bluuebunny/crossref_metadata_2025_split huggingface dataset:
The drying of barley malt in the spouted bed dryer
Authors: Brunello Giovanni , Peck Ralph E. , Nina Gilberto Della 
Published: March 2009

AbstractThe drying of barley malt was studied in a batch spouted‐bed dryer using three inlet air temperatures (60, 80 and 90°C) and three initial masses of malt (25, 30 and 35 kg).One of the conclusions was that the drying can be conducted at higher temperatures than in the classical equipment.A general correlation was obtained through the use of reduced moisture and reduced time.A mathematical model which assumes only an external resistance of diffusion or heat transfer does not apply. Also, the model based on internal water diffusion does not predict the results. A new semi‐empirical model based on semi‐permeable membranes has been proposed.A method of using batch laboratory drying data to predict the performance of continuous spouted‐bed driers has been outlined.
Eccentric laminar couette flow of long cylindrical capsules
Authors: Epstein Norman , Bianchi R. J. , Lee V. T. Y. , Bentwich Michael 
Published: March 2009

AbstractThe equation of motion for laminar Couette flow of an incompressible Newtonian fluid, induced by the eccentric longitudinal motion of a long circular cylinder in a circular pipe, is solved analytically. Expressions are obtained and typical plots presented for local velocity distribution, local shear stress distributions on both the surface of the pipe wall and the surface of the cylindrical core, total drag force on both pipe wall and moving core, twisting moment on the core, and volumetric flow rate of the liquid. As the eccentricity approaches unity, the solution for flow rate is shown to coincide exactly with a practical formula developed by Kruyer and Ellis to represent the Couette flow induced by the motion of cylindrical capsules.
Flow of a slurry through a venturi meter
Authors: Shook C. A. , Masliyah J. H. 
Published: March 2009

AbstractSome of the factors governing discharge coefficients for slurries following through venturis are examined theoretically and experimentally. Coefficients greater than unity are predicted theoretically in the absence of wall friction effects. Experimental studies confirmed these values in an extreme case and indicated that like pipe flow, wall friction effects increase with particle density and diameter. The results suggest that the venturi meter should be more widely used for flowing slurries.
Oxygen transport in the intact red cell
Authors: Ho Shou‐Yien , Hershey Daniel 
Published: March 2009

AbstractA rapid‐flow technique was used to study and determine the resistance of the red cell membrane to oxygen transport and the diffusion coefficient for oxygen transport in the red cell interior. With a mathematical description for the process in the intact red cell and experimental results, the magnitude of the membrane transfer coefficient (h) and the diffusion coefficient (D) can be obtained. Two models were considered. One is that of simple unidimensional diffusion through a red cell, shaped as a rectangular slab with no end effects (model 1) and the other is two‐dimensional diffusion through a cylindrical disc (model 2).As a result of this study, it was found that, for model 1, the value of h, the oxygen transport coefficient for the membrane was 2.6 cm/sec, and D, the diffusion for oxygen transport inside the red cell, was 4.3 × 10−6 cm2/sec. For model 2, h and D were, respectively, 0.9 cm/sec and 3.8 × 10−6 cm2/sec.
Modelling of dispersion and dead space in an air chamber
Authors: Fan L. T. , Pereira N. C. 
Published: March 2009

AbstractA combined model consisting of an active region and a stagnant region is used in representing the air flow characteristics in a continuous flow system. The active region is represented by the one dimensional axial dispersion model while the stagnant region is considered to be a dead volume having no fluid interchange with the active region. The mathematical model is fitted to experimental data obtained by subjecting the system to tracer step inputs. In the process of model fitting a dimensionless parameter of Pe. (Peclet number of the active region) is estimated. The effects of the internal geometry and structure of the flow system on the flow patterns are analyzed and substantiated by experimental data. Two possible mechanisms explaining the formation of stagnant regions have been proposed — that of reduced length, and that of reduced cross‐section. For the present investigation, the reduced length mechanism is found to explain the experimental data better.
Pyrolysis of municipal solid waste
Authors: Mcintyre A. D. , Papic M. M. 
Published: March 2009

