bluuebunny/crossref_metadata_2025_split huggingface dataset:
New mixing rules for the BWR parameters to predict mixture properties
Authors: Bishnoi P. R. , Robinson D. B. 
Published: March 2009

AbstractNew mixing rules which are general and easy to use have been developed to predict the properties of mixtures from the BWR equation. The rules contain a binary interaction parameter, readily obtainable from the experimental values of the second virial cross‐coefficients. The mixing rules were used to predict the densities of binary mixtures of carbon dioxide with methane, ethane and propane at elevated pressures. For any of the three mixtures, the standard error of the predictions was approximately equal to or less than the sum of the standard errors of fit for the pure components. The BWR parameters for the pure components, required in the above predictions, were determined by minimizing the sum of relative error squares in specific volume.
Fluid‐fluid interactions and hydrodynamics in agitated dispersions: A simulation model
Authors: Zeitlin M. A. , Tavlarides L. L. 
Published: March 2009

AbstractA model which accounts for complex fluid‐fluid interactions and hydrodynamic effects in a fully baffled turbulently agitated dispersed phase system for batch, semi‐batch, or continuous operation is developed. Both micromixing and macromixing effects on particle size distributions are taken into account. Coalescence and breakage functions are developed and examples are given of the normalized number and/or volume size distributions for various vessel regions. Calculated distributions are compared with experimental data to estimate values of coalescence and breakage parameters. Effects of coalescence, breakage, and system parameters on transient and steady state distributions are determined.
Pressure drop in a mobile‐bed contactor
Authors: Tichy J. , Wong A. , Douglas W. J. M. 
Published: March 2009

AbstractThe overall pressure drop and the vertical static pressure profile in a 0.14‐m. diameter mobile‐bed contactor have been investigated for two packing sizes and three packing heights. The gas and liquid flow rates were the two other variables studied. Foam polystyrene spheres were used as packings.The relationship between the static pressure and vertical position of the bed was found to be linear. A correlation of the drag parameter with Gg, Gt and Lp is presented. States of fully‐mobile bed operation are discussed.
A mathematical simulation of radiant heat transfer in a cylindrical furnace
Authors: Osuwan S. , Steward F. R. 
Published: March 2009

AbstractThe radiative heat transfer in a cylindrical furnace was investigated both experimentally and theoretically.The flow pattern within the combustion chamber was measured and found to differ from that of an identical cold model for which extensive theoretical and experimental work had been previously carried out.The Monte Carlo Method was used to solve for the radiative transfer part of the non‐linear integro‐differential equations describing the combustion and heat transfer in a cylindrical furnace.The radiative heat flux distribution obtained from the simulation agreed well with data obtained from a cylindrical test furnace.
Heat transfer in tubes and ducts with wall mass transfer
Authors: Raithby G. D. 
Published: March 2009

AbstractThis study is concerned with the developing temperature field for flow in circular tubes and parallel plate channels with mass transfer through the wall. Some unique features of the developing temperature field are outlined for both constant temperature and constant heat flux boundary conditions. Solutions to the heat transfer problem are extended to include arbitrary prescribed temperature or heat flux boundary conditions. A practical problem is solved in two ways, utilizing respectively these solutions, and a comparison of the results is made.
A general asymptotic analytical solution for non‐catalytic gas‐solid reactions
Authors: Williams R. J. J. , Calvelo A. , Cunningham R. E. 
Published: March 2009

AbstractThe reaction between a porous solid pellet and a gas is analyzed in the asymptotic region of the effectiveness factor. The solid consumption is divided in two stages. The influences of effective diffusivity and surface area profiles are taken into account for both stages through a correction modulus of the effectiveness factor. The conversion — time relationship can be calculated for a selected model of porous structure and any reaction order for the gaseous reactant. The results are extended to non‐equimolar counterdiffusion and a non‐isothermal situation with external heat and mass transfer resistances.
Second virial coefficients of polar gases — a correlation with stockmayer potential function
Authors: Polak Jiri , Lu Benjamin C. Y. 
Published: March 2009

