bluuebunny/crossref_metadata_2025_split huggingface dataset:
Drop formation mass transfer
Authors: Rajan S. M. , Heideger W. J. 
Published: June 2004

AbstractThe mass transfer occurring between a liquid drop during its formation and the surrounding liquid phase was directly evaluated by a photographic technique. Slightly soluble organic drops containing no additional solute were formed in a continuous aqueous phase so that only the continuous phase resistance existed. Effects of nozzle diameter and both phase flow rates were evaluated and the possible influence of surfactant was investigated.Mass transfer coefficients were observed to decrease sharply with time early in the formation period. This, together with the parameteric study of dispersed phase feed rate, indicates the strong effect of internal drop convection for this high Schmidt number system. The measured coefficients are substantially higher than would be expected for free drops.
Diffusion and chemical reaction in a tubular reactor with non‐Newtonian laminar flow
Authors: Homsy R. V. , Strohman R. D. 
Published: June 2004

AbstractThe problem treating an irreversible, first‐order chemical reaction in an isothermal, tubular reactor operating under steady, non‐Newtonian, laminar flow is studied. Numerical results for the eigenvalues, eigenfunctions, expansion coefficients and bulk concentration are reported for Ostwald‐de Waele and Prandtl‐Eyring fluids. Results show that chemical conversion in a tubular reactor may be significantly influenced by the non‐Newtonian characteristics of a fluid.
Prediction of vapor‐liquid equilibria of petroleum fractions
Authors: Mikolaj Paul G. , Dev Lachhman 
Published: June 2004

AbstractThe thermodynamic treatment of phase equilibria proposed by Chueh and Prausnitz has been modified to extend their method to systems of petroleum fractions. These modifications, which include the use of a symmetric convention for normalizing activity coefficients and replacement of the dilated van Laar model with a regular solution model, were required because existing data were insufficient to establish the needed binary interaction parameters. The resulting correlation was compared with experimental data on a naphtha‐furnace oil mixture at conditions up to 660°F. and 517 lb./sq.in.abs. The computed K values showed an average absolute deviation of 9.1%, while K values predicted by the Chao‐Seader correlation deviated by 12.4%.
Diffusion and reaction in ideal multicomponent systems: I. Tubular reactor near equilibrium
Authors: Solomon R. L. , Hudson J. L. 
Published: June 2004

AbstractDiffusion and either surface or gas‐phase reaction in a ternary ideal gas mixture in steady fully developed laminar flow in a tube is considered. The linearized equations valid near equilibrium and under isothermal conditions are solved. Concentration profiles predicted using a multicomponent diffusivity matrix are compared to those predicted using more approximate diffusivities. Local overshoots past equilibrium occur, but oscillations (with axial position) are not possible. A simplified diffusivity expression is found which predicts cup‐mixing mole fractions in good agreement with those predicted using the multicomponent diffusivities.
Effects of molecular characteristics of polymers on drag reduction
Authors: Liaw Gin‐Chain , Zakin Jacques L. , Patterson Gary K. 
Published: June 2004

AbstractTurbulent measurements in capillary tubes and in pipes were made on nonpolar solutions of seven polymer species, three at more than one molecular weight, over wide concentration ranges.A critical concentration, Cc, was taken as the minimum concentration for disappearance of the turbulence transition region. Above this concentration, friction factor‐generalized Reynolds number data show only a gradual deviation from extension of the laminar line. Cc increases with tube diameter and decreases with molecular weight. The critical dimensionless volume friction Cc [η] is less dependent on molecular weight.The levels of Cc [η] for different polymer species in a given tube show marked differences which are related to β, the molecular rigidity parameter. Low β values, or high flexibility, are associated with low Cc [η] values. Available data for Cc [η] in good and in poor solvents show little solvency effect.Polymer samples of low m′, the ratio of the polymer molecular weight to the critical tanglement molecular weight of the polymer, give solutions with little or no drag‐reducing capacity, even those with low β values. Samples must have m′ values of 50 or more to show significant drag reduction. This allows prediction of the minimum useful molecular weights for drag reduction for any polymer species.For solutions above Cc, all of these data and literature data (for aqueous and nonaqueous systems with a wide range of n′ values) fit a single f/fpv versus generalized Reynolds number relationship.
Pressure drag measurements for turbulent air flow through a packed bed
Authors: Van Der Merwe D. F. , Gauvin W. H. 
Published: June 2004

