bluuebunny/crossref_metadata_2025_split huggingface dataset:
Application of controlled cooling and seeding in batch crystallization
Authors: Bohlin Martin , Rasmuson Åke C. 
Published: March 2009

AbstractSome aspects of batch cooling crystallization in the industrial practice are analysed by computer simulations. The results indicate that without appropriate kinetics and very accurate process control, even the qualitative effects of applying controlled cooling and seeding are highly unpredictable. An increase in product size by applying controlled cooling is likely to be successful only rather randomly and the size distribution becomes broader. A linear or weakly non‐linear cooling curve usually produces larger crystals than a natural cooling curve, and a better reproducibility than a controlled cooling curve. Seeding increases both size and reproducibility, but is also likely to increase significantly the coefficient of variation of the product distribution. The product weight mean size and coefficient of variation may increase or decrease at increasing amount of seeds, depending on governing kinetics.
Optimum CFST bioreactor design: Experimental study using batch growth parameters for saccharomyces cerevisiae producing ethanol
Authors: Wall Jason B. , Hill Gordon A. 
Published: March 2009

AbstractAn optimum CFST bioreactor design equation is presented which can be used with linear growth‐associated product inhibition models. Batch experiments were performed to determine Saccharomyces cerevisiae growth parameters required for solving the optimum design equation.The three bioreactors were designed in decreasing volumes to achieve theoretical glucose conversions of 99.9% and 99.99%. At steady state, the bioreactors appeared to reach the theoretical conditions as long as the flowrates were held equal or slightly below the optimum conditions. At very low flowrates, biomass death was observed in downstream reactors while at high flowrates, the theoretical conversions were not achieved. The experimental results confirm that optimally designed bioreactors can offer lower processing volumes to achieve high substrate conversions as compared to single CFST bioreactors.
Interactive behaviour of the α‐methylstyrene‐toluene mixture
Authors: Bui V. T. , Hamdouni A. , Léaonard J. 
Published: March 2009

AbstractThe Flory‐Huggins polymer solution theory can be extended to be applicable to a binary liquid mixture, yielding a parameter which represents the interactive behaviour of the mixture over the entire concentration range. Static vapour pressures of α‐methylstyrene‐toluene mixture were measured from 20 to 40°C by using a MKS Baratron manometer. The interaction parameter was then computed by means of the Wilson's equation. Positive values of the parameter and its concentration dependence may be explained by a lack of intermolecular interaction as well as by the free volume effect on mixing. These findings can also be supported by positive volume excess of the mixture, deduced from density measurements using a SODEV densimeter. The interactive pattern of the present mixture will be compared with that of other mixtures of α‐methylstyrene in tetrahydrofuran, cyclohexane and p‐dioxan.
Mixing rules for predicting the viscosity of bitumens saturated with pure gases
Authors: Mehrotra Anil K. 
Published: March 2009

AbstractMixing rules are developed and evaluated for predicting the viscosity of Alberta bitumens saturated with each of N2, CO, CH4, CO2 and C2, H6. The viscosity‐temperature variation for all bitumens and gases is expressed as [log(μ + 0.8) = ± 10 T]. A linear cross‐correlation between parameters b1 and b2 in the above relationship is identified and used subsequently to derive a one‐parameter viscosity equation: [log(μ + 0.8) = θ(ΦT)b]. where θ = 160, Φ = 0.008 for all bitumens and θ = ‐0.1, Φ = 0.015 for all gases. The two mixing rules examined in this study are: \documentclass{article}\pagestyle{empty}\begin{document}$ \log \left( {\bar \mu + 0.8} \right) = \sum v_i \,\log \left( {\mu _i + 0.8} \right) $\end{document} and \documentclass{article}\pagestyle{empty}\begin{document}$ \log \left( {\bar \mu + 0.8} \right) = \sum v_i \,\log \left( {\mu _i + 0.8} \right) + \sum \sum v_i v_j B_{ij} $\end{document}, where v represents the geometric mean of mass and mole fractions and Bij is a binary viscous interaction term. Predictions for the viscosity of gas‐saturated bitumens are validated with over 400 experimental data points for five Alberta bitumens at temperatures from 12 to 120°C and pressures up to 10 MPa.
Gas phase complete catalytic oxidation of aromatic hydrocarbon mixtures
Authors: Barresi Antonello A. , Mazzarino Italo , Baldi Giancarlo 
Published: March 2009

