for the separation of ternary mixtures, structures that perform a lateral extraction in one of the columns of the integrated arrangement have been shown to provide significant energy savings. The structure of existing sequences, based on conventional distillation columns, might provide the basis for alternate thermally coupled designs. In this paper, it is shown how a thermally coupled system derived from an indirect conventional sequence can provide energy savings through a proper optimization of the interconnecting streams.
Closed‐loop Fault Detection Using the Local Approach
Authors: Cheng Luke L. , Kwok K Ezra , Huang Biao 
Published: July 2010

AbstractFault detection and isolation (FDI) has become a crucial issue for industrial process monitoring in order to increase availability, reliability and production safety. Model‐based FDI methods rely on a mathematical model and input‐output data of a process to perform detection. The local approach is a new model‐based FDI method that aims to detect slight changes of a system's parametric properties. Closed‐loop detection is an important issue for the local approach since all control systems work under closed‐loop conditions. A new algorithm was proposed to revise the original detection algorithm in order to make it work for closed‐loop data. Simulation results show that the proposed method can detect the changes of parameters of a system that can affect closed‐loop performance.
Radial Liquid Dispersion and Bubble Distribution in Three‐Phase Circulating Fluidized Beds
Authors: Kang Yong , Cho Yong J. , Lee Chan G. , Song Pyung S. , Kim Sang D. 
Published: July 2010

AbstractThe liquid dispersion and bubble distribution in the radial direction have been investigated in the riser of a three‐phase circulating fluidized bed whose diameter is 0.102m and 3.5m in height. Effects of gas and liquid velocities and solid circulation rate have been determined. It has been found that the radial distribution of bubbles is related closely to the liquid dispersion in the radial direction. The size and rising velocity of bubbles tend to increase as the radial position approaches to the center of the riser. The bubble size increases with increasing UG, but it decreases with increasing UL or GS in all radial positions. The radial dispersion coefficient of the liquid phase increases with increasing UG or GS, however, it tends to decrease with increasing UL. The value of Dr has been well correlated in terms of dimensionless groups based on the isotropic turbulence model.
The Heterogeneous and Homogeneous Combustion of Methane Over Inert Particles
Authors: Sotudeh‐Gharebagh Rahmat , Chaouki Jamal 
Published: July 2010

AbstractThe combustion of methane was studied in a fixed bed reactor to determine the effect of inert particles through heterogeneous and homogeneous reactions. Methane and CO2 mole fractions are measured at the reactor outlet. The results show that any accelerating catalytic effect of the inert particles is quite small, while considerable inhibition effect was found at moderately high temperatures. A plug flow model with a complete and reduced reaction scheme was developed to explain the experimental findings. Both reaction schemes fail to fully predict the experimental data. Therefore, an improved combined mechanism is proposed, which is now able to predict the experimental data.
Catalytic Combustion Kinetics: Using a Direct Search Algorithm to Evaluate Kinetic Parameters from Light‐Off Curves
Authors: Hayes Robert E. , Bertrand François H. , Audet Charles , Kolaczkowski Stan T. 
Published: July 2010

AbstractThis paper describes a method for evaluating the kinetic constants in a rate expression for catalytic combustion applications using experimental light‐off curves. The method uses a transient one‐dimensional single channel monolith finite element reactor model to simulate reactor performance. The heat and mass transfer models used account for developing flow in the entrance region. A parameter global optimization routine based on a generalized pattern Search algorithm is used to determine the best fit parameters in the rate expression for the oxidation of CO and mixtures of CO and CH4. The algorithm is compared to a more classical gradient method, the Fletcher‐Reeves method.
Biodegradation of High Strength Phenolic Wastewater in a Modified External Loop Inversed Fluidized Bed Airlift Bioreactor (EIFBAB)
Authors: Aye Thin Thin , Loh Kai‐Chee 
Published: July 2010

AbstractAn EIFBAB was modified with a mixed‐tank reactor placed in series to extend the phenol treatability range. Phenol degradation at high concentrations was investigated at recycle rates from the mixed‐tank reactor from 0 to 15 L/h under batch operation. With a total working volume of 10 L, the new setup could handle 3000 mg/L phenol at a comparable volumetric biodegradation rate of 9 mg/L·h at optimized operation of 5 L/h recycle rate, as the 11 mg/L‐h in the original EIFBAB. While the original EIFBAB could not handle phenol concentrations exceeding 3000 mg/L, continuous operation was ascertained in the modified EIFBAB for phenol degradation of up to 5000 mg/L phenol and feed flow rates up to 160 mL/h. The recoverability of the system under shock loading of phenol up to 5000 mg/L was also assessed.
A Discussion on Minimum Spout Velocity and Jet Penetration Length
Authors: Bi Hsiaotao T. 
Published: July 2010