AbstractThe parameters of the Stockmayer potential function were calculated by a least‐squares analysis of the second virial coefficient data for 66 polar substances. By using these parameters, the second virial coefficient of these tabulated materials can be calculated with a mean standard deviation of 20.2 cm3 mole−1 or 3.2%. The possibility of extrapolating second virial coefficients from high to low temperatures is also demonstrated.
The hydrodynamics or gas‐liquid contacting in towers with fluidised packings
Authors: O'neill B. K. , Nicklin D. J. , Morgan N. J. , Leung L. S. 
Published: March 2009

AbstractA model is developed of gas liquid contactors in which packing pieces are maintained in the fluidized state. The model proposes that the column can exist in either of two modes, namely fluidisation without flooding and fluidisation due to incipient flooding. The mode of operation established depends primarily on the packing density and to a lesser extent on the packing size, liquid flow and liquid properties. Equations predicting the transition from one mode to the next are developed. The inherent advantages of operating in the “incipient flooding” mode are stressed. It is argued that the pressure build up associated with flooding will be sufficient to support the weight of packing pieces and the liquid in the column. At this stage, rather than reject counter current flow (true flooding) the bed expands to maintain a state of incipient flooding. In this way counter current flow can be maintained in a situation well above the normal flooding point. This explains the high performance of such units.
The flow of thin films inside rotating cylindrical tubes
Authors: Barnea E. , Kovalivker E. , Mizrahi J. , Yacoub N. 
Published: March 2009

AbstractA mathematical model was derived for the calculation of the film thickness, total holdup and overall residence time of a thin liquid film flowing inside a rotating cylindrical tube, as a function of the liquid throughput and physical properties and of the tube diameter, length, rotational speed and angle of inclination.The experimental data with short tubes showed good agreement with the model for average film thickness above a certain critical value (which may indicate a change in the flow regime).
Hold‐up and axial mixing characteristics of two and three phase fluidized beds
Authors: Kim S. D. , Baker C. G. J. , Bergougnou M. A. 
Published: March 2009

AbstractThe hydrodynamics of two (water‐air, water‐solids) and three (water‐air‐solids) phase fluidized beds have been studied in a large two‐dimensional column. Two solids were used, namely 6 mm glass beads and 2.6 mm irregular gravel.The individual phase holds‐ups, bed expansion, and axial mixing characteristics were measured. The data were correlated empirically by equations involving liquid and gas phase Reynolds and Froude numbers, and the ratios of the particle and fluid densities. Bubble sizes and rising velocities were determined photographically and found to be of great importance in determining the hydrodynamics of the different beds.
Influence de léagitation mécanique sur les transferts thermiques en fluidisation homogène
Authors: Varela B. , Couderc J. P. , Angelino H. 
Published: March 2009

AbstractIt is possible, through the use of an agitator with a particular shape which renews in a rapid sequence the matter contacting the column walls, to increase significantly the intensity of the thermal transfer between a liquid fluidized layer and the walls. It is shown experimentally that the rotative speed of the agitator has an important effect on the transfer. The whole results are qualitatively interpreted within the framework of a transiant‐state mechanism.
Viscosity of nitrogen gas at low temperatures up to high pressures: A new appraisal
Authors: Latto B. , Saunders M. W. 
Published: March 2009

AbstractThe absolute viscosity of nitrogen gas was determined experimentally for the pressure and temperature range 1 to 150 atmospheres and 90°K to 400°K respectively. The maximum error in the data presented is believed to be better than ±1.5%, and ±1% for the high and low pressure data respectively.Two general correlating equations, one for atmospheric pressure and the other for all the available high pressure data, (i.e. densities up to 0.4 g/cc or 1.5 ρ (critical)) are presented, together with a table of recommended smoothed data, which are felt to be accurate to ±1.5% or better. Values for the low velocity collision diameter σ and maximum energy attraction functions are also presented for the low pressure data.
Application of wilsonés equation to determination of vapor‐liquid equilibrium data and heats of mixing for non‐ideal solutions
Authors: Tai Trinh Ba , Ramalho Rubens S. , Kaliaguine S. 
Published: March 2009