AbstractIn this work oxidation of benzene and ethenylbenzene (IUPAC name for styrene) as single compounds and in binary mixtures over a Pt honeycomb catalyst were investigated.Both aromatic compounds showed zero‐order kinetics over a wide concentration range. The ethenylbenzene reaction rate was affected weakly by the presence of benzene, whereas benzene oxidation was inhibited strongly by ethenylbenzene. The Mars‐van Krevelen mechanism (which is generally accepted for single aromatic compound oxidation kinetics) gave rise to inconsistencies in describing mixture behaviour.A different kinetic model is proposed, where benzene reacts from the gas phase and ethenylbenzene is adsorbed on the catalyst competing with oxygen for active sites. This model was able to interpret the oxidation of mixtures quite satisfactorily.
Solubilities of solids in supercritical fluids
Authors: Burk Robert , Kruus Peeter 
Published: March 2009

AbstractThe solubilities of several low‐volatility compounds in supercritical fluids were measured. The fluids used were pure carbon dioxide or carbon dioxide modified with small amounts of organic liquids. Some enthalpies of solution of solids in carbon dioxide at a density of 0.80 g/mL are presented. The enthalpy of solution of fluoranthene in carbon dioxide was found to be less endothermic at higher CO2 density. The order of solubilities in the modified fluids was the same as that in the pure liquid modifiers. The same apparatus was used to measure vapor pressures of some substances as well as solubilities.
The effect of liquid film vaporization on natural convection heat and mass transfer in a vertical tube
Authors: Yan Wei‐Mon 
Published: March 2009

AbstractA numerical analysis was carried out to investigate the effects of film vaporization on natural convection heat and mass transfer in a vertical tube. Results for interfacial Nusselt and Sherwood numbers are presented for air‐ethanol and air‐water systems for various conditions. Predicted results show that heat transfer along the gas‐liquid interface is dominated by the transport of latent heat in association with the vaporization of the liquid film. Additionally, the predicted results obtained by including transport in the liquid film are contrasted with those where liquid film transport is neglected, showing that the assumption of an extremely thin film made by Chang et al. (1986) and Yan and Lin (1990) is only valid for systems with small liquid mass flow rates. For systems with a high liquid film Reynolds number, Re10, the assumption of an extremely thin film is seriously in error.
Spouted bed and spout‐fluid bed behaviour in a column of diameter 0.91 m
Authors: He Y‐L. , Lim C. J. , Grace J. R. 
Published: March 2009

AbstractHydrodynamic measurements were obtained in a half‐column of diameter 0.91 m equipped with a conical base using particles of diameter 3.3 to 6.7mm with operation both as pure spouted beds and in the spout‐fluid bed mode. Comparison of the experimental results for minimum spouting velocity with equations in the literature generally gave unsatisfactory agreement. On the other hand, the correlations of McNab (1972) and Hadžisdmajlović et al. (1983) gave reasonable predictions of spout diameters in spouted and spout‐fluid beds respectively. Hydrodynamic regimes with auxiliary air present were broadly similar to those determined in smaller columns. However, there were substantial dead regimes at the bottom of the column. A finite difference model based on the vector form of the Ergun equation gave good predictions of air flow distribution and longitudinal pressure profiles.
Separation and residence times of larger particles in a spout‐fluid bed
Authors: Waldie B. 
Published: March 2009

AbstractOptimum conditions for the separation of added large particles from a spout‐fluid bed of Geldart Type B powder have been determined. A shallow bed, 100 mm in diameter, with porous conical distributor was used. Mean and distributions of residence time of the large particles depend on the two gas flow rates, especially that to the distributor, and on spout inlet diameter and large particle size. Bed regimes studied were mainly spouting with aeration and spout‐fluidization. In the latter regime an optimum range of fluidizing gas flow rates that minimised mean and spread of residence times was identified. RTD data were correlated by a model incorporating a minimum time supplemented by a distribution for an ideally mixed system.
Fluid flow pattern and solids circulation rate in a liquid phase spout‐fluid bed with draft tube
Authors: Grbavčić Ž. B. , Vuković D. V. , Jovanović S. Dj. , Garić R. V. , Hadžismajlović Dž E. , Littman H. , Morgan M. H. 
Published: March 2009

