bluuebunny/crossref_metadata_2025_split huggingface dataset:
Importance of using the correct impeller boundary conditions for CFD simulations of stirred tanks
Authors: Fokema M. D. , Kresta S. M. , Wood P. E. 
Published: March 2009

AbstractTwo experimentally determined sets of impeller boundary conditions were used to simulate the flow generated by a pitched blade turbine in a cylindrical baffled tank. Use of these two sets of boundary conditions in simulations with two different off bottom clearances led to the conclusion that the flow generated by a pitched blade impeller cannot be successfully predicted without considering the impeller location. Correct prediction of velocity fields in the tank required the correct specification of velocity boundary conditions. Successful prediction of the turbulent energy distribution required proper specification of the turbulence boundary conditions. There was almost no interaction between the velocity and turbulence fields. The turbulet kinetic energy dissipation rate was at a maximum close to the impeller in both geometries. Within this region the average dissipation rate was five and a half times greater that the average dissipation rate in the tank.
Changes in liquid hold‐up in foam and size of foam by perforated plates and contribution to mechanical foam‐breaking
Authors: Kuni M. , Onodera M. , Hosokaz K. , Yamagiwa K. , Ohkawa A. 
Published: March 2009

AbstractChanges in the liquid hold‐up, ϵ, and the diameter of d, of a foam that are induced by perforated plates (PPs) and the contribution of PPs to foam‐breaking were studied. A foaming system containing a dilute detergent solution in a column with mechanical agitation fitted with a rotating‐disk foam‐breaker (MFRD) was used. After the foam passed through the PPs, ϵ and d decreased and increased, respectively. The use of PPs to achieve a maximum reduction in ϵ and a maximum increase in d is confirmed. It is also demonstrated that use of PPs contributes not only to improving the foam‐breaking performance of the MFRD, but also to power savings.
Dispersed phase characteristics in three phase (liquid‐liquid‐solid) fluidized beds
Authors: Kim Sang Done , Kim Dong Yun , Han Joo Hee 
Published: March 2009

AbstractTwo ideal droplet length (l,) distributions have been derived for two different droplet shapes. The dispersed phase holdup (ϵd) increases with increasing dispersed phase velocity (Ud), but decreases with increasing continuous phase velocity, (Uc) in three‐phase fluidized beds. In the droplet‐coalescing flow regime, lv and the droplet rising velocity (vd) increase, but the spherical droplet fraction (k) decreases with increasing Ud and uc. In the droplet‐disintegrating flow regime, the effects of ud and Uc on lv and k are insignificant, but vd increases with increasing Uc. Maximum values of lv, occur in the bed containing 1.7 mm diameter particles and lv has an uniform length of around 2.0 mm in beds with particle size larger than 3.0 mm.
Hydrodynamic characteristics of a trickling bed of peat moss used for biofiltration of wastewater
Authors: Karamanev D. G. , Bélanger M.‐C. , Chavarie C. , Chaouki J. , Talbot P. , Mayer R. 
Published: March 2009

AbstractThe retention time distribution of liquid in a trickling bed of peat moss was studied. Two different flow regimes have been detected. This is due to the fractal‐like structure of peat moss. At low velocities, the liquid flows through the aggregates of peat moss particles. In this case, the tracer is distributed evenly in all the volume of the liquid because of the small characteristic time of diffusion. When the superficial liquid velocity is high, the liquid mainly flows between the solid aggregates and only a small amount of tracer penetrates the liquid inside and between the particles forming the aggregates.The results obtained are important for modelling the process of biofiltration with peat moss, a new system for environmental protection.
Effect of electrode geometry and charge on the production of polymer microbeads by electrostatics
Authors: Bugarski B. , Amsden B. , Goosen M. F. A. , Neufeld R. J. , Poncelet D. 
Published: March 2009

AbstractExperimental parameters which are critical for producing small diameter (i.e. 100‐300 μm) polymer microbeads, using electrostatic droplet generation, were investigated with three types of electrodes; a parallel plate, a positively charged needle and a grounded needle with alginate as the polymer. Electrode spacing was a critical factor controlling microbead size, but only for the parallel plate set‐up. While the applied potential affected droplet size in all three set‐ups, the smallest droplet size was produced with the positively charged needle. In some experiments needle oscillation was observed resulting in even smaller microbeads (i.e. < 100 μm). Calculated microbead diameters agreed well with experimental values.
Use of mixed surfactants to improve the transient interfacial tension behaviour of heavy oil/alkaline systems
Authors: Chiwetelu C. I. , Hornof V. , Neale G. H. , George A. E. 
Published: March 2009