AbstractPressure drag coefficients of spheres in a cubic packing of equal spheres have been determined at Reynolds numbers of 27,000, 10,000, 5,000 and 2,500, where NRe is based on superficial air velocity and a sphere diameter of 7 cm. Two cubic arrangements were used: in the regular arrangement, the mean flow was parallel to one of the principal axes, while in the skewed arrangement, the mean flow made equal angles with the three principal axes of the packing.The pressure drag coefficient of the central sphere has been measured for each of the 12 banks in the regular arrangement, and the effect of bed length has been determined for lengths varying between 1 and 12 banks. The pressure drag coefficient for the central sphere and the overall pressure drop in the skewed arrangement were found to be lower than for the regular arrangement at the same Reynolds number. From the distribution of local pressure measurements, the separation and reattachment points on the central sphere in each bank were determined, indicating that the boundary‐layer behavior on a sphere in a packing is similar to that over a single sphere, when allowing for the effects of turbulence and of pressure gradient.
Parameter sensitivity of systems described by nonlinear ordinary differential equations
Authors: Rayzak R. J. , Luus Rein 
Published: June 2004

AbstractAn approximate analytical method is developed to estimate the parameter sensitivity of the solution of a set of nonlinear ordinary differential equations describing a system which exhibits periodic behavior. An approximate solution is constructed in terms of both the approximate periodic solution determined from Galerkin equations and the envelope and phase of the oscillation away from such a periodic solution. Parameter sensitivity information is then obtained by examining the parameter variation effect on the approximate solution.Examples of two‐ and three‐dimensional nonlinear systems illustrate this procedure and show that the effect of parameter change on the solution is predicted with sufficient accuracy to make this method useful for nonlinear analysis.
On suspended particles in tube flow
Authors: Schreiner Kristian E. 
Published: June 2004

AbstractThe paper considers the effect on fluid flow in a tube when rotationally symmetric particles follow the flow on the tube axis. It is found that a region of disturbed flow, similar to inlet flow, adheres to the particle. A model describing this disturbed flow is suggested, and an expression for the change in the apparent viscosity of the flow is developed. It is found that the accompanying disturbance may have an appreciable effect on the flow. The model should be applicable when the tube Reynolds number is larger than 10.
Adsorption equilibria of the light hydrocarbon gases on the activated carbon and silica gel
Authors: Gonzalez A. J. , Holland C. D. 
Published: June 2004

AbstractA new method is presented for the determination of adsorption equilibria for pure components and mixtures both at high and low pressures. Isotherms for carbon dioxide, methane, ethane, propane, i‐butane, n‐butane, i‐pentane, and n‐pentane on activated carbon (Columbia grade NXC 8/10) and on silica gel (Mobil Sorbead H) at 75°, 125°, 200°, and 300°F. are given for pressures ranging from below atmospheric to 1,000 lb./sq. in. Also, adsorption equilibria data are presented for several multicomponent mixtures of the light hydrocarbon gases.The data collected were correlated with good accuracy by use of the two‐layer kinetic model developed previously by Gonzalez.
Multivariate control of a phase separation process
Authors: Kleinpeter Joseph A. , Weaver Robert E. C. 
Published: June 2004

AbstractThis paper presents a nonequilibrium mathematical model of a vapor‐liquid separator. The model is used as the focus of a computer simulation control study conducted to provide the foundation for applying recent multivariate control developments to distillation systems.Greenfield and Ward's structural analysis was found to provide reasonably good feedforward and decoupling control of pressure, liquid temperature, and liquid pressure. Because of implicit relationships between product composition variables and their manipulative inputs, structural analysis was inapplicable when these composition variables were among the controlled variables.A method is presented which provides feedforward and some decoupling control for linear multivariable systems despite the existence of implicit relationships between controlled variables and their manipulative inputs. It is seen however that genuinely decoupled servo action on isolated state variables requires control through derivatives and thus an expansion of state space.
Velocity and turbulence measurements of air flow through a packed bed
Authors: Van Der Merwe D. F. , Gauvin W. H. 
Published: June 2004

AbstractMean velocity and turbulence measurements in the void spaces of a cubic packing of equal spheres have been made at Reynolds numbers of 27,000, 10,000, 5,000 and 2,500, where NRe is based on superficial air velocity and a sphere diameter of 7 cm. Two cubic arrangements were used: in the regular arrangement, the mean flow was parallel to one of the principal axes, while in the skewed arrangement, the mean flow made equal angles with the three principal axes of the packing.Transverse mean velocity and turbulence intensity profiles across the center line of a central pore have been measured behind every bank and behind the bed for the regular arrangement of ten banks of spheres. The power spectrum and probability distribution of the fluctuating velocity have also been determined.
Convective dispersion of blood gases in curved channel exchangers
Authors: Chang Hsin‐Kang , Mockros Lyle F. 
Published: June 2004