AbstractThe fluid flow pattern and solids circulation rate in a liquid phase spout‐fluid bed with a draft tube were studied in a semi‐circular column 196 mm in diameter equipped with a semi‐circular draft tube 34.5 mm in diameter using water and spherical glass particles 1.20, 1.94 and 2.98 mm in diameter. Both the solids circulation rate and fluid distribution between the draft tube and the annulus are influenced by the location of the draft tube, the relative magnitude of the inlet spouting and annulus flowrates, and the total fluid flowrate entering the bed.A one‐dimensional steady state model of vertical non‐accelerating liquid‐solids flow predicts the solids mass flux in the draft tube with a mean deviation of 12.3% when experimental values of the axial pressure gradients in the draft tube and annulus are specified. A simple correlation for the fountain height is also presented.
Fluid dynamics characterization of a pneumatic bed using a spouted bed type solid feeding system
Authors: Ferreira M. C. , Freire J. T. 
Published: March 2009

AbstractThe development of a bed is reported, in which characteristics from spouted beds and pneumatic conveying are combined. The apparatus can be described as a pneumatic transport bed modified by the introduction of a recirculation process for inert materials, which leads to a final configuration akin to that of spouted beds. The dependency of the particle recirculation rates on the air flow rates and on the distance between the air inlet and the lower end of the central tube (z0) was investigated. Also studied was the variation of the total pressure drop with air flow rate, for different loads of inert materials (glass spheres, dp = 2.8 mm) and different z0 values.
Hydrodynamics and interphase heat transfer in a swirled spouted bed
Authors: Dolidovich A. F. 
Published: March 2009

AbstractA new modification of a spouting technique, a swirled spouted bed (SSB), is developed and proposed to increase the efficiency of heat treatment of polyfractional and fine particles and to reduce their entrainment. It is shown that under the developed spouting conditions the SSB pressure drop is 20‐30% and incipient spouting velocity is 40‐50% lower whereas an interphase heat transfer rate is 15‐25% higher as compared to a classical spouted bed (CSB). An empirical correlation is proposed to determine the SSB pressure drop under developed conditions.
Batch and continuous spouted bed drying of cereal grains: The thermal equilibrium model
Authors: Zahed Adnan H. , Epstein Norman 
Published: March 2009

AbstractA complete set of equations with no adjustable parameters are written for numerically predicting the variation of grain temperature and moisture content with time for batch drying of well mixed deep beds of three cereal grains, as well as the exit grain and air moisture contents and temperatures for continuous drying. Unlike previous studies, the surface moisture content of the grains is not assumed constant.Agreement with both batch and continuous spouted bed drying data from the literature is good, in the continuous case especially when the assumed exit age distribution of the isothermal bed solids is specific to spouting.
Prediction of spouted bed reactor performance using kinetic models
Authors: Gorshtein A. E. 
Published: March 2009

AbstractThe form of the equation governing the kinetic model of a reactor depends on the mixing regime of the reacting phases and the conversion kinetics. The formation of detached flow in a spouted‐bed reactor results in backmixing of the solid material. Therefore, the processes in a spouted‐bed reactor can be described by a diffusion (quasihomogeneous) model equation. The paper compares the values of the production capacity of a spouted‐bed reactor calculated using the diffusion model with experimental values of the efficiency of green ultramarine oxidation (kinetic region), of oxidative calcination of some metal sulphides (mixed region), and of the ion exchange extraction of copper from solutions (diffusion region). The kinetics of the corresponding conversions are also described.
Mass transfer in tube banks with two‐phase flow
Authors: Giorgio Ana Chiappori De Del , Cavatorta Omar N. , Böhm Ursula 
Published: March 2009

AbstractThe fluid dynamic behaviour and the liquid‐solid mass transfer to horizontal cylinders, under bubble induced convection, was investigated. The gas void fraction was measured and overall mass transfer coefficients were determined for single cylinders as well as for banks of tubes with various characteristics.
Multiple reactor testing of a synthetic sorbent for regenerative sulfur capture in fluidized bed combustion of coal
Authors: Wolff E. H. P. , Gerritsen A. W. , Van Bleek C. M. Den 
Published: March 2009

