bluuebunny/crossref_metadata_2025_split huggingface dataset:
Optimization of beech wood pulping in catalyzed acetic acid media
Authors: Vila Carlos , Santos Valentín , Parajó Juan Carlos 
Published: May 2010

AbstractFagus sylvatica wood samples were treated in HCl‐catalyzed, acetic acid solutions. The effects of selected operational variables (catalyst concentration, reaction time and liquor to wood ratio) on pulp yield, composition of pulps and composition of pulping liquors were assessed using incomplete, second‐order, centred, factorial designs. Pulp composition was measured by the contents in cellulose, xylan and lignin. The concentrations of glucose, xylose and furfural in pulping liquors were also considered as experimental variables. Under selected conditions, pulps with 5.8% to 7.5% Klason lignin (kappa numbers in the range 25 to 33), 77.2% to 85.3% cellulose and 3.3% to 6.1% xylan were obtained at 45.8% to 50.0% pulp yield. The selected pulps showed good SCAN viscosity (723 to 814 mL/g) and alkaline resistances which were affected by the acetyl group content of samples (6.6 to 7.6 weight percent).
Influence of fibre length and filler particle size on pore structure and mechanical strength of filler‐containing paper
Authors: Kinoshita Noriyoshi , Katsuzawa Hideo , Nakano Satoko , Muramatsu Hiroki , Suzuki Jyunko , Ikumi Yuko , Toyotake Yukie 
Published: May 2010

AbstractTest sheets were prepared by incorporating softwood pulp with silica filler, PW‐5 (diameter 4.5 μm) or PW‐20 (15 μm). Length‐weighted averages of fibre were 2.5 (uncut fibre) and 1.25 mm (short‐cut fibre). Pore sizes less than 150 urn were measured by mercury porosimeter. Sheets of short‐cut fibres and mixed with uncut fibres at ratio of 3:1 or 1:3 had larger pore volumes than others tested. When filler content increased, the total pore volume increased for PW‐20 sheets, but it did not for PW‐5 sheets with short‐cut fibres. Tensile index and folding endurance were very much affected by fibre length. Contact number on a fibre was calculated by computer simulation, and it had a linear relation with tensile index of sheet.
Gas holdup for high gas velocities in a gas–liquid cocurrent upward‐flow system
Authors: Lee Dong‐Hyun , Grace John R. , Epstein Norman 
Published: May 2010

AbstractGas holdup has been measured in an 83‐mm diameter, 2.2‐m high column at high gas superficial velocities — 0.22 to 2.7 m/s — and at liquid (water) superficial velocities of 0 to 0.47 m/s, by means of a differential pressure transducer. The equation of Hills (1976) based on the slip velocity gives good predictions of the gas holdup for 0.1 ≤ Eg ≤ 0.4. However, the holdups predicted by this approach are considerably higher than the experimental values at gas velocities high enough that Eg > 0.4. Other equations from the literature are also shown to be inadequate. The new data and earlier data at high gas velocities are therefore correlated with a new dimensional equation for Ul ≤ 0.23 m/s.
Characteristics of air–water two‐phase flow in a 3‐mm smooth tube
Authors: Wang Chi‐Chuan , Yang Kai‐Shing , Chang Yu‐Juei , Lu Ding‐Chong 
Published: May 2010

AbstractTwo‐phase flow pattern and friction characteristics for an air–water system in a 3.17 mm smooth tube are reported in this study. The range of mass flux is between 50 and 700 kg/m2s. The experimental data show that the two‐phase friction multipliers are strongly related to the flow pattern. For a stratified‐wavy flow pattern, a mass‐flux dependence of the two‐phase multipliers is seen. For a non‐stratified flow pattern, the two‐phase frictional multipliers are comparatively independent of mass flux. Correlations of the frictional multipliers are developed for stratified and non‐stratified flow. To use the appropriate correlation in different regime, a simple criterion is proposed.
The effect of impeller pumping and fluid rheology on solids suspension in a stirred vessel
Authors: Wu Jie , Zhu Yonggang , Pullum Lionel 
Published: May 2010