AbstractThe rates of hemoglobin saturation and carbon dioxide reduction in blood flowing in a curved channel membrane exchanger were studied theoretically by considering the fluid‐limited process and the wall‐limited process. The fluid‐limited process was studied for laminar flows with and without secondary circulations. The relatively nontraumatic centrifugally induced circulations in the curved channel can reduce the required channel length to less than 1/500 that required for unperturbed flow. Such improvement, however, is practical only if very permeable membranes are available. If thePO2= 715 mm. Hg andPCO2= 0 mm. Hg at the walls, the fluid‐limited analyses show oxygenation to be the slower process and the wall‐limited analyses indicate CO2removal to be the limiting process. If the best available silicone rubber membranes are used, the process will be fluid limited for the unperturbed flow and wall limited for the flow with secondary circulations.
Theoretical analysis of the turbulent flow of non‐newtonian slurries in pipes
Authors: Hanks Richard W. , Dadia Bharat H. 
Published: June 2004

AbstractA theoretical model is derived which permits the analytical calculation of the friction factor‐Reynolds number curves for non‐Newtonian slurries flowing isothermally in smooth pipes. This model is based upon the Bingham plastic rheological equation of state.A change of mechanism in the transition phenomenon is observed to occur for NHe = 5 (105), where NHe is the familiar Hedstrom number. Below this value turbulence is suppressed relative to Newtonian flow, while above this value the transition is delayed but turbulence is enhanced relative to Newtonian flow.A set of theoretical design curves of friction factor versus Reynolds number covering laminar, transitional, and turbulent flows is calculated and presented for a range of NHe values from 103 to 109.
Drop‐size distributions from pneumatic atomizers
Authors: Kim K. Y. , Marshall W. R. 
Published: June 2004

AbstractA study was made of the atomizing characteristics of convergent‐type pneumatic nozzles. Drop‐size correlations were obtained for the following ranges: drop size, 6 to 350 μ, mass median diameter; mass flow ratio, 0.06 to 40; relative velocity, 250 ft./sec. to sonic velocity; and viscosity. 1 to 50 cp. The technique employed was to spray cool a molten wax, and melts of wax‐polyethylene mixtures. The most important operating variables in pneumatic atomization are the dynamic force of the atomizing gas, and the mass flow ratio of air to liquid. The cumulative volume drop‐size distribution of spray from a pneumatic nozzle was fitted by a modified logistic equation. Empirical correlations developed in the study can be used to design nozzles or to predict drop size for sprays produced by the types of nozzles studied. In particular, this study provides new experimental data on the performance of pneumatic atomizers in producing relatively large drops.
Simultaneous computation of heat transfer and dispersion coefficients and thermal conductivity value in a packed bed of spheres: II. Technique of computing numerical values
Authors: Goss M. J. , Turner G. A. 
Published: June 2004

AbstractThe method of computing the numerical values is given. It is illustrated with a simulated example to show the high accuracy that is possible, the unknowns being found to four significant figures. The only quantities required are ones that can be measured accurately: the radius of the spherical packing, its volumetric specific heat, and values of the amplitude attenuation and phase angle lag at a minimum of four finite values of the frequency.
Statistical analysis of growth of microorganisms
Authors: Aiba Shuichi , Endo Isao 
Published: June 2004

AbstractA mathematical model is derived in the form of a functional equation to describe a population dynamics of microorganisms (bacteria). The individual cells are due to experience a cycle of growth and division during the proliferation period.The interdivision growth rate of bacterial cells (Azotobacter vinelandii) in a continuous and steady state culture is assessed by introducing a probability of division and by using the cell size distributions which are measured with the Coulter counter.Sigmoid patterns, the single‐cell volume versus time, agree incidentally with the previous data which have been published by Harvey et al. from an approach devoid of a particular model. A mutual relationship between the microbial activities from the macroscopic scale of cell mass concentration and those from a statistical analysis is discussed briefly.
Nucleate and film pool boiling of ethane‐ethylene mixtures
Authors: Wright R. D. , Clements L. D. , Colver C. P. 
Published: June 2004

AbstractExperimental results are presented for saturated nucleate and film pool boiling heat transfer to ethane, ethylene, and three binary ethane‐ethylene mixtures containing approximately 25, 50, and 75 mole % ethylene. Data were obtained at reduced pressures from 0.05 to 0.75. The nucleate boiling data are compared with several predictions; the film boiling data are favorably compared with the Sciance, Colver, and Sliepcevich correlation.
Suboptimal control of nonlinear systems: II. Constrained
Authors: Weber A. P. J. , Lapidus L. 
Published: June 2004

AbstractThe previous development in suboptimal control of nonlinear unconstrained systems is extended to constrained systems by the use of penalty functions in an augmented sense. This converts the constrained control problem into an unconstrained one with all of the advantages previously discussed. Numerical examples are presented.
Mass transfer with homogeneous chemical reaction in turbulent pipe flow
Authors: Randhava S. S. , Wasan D. T. 
Published: June 2004