AbstractThe objective of this study was to identify suitable combinations of additives to aqueous alkaline formulations for the potential recovery of Saskatchewan heavy crude oil. A previously developed strategy was applied to screen various additive combinations consisting of three commercial petroleum sulfonate surfactants and two commercial lignosulfonate surfactants. The selection of the additives was based on a large number of physical and interfacial property measurements in conjunction with phase stability tests at different temperatures. The resulting ternary formulations, labelled here as Mixed‐Surfactant‐Enhanced Alkaline (MSEA) systems, were very successful in reversing the trend of increasing interfacial tension with time that characterizes additive‐free alkaline/crude oil systems. This success came at the expense of initial IFT values that were considerably higher than those exhibited by the corresponding additive‐free alkaline solutions. However, at higher temperatures (65 °C), these ternary MSEA formulations were capable of generating very low IFT values against the crude oil (in the range of 5 × 10−2 to 10−1 mN/m), which suggests that they could be suitable candidates for commercial exploitation of heavy oil recovery processes.
Correlation and prediction of the viscosity of pure hydrocarbons
Authors: Mehrotra Anil K. 
Published: March 2009

AbstractA relationship is identified between the effective carbon number (ECN) and parameter b in the one‐parameter viscosity euation: log (μ + 0.8) = 100 (0.0lT)b. The generalized correlation, b = ‐5.745 + 0.616 In (ECN) ‐ 40.468 (ECN)−15, provides an equation to predict parameter b, which gives values that are within the maximum deviation of 5% for ECN < 10 and 1% for 10 < ECN < 44 of the empirically‐determined values for 70 liquid hydrocarbons. The calculated viscosities are within 5% of literature data. The viscosity prediction method is simple to use, and it can be extrapolated reliably to heavier hydrocarbons.
Hydrodynamics of turbulent bed contactor: Flooding aspects
Authors: Soundarajan K. , Krishnaiah K. 
Published: March 2009

AbstractExperimental data on flooding characteristics were obtained in a Turbulent Bed Contactor (TBC). The flooding conditions and the mechanism of flooding in a single stage TBC have been analyzed for light and dense particles in order to obtain useful correlations that are easier to comprehend. The proposed correlations predict all the combinations of flooding velocities over a large range of variables.
Two‐Stage pyrolysis model of PVC
Authors: Wu Chao‐Hsiung , Chang Ching‐Yuan , Hor Jwo‐Luen , Shih Shin‐Min , Chen Leo‐Wang , Chang Feng‐Wen 
Published: March 2009

AbstractThe pyrolysis of polyvinyl chloride (PVC) was examined with a thermal gravimetric analyzer (TGA). The experiments were carried out over the temperature range of 400‐800 K at three heating rates of 1, 2, and 5.5 K/min and in a nitrogen atmosphere. The results indicate that the entire process of PVC pyrolysis under the experimental conditions of this investigation consists of two distinct pyrolysis stages, namely, the thermal dehydrochlorination and the breakdown of the intermediate products produced after the dehydrochlorination stage. The corresponding activation energy, pre‐exponential factor, and reaction order were determined. A two‐stage pyrolysis model, which is composed of four reactions including a number of independent, consecutive and competitive reactions with volatiles and solid products, was developed. This kinetic model gives good agreement with the experimental results.
Liquid‐Liquid equilibria of heptane‐methanol‐toluene‐calcium chloride and ethyl acetate‐water‐ethanol‐calcium chloride quaternary systems
Authors: Kumagae Yoshio , Suzuta Tetsuya , Abe Tadashi , Iwai Yoshio , Arai Yasuhiko 
Published: March 2009

AbstractLiquid‐liquid equilibria (LLE) data for the heptane‐methanol‐toluene‐calcium chloride and ethyl acetate‐water‐ethanol‐calcium chloride quaternary systems were measured under various salt concentrations at 298.15 K and the results obtained were correlated with a modification of Hàla's model. Distribution of the salt between the two liquid phases was found to be strongly influenced by the content of methanol or ethanol while the solubility of the salt in the heptane or ethyl acetate rich phase was very small. The two‐liquid region, i.e. the miscibility gap was enlarged by adding the salt. Correlations of LLE data including the salt distribution for both the non‐aqueous and aqueous quaternary systems were possible with reasonable accuracy.
The influence of solid properties on the just‐suspended agitation requirements of pitched‐blade and high‐efficiency impellers
Authors: Myers Kevin J. , Fasano Julian B. , Corpstein Robert R. 
Published: March 2009