AbstractPumping velocities of different impellers were measured using laser Doppler velocimetry. It was found that there is a link between impeller pumping capacity and the 5 parameter in the Zwietering correlation. Measurements showed that Njs increases with impeller spacing for dual impeller configurations. A dual‐impeller configuration shows less sensitivity to solids loading change than a single‐impeller configuration, and the change in Njs is larger for small impeller spacing than for large impeller spacing. An increase in slurry cloud height and a reduction in Njs resulted at a small increase of non‐Newtonian viscosity.
Scalar mixing measurements in a continuously operated stirred tank
Authors: Distelhoff Markus F. W. , Marquis Andrew J. 
Published: May 2010

AbstractAn LIF (Laser induced flourescence) line scan system was used to obtain unobtrusive scalar concentration measurements in a continuously operated stirred tank agitated by a radial flow Rushton turbine and an axial flow 60°‐pitched blade impeller. A better blending process was generally achieved in the axial flow field, with macro‐ and micromixing in the radial flow field being most complete with fluid injected into the radial discharge jet, and in the axial flow field with fluid injected from above into the rotating impeller. Local concentration levels and fluctuations scaled with the feed pipe flow rate, and the degree of concentration uniformity throughout the tank scaled with the impeller speed and increased with the cube of the power input.
Optimization of low pressure chemical vapour deposition reactors using hybrid differential evolution
Authors: Lu Jhy‐Chang , Wang Feng‐Sheng 
Published: May 2010

AbstractIn this study, hybrid differential evolution (HDE) was applied to solve four low‐pressure chemical vapour deposition (LPCVD) reactor optimal design problems. The mathematical model for this reactor is described using a two‐point boundary value differential‐algebraic equation (TPBVP‐DAE) problem. HDE is not only applied to solve the optimization problems but also to obtain the solution to TPBVP‐DAE. Under this situation, the HDE subroutine should call itself to evaluate the optimal solution to the optimization problem and the solution to TPBVP‐DAE. In this study, Fortran 90 was used to implement the HDE subroutine to achieve the calling itself requirement. The recursive HDE subroutine can be efficiently applied to solve the four LPCVD reactor optimal design problems. From the computational results, we observed that the combined optimal design obtain the smallest axial uniformity variation. Furthermore, test function maximization problems were used to compare the performance of the HDE with other methods.
Formation de nano‐gouttelettes d'eau au sein d'un éjecteur à air induit: Une étude qualitative par visualisation de l'écoulement
Authors: Desevaux Philippe 
Published: May 2010

AbstractCet article traite de la formation de nano‐gouttelettes d'eau au sein d'un éjecteur à air induit. Les deux processus de formation qui interviennent simultanément lorsque l'éjecteur est alimenté avec de l'air humide sont clairement mis en évidence par des visualisations de l'écoulement. Une brève analyse du régime de diffusion lumineuse des gouttelettes formées par condensation au sein de l'écoulement montre que leur diamètre moyen n'excède pas 0.1 μm.
Gas recirculation rate and its influences on mass transfer in multiple impeller systems with various impeller combinations
Authors: Lu Wei‐Ming , Wu Hong‐Zhang , Chou Cheng‐Ying 
Published: May 2010

AbstractBoth the numerical and experimental approaches were used to study the effects of the gas recirculation and non‐uniform gas loading on the mass transfer rate for each impeller in a multiple impeller system. By combining the calculated gas velocity and local gas holdup, the gas recirculation rate around each impeller was estimated. The local mass transfer coefficients for systems equipped with various combinations of the Rushton turbine impeller (R) and pitched blade impeller (P) were determined by using the dynamic gassing out method. It is found that the Rushton turbine impeller has to be served as the lowest impeller in order to have a better gas dispersion and to give a higher overall KLa for a multiple impeller gas‐liquid contactor. The upper pitched blade impeller always enforces the circulating flow around the Rushton turbine impeller just beneath it and gives a higher overall average mass transfer rate. However, the system equipped with only the pitched blade impellers results in a much lower mass transfer rate than the other systems owing to the poor gas dispersion performance of the pitched blade impeller.
Monitoring of emulsion polymerisations: A study of reaction kinetics in the presence of secondary nucleation
Authors: Othman Nida , Mckenna Timothy F. , Santos Amilton M. , Févotte Gilles 
Published: May 2010

