bluuebunny/crossref_metadata_2025_split huggingface dataset:
An experimental model for visual studies of turbulent flow in porous materials
Authors: Kyle C. R. , Perrine R. L. 
Published: March 2009

AbstractA two‐dimensional experimental model has been developed to simulate turbulent flow in porous materials. It uses cross flow through a matrix of cylinders between parallel plexiglass plates. Matrix geometry was chosen to approximate a bed of packed spheres.Pressure loss and axial dispersion in several models have been measured over a wide range of flow rates in the non‐Darcy region. Photographs have been taken of flow patterns developed in the transition from laminar to fully turbulent flow. All typical characteristics of flow through beds of packed spheres were exhibited; however, both pressure loss and dispersion differed somewhat when compared to similar three‐dimensional flow.
Condensation on a vertical rotating finned tube
Authors: Williams A. G. , Nandapurkar S. S. , Holland F. A. 
Published: March 2009

AbstractExperiments have been carried out to determine the effect of centrifugal force on the rate of condensation of vapors. Methanol and isopropanol vapors were condensed on a vertical rotating finned tube and it was found that the data could be correlated by the equation:

Condensation film heat transfer coefficients in excess of 5,700 W/(m2 °K) and 4,200 W/(m2 °K) were obtained for methanol and isopropanol respectively at a tube rotational speed of 1,000 rpm.
Dynamics of cyclic fixed bed ion exchange an analysis based on a linear mass transfer model
Authors: Tan K. S. , Spinner I. H. 
Published: March 2009

AbstractSolutions for fixed bed ion exchange based on a linear mass transfer model (linear isotherm and linear driving force rate equation) and general initial and boundary conditions are presented. The linear model solutions are applied to the study of the cyclic operation of fixed bed ion exchange and the equations describing both the transient and cyclic fixed bed processes for co‐current regeneration are derived. Examples which illustrate the simplicity of application of the analytical solutions are discussed.
Interpretation of chromatographic peaks by fourier analysis
Authors: Gangwal S. K. , Hudgins R. R. , Bryson A. W. , Silveston P. L. 
Published: March 2009

AbstractExtraction of model parameters, such as kinetic rate coefficients, equilibrium constants and transport rate coefficients, may be obtained by determining the coefficients of the Fourier series which describe chromatographic peaks. Error buildup due to noise occurs slowly with successive harmonics in contrast to the rapid buildup in successive moments which make higher moments unreliable for extracting model parameters. Fourier analysis is applied to the simplest case of axial dispersion in a non‐porous, non‐adsorbing packing and to the important case of adsorption on a porous packing. Expressions for the Fourier coefficients, amplitude ratios and phase lags are derived for the axial dispersion case, the Kubin‐Kucera model for adsorption on a porous packing and, as well, for the case of axial dispersion and inter‐particle diffusion without adsorption.
Dynamics of convection heat exchangers
Authors: Heidemann R. A. , Huckaba C. E. , Eisen F. S. , Weissman L. I. , Gallatig G. M. 
Published: March 2009

AbstractA mathematical model is developed for heat exchangers with condensing vapors on one side which includes the effects of variations in the local film heat transfer coefficients and allows for energy accumulation and conduction in the tube wall. A numerical integration scheme for the flow forced case is presented. The model is tested against experimental steady state and transient data for a steam‐water exchanger. It was necessary to modify the standard correlations of heat transfer coefficients to get a match of the overall steady state heat flux actually obtained in the apparatus. With these modified heat transfer coefficients, the model proved capable of predicting flow forced transients. These results are contrasted with transients predicted by a simple lumped parameters model employing empirically fit overall heat transfer coefficients. The lumped parameters model is shown quite adequate for predicting transient behavior under the specific conditions studied. The reasons for and limitations on the success of this very simple model are explored.
Expansion of a single gas bubble rising in a column of liquid
Authors: Weller K. R. 
Published: March 2009

AbstractMeasurements of the expansion behavior of single bubbles of an insoluble gas by monitoring the pressure change in a gas space at the top of a closed column show that the same expansion law applies both to the bubble and the gas space, but the correct expansion law cannot be deduced from pressure measurements alone. Results from a semi‐quantitative heat transfer experiment indicate that isothermal expansion should be assumed.
Friction factors in pulsed turbulent flow
Authors: Baird M. H. I. , Round G. F. , Cardenas J. N. 
Published: March 2009