AbstractExtensive experimental data indicates that the particle property dependence of the just‐suspended agitation speed of pitched‐blade turbines and high‐efficiency impellers can be described with reasonable accuracy using a Zwietering power‐law correlation. However, there are indications that the effect of particle size is divided into two regimes, one for particle sizes less than 1000 μm and one for larger particles. Comparison of the two impeller types indicates that the pitched‐blade turbine requires somewhat higher power inputs and substantially higher torque levels to produce the same level of agitation as the high‐efficiency impeller.
Variations in the porous structure of a Cr2O3/Al2O3 catalyst by coke deposition
Authors: Menéndez M. , Braña A. 
Published: March 2009

AbstractThe porous structure of a Cr2O3/Al2O3 catalyst deactivated by coke deposition has been studied at various levels of coke content. The results obtained agree satisfactorily with a model of uniform coverage of the catalyst pores, thus allowing the hypothesis of pore blockage to be discarded under the conditions investigated.
Liquid‐liquid equilibria of water + methanol + (MTBE or TAME) mixtures
Authors: Arce Alberto , Blanco Antonio , Blanco Manuel , Soto Ana , Vidal Isabel 
Published: March 2009

AbstractExperimental liquid‐liquid equilibrium data obtained at various temperatures for water + methanol + methyl tert‐butyl ether and water + methanol + tert‐amyl methyl ether were satisfactorily fitted by both NRTL and UNIQUAC models using Sϕrensen's well‐known correlation program, which nevertheless performed anomalously when run seeking minimum error in the solute distribution ratio.
Modelling the flow in a hydrocyclone
Authors: Malhotra A. , Branion R. M. R. , Hauptmann E. G. 
Published: March 2009

AbstractA computational procedure is employed in the present work to predict the flow field in a hydrocyclone. Computations are carried out for turbulent flow under assumptions of axial symmetry. Turbulence closure has been affected with the help of the conventional k→ ϵ model that includes a new formulation of the turbulence dissipation equation. The existing formulation of the dissipation equation proved to be inadequate in predicting the true nature of the present flow field. Results of the procedure are discussed. The new model appears to predict correctly the behaviour of a conventional water‐fed hydrocyclone in the absence of an air core.
Pre‐treatment of kraft pulp bleach plant effluent by selected ultrafiltration membranes
Authors: Yao Wendy X. , Kennedy Kevin J. , Tam Chung Ming , Hazlett John D. 
Published: March 2009

AbstractThree ultrafiltration membranes in series with molar mass cutoffs of 130,000, 15,000, and 5,000 Da, respectively were used to pretreat Kraft pulp bleach plant effluent prior to biological treatment. The TOC (total organic carbon), COD (chemical oxygen demand) and AOX (adsorbable organic halogen) reductions for the permeate were 65, 70 and 85%, respectively with no significant change of toxicity. Treatment of the ultrafiltration permeate using tighter ultrafiltration (UF) and nanofiltration (NF) membranes with molar mass cutoffs less than 1,500 Da, yielded TOC and AOX reductions of 90 and 99%, respectively with a permeate Microtox EC50 level of 100%.
Pressure drop in two phase cocurrent upward flow in packed beds: Air/non‐newtonian liquid systems
Authors: Srinivas K. V. , Chhabra R. P. 
Published: March 2009

AbstractNew data on the two phase pressure drop for the concurrent upflow of air‐liquid (Newtonian and non‐Newtonian) mixtures through packed beds of spherical and non‐spherical particles are presented. The results for single phase flows and for the air‐Newtonian liquid mixtures have been used both to gauge the overall accuracy of the present experimental methods and to evaluate the validity of the predictive expressions available in the literature. The two phase pressure drop has been measured as a function of the liquid and gas flow rates, column diameter and the power law model constants. Depending upon a suitable combination of the gas and liquid fluxes and the power law index, the two phase pressure drop may be less than its value for the flow of liquid alone. A simple expression is proposed which correlates the present set of experiments (nearly 500 data points) with satisfactory levels of accuracy over the following ranges of conditions: 0.54 ≤ n ≤ 1; 0.001 ≤ ReL* ≤ 50; 3.7 ≤ ReG ≤ 177 and 0.9 ≤χ (Lockhart‐Martinelli parameter) ≤ 104.
Evolution axiale du coefficient de transfert de matière en colonne à bulles et en lit fluidisé triphasique
Authors: Tavakoli T. , Syaiful S. , Bascoul A. , Delmas H. 
Published: March 2009