AbstractA state‐of‐the‐art review describing the characteristics of municipal solid waste (MSW) and assessing the chemistry and technology of pyrolysis of municipal solid waste is presented. The economics of the pyrolysis process are outlined.Combustibles constitute on average about 60% of the weight of MSW and result in an average heating value (“as received” basis) of about 3,000 to 6,000 Btu/Ib. This makes MSW attractive for thermal treatment.Municipal solid waste can be converted to gas, liquid and solid products by pyrolysis. Due to the complexity in composition of MSW the exact mechanism of pyrolysis is not known. Both homogeneous and heterogeneous reactions occur at the same time and both heat and mass transfer take place during the process. The relative yields of different products depends on the temperature of pyrolysis and the rate of heating. High pyrolysis temperatures and high heating rates favour the production of gases indicating high energies of activation for gasification reactions. At low temperatures, below 800°C, the pyrolysis process is reaction‐rate controlled, while at high temperatures, above 1,200°C, the process is diffusion‐rate controlled. Conditions of good heat and mass transfer are required for gasification of MSW. The residual char after pyrolysis can be gasified by further treatment with steam, hydrogen or carbon monoxide and water. The heat available from the products of pyrolysis is sufficient to sustain the process and yield some excess energy.Three types of reactor design have been generally used in the investigation of pyrolysis of MSW; fixed bed reactor, fluidized bed reactor and rotary kiln reactor. The advantages and weak points of each of these are briefly discussed.The costs of disposal of MSW by pyrolysis appear to be competitive with incineration.
Analysis of mednikov's equation for the transport of aerosol particles across a turbulent boundary layer
Authors: Beeckmans J. M. 
Published: March 2009

AbstractNumerical solutions are presented for the problem of transport of aerosol particles across a turbulent boundary layer to an absorbing wall, using Mednikov's migration velocity mechanism in addition to molecular and turbulent diffusivity terms in the transport equation. It is shown that inclusion of the migration velocity term leads to a gross overestimate of the rate of transport at certain velocities, and it is concluded that Mednikov's expression cannot be valid in its present form.
The effect of isomerization on chemical equilibrium
Authors: Smith W. R. , Missen R. W. 
Published: March 2009

AbstractA proof is given of the following statement: “If a set of isomeric forms is accessible to a chemical substance at equilibrium in a closed system (at given T and P, say) then the (relative) amount of the substance present at equilibrium is greater than it would be if only a strict subset of these forms were accessible”. The proof is restricted to ideal solutions. The statement is illustrated by calculations on the system consisting of benzene and the methyl benzenes to show the implications for equilibrium conversion and yield.
Performance studies on a high temperature thermal regenerator with radial flow geometry
Authors: Handley D. , Heggs P. J. , Stacey J. M. 
Published: March 2009

AbstractThis paper describes the design, construction and performance of a high temperature thermal regenerator of annular geometry with radial air flow present. This regenerator has possible application to the efficient exploitation of high temperature gas reactions and in particular to the fixation of atmospheric nitrogen for which this investigation was made. A mathematical model is formulated for the transient heat transfer between a fluid and an annular solid matrix with reversing flows and is solved numerically. The model is used to predict and analyse the operating performance of the regenerator over a range of flow rates (650 Kg/hr maximum), flow reversal periods (100 seconds maximum) and core temperatures (1431°C maximum). The model is tested by comparison of the theoretical and observed regenerator effectiveness, internal bed temperature profiles and the bed pressure drop under conditions of cyclic equilibrium. Apparent effective heat transfer coefficients for the regenerator packing are obtained and compared with an empirical correlation based on independant measurements.
Investigation of the fundamental assumptions relating compression‐permeability data with filtration
Authors: Willis M. S. , Shen M. , Gray K. J. 
Published: March 2009