AbstractA new synthetic regenerable sorbent was developed as an alternative to limestone and dolomite for regenerative sulfur capture in fluidized bed combustion (FBC of coal. The sorbent consists of CaO (8‐9 wt%) on a spherical 3 mm diameter γ‐Al2O3 support. A shrinking unreacted core model (SURE2) is proposed to describe the sulfation process. Experiments have been carried out in a 12 mm internal diameter fixed bed reactor, a 0.05 m ID fluidized bed reactor and a thermobalance. The results obtained for all three reactors are in good agreement with the predictions of the SURE2 model.
Comportement thermique et chimique de particules solides subissant une réaction de décomposition endothermique sous ľaction ďun flux de chaleur externe
Authors: J. Lédé  , Villermavx J. 
Published: March 2009

AbstractLe présent article a pour objet ľétude théorique et expérimental des conditions thermiques et chimiques dans lesquelles s ' effectue la décomposition endothermique de particules solides sous ľaction ďun flux de chaleur extérieur. La réaction, du type Solide1 → Solide2 + Fluides est supposée s ' effectuer en régime chimique. Après une phase de chauffage pur, le grain solide commence à réagir dès q 'il atteint une certaine température seuil TR. La réaction s ' effectue alors dans des conditions quasi isothermes. Les variations de TR ainsi que ľeffet de stabilisation de température dépendent des propriétés des particules, de la réaction chimique (cinétique et thermodynamique) et des conditions de transfert de chaleur, que ľon fait apparaǐtre sous forme de trois critères adimensionnels: critère ďactivation, de thermicité et nombre de Damköhler. Les prévisions théoriques sont en très bon accord avec les résultats de mesures expérimentales effectuées sur la réaction de décarbonatation de NaHCO3 en réacteur cyclone.
Gas hold‐up behavior of mechanically agitated gas‐liquid reactors using pitched blade downflow turbines
Authors: Rewatkar V. B. , Deshpande A. J. , Pandit A. B. , Joshi J. B. 
Published: March 2009

AbstractFractional gas holdup was measured in 0.57, 1.0, and 1.5 m i.d. vessels. Pitched blade downflow turbines (PTD) were used as the impeller. Design details of the impeller, such as the impeller diameter (0.22 T to 0.5 T) and blade width (0.25 D to 0.4 D), were studied. The effect of sparger type, geometry and size on fractional gas hold‐up has been investigated in detail. Four different types of spargers (pipe, conical, ring and concentric ring spargers) were used. Sparger location was varied for all the types studied. Further, design details of the ring sparger, which gave the highest hold‐up were then studied in detail. These included ring diameter, number of holes and hole size. All the reported correlations for fractional gas hold‐up in mechanically agitated gas‐liquid reactors were tested and compared. A better correlation has been developed for pitched blade turbines.
Measurement of air bubble size using densitometer
Authors: Zhu S. , Pelton R. H. , Ajersch M. , Towers M. , Baird M. H. I. 
Published: March 2009

AbstractA simple mass‐transfer model is derived which gives the initial air bubble size distributions in a dispersion of air bubbles in water from the density/time responses to a step increase of pressure. Bubble size distributions from the model showed reasonable agreement with direct optical measurements. This work is applicable to dilute dispersions of bubbles which experience a sufficiently large increase in pressure such that the resulting solution is unsaturated with air.
Solubility of H2S in n‐hexadecane at elevated pressure
Authors: Feng Guo‐Xiang , Mather Alan E. 
Published: March 2009

AbstractThe solubility of H2S in n‐hexadecane has been determined at 50, 100 and 150°C at pressures up to 7.4 MPa. The results were correlated with the Peng‐Robinson (1976) equation of state and Henry's constants were derived for comparison with low pressure data in the literature.
Performance of a divided flow exchanger
Authors: Subramaniyan N. M. , Changrani Rajnish , Narayan Rashmi , Vishavanath Shekhar , Kurdikar Somdatt , Suburamaniyan V. , Sankholkar Yatin 
Published: March 2009

AbstractAn analysis is presented of a 1‐2 divided flow exchanger where the temperature of shell and tube streams depend on tube arrangement. Effect of having unbalanced tube passes is assessed for two possible cases. Graphs are plotted that show the variation of thermal effectiveness and logarithmic mean temperature difference correction factor with ratio of heat capacity rates and number of transfer units. Combination of such exchangers is also studied.
Heat and mass transfer on the wavy film absorption process
Authors: Yang Ru , Jou Derming 
Published: March 2009