AbstractA non‐linear state estimator that provides on‐line information on residual monomer concentration and radical concentration is experimentally validated under dynamic conditions, and in particular in the presence of secondary particle nucleation. The proposed estimator uses the heat of reaction as an input. Practical methods for determining the initial values of the parameters in the energy balance are also proposed and tested on laboratory and pilot scale installations. It is shown that this method provides a robust tool for the on‐line monitoring of batch (with and without shot additions of monomer, surfactant and initiator) and semi‐batch emulsion polymerisation reactors. The observer was shown to converge rapidly, even under conditions where the number of particles per litre of emulsion (Np) changed rapidly.
Diffusivity of CO2, CH4, C2H6 and N2 in athabasca bitumen
Authors: Upreti Simant R. , Mehrotra Anil K. 
Published: May 2010

AbstractExperimental data for the diffusivity of carbon dioxide, methane, ethane and nitrogen in Athabasca bitumen are presented in the range 25–90°C at 4 and 8 MPa. The diffusivity of these gases has been determined as a function of gas concentration in bitumen using a non‐intrusive experim̀ental method. The diffusivity of gas in general is found to increase with temperature and pressure, and is a unimodal function of concentration. A correlation is provided for the average diffusivity of these gases as a function of temperature.
Liquid holdup in concentric annuli during cocurrent gas‐liquid upflow
Authors: Das Prasanta K. , Das Gargi , Purohit Nalani K. , Mitra Arun K. 
Published: May 2010

AbstractIn the recent paper, an in‐depth investigation of liquid holdup during air‐water upflow through concentric annuli has been reported. The liquid holdup has been determined experimentally for the bubbly, slug and churn flow regimes. The drift flux model has been adopted for the theoretical estimation of holdup in the bubbly, dispersed bubbly and slug flow regimes. The pronounced effect of flow regime on this parameter as observed from experiments has been incorporated in the model by adopting different values of U0, n and C0. The asymmetry of the Taylor bubbles has been incorporated in the slug flow regime. The theoretical predictions exhibit a good agreement with the experimental data of the present work and that available in literature (Caetano et al., 1989b). The Hughmark's correlation is observed to correlate the churn flow data of the present work reasonably well.
Extended kalman filter based nonlinear geometric control of a seeded batch cooling crystallizer
Authors: Xie Wei , Rohani Sohrab , Phoenix Aaron 
Published: May 2010

AbstractA nonlinear dynamic model of a seeded potash alum batch cooling crystallizer is presented. The model of the batch crystallizer is based on the conservation principles of mass, energy and population. In order to maintain constant supersaturation, a nonlinear geometric feedback controller is implemented. It is shown that compared to a natural and a simplified optimal cooling policies, the nonlinear geometric control (NCC) leads to a substantial improvement of the final crystal quality. An extended Kalman filter (EKF) is used as a closed loop observer for this nonlinear system to predict the non‐measurable state variables. It is found that the EKF is capable of effectively predicting the first four leading moments of the population density function. The effectiveness of the EKF based nonlinear geometric controller in the presence of plant/model mismatch is also studied. Simulation results show that the EKF based nonlinear geometric controller is reasonably robust in the presence of modeling error.
Packed bed structure: Evaluation of radial particle distribution
Authors: Mariani Néstor J. , Salvat Wilson I. , Martínez Osvaldo M. , Barreto Guillermo F. 
Published: May 2010

AbstractA model describing the radial distribution of monosized spheres in randomly packed beds up to distances of about two particle diameters from the vessel wall is presented here. The model is based on the existence of a highly ordered layer of particles adjacent to the wall followed by a more diffuse, but still identifiable, second layer. Expressions generated from simple geometrical concepts (intersection between a cylindrical surface and a sphere) straightforwardly allow calculating the radial voidage profile given the radial distribution of particle centers and vice versa. These expressions are employed to fit the model to measures of voidage profiles within a wide range of aspect ratios, a = (RT/RP). The model can be used to accurately predict radial voidage profiles, but it is stressed that the identification of particle distribution constitutes more valuable information than an empirical expression for describing voidage variations.
Reaction rate hysteresis in the hydrotreating of thiophene in wide‐ and narrow‐pore catalysts during temperature cycling
Authors: Fatemi Shohreh , Moosavian Mohammad A. , Abolhamd Giti , Mortazavi Yadollah , Hudgins Robert R. 
Published: May 2010