AbstractA recently reported investigation indicates several inaccuracies in the methodology of compression‐permeability (C‐P) testing which suggest that previously reported agreement between C‐P and filtration data may be fortuitous. Until now, there has been no separate and direct confirmation of each of the two assumptions necessary to obtain a unique correspondence between C‐P and filtration data.The first assumption that the specific filtration resistance is a function solely of cumulative‐drag‐stress is generally accepted. Direct proof requires that the parabolic filtration equation, which is derived primarily on this assumption, describes both incompressible and compressible cake behavior. Most materials produce compressible cakes and “a priori” screening to find an incompressible cake requires identification of a material (Geon) that produces a cake with a linear axial pressure distribution. Results show that the parabolic filtration equation fits both types of cake behavior but an equation based on constant filtration resistance describes only incompressible cake behavior. To engineering accuracy and for dilute slurries, the assumption is verified.The second assumption that the cumulative‐drag‐stress equals the cake pressure drop is a macroscopic force balance and experimental verification requires a filter chamber designed to measure both of these quantities. A theoretical development, based on integral averaging, and experimental results both indicate that the ratio of cumulative‐drag‐stress to cake pressure drop correlates extremely well with cake porosity.A unique one‐to‐one correspondence between C‐P and filtration data is not possible without “a priori” knowledge of filter cake porosity. Previously reported agreement between C‐P and filtration data can probably be attributed to the L/D dependence of C‐P specific filtration resistances. Consequently, C‐P data can be used as a research tool to simulate filtration data but predicted filtration times based solely on C‐P data can be in considerable error.
Powder processing in a plasma jet: A proposed model
Authors: Boulos M. I. , Gauvin W. H. 
Published: March 2009

AbstractA theoretical study is reported on the use of d.c. and r.f. plasma jets as chemical reactors for the processing of minerals in the form of a fine powder. The temperature and flow fields of the jet are calculated by solving the integral boundary layer equations. Single particles trajectories are obtained by solving the Basset‐Odar equations. A multi‐particle model is then developed for a feed of known particle size and injection velocity distributions under low loading conditions. Calculators are made on the thermal decomposition of molybdenum disulphide (5 to 30‐micron equivalent diameter). The parameters investigated are the free jet velocity, the mean injection velocity, and the reactor ambient conditions. The results are presented as the probability density distributions of the gas loading, particle temperature, and conversion at different levels downstream of the nozzle.
Kinetic study of the solid‐state reaction between phthalic anhydride and P‐nitroaniline
Authors: Ramachandran S. , Baradarajan A. , Satyanarayana M. 
Published: March 2009

AbstractThe addition reaction between the compacted powders of phthalic anhydride and p‐nitroaniline was studied. Both the reactants of equal particle size, were mixed in 1‐to‐1 molar ratio and compacted. Three particle sizes — 0.0065 cm, 0.0178 cm and 0.0376 cm and three compaction pressures — 302.0 kgf/cm2, 785.0 kgf/cm2 and 1208.0 kgf/cm2 were used for the study. Conversions were measured at 80°, 90°, 100°, 110° and 120°C for 1/2, 1, 2, 4, 8, 12, 16, 20 and 24 hours. The reaction rate changed to a constant value, after an initial phase boundary process. The mole percentage conversions increased with decrease in particle size, increase in compaction pressure corresponding to a decrease in the initial porosity of the compact. It was also observed that the final porosity of the compact increased with increase in reaction temperature. Combination of Jander's model and parabolic rate law was used to calculate the values of the reaction rate constant equivalent. The activation energy was calculated to be 14 to 34 kilocalories per gram mole.
Kinetics of reduction of solid copper sulphate by hydrogen and carbon monoxide
Authors: Van Kim Vo , Habashi Fathi 
Published: March 2009

AbstractCupric sulphate is reduced to metallic copper by H2 at 225° to 400° with formation of Cu2SO4 as an intermediate product. Under the present experimental conditions, the reduction followered the equation k = 1 — (1 — R)1/3, where R is the fraction reacted at time t and k is the velocity constant. The activation energy of the overall process in this temperature range lies between 15 and 17 Kcal/mole. Reduction by CO takes place at 400° to 650°C with formation of Cu2SO4 and Cu2O and the activation energy in this temperature range lies between 24 and 29 Kcal/mole. Reduction in both cases is exothermic.
Polymerization of butadiene with tii4‐Al(i‐Bu)3 Catalyst: Part II: Kinetic model development
Authors: Loo C. C. , Hsu C. C. 
Published: March 2009