AbstractAn apparatus for investigating pulsed turbulent liquid flow in a 2 in. diameter, 80 ft. pipeline is described. The pulsation unit was powered by compressed air with a consumption of up to 2.7 std. cu.ft./min. at 35 lb/in2 gauge. The pressure drop for water flowing at mean velocities of 7.66 to 12.28 ft./sec. has been measured, both for steady flow and for pulsed flow, at frequencies between 0.48 and 0.82 Hz. The experimentally measured pressure versus time curves for pulsed flow can be matched fairly closely by a solution of Euler's equation employing the friction factors measured under steady flow conditions.
Composition dependence of viscosity of some binary solutions
Authors: Ghai R. K. , Dullien F. A. L. 
Published: March 2009

AbstractViscosities of eleven binary liquid systems, mostly regular solutions, have been measured over the entire composition ranges at 25°C. Most of the systems had not been investigated before. The procedure, the precautions observed for the measurement of viscosity, and the calibration of the viscometers have been discussed. Of the many empirical and semi‐empirical equations tested for their validity the McAllister equation has been found to fit best the experimental data for all the solutions. Non‐ideality of a solution, as expressed in terms of excess activation energy for viscous flow or in terms of excess molal volume, has also been briefly discussed.
Regional stability for a tubular reactor with axial mixing
Authors: Wang F. S. , Perlmutter D. D. 
Published: March 2009

AbstractA graphical phase‐plane procedure is suggested by which regions of stability can be estimated for a tubular reactor. The technique uses a super‐position of limits for primary flow and reaction effects and those arising from secondary axial dispersion. Several detailed numerical tests are reported to substantiate the conjecture.
Transport of solids by gas‐liquid mixtures in horizontal pipes
Authors: Scott D. S. , Rao P. K. 
Published: March 2009

AbstractTwo sizes of particles of 500μ and 100μ mean diameter were conveyed as water slurries through 1 inch and 2 inch horizontal pipelines. Pressure drops and saltation velocities were measured over a range of slurry concentrations to 14% by volume with and without concurrently flowing air. In the former case, the principal flow patterns studied were in the bubble and plug flow regimes. Although small effects on saltation point were noted due to the induced turbulence from the air bubbles, these were not significant, and a reasonable estimate of saltation velocities could be made from Durand's correlation. Pressure drops were found to be correlated reasonably well by modified Lockhart‐Martinelli parameters as used for turbulent‐turbulent horizontal gas‐liquid flow except at conditions near the saltation point. Pressure drops for slurry flow alone were predicted reasonably well by the modified Durand equation.
Theoretical interpretation of gas oil conversion data on an x‐sieve catalyst
Authors: Pachovsky R. A. , Wojciechowski B. W. 
Published: March 2009

AbstractA four parameter model based on the catalyst aging theory of Wojciechowski(5) is applied to experimental conversion data in gas oil cracking. The data extends over a range of cat/oil ratios from 0.094 to 3.0, and run times from 1.25 to 40 minutes. Within this range of conditions the model is applied to data with and without thermal conversion and excellent correlation between experimental results and calculated values is obtained. The technique for fitting data to the model is described in some detail.
Modeling and parametric studies of a vapour recompression distillation system
Authors: Menzies M. A. , Johnson A. I. 
Published: March 2009

AbstractA vapor recompression system for the separation of ethylene from a multicomponent feed has been modeled using the CHESS program and based on data from the Polymer Corporation. The experience in implementing CHESS on a CDC6400, and in using its property calculation features are reviewed. The modification of the CHESS modules, and new unit computations required for the study are described. Some typical applications of the model to seek improvements in plant operation are discussed.
Motion of entrained particles in gas streams
Authors: Clift R. , Gauvin W. H. 
Published: March 2009