AbstractThe influence of capillary condensation of reagents in porous catalysts for hydrodesulfurization at temperatures below 195°C and at pressures around 0.95 MPa was investigated experimentally and by modelling. The rate of reaction of thiophene in a solution of n‐heptane was studied in steady and dynamic modes over two Ni‐Mo/γ‐Al2O3 mesoporous catalysts with mean pore diameters differing by 2.6‐fold. Pronounced rate hysteresis was observed under thermal cycling for the narrow‐pore catalyst, but less so for the wide‐pore catalyst. The process was modelled for a mixed‐flow reactor under steady and dynamic conditions by means of the Kelvin equation and introducing two kinetic models for liquid and vapour phase to estimate the concentration of reactant in both phases. The model exhibited good agreement with hysteresis results.
Comparison of experimental and computational results in a cyclic flow
Authors: Li Wei , Sullivan Pierre E. , Davis Jeffrey A. 
Published: May 2010

AbstractAn investigation of cyclic flow within an optical water analog engine oriented horizontally and with a square cross‐section has been carried out using a computational code, KIVA, and compared with particle image velocimetry results. The simulation results highlight the ambiguity with regard to the velocity direction in the experiment and provide more insight into the velocity profile at the latter part of the intake stroke. The computational work is found to not adequately capture the higher order turbulence statistics obtained in the experimental results. The study concludes that the Reynolds stress transport is the dominant component of the equation of motion near the piston surface and causes the turbulent mixing responsible for the mixing and combustion efficiency in an engine.
A simple correlation for gas bubbles rising in power‐law fluids
Authors: Rodrigue Denis 
Published: May 2010

AbstractRecently, the author (Rodrigue, 2001 a, b) proposed a generalized correlation for the steady rise of gas bubbles in uncontaminated viscous Newtonian fluids of infinite extent. It is the purpose of this note to show that this model can be modified for inelastic non‐Newtonian power‐law fluids. Using data taken from six different studies, it is shown that the modified model can predict quite nicely the bubble velocity for these non‐Newtonian inelastic fluids.
Effect of mixed solvent on selective removal of lead (II) ions by dicyclohexano‐18‐crown‐6 from aqueous solutions containing heavy metals
Authors: Dernini Stella , Loi Annalisa , Palmas Simona , Polcaro Anna M. 
Published: May 2010

AbstractThe effect of the organic solvent on the transport of lead ions through a bulk liquid membrane containing dicyclohexano‐18‐crown‐6 (DC18C6) as carrier was studied. Chloroform, 1,2‐dichloroethane, chlorobenzene, nitrobenzene and their binary solutions were employed as solvents. SCN‐, NO3‐, CI‐ and CH3COO‐ were used as anions. The selectivity and the efficiency of lead transport from aqueous solutions containing other cations such as Ni2+, Cu2+, Co2+, and Zn2+ were also investigated.
Short fibers suspension in steady recirculating flows
Authors: Chinesta Francisco , Chaidron Cuillaume 
Published: May 2010

AbstractNumerical modeling of short fiber suspensions flows involves the coupling between motion equations, which definean elliptic problem, and the fluid constitutive equation, which introduces a non‐linear advection problem related to the fiber orientation (induced anisotropy). In a previous work these authors have proposed a numerical procedure to determine a steady solution of the fibers orientation in steady recirculating flows, taking into account that neither initial nor boundary conditions are given. This procedure may be used in the numerical simulation of SFRT flows involving recirculating parts as encountered in the simulationof industrial processes, as well as in inverse rheological identification using, for example, rotative rheometric devices.
Drying of solids in vacuum fluidized bed
Authors: Kozanoglu Bulent Umur , Vilchez Juan Antonio , Casal Joaquim , Arnaldos Josep 
Published: May 2010

AbstractA drying process in a fluidized bed under vacuum conditions is experimentally and theoretically studied. A fluidized bed operating in reduced pressure presents a possibility for a better quality of production, with safer process conditions. A mathematical model is developed for the reduced‐pressure drying process in a fluidized bed. Some parameters were analyzed by comparing experimental results with model predictions. The predictions from the model agreed quite closely with the experimental data. The results showed that a decrease in pressure reduces the interparticular resistance. A good agreement was also found applying the model to data, at atmospheric pressure, from other authors.
Membrane‐liquid emulsion membrane process using a liquid emulsion membrane process using methane sulfonic acid as a strippant
Authors: Kulkarni Prashant S. , Tiwari Krishna K. , Mahajani Vijaykumar V. 
Published: May 2010