AbstractExpressions for conversions, Mn and Mw have been derived for the proposed kinetic scheme for the polymerization of butadiene using Til4 — Al(i‐Bu)3 as catalyst. The rate constants kp, kta and kd and the active sites were estimated from experimental data of conversion and molecular weight averages. The logarithm of both kp and kta are linearly related to Al/Ti ratio. On the other hand, kd and Co appear to be uncorrelated with the reaction variables studied in this investigation. The activation energy for propagation reaction was found to be 12.05 ± 1.31 which agrees well with those reported previously. The small difference in the activation energies for kp and kta accounts for the independence of the molecular weight of the polymer on the reaction temperature.
Statistical identification of the dynamic behavior of a dual input heat exchanger network
Authors: Wright J. D. , Bacon D. W. 
Published: March 2009

AbstractStatistical modelling procedures proposed by Box and Jenkins are used to develop models for the transfer function and noise behaviour of a dual input pilot scale heat exchanger network. Data were collected under operating conditions closely resembling full scale industrial operation first with uncorrelated inputs and then with correlated inputs. Two modelling strategies, a superposition approach and a transformed input approach, are employed to analyze the data. Computational advantages of the transformed input procedure for correlated input situations is demonstrated and the effectiveness of both strategies in detecting nonstationarity in the system noise is also illustrated.
Comments on the prediction of liquid holdup for gas‐liquid flow in inclined pipes
Authors: Gregory G. A. 
Published: March 2009

AbstractFour correlations for predicting the in situ liquid volume fraction for gas‐liquid flow in inclined pipes have been tested against available data from the literature. It is demonstrated that the commonly used correlations of Baker(4) and Flanigan(5) are subject to large errors. It is recommended that the correlation of Guzhov et al(2) be used unless it predicts values of EL less than 0.25. In the latter case, the Lockhart‐Martinelli(3) correlation should be used.
Practical significance of brinkman's extension of darcy's law: Coupled parallel flows within a channel and a bounding porous medium
Authors: Neale Graham , Nader Walter 
Published: March 2009

AbstractProblems involving fluid flow past permeable surfaces have customarily been solved by matching Darcy's Law with the Navier‐Stokes equation via an empirical slip‐flow boundary condition at these surfaces. The present analysis serves to place the semi‐empirical theory proposed by Beavers and Joseph (1967) on a more rigorous physical and mathematical basis. It is demonstrated that the predictions of these workers may be derived independently, without having to formulate empirical boundary conditions, by employing Brinkman's extension of Darcy's Law within the porous medium. These predictions are in satisfactory agreement with experimental data, thereby providing a quantitative verification of Brink‐man's equation to complement its theoretical verification presented recently by several authors.
Purging calculations for cascades of mixing stages
Authors: Tomiak A. 
Published: March 2009

AbstractGeneralized algebraical expressions were obtained for average individual stage and final effluent concentrations in a cascade of mixing stages in series, without specifying the mixing pattern. Such expressions, combined with the knowledge of particular mining patterns, may be used for solving more complex purging problems.A detailed computation method was given for the specific case of countercurrent purging of a cascade under perfect mixing conditions as an example.
Some surface and kinetic effects of trace additions of selected metal oxides and halides on the thermodehydration of silica xerogel spheroids
Authors: Ross R. A. , Henry N. 
Published: March 2009