AbstractRecent work on the drag experienced by an entrained particle in relative motion through a fluid is reviewed. It is shown that fluid turbulence, acceleration, particle shape and orientation, and particle‐fluid mass transfer can all have a significant effect on the value of the drag force, particularly when the non‐idealities cause a change in the flow pattern around the particle. Conditions under which the drag force can be predicted with certainty are still very limited, and some potentially valuable directions for future research are suggested.
Internal age and residence time distributions of a fluid in non‐ideal stirred tanks in series
Authors: Chiang David , Cholette A. 
Published: March 2009

AbstractThe internal age distribution of a fluid, for p imperfectly mixed vessels in series, is presented and interpreted in the light of the laws of probabilities.An expression is presented for the residence time distribution. Five graphs show the variation of this expression as a function of the reduced effective time, each graph being characterized by a given degree of channeling. The curves, similar to those for the dispersion model, indicate that the model can represent mixing conditions extending all the way from an imperfectly mixed reservoir to plug flow.An expression is also presented for the mean residence time.
Prediction of excess free energies of liquid mixtures containing aromatic hydrocarbons using a group solution model
Authors: Maripuri V. C. , Ratcliff G. A. 
Published: March 2009

AbstractThe group solution model of Ratcliff and Chao for the excess free energies of liquid mixtures has been tested and found satisfactory for six mixtures of alcohols and aromatic hydrocarbons. The model was tested by comparing experimental and predicted vapor‐liquid equilibrium data.The assumption that aliphatic and aromatic carbon atoms are equivalent appears satisfactory for the mixtures considered. Group contribution functions were generated from experimental data on ethanol/benzene mixtures at 45°C, and are presented. These functions allow the prediction of excess free energies of mixtures containing alcohols and aromatic hydrocarbons at 45°C. No experimental data is required. Predictions at temperatures close to 45°C, using the same functions, should be satisfactory.The group contribution functions were close to those generated previously from alcohol/alkane data. The latter may be used for predicting excess free energies of alcohol/aromatic hydrocarbon mixtures with little loss of accuracy.
Optimal switching policies for fixed bed catalytic reactors in series
Authors: Miertschin G. N. , Jackson R. 
Published: March 2009

AbstractIt frequently occurs in catalytic reforming that several fixed bed catalytic reactors are run in series. Periodically a bed must be removed and regenerated while a previously regenerated bed is used in its place. An algorithm that finds which bed to remove and how to order the remaining beds and the previously regenerated bed so that some suitable objective function is optimized is presented for the case where the catalyst decays uniformly down the length of each reactor.
A minimum time operating policy for a liquid‐liquid extraction column
Authors: Pang K. H. , Johnson A. I. 
Published: March 2009

AbstractTwo methods, both based on linear programming techniques, have been applied to determining the minimum time control policy for effecting a grade change in the product from a liquid‐liquid extraction column. The method was made possible by the existence of a linear dynamic model for the column derived from a previous frequency response study of the laboratory unit. Both methods predicted policies of a partial bang‐bang nature. As expected the control paths were not the same; additional control criteria such as minimum control effort or minimum number of switchings are suggested as a means of further defining a best control policy.Suitable bounds on the controlled variables were found in the study so that physically realizable control policies were formulated.
Preparation of amorphous silica
Authors: Funnell N. A. , Sirianni A. F. , Puddington I. E. 
Published: March 2009

AbstractAmorphous silica having reinforcing properties for styrene butadiene rubber (SBR) was obtained by contacting silica aquagel seed, containing 1‐3% SiO2 by weight, with a freshly prepared silica sol. Reinforcing by the isolated silica was greatly affected by the pH of the aquagel‐sol system and moderately affected by temperature and by the silica content of the aquagel seed. Maximum tensile strengths for the vulcanizates were found using the product obtained from a 2 to 2.5% silica aquagel seed‐sodium silicate system acidified with sulphuric acid to pH 3 at 85 to 95°C.
Dissolution of ferritic stainless steel scrap in hydrochloric acid
Authors: Rigg T. , Rahaman M. S. 
Published: March 2009

AbstractThe dissolution of a ferritic stainless steel (15.44% Cr, 0.39% Mn, 0.12% C) in hydrochloric acid has been investigated from the point of view of large scale processing. Over the range of experimental conditions employed, the rate of dissolution at 80.5°C can be represented by the equation:

where [MCl2] is the total molar concentration of divalent metal chlorides in the acid solution. The rate of dissolution is not influenced by the degree of agitation. The apparent activation energy is 21.6 K. cal. mole−1.
On the motion of gas bubbles in a viscoelastic liquid
Authors: Leal L. G. , Skoog J. , Acrivos A. 
Published: March 2009