AbstractA calculation technique, starting from total pressure data of binary systems and utilizing Wilsonés equation was developed, leading to isothermal vapor liquid equilibrium data for binary and ternary systems. Heats of mixing for ternary systems were also calculated from binary data.
Parameter estimation using linear programming and quasilinearization
Authors: Nieman R. E. , Fisher D. G. 
Published: March 2009

AbstractA generalized algorithm for the estimation of parameters in a process model from experimental data is presented in this paper. The algorithm, which combines linear programming with quasilinearization, is formulated and its advantages and limitations are discussed. Examples are included to illustrate application of the algorithm to real engineering problems, one of which was encountered in industry and another of which was encountered in a control study. The examples demonstrate the incorporation of constraints, convergence promotion and reliability estimates into the identification.
Vertical pneumatic conveying: A theoretical study of uniform and annular particle flow models
Authors: Capes C. E. , Nakamura K. 
Published: March 2009

AbstractTwo models for vertical pneumatic conveying, a uniform flow model at high gas velocities and an annular flow model near the particle terminal velocity, have been examined theoretically. The uniform flow model leads to the following relationship between gas and particle velocity and line porosity:No simple analytical solution was found for the annular flow model but a numerical solution was possible.Both models indicate that slip velocity may exceed the particle terminal velocity under certain conditions. The theoretical predictions agree reasonably well with experimental observations.
Flow behavior of power‐law fluids in the entrance region of annuli
Authors: Tiu Carlos , Bhattacharyya Satinath 
Published: March 2009

AbstractMomentum‐integral and momentum‐energy‐integral methods are used to study the laminar entrance behaviour of power‐law fluids in annuli. The momentum‐energy method, which yields a longer entry length, appears to provide a better overall description of the entry flow behaviour. The method compares favourably with the existing Newtonian solutions for annular flow and with the non‐Newtonian flow in pipes and parallel plates in the limiting cases. The linearisation technique is also extended to power law fluids utilising the geometric parameter method. The loss coefficients predicted by the linearisation technique agree well with those obtained by the integral methods.
Wall heat transfer to chemical reactors
Authors: Chao Raul E. , Caban R. A. , Irizarry M. M. 
Published: March 2009

AbstractThe effects of chemical reactions on wall heat transfer coefficients in packed bed reactors operating at equilibrium or near equilibrium conditions are explored by means of one‐dimensional and two‐dimensional models. Both approaches suggest using Damköhler number or ratios of reacting to frozen heat capacity as parameters in heat transfer correlations. Available data for the methane‐steam reforming reactors were used to establish a suitable correlation for use in thermal design of reacting beds of solids, i. e. NNu = 0.195 NRe0.8 exp. (0.21 σ)This correlation can be applied with reasonable accuracy for beds which are 3 to 5‐in. in diameter and bed to particle diameter ratios from 5 to 10. A review of available correlations for wall coefficients obtained under non‐reacting packed bed conditions is also presented.
Some observations on uniqueness and multiplicity of steady states in non‐adiabatic chemically reacting systems
Authors: Varma Arvind , Amundson Neal R. 
Published: March 2009

AbstractAn investigation of uniqueness and multiplicity of the steady states in two non‐adiabatic chemically reacting systems, the stirred tank and the tubular reactors, is presented. Exact uniqueness and multiplicity criteria are presented, and some conclusions derived therefrom, for the stirred tank reactor. For the tubular reactor, some numerical results are reported and multiplicities of the type 1‐3‐1, 1‐3‐1‐3‐1 and 1‐3‐5‐3‐1 noted. Criteria obtained earlier and those obtained from a lumping approximation of the distributed system are evaluated. In addition, two asymptotic solutions are obtained for the non‐adiabatic tubular reactor.
A general method of predicting the water activity of ternary aqueous solutions from binary data
Authors: Chen H. , Sangster J. , Teng T. T. , Lenzi F. 
Published: March 2009