AbstractLes coefficients de transfert de matière volumétriques de la phase liquide pour l'oxygène sont déterminés en colonne à bulles et en lit fluidisé. Le concept d'une variation axiale du coefficient de transfert kla exponentiellement décroissant conduit à une meilleure représentation des profils de concentration en oxygène dissous à l'intérieur de la colonne. Contrairement à la colonne à bulles, les variation axiales de kla sont très importantes surtout dans la partie inférieure de la colonne en lit fluidisé où la présence de particules solides accélère le phénomène de coalescence particulièrement marqué pour les liquides visqueux.
The solubility of CO2 in triethylene glycol monomethyl ether
Authors: Henni Amr , Mather Alan E. 
Published: March 2009

AbstractThe solubility of CO2 in triethylene glycol monomethyl ether (TEGMME) has been measured at 40, 70 and 100°C at pressures up to 8.8 MPa. The results were correlated with the Peng‐Robinson (1976) equation of state. The interaction parameters and Henry's constants were derived.
Gas holdup and overall volumetric mass transfer coefficient in a modified reversed flow jet loop reactor
Authors: Prasad K. Yagna , Ramanujam T. K. 
Published: March 2009

AbstractExperiments were conducted in a modified reversed flow jet loop reactor having the liquid outlet at the top of the reactor to determine the gas holdup and overall volumetric mass transfer coefficient in the air‐water system. The influence of gas and liquid flow rates, and the draft tube to reactor diameter ratio were studied. It was observed that both gas holdup and volumetric mass transfer coefficient increased with increased gas and liquid flow rates and were found to be significantly higher in the modified reactor compared to the conventional one. The optimum draft tube to reactor diameter ratio was found to be in the range of 0.4 to 0.5. Empirical correlations are presented to predict gas holdup and overall volumetric mass transfer coefficient in terms of operational and geometrical variables.
Air stripping of hydrocarbon‐contaminated soils: Investigation of mass transfer effects
Authors: Karan Kunal , Chakma Amitabha , Mehrotra Anil K. 
Published: March 2009

AbstractBench‐scale experiments were carried out to simulate air stripping of soil contaminated with a semi‐volatile hydrocarbon, n‐octane. The experiments were conducted in an 8‐cm diameter glass column, packed with two types of packings: glass beads to represent non‐adsorbing materials and soil particles to represent adsorbing materials. Effects of gas superficial velocity, particle size and soil organic matter on the column outlet concentration and temperature profile were studied. Nitrogen adsorption/desorption experiments were performed to establish the desorption characteristics of the soil sample.Additionally, a mathematical model is presented which treats the interphase contaminant transport as a mass transfer rate‐limited process. The predictions from the mathematical model are shown to be in good agreement with the experimental results. Most importantly, the numerical results show that, contrary to the common assumption of local equilibrium, the interphase contaminant transport (from the sorbed to the vapour phase and/or from the liquid to the vapour phase) is mass transfer controlled.
Hydrodesulfurization of athabasca fluid coke — conversion and mechanism
Authors: Saha Chandreyee , Tollefson Eric L. 
Published: March 2009

AbstractHydrodesulfurization of Athabasca (Syncrude) fluid coke was studied for particle sizes of −74 + 53, −53 + 44 and −44 μm using a quartz reactor. Five flow rates of hydrogen from 1.2 × 10−6 to 2.5 × 10−6 m3/s were investigated with from 0.45 to 1.0 g of coke. Gas production — time profiles for H2S and CH4 were obtained at temperatures from 973 to 1073 K for each particle size range. Desulfurization rates were functions of particle size and temperature. Results agree with predictions of the shrinking core model, the rate being controlled initially by the gas film and chemical reaction resistances followed by control due to diffusion of hydrogen through the increasing ash layer. Below 998 K, the apparent activation energy was determined to be 293 kJ/mol · K, while at temperatures between 998 and 1073 K it was 29 kJ/mol · K.
Calcium sulphide formation in fluidized bed boilers
Authors: Lyngfelt Anders , Langer Vratislav , Steenari Britt‐Marie , Puromäki Kazimiera 
Published: March 2009

AbstractAnalyses of samples of bed ash from a stationary fluidized bed boiler show the presence of calcium sulphide. In some samples, half of the total sulphur was present as sulphide. The samples containing CaS were obtained under unstaged conditions and with a high excess air ratio, 1.3 to 1.4. The samples were taken after a stop in the limestone addition, i.e. at high SO2 emissions of about 1000 mL/m3 (ppm). No CaS was found during limestone addition when the SO2 emission was 300–400 mL/m3. This indicates that formation of large amounts of CaS may be initiated as the SO2 concentration exceeds some critical level.
A momentum integral model for central recirculation in swirling flow in a sudden expansion
Authors: Hallett W. L. H. , Ding C.‐Y. 
Published: March 2009