AbstractThe application of a liquid emulsion membrane (LEM) process in the recovery of zinc from aqueous solutions is discussed. The role of a stripping agent is very important in the LEM extraction process. Various stripping agents, such as hydrochloric, sulfuric, nitric and methane sulfonic acids, were tested for the stability of membrane. Methane sulfonic acid outperforms the other acids as a strippant. Further importance was given to the stability of the liquid emulsion membrane during the extraction process. The important variables affecting the LEM permeation process of zinc in a mechanically agitated contactor (MAC), such as residence time for extraction, speed of agitation, organic diluents, surfactant concentration and internal strip acid concentration, were systematically investigated. Emulsion swelling and breakage that occurred during these investigations were also described. Finally, the static mixer (SM) device was shown to have a very good potential for LEM extraction of zinc as it outperforms MAC.
Using truncated relaxation spectra in the simulation of viscoelastic flows
Authors: Heuzey Marie‐Claude , Wood‐Adams Paula , Fortin AndrÉ 
Published: May 2010

AbstractThe simulation of polymer flows is a complicated problem. One of the limiting factors is the degree to which elasticity plays an important role in the flow. For a given constitutive equation and numerical technique, a higher material relaxation time will result in a lower maximum deformation rate for which convergence is possible. Since industrial processes typically involve large deformation rates, a practical way to allow their simulation is to truncate the longest relaxation times. In this work the Leonov constitutive equation was used to simulate flow through an abrupt contraction. The possibility of truncating the relaxation spectrum was explored and the impact of using truncated spectra on simulations is described. Finally, we propose a technique for obtaining a truncated relaxation spectrum that will be useful for flow simulations.
Influence of horizontal return bend on the two‐phase flow pattern in a 6.9 mm diameter tube
Authors: Wang Chi‐Chung , Chen Ing Youn , Yang Yung‐Wei 
Published: May 2010

AbstractThe two‐phase flow pattern for air‐water mixtures inside a 6.9 mm U‐tube is reported to have curvature ratios of 3˜7.1. At a lower total mass flux of 50 kg/m2·s and a quality of 0.1, or at a larger curvature ratio of 7.1, no influence on the flow patterns is seen. However, if the curvature ratio is reduced to 3, the flow pattern in the recovery region just after the return bend is temporally turned from stratified flow into annular flow. For a quality larger than 0.4, the annular flow pattern prevails in the entire tube. For G = 400 kg/m2·s and x < 0.01, the size of the plug in the downstream is usually larger than that in the upstream due to the coalesce in the return bend. This coalescence phenomenon continues to further increase the total mass flux at the lower quality region. For a total mass flux above 500 kg/m2·s, the bubbly flow pattern in the upstream region may become intermittent.
Gas holdup in a gassed reciprocating plate column with rashig rings placed in interplate spaces
Authors: Aleksić M. , Veljković V. B. , Banković‐Ilić Ivana , Lazić M. L. , Skala D. U. 
Published: May 2010

AbstractThe gas holdup is studies in a gassed reciprocating plate column with the addition of the Rashig rings placed in each interplate space. The gas holdup generally increases with increasing the vibration speed, the superficial gas velocity, and the solids concentration in the range of operating conditions applied. Independently of the solids concentration, the gas holdup is correlated with the power consumption and the superficial gas velocity. The Rashig rings are shown to have more effective dispersion action than the polypropylene spheres under the same other operating conditions.
Removal of 230Th by solvent extraction from high grade uranium ore liquid tailings to arrest 226Ra production in the tailings
Authors: Nirdosh Inderjit 
Published: May 2010

AbstractPrimene JM‐T, D2EHPA and TBP were used as solvents to extract 230Th from sulphuric acid uranium leachate and barren solutions from a Saskatchewan, Canada uranium mill. This was done with the objective of eliminating the source for 226Ra production in the tailings in perpetuity. A 0.1 vol% Primene JM‐T, 5 vol% isodecanol (modifier), and kerosene diluent mixture was found to completely remove thorium from the solutions. The thorium was stripped from the loaded organic with a 15 wt% ammonium carbonate solution.