AbstractAn isopiestic method has been developed to predict aw for ternary solutions from binary aw data. Another method, previously outlined by Robinson and Bower, has been extended to include non‐electrolytes. Both methods have been used to predict aw's for 51 representative systems. The results show that the isopiestic method is as good as, or better than Robinson and Bower's in predicting aw for ternary aqueous electrolyte/ electrolyte, electrolyte/non‐electrolyte and non‐electrolyte/non‐dectrolyte systems.Calculated aw values are in good agreement (<0.5%> error on the average) with experiment.The methods are applicable to relatively concentrated solutions up to 12 m.
Flow patterns in viscoelastic liquids upstream of orifices
Authors: Oliver D. R. , Bragg R. 
Published: March 2009

AbstractThe flow patterns obtained when aqueous polyacrylamide solutions flow into orifices are photographed. The polymer concentrations are 0.01, 0.03 and 0.10 per cent, the orifice diameters 1.27, 0.95, 0.50, 0.20 and 0.10 cm and the flow velocities 7‐700 cm/sec.Various flow patterns are identified, including the well‐defined conical form. The semi‐angle of the cone decreases with decreasing orifice size and also depends on flow velocity, particularly when the larger orifices are being used. Cone angle also depends on the concentration of the solution. The flow pattern sometimes changes abruptly when flow velocity is increased; flow instability is often present.Finally, it is suggested that the flow pattern is established as a result of interplay between extensional forces present in the liquid at the orifice and viscous and kinetic effects in the upstream fluid.
Heat transfer from a vibrating vertical array of horizontal cylinders
Authors: Hsieh R. , Marsters G. F. 
Published: March 2009

AbstractResults are presented for experiments performed on a vibrating array of five identical heated cylinders. The cylinders are arranged with their axes horizontal and in the same vertical plane. They are held by a U‐shaped yoke. The spacing between cylinders was set at two diameters for most of the work. The array yoke is clamped to a resonant beam which is driven by a magnetic vibrator. The range of vibration intensities from zero to 0.61 has been studied. The vibrating array showed an increase in heat transfer rate of up to 54% for the conditions covered in this report. The trend of the data indicates greater increases at higher vibration intensities.
The effect of local gas velocity and temperature on local heat transfer to a sphere in a high‐temperature jet
Authors: Katta S. , Gauvin W. H. 
Published: March 2009

AbstractCorrelations for overall or local heat transfer to spheres based on flow conditions prevailing just ahead of the sphere or in its absence constitute an oversimplification, particularly in the presence of the steep temperature and velocity gradients existing in a plasma flame. This study presents correlations based on local values of heat flux and on local values of the free‐stream temperature and velocity of an argon plasma jet, as well as data obtained in helium. A single correlation for the argon and helium data was obtained with the use of a thermal conductivity ratio correction. The characteristics of the argon plasma jet were interpreted according to classical jet mixing theory.
Influence de la pulsation sur les transferts de matière entre une sphère et un liquide
Authors: Gibert H. , Angelino H. 
Published: March 2009

AbstractUtilisant une technique de mesure électrochimique, les auteurs ont mesuré les coefficients globaux de transfert de matière entre une sphère solide et un liquide, l'une ou l'autre de ces phases étant soumise à un mouvement sinusoïdal alternatif.l'intensité des transferts est fortement accrue pendant la pulsation; elle s'avèrve indépendante de la technique d'agitation utilisée, et ceci à moins de 10% près.Dans le cas de la vibration de la sphère, les équations de transfert s'écrivent:

Il est important de souligner que l'exposant du facteur caractéristique de la vibration est égal à celui obtenu pour des transferts en convection forcée dans le cas d'un écoulement permanent. Cependant l'hypothèse de l'état quasi stationnaire n'est pas valable, l'intensité de transfert mesurée étant supérienre d'au moins 25% à la valeur théorique.
Evaporation rates of liquid hydrocarbon spills on land and water
Authors: Mackay Donald , Matsugu Ronald S. 
Published: March 2009

AbstractThe mass and heat transfer processes occurring during the evaporation of liquid hydrocarbon spills on land and water are described and equations developed to enable the liquid temperature and evaporation rate to be predicted. Experiments on the evaporation of cumene, water and gasoline are described and the evaporation mass transfer coefficient correlated with the wind‐speed, liquid pool size and the vapour phase Schmidt Number. Good agreement is obtained between experimental and computed cumene temperature and evaporation rates. Comparison of the correlation with flat plate mass transfer correlations shows satisfactory agreement and suggests that turbulent transfer occurs, the rate being enhanced by the liquid surface roughness. The more complex problem of estimating evaporation rates of hydrocarbon mixtures is discussed briefly.
Simulated random packing of equal spheres
Authors: Tory E. M. , Church B. H. , Tam M. K. , Ratner M. 
Published: March 2009