AbstractThe discontinuity of terminal velocity versus bubble volume previously reported as taking place in viscoelastic liquids, was studied experimentally and theoretically. A comparison of terminal velocity data for gas bubbles and glass spheres in aqueous polymer (Separan‐AP30) solutions provides strong evidence that the discontinuity results from a change in interfacial conditions from “no‐slip” to free shear. A numerical solution of the creeping flow equations using an empirical curve fit for viscosity versus shear‐rate indicates that only a fraction of the experimentally observed velocity jump is due to the shear dependence of the viscosity alone (neglecting elastic effects). However, simple qualitative arguments seem to suggest that a relatively modest elastic contribution to the force balance on the bubble would be sufficient to account for the experimental observations.
The effect of liquid maldistribution on the performance of a packed tower absorber
Authors: Stanislav J. , Gregory G. A. 
Published: March 2009

AbstractA study of the effect of liquid maldistribution on the performance of a gas absorber is reported. The experimental work was carried out using the carbon dioxide‐water system in a simulated packed column consisting of an ordered array of spheres. This device has been shown to closely approximate the behaviour of an actual column and permits the artificial manipulation of the liquid distribution. The results indicate that maldistribution causes only a small decrease in the mass transfer coefficient at low liquid flow rates, and has almost no effect at higher flows. A proposed iterative procedure for calculating the effect is presented.
La réduction de l'oxyde de nickel par l'hydrogène
Authors: Chiesa F. , Rigaud M. 
Published: March 2009

AbstractL'étude cinétique de la réduction isotherme de comprimés de poudre d'oxyde de nickel par l'hydrogène a révélé l'influence de la transformation de Curie de l'oxyde sur la vitesse de réduction.Entre 180 et 250°C, les courbes de vitesse présentent un maximum très net et l'énergie d'activation, déterminée à partir de ce maximum, est de 26.3 kcal./mole.Au‐dessus de 250°, la forme des courbes changent brutalement pour présenter un palier correspondant à une vitesse constante. Entre 250 et 300°C, l'énergie d'activation calculée sur la vitesse du palier, est de 11.3 kcal./mole. Au‐dessus de 300°C, la cinétique est seusiblement indépendante de la température. D'autre part, des expériences réalisées avec un mélange H2‐H2O ont mis en évidence une très forte influence inhibitrice de l'eau au‐dessus de 250°C.
An evaluation of methods for determining the parameters in the BWR equation of state using volumetric and heat capacity data
Authors: Bishnoi P. R. , Robinson D. B. 
Published: March 2009

AbstractThe use of linear programming was compared with non‐linear least squares techniques for estimating Benedict‐Webb‐Rubin (BWR) equation of state parameters to correlate the volumetric behavior of a fluid. The techniques were extended to estimate the parameters from the volumetric and heat capacity properties of a pure component. In the non‐linear least squares technique a convergence scheme, which is a combination of the Levenberg and Marquardt algorithms, was used. The volumetric behavior of carbon dioxide, methane and their mixtures was best correlated by the parameter sets obtained by the non‐linear least squares technique when volume was chosen as the dependent variable. For the simultaneous correlation of volumetric and heat capacity properties of carbon dioxide the non‐linear least squares technique was found to be superior to the linear programming technique.
Application of numerical hill‐climbing in control of systems via Liapunov's direct method
Authors: Bennett Howard A. , Luus Rein 
Published: March 2009

AbstractThe procedure of determining the control effort which minimizes the forward difference of the quadratic function x(k)TQx(k) combined with improving Q by numerical hill‐climbing is investigated to determine the feasibility of establishing time sub‐optimal control policies for both linear and nonlinear systems.For linear systems, Rosenbrock's hill‐climbing procedure is more efficient for improving Q than the method of Hooke and Jeeves; moreover it yields policies closer to the optimum when the number of state variables exceeds six. The “best” value of Q obtained by hill‐climbing depends on the initial choice of Q and the initial state of the system x(0).The evaluation, carried out with a linear gas absorber and a nonlinear continuous stirred tank reactor, shows that the combined sub‐optimal procedure yields results close to time‐optimal control with little computational effort.
A reversed two‐environment model for micromixing in a continuous flow reactor
Authors: Chen Michael S. K. , Fan L. T. 
Published: March 2009