AbstractThe similarity and difference between the flat‐bottom and cone‐bottom cylindrical spouted beds, conical spouted beds and vertical upward jets in fluidized beds have been analyzed in this paper based on the effects of geometrical parameters on the minimum spouting velocity and operating stabilities of the spouted beds. The effect of angle on minimum spouting velocity was found to be only significant within the range of 30 to 60 degrees cone angles. Minimum spouting velocity in deep cylindrical spouted beds was proportional to the square root of the static bed height, but was proportional to the static bed height in conical spouted beds and large cylindrical spouted beds with small height‐to‐diameter ratio. The relationship between the minimum spouting velocity and the static bed height was consistent with that between jet velocity and the vertical jet penetration length in jetting fluidized beds.
Validation of a Discrete Particle Model in a 2D Spout‐Fluid Bed Using Non‐Intrusive Optical Measuring Techniques
Authors: Link Jeroen , Zeilstra Christiaan , Deen Niels , Kuipers Hans 
Published: July 2010

AbstractTo gain insight into the hydrodynamics of spout‐fluid beds, an experimental and numerical study was carried out. Particle image velocimetry was successfully developed and applied to determine particle velocity profiles, whereas voidage profiles were determined by digital image analysis. A 3D hard‐sphere discrete particle model was used to simulate the flow in a spout‐fluid bed. The simulations and experiments showed a similar influence of the background fluidization velocity on the spout behaviour.
Analysis of Regime Transitions and Flow Instabilities in Vertical Conveying of Coarse Particles Using Different Solids Feeding Systems
Authors: Costa Ione A. , Do Carmo. Ferreira Maria , Freire José T. 
Published: July 2010

AbstractThe transition between dense and dilute flow in vertical conveying of Geldart D particles were investigated for risers of different diameters using a spouted bed as a solid feeding system. The transition and choking velocities were identified by combining analyses of pressure gradient versus air velocity diagrams, pressure fluctuation signals and voidage values. Experimental data were used to evaluate the effect of particle and riser diameters on the pressure gradient, mean mixture voidage, the regime transition and choking velocities. The transition velocity from dilute to dense phase could be identified, as well as the onset of the choking condition, which appeared as the air velocity was further reduced. Data obtained in the same experimental apparatus facility using a screw conveyor and a gravitational system as solid feeding devices have been used as a reference to be compared to those obtained using the spouted bed feeder.
Identification of Flow Regimes in Slot‐Rectangular Spouted Beds using Pressure Fluctuations
Authors: Freitas Luis A. P. , Dogan Ozkan M. , Lim C. Jim , Grace John R. , Bai Dingrong 
Published: July 2010

AbstractPressure fluctuation data recorded in slot‐rectangular spouted beds of 1.44 mm diameter glass beads were analyzed with the aid of statistical and chaotic tools. The column width was maintained at 150 mm, while the thickness and slot width were both varied. It is shown that there are significant shifts in both statistical and chaos measures as the gas flow rate is increased. The results suggest that pressure fluctuations can be used to provide diagnostics of flow regime transitions in spouted beds when viewing is impossible.
Flow Characteristics in Slot‐Rectangular Spouted Beds with Draft Plates
Authors: Luo Baolin , Lim C Jim , Freitas Luis A. P. , Grace John R. 
Published: July 2010

AbstractAn experimental investigation was conducted of slot‐rectangular spouted beds with air entry slots spanning the full thickness of the column and vertical draft plates intended to help control the solids circulation rate. With increasing superficial gas velocity, the flow between the draft plates changed from bubbling to slugging and then to spouting with dilute pneumatic between the plates and moving‐bed downward motion on both sides. However, there was difficulty maintaining stability and symmetrical flow on the two sides. Once spouting is established, pressure drops and local voidages vary with gas velocity, particle size and gas entry size in broadly similar manners as for conventional spouted beds
Influence of Operating Parameters on the Average Spout Width in Two‐Dimensional Spouted Beds
Authors: Zanoelo Éverton F. , Rocha Sandra C. S. , Rezende Daiton F. 
Published: July 2010

AbstractIn this work a set of experiments were performed in a two‐dimensional spouted bed to study the effect of different operating conditions on the spout cavity width. The measurement of spout‐annulus interface along the bed level was made by visual observations on a flat face column. A numerical integration formula was used to calculate the average spout width. The experimental runs were performed with different materials, bed dimensions, static bed heights, fluid velocities and gas inlet orifice width. The influences of these variables on average spout width were verified through a statistical analysis. An empirical correlation is proposed to predict the average spout width. The empirical model parameters were found through a statistical analysis.
Residence Time Distributions in Staged Spouted Beds
Authors: Arriola Enrique , Cruz‐Fierro Carlos Francisco , Alkhaldi Khaled Hamed , Reed Brian Patrick , Jovanovic Goran 
Published: July 2010