AbstractPACS, a computer program to simulate very slow settling of rigid equal spheres into a randomly packed bed, is described. Simulated packings of 6,000, 10,000, and 15,000 spheres are anisotropic. Mean void fraction is 0.42 and mean number of nearest neighbours 6.0. There are numerous cases of four spheres arranged in a tetrahedron, but no larger ordered regions. These findings, plus local voidage, distribution of circles in a section, angular distribution, and radial distribution are compared to theoretical and experimental results.
Coalescence and break‐up in dilute polydispersions
Authors: Shiloh K. , Sideman S. , Resnick W. 
Published: March 2009

AbstractFunctional relationships for coalescence rate dependence on drop size and hold‐up were derived via the collision rates and coalescence efficiency. Experiments in an agitated vessel indicated the coalescence rate to be controlled by the viscous flow regime and, per unit drop concentrations, to be proportional to the third power of the sum of the diameters of the two coalescing drops. By combining the experimentally known coalescence rate dependence on drop diameter with the independently determined dependence of the latter on the dispersed phase hold up, the breakup rate was found to depend on d2.0.
Viscous flow across banks of circular and elliptical cylinders: Momentum and heat transfer
Authors: Masliyah Jacob H. 
Published: March 2009

AbstractNumerical solutions of the Naviet‐Stokes equation have been used to extend Kuwabara's zero voiticity cell model to flow past banks of circular and elliptical cylinders for Reynolds numbers up to 50 and for porosities between 0.4 and 0.8. Total drag coefficients are presented. The complete energy equation was also solved numerically for Prandtl numbers of 0.7 and 7. Good agreement between existing experimental results for heat transfer in banks of circular cylinders and the numerical solution was obtained. In the assemblage, the ratio of the total heat transfer to pressure drop was highest when the main flow was parallel to the major axes of the elliptical cylinders. In all cases considered, the ratio of the minor to the major axis was 0.2.
Symposium on application of pulse techniques to kinetic measurements: Influence of cycling on the rate of oxidation of SO2 over a vanadia catalyst
Authors: Unni M. P. , Hudgins R. R. , Silveston P. L. 
Published: March 2009

AbstractFeed composition cycling of the catalytic oxidation of SO2 to SO3 in an isothermal, differential reactor was studied using an industrial vanadia catalyst. Reaction was carried out at 405°C using square‐wave cycles of SO2, O2 and N2 at pressures close to atmospheric and at constant total molar flow through the reactor. Significant increases were found in the rate of oxidation of SO2 over steady‐state values, depending upon the choice of both amplitude and period.Some preliminary interpretation of these results is provided.
A new class of solution methods for multicomponent, multistage separation processes
Authors: Boston J. F. , Sullivan S. L. 
Published: March 2009

AbstractA new algorithm was developed for the solution of the equations that describe multicomponent, multistage separation processes operating at steady state. The algorithm is based on the use of newly defined energy and volatility parameters as the primary successive approximation variables. A third parameter was defined for each stage as a unique combination of the liquid and vapor phase rates and the temperature, and the quasi‐Newton method of Broyden was employed to iterate on these parameters. The exceptional stability of the new algorithm in very difficult cases, as well as its efficiency in easy cases, are demonstrated using a variety of example problems.
Time‐optimal control of linear systems
Authors: Luus Rein 
Published: March 2009

AbstractA useful procedure for the solution of time‐optimal control problems for linear systems is presented. The procedure consists of a direct search method for the determination of the best diagonal weighting matrix used in a Liapunov function for the system. The control policy chosen to minimize the forward difference of the Liapunov function yields very rapid approach to the origin.Numerical results are presented for a linear six‐plate gas absorber to show the feasibility of the proposed method. Even in the presence of disturbances the system can be taken to and kept at the vicinity of the origin.