AbstractRecently the absorption heat pumps and chillers have received considerable attention due to their low electricity consumption rate. Therefore, it is important to understand the transport mechanism of an absorption process. In this paper, a numerical study of the heat and mass transfer taking place on a wavy falling liquid film of an absorption process is presented. With previously solved periodic wavy film flow solutions, the finite difference method is employed to solve the heat and mass transport equations. The numerical solution indicates that the waves significantly increase the transport rates. A comparison of the transfer rates of the wavy film to that of the smooth film is presented to show that the mass transfer rate can be doubled.
A mathematical model of fluidized bed biomass gasification
Authors: Bilodeau J.‐F. , Thérien N. , Proulx P. , Czernik S. , Chornet E. 
Published: March 2009

AbstractA mathematical model of biomass gasification in a fluidized bed has been developed. It considers axial variations of concentrations and temperature in the bubble and emulsion phases. The mass balance involves instantaneous oxidation and equilibrium devolatilization of the biomass, kinetics of solid‐gas gasification reactions as well as of gaseous phase reactions and interphase mass transfer and gas convection. The energy balance is solved locally for each vertical volume element, and globally on the reactor by iteration on the temperature at the bottom of the bed. Three parameters have been adjusted based on the experimental results: the heat transfer coefficient at the wall, the weighting of the kinetics of the water‐gas shift reaction and the fraction of biomass carbon remaining as char after devolatilization. The model is used to simulate a pilot scale (50 kg/h) biomass gasifier, and its predictions compared to experimental measurements. The temperature and gaseous concentrations are estimated with good accuracy for the experiments using a wood feedstock, except for the concentration of hydrogen which is overestimated.
Evaluation of capital cost data. part 7: Liquid waste disposal with emphasis on physical treatment
Authors: Wright David G. , Woods Donald R. 
Published: March 2009

AbstractCapital cost correlations are given for oil‐water separators, equalization basins, primary clarifiers, clarifiers and clarifier mechanisms, reverse osmosis unit, ultrafiltration units, gravity filters and miroscreens. Data are included for raw sewage, intermediate and recirculation pumping stations and for preliminary treatment (or bar screens, grit removal, overflow and bypass chamber and Parshall flume), for grit removal, comminution and gas stripping. The correlations are accurate to ± 30%, expressed in Canadian dollars and adjusted to a Marshall and Swift value of 1000. Details as to what components are included in the cost are given. Data are given for the labour and material costs to create a working process module.For inflation indices, a critique of the Engineering News Record, EPA small city, Marshall and Swift, Chemical Engineering and Southam inflation indices suggested that the Marshall and Swift index is most appropriate for the construction and process equipment studied here. Concerning the currency exchange, for the equipment and processes in this study, equipment costs the same whether expressed directly in US or Canadian dollars.To put the current data into perspective, several hundred sources of cost data were analyzed. The major correlations are compared, on a consistent basis, with current data.
Modeling of unsteady flow around accelerating sphere at moderate reynolds numbers
Authors: Li R. , Boulos M. 
Published: March 2009

AbstractThe flow around an accelerating spherical particle of diameter ranging from 50 to 200 m̈m is studied in the range of Reynolds number between 0.1 and 100. The flow around the sphere is assumed to be laminar and two‐dimensional axisymmetric. The calculated drag coefficient is compared with the theoretical predictions of added mass term and Basset history term. Appropriate corrections for those two terms are proposed as function of the acceleration rate and the particle diameter.
Excess pressure losses in capillary flows
Authors: Kozicki W. , Kuang P. Q. 
Published: March 2009

AbstractAccurate determinations of excess pressure losses at the entry and exit of capillary flows are essential for rheological characterization of fluids by capillary viscometry. A modification of Bagley's end correction method is presented which accounts for the effects of slight variations in the diameters of the tubes of varying length used in the evaluations. The method was applied to capillary flows of dilute aqueous Polyox solutions using the three homologues WSR 301, Coagulant and FRA of Polyox. The excess pressure losses were found to increase with increase in the apparent shear rate, polymer concentration and tube diameter.