AbstractA novel design of a multi‐staged, continuous flow spouted bed, suitable for counter‐current, cross‐current, and fed‐batch gas‐solid contacting is developed. Single and three‐stage conter‐flow units are studied, the residence time distributions (RTD's) of the solids therein are measured and two compartmental models are developed to fit this family of RTD's. The first (two‐parameter) model is satisfactory for the single stage units, and three‐stage units at high gas flow rates. The second (three‐parameter) model describes each stage as two CSTVs in parallel with a PFV in series. It provides better agreement with experimental data in the three‐stage case.
The Effect of Operating Conditions and Design Parameters on the Dynamic Behaviour of Agitated Pulp Stock Chests
Authors: Ein‐Mozaffari Farhad , Kammer Leonardo C. , Dumont Guy A. , Bennington Chad P. J. 
Published: July 2010

AbstractAgitated pulp chests provide attenuation of high‐frequency disturbances in pulp properties ahead of many pulping and papermaking unit operations. The effect of process and design variables on the extent of non‐ideal flows was examined in a laboratory‐scale pulp chest. Dynamic tests were made using the frequency‐modulated random binary input of a brine solution with the pulp feed to determine the magnitude of non‐ideal flows (channeling, recirculation and stagnant zones). Results showed that the degree of upset attenuation is a function of impeller momentum flux and fibre mass concentration and that existing design criteria underpredict the power needed to produce a fully mixed system.
Phase Transformation and Rheological Behaviour of Highly Paraffinic “Waxy” Mixtures
Authors: Tiwary Dharmendra , Mehrotra Anil K. 
Published: July 2010

AbstractAn experimental investigation was undertaken for the rheology and phase transformation of prepared solutions comprising a paraffin wax dissolved in n‐dodecane or n‐hexadecane. The liquid‐solid phase transformation in wax‐solvent mixtures was investigated through the measurement of wax appearance/disappearance temperature (using cross polar microscopy, differential scanning calorimetry, viscometry and a visual method), pour point temperature and crystallization temperature. The results were utilized to prepare a temperature‐composition phase diagram for the wax+n‐C16H34 pseudo‐binary system. The effects of composition, temperature, cooling rate and shear rate were studied on the rheology of wax‐solvent mixtures. A correlation was developed for the apparent viscosity of wax‐solvent mixtures.
Isomérisation du n‐hexane sur des catalyseurs Ni‐WOx/Al2O3‐SiO2
Authors: Guemini Miloud , Rezgui Yacine , Bouchemma Ahcene , Tighezza Ammar 
Published: July 2010

AbstractIsomerization of n‐hexane into bi‐ and tri‐branched products was studied at atmospheric pressure on Ni‐WOx/Al2O3‐SiO2 catalysts. Two groups of catalysts (A and B) were prepared by using the sol‐gel method. The objective of the present study is the selection of the catalyst having the best isomer (bi‐ and tri‐branched) yield under optimum operating conditions (reaction temperature, reduction temperature, flow duration, etc.). The results show that the introduction of tungsten (group B) modifies siginificantly the catalyst activity and that the optimum nickel amount in these catalysts is 15 wt. %. When a steady flow is achieved (100 min), the catalyst containing 15 % nickel and 10 % tungsten exhibits the highest and largest selectivity at a reaction temperature of 250°C and a reduction temperature of 430°C.
Effect of Water on α‐Methylstyrene Hydrogenation on Pd/Al2O3
Authors: Meille Valérie , De Bellefon Claude 
Published: July 2010

Abstractα‐methylstyrene catalytic hydrogenation on Pd/Al2O3 is frequently used to characterize new reactors. However, whereas many authors report some problems of reproducibility or possible poisoning of the catalyst, no consistent advice is available in the literature to carry out the reaction without these problems. This work points out the inhibition of the reaction by trace amounts of water. An experimental procedure is explained to guarantee the reproducibility of the measures.
Removal of VOCs by Sorption in Fixed Beds of Popcorn
Authors: Mak Vivian W. Y. , Chatzis Ioannis , Hudgins Robert R. , Fayed Muhammad E. 
Published: July 2010

AbstractPopcorn was the sorbent in a fixed‐bed study on removing VOC contaminants from air. Acetone, toluene, and trichloroethylene were selected as model VOCs to represent industrial solvents with diverse properties. Other variables studied were the inlet VOC concentration and pre‐treatment of the popcorn. Inlet and outlet concentrations were monitored by gas chromatography. The Wheeler equation satisfactorily correlated the breakthrough times of the model VOCs. Because of its low specific surface, popcorn is unlikely to replace activated carbon as a sorbent for VOCs.
Process Design Aspects of Jet Mixers
Authors: Patwardhan Ashwin W. , Thatte Amit R. 
Published: July 2010