AbstractA kinetic study of the sintering of silica xerogel has been carried out by following the rate of dehydration of xerogel spheroids, 2000 ‐ 841 μ, on a thermal balance in the presence of small additions, usually 5 g. ion percent of selected metal oxides and halides. First order rate constants calculated from the classical kinetic expression were in excellent agreement with those obtained from the Avrami‐Erofeev equation for nucleation and growth in the case of a monomolecular reaction. The surface areas and mercury densities of samples cooled from 900°, 850°, 800° and 500°C have been measured and X‐ray powder diffraction patterns obtained for most samples in an attempt to identify phases formed by solid‐solid interaction between the gel and the additives.The activation energies of the dehydration for the oxide additives, (CuO, NiO, Cr2O3, BeO, ZnO and Al2O3), did not show substantial enough differences to allow any decisive analysis to be made on the basis of established properties of the oxides. CdO was the most active oxide in xerogel dehydration and it is shown that this oxide takes part readily in solid‐solid reactions with the xerogel in the vicinity of the Tamman temperature of silica. In the presence of the transition metal halides, (NiCl2, CrCl3, CuCl2 and CoCl2), hydrogen chloride was evolved from the matrix and xerogel dehydration may be accentuated by reaction of this gas with accessible surface hydroxyl groups. The addition of sodium halides showed no significant differences in dehydration rates whereas with lithium salts, the rate and amount of dehydration varied with the melting point of the additive.
A method for simplifying linear multivariable dynamic systems
Authors: Gupta Y. P. , Donnelly J. K. , Andre H. 
Published: March 2009

AbstractA method for reducing the order of linear multivariable stable dynamic systems is proposed. The main advantage of this method is that the problem of determining a simplified model is reduced to few matrix manipulations and solution of a few algebraic equations which can be easily programed. The simplified model is obtained so that a quadratic functional of the difference between the output vector and that of the original model is automatically minimized for either step or impulse inputs. Applications of the method include simplification of a dynamic model of a pilot plant for the azeotropic distillation of n‐butyl acetate and n‐butanol. Very good agreement between the step responses of the original and simplified model is obtained.
Diminution du temps de préchauffage d'un réacteur isothermique
Authors: Pineault Gilles , Dekee Daniel 
Published: March 2009

AbstractL'étude de la cinétique d'une réaction chimique effectuée dans un réacteur discontinu et muni d'un mécanisme de chauffage inadéquat, a conduit à la mise au point d'un systénie de préchauffage plus efficace du réacteur. Le manchon de chauffage électrique à été remplacé par un bain d'huile maintenu à température constante et muni d'un agitateur couplé au moteur électrique au moyen d'un joint d'étanchéité au mercure afin d'assurer une distribution uniforme de température à l'intérieur du bain d'huile. Le temps de préchauffage théorique de ce nouveau systéme est considérablement inférieur au temps de préchauffage du réacteur original, éliminant presque complétement les erreurs dans l'évaluation du taux de réaction chimique.
Effect of cations on the maximum yield values of a bentonite clay gel
Authors: Hu C.‐S. , Pinder K. L. 
Published: March 2009

AbstractThe effect of cations on the gel strength of a bentonite clay was studied by measuring the maximum yield value of clay salt mixtures.Cations which are in large concentration as exchanged ions on the clay act very differently upon the clay strength than do cations which are only in trace concentrations in the clay. For those cations which were originally in only trace concentrations, the ability to build up the gel strength is inversely proportional to their valence.Sodium and calcium ions reacted completely differently. The clay was tolerant to a large sodium concentration but lost gel strength with the addition of only a small amount of calcium. This result is explained in the light of previously reported ion exchange properties of clay.
Scaling of enhanced heat exchanger tubes
Authors: Watkinson A. P. , Louis L. , Brent R. 
Published: March 2009

AbstractThe performance of inner‐fin and spirally indented heat exchanger tubes is compared with plain smooth tubes under severe scaling conditions. Artificially hardened water was recirculated through a heat exchanger which contained an enhanced tube and a plain tube in parallel and the decrease in heat transfer coefficient due to scale deposition followed with time. Inner‐fin and spirally indented tubes maintained advantages in heat transfer coefficient over plain tubes of 10 to 100% after scaling. Asymptotic fouling resistances were larger for the inner fin tubes than for plain tubes, and smaller for the spirally indented tubes at velocities above 3 ft/sec.