AbstractA momentum integral model is developed to predict the size and maximum recirculating mass flow rate for the central recirculation zone produced by a swirling flow in a sudden expansion as a function of expansion ratio, swirl intensity, and inlet velocity profile shape. Experimental measurements of velocity profiles in the recirculating flow are presented for three different expansion ratios and are used to validate the model. The model is shown to give good agreement with the measurements. The recirculation rate is found to increase roughly linearly with inlet swirl intensity and expansion size.
Self‐Assembly from Discrete Clusters to 2D Network Based on [Fe(phen)(CN)4]– and [Fe(bipy)(CN)4]–: Synthesis, Structures and Magnetic Properties
Authors: Xiang Hua , Wang Shao‐Jun , Jiang Long , Feng Xiao‐Long , Lu Tong‐Bu 
Published: March 2009

AbstractA series of cyanido‐bridged complexes {[FeIII(phen) (CN)4]2[NiL1]}·4H2O (1), {[FeIII(bipy)(CN)4]2[NiL1]}·4H2O (2), [FeIII(bipy)(CN)4]2[NiL2] (3), {[FeIII(phen)(CN)4]2[CuL3]}·5H2O (4), {[FeII(phen)(CN)4][Ni(ea)2]}2·2H2O (5), {[FeII(phen)(CN)4] [NiL2]·2H2O}n (6), {[FeIII(bipy)(CN)4]2[Ni(H2O)2]}·6.5H2O}n (7) and {[FeII(bipy)(CN)4][Ni(ea)2]·H2O}n (8) were synthesized using H[Fe(phen)(CN)4]·2H2O and H[Fe(bipy)(CN)4]·2H2O as precursors [L1 = 5,5,7,12,12,14‐hexamethyl‐1,4,8,11‐tetraazacyclotetradecane, L2 = 3,10‐bis(2‐phenylethyl)‐1,3,5,8, 10,12‐hexaazacyclotetradecane, L3 = 3,10‐bis(2‐hydroxyethyl)‐1,3,5,8,10,12‐hexaazacyclotetradecane, phen = 1,10‐phenanthroline, bipy = 2,2′‐bipyridine, ea = ethanolamine). Complexes 1–4 are trinuclear clusters, and 5 is a tetranuclear square. In 6, the [FeII(phen)(CN)4]2– anions alternately bridge the [NiL2]2+ cations to generate a 1D wavy chain. The structure of 7 possesses a 4,2‐ribbonlike chain, which contains a NiII2(CN)4FeIII2 square with each NiII atom shared by two adjacent squares. Each FeII and NiII atom in 8 acts as a three‐connected node through the cyanido‐bridges to generate a 2D network with a 4,82 topological net. Ferromagnetic couplings are found between the low‐spin FeIII ions and the NiII ions through the cyanido groups in 1–3 and 7, and a metamagnetic behavior and a frequency dependence of the out‐of‐phase ac susceptibility are observed in 7. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2009)
Arsenic speciation in natural and contaminated waters using CZE with in situ derivatization by molybdate and direct UV‐detection
Authors: Koshcheeva Olga S. , Shuvaeva Olga V. , Kuznetzova Lidiya I. 
Published: March 2009

AbstractA simple and sensitive procedure for simultaneous determination of arsenate, arsenite, monomethylarsonate and dimethylarsinate (DMA) ions in waters using CZE with chemical derivatization in situ and UV‐detection at 250 nm was developed. The separation was performed in a fused‐silica capillary using solution containing sodium molybdate and sodium perchlorate as electrolyte. Molybdate forms heteropolycomplexes with arsenic species in low acidic media, while sodium perchlorate masks silicate ion. The analysis conditions were optimized; the best results were achieved with the electrolyte consisting of 10 mM Na2MoO4 and 10 mM NaClO4 at pH 3.0 using negative voltage and pneumatic injection of the sample. Nevertheless, the signal of arsenite ion was not detected, probably because of its instability. Arsenite ion was quantified as a difference between arsenate ion contents after and before oxidation by bromine water. The detection limits for the fresh water at the level of 5.0 μg/L for AsIII and AsV, 16 μg/L for DMA and 20 μg/L for MMA were achieved. The reproducibility varied in the range of 0.06–0.25 relative units. To reduce the interferences of the sample salinity an addition of organic substances and isotachophoretic effect were used.