AbstractA reversed two‐environment model which consists of a maximum mixedness environment followed by a complete segregation environment is proposed. The model may be used to explain the segregation effect which is enhanced by the viscosity increase during the reaction. Comparison between the predicted results and the experimental data for the polymerization of styrene in a stirred tank flow reactor is presented.
Viscous flow through particle assemblages at intermediate reynolds numbers — a cell model for transport in bubble swarms
Authors: Leclair B. P. , Hamielec A. E. 
Published: March 2009

AbstractThe fluid mechanical behaviour of a bubble swarm was simulated using a cell model. The Navier‐Stokes equations were solved numerically for the liquid flow in a uniform assemblage of circulating, spherical bubbles. Ranges of parameters studied included, Reynolds numbers, 0–1000 and porosities, 0.4–1.The numerical calculations show the effects of variations in Reynolds numbers and porosity on: surface vorticity and pressure distributions and form and friction drag coefficients. For all Reynolds numbers investigated a standing vortex ring was absentPredicted drag coefficients and Sherwood or Nusselt numbers agree with limiting analytical solutions for low and high Reynolds numbers. The theoretical results show good agreement with experimental data for porosity as a function of superficial gas velocity. Predicted and measured Sherwood and Nusselt Numbers were in substantial disagreement, making detailed comparison unwarrantedThe calculations should also be valid for dispersions of uniform, circulating, spherical droplets for the special case where the droplet viscosity is much less than the viscosity of the continuous fluid
Flow through porous media in the presence of sound
Authors: Beeckmans J. M. , Sen‐Gupta P. 
Published: March 2009

AbstractThe pressure gradient at a specified flow of air through beds of randomly packed spheres was found to be increased in the presence of sound in the frequency range 500 Hz to 1100 Hz. The phenomenon was studied at several sound frequencies, sound intensities, and flow velocities. A theoretical analysis yielded predictions of the magnitude of the increased pressure drop due to sound which agreed moderately well with experiment
Longitudinal mixing of the liquid phase in packed columns with countercurrent two phase flow
Authors: Co Pham , Bibaud R. 
Published: March 2009

AbstractAxial mixing of the liquid phase in trickle flow through two columns packed with Raschig rings was determined by least square fitting of the experimentally obtained F‐curve applying the Fibonacci optimal search method. The Péclet number was found to be independent of the gas flow rate and proportional to the liquid Reynolds number. The one parameter axial dispersed plug flow model was shown to be acceptable in describing axial mixing of the liquid phase. A simple correlation of the Péclet number is proposed for application in mass transfer design calculations
Expansion‐contraction behavior of dilute polymer solutions
Authors: Bilgen E. 
Published: March 2009

AbstractExpansion‐contraction behavior of capillary jets of dilute polymer solutions has been studied by using small diameter capillary tubes. The test liquids were water, glycerine solution and dilute solutions of polyethylene oxide and guar gum. It has been found that polyethylene oxide molecules degraded considerably at high shear rates; however the molecular degradation had little effect on the observed expansion‐contraction behavior of capillary jets. On the other hand, the solvent viscosity had an appreciable effect on the issuing jets and on the final magnitude of the evaluated normal stresses
The kinetics of titanium dioxide agglomeration in an agitated liquid suspension
Authors: Wahl E. F. , Baker C. G. J. 
Published: March 2009

AbstractThe agglomeration of two TiO2 pigments (0.2‐1.0μ) dispersed in an agitated 1% saline solution has been studied by a sequential count method using a Coulter counter. A model based on collision frequency due to the turbulent motion in a stirred vessel predicts the second order rate constant k to be proportional to agglomerate volume and to stirrer speed to the power 3/2. Experimental values of k were proportional to threshold volume to the power 0.79, stirrer speed to the power 1.3, and independent of TiO2 concentration