AbstractIn the present work, mixing time measurements have been made with jet mixers over a wide range of jet velocities, liquid levels and tank sizes. The nozzle was kept along the axis of the vessel and the nozzle clearance was varied over a wide range. It was observed that the mixing time decreases with an increase in the jet path length (nozzle clearance) for a given tank size and given amount of liquid. The reasons for this behaviour are explained with the help of CFD modelling. The effect of tank diameter has been studied independent of the jet path length. A correlation has been developed for process design. Jet mixers have been compared with impeller‐stirred tanks in terms of their energy efficiency. Reasons for the observed behaviour have been provided.
Turbulence Modulation in Gas‐Particle Flows: A Comparison of Selected Models
Authors: Lightstone Marilyn F. , Hodgson Sarah M. 
Published: July 2010

AbstractThe problem of turbulence modulation, the process whereby the gas‐phase turbulence is modified by the presence of particles, is investigated. Experimental trends are examined and parameters affecting turbulence modulation and the mechanisms by which turbulence modulation occurs are identified. A new model that accounts for the crossing trajectory effect through fluid velocity correlations is presented. This model and the turbulence modulation models of Chen and Wood (1985), Tu and Fletcher (1994), and Mostafa and Mongia (1988) are compared directly to determine inherent differences or similarities of the models. The models are also invoked to simulate a particle‐laden pipe flow and predictions are compared to the experimental results of Tsuji et al. (1984).
Bubble Motion Pattern and Rise Velocity in Two‐dimensional Horizontal and Vertical Vibro‐fluidized Beds
Authors: Zhou Tao , Ogura Hironao , Yamamura Masato , Kage Hiroyuki 
Published: July 2010

AbstractThe motion pattern of a bubble was examined and the bubble rise velocity was measured in horizontally and vertically sinusoidal vibro‐fluidized beds. Experimental results showed that the motion pattern of a bubble depends on the vibration direction. Compared with the case of no vibration, it seems that the flow pattern of bubbles is not affected significantly by vertical vibrations, while bubbles rise in the form of a tower for horizontal vibrations. For vertical vibrations, all the local average bubble rise velocities were larger than those in the case of no vibration, but they were hardly influenced by horizontal vibrations at the lower bed height and were larger than those in the case of no vibration at the higher bed height.
The Two‐Phase Flow in an Axially Stirred Vessel Investigated Using Phase‐Doppler Anemometry
Authors: Ljungqvist Mattias , Rasmuson Anders 
Published: July 2010

AbstractThe phase‐Doppler technique has been used to characterize the two‐phase flow of liquid and particles in a stirred vessel agitated by a pitched blade turbine. The number of measurement locations used is considerably larger than in previous investigations and the behaviour of four different types of particles is studied. The fluid phase and particle phase flow is studied with particular emphasis on the relative velocities of the two phases. The largest slip velocities in the tank were found just beneath the impeller, and large slip velocities generally coincide with large velocity gradients. Generally, particles lag in relation to the fluid when the fluid flow is directed upwards, and vice versa, but exceptions to this are not unusual.
Low Inclination Oil‐water Flows
Authors: Lum Jason Y.‐L. , Lovick Jonathon , Angeli Panagiota 
Published: July 2010

AbstractTwo‐phase liquid flows at +5° inclination from the horizontal were studied experimentally for mixture velocities between 0.7 and 2.5 m/s and input oil fractions between 10% and 90%. The results were compared with a two‐fluid model that includes entrainment. The investigations were performed in a 38‐mm ID stainless steel test section, with water and oil as test fluids. Dual continuous flow (both phases remain continuous with inter‐dispersion) prevailed, while the two‐phase pressure gradient was found lower than the single‐phase oil or water. At low mixture velocities the velocity ratio increased with oil fraction while at high ones it decreased. Compared to horizontal flow, water holdup was higher and frictional pressure gradient lower.
A Composite Heat Transfer Model For Pool Boiling on a Horizontal Tube at Moderate Pressure
Authors: Das Sarit K. , Roetzel Wilfried 
Published: July 2010

AbstractThe present work is aimed at building a comprehensive heat transfer model for pool boiling on horizontal tubes combining sliding bubble mechanism with natural convection, microlayer evaporation and transient conduction during boundary layer reformation, to predict the boiling heat flux for a given wall superheat. The model has been compared to experimental results from literature for R134a and also to independent experiments conducted by the authors for water. Even with a number of simplified assumptions a reasonably good agreement has been observed between model and experiments in the low and medium heat flux region and moderate pressure.