AbstractMass transfer with chemical reactions in fully developed turbulent pipe flows has been studied theoretically. The pipe walls are assumed to remain at a constant prescribed concentration. The effect of arbitrary reaction orders and of Reynolds and Schmidt numbers upon the transfer coefficients was investigated. Radial and longitudinal concentration profiles were obtained to show the effect of reaction orders and dimensionless rate constants. Effects of concentration levels on these phenomena were also studied and proven significant. The ratio of the transfer coefficients with chemical reactions to those without chemical reactions increases as a function of the downstream aspect ratio.
Linear analysis of liquid film flow
Authors: Rushton Eric , Davies Graham A. 
Published: June 2004

AbstractAnalyses of the flow of thin Newtonian liquid films over vertical plane surfaces at low Reynolds number in the wavy flow regime have been considered. The results of a linear analysis of the equations of motion, seeking a steady periodic solution to characterize the wave profile, are presented. The solutions derived in this work give better agreement with experimental results than previously published solutions using a linear analysis. Predictions of the wave properties (wave celerity, wave number, and wavelength) as functions of the flow conditions are derived from the theory.
Measurement of velocity in gas mixtures: Hot‐wire and hot‐film anemometry
Authors: Wasan D. T. , Baid K. M. 
Published: June 2004

AbstractThis paper extends the use of hot‐wire and hot‐film anemometry to the measurement of velocities in gas mixtures. It is demonstrated that the velocity data in binary gas mixtures can be satisfactorily predicted by calibration tests in pure systems alone or at any two convenient composition conditions. Furthermore, the actual transport properties of a fluid mixture may be inferred from direct calibrations of hot‐wire, or hot‐film anemometers in the mixture with known compositions.
An exact analysis of low peclet number thermal entry region heat transfer in transversely nonuniform velocity fields
Authors: Hsu Chia‐Jung 
Published: June 2004

AbstractA theoretical method is described for obtaining the exact solution to the problem of thermal entry region heat transfer which takes into account both transverse non‐uniformity in the velocity field and axial conduction. To allow for the effect of upstream conduction, the fluid temperature was taken to be uniform at × = – ∞, and the first 20 eigenvalues and the corresponding eigenfunctions were determined separately for the heated and adiabatic regions. Both the temperatures and temperature gradients were then matched at × = 0 by constructing a pair of orthonormal functions from the nonorthogonal eigenfunctions.Nusselt numbers calculated for pipe flow subject to the boundary condition of uniform wall heat flux show virtually perfect agreement with those reported recently by Hennecke, who solved the governing partial differential equation numerically. To illustrate its general applicability, the present method was further employed to analyze the corresponding problem in parallel‐plate channel flow, for which no solution has hitherto been reported.
The role of wakes in the mechanism of extraction in spray columns
Authors: Kehat Ephraim , Letan Ruth 
Published: June 2004

AbstractExtraction in spray columns is reexamined in view of recent information on wakes of drops and the role of wakes in the mechanism of heat transfer in spray columns. In the proposed mechanism, mass is extracted from a highly mixed drop to a highly mixed wake in the wake growth zone. Elements of wakes are shed, mixed with continuous phase, and are replaced by the continuous phase in the wake shedding zone. A narrow mixing zone exists at the entrance of the continuous phase and above it the coalescence zone.A mathematical model for extraction in spray columns is presented. This model was used to calculate the top concentrations from the bottom concentrations, for 258 runs from nine papers covering very wide ranges of columns, systems, and operation parameters. Better than 20% agreement was obtained for 10 runs and the poorer agreement of most other runs can be attributed to the sensitivity of the calculations to the uncertainties in the average distribution coefficients of the solute between the two liquid phases, and, to a lesser extent, to the uncertainties in the length of the wake shedding zone and wake parameters. For very large or very small values of the distribution coefficient, the assumption of local equilibrium between drop and wake, used in the model, does not hold.
Concentration distribution, effectiveness factor, and reactant exhaustion for catalytic reaction with volume change
Authors: Lin Kan , Lih Marshall M. 
Published: June 2004

AbstractAnalytic expressions for the concentration distribution of reactant and for effectiveness factor have been obtained for zero‐order catalytic reactions of the type A → bB. They can be summarized for various physical forms of catalyst to be

and

where

, and Mi are differently defined for thin‐disk (i = 1), infinite‐cylinder (i = 2), and spherical (i = 3) geometries. The results are also presented graphically for rapid calculation of these quantities. The phenomenon of reactant exhaustion associated with a zero‐order reaction and the criteria for its occurrence are also discussed.
Nucleation and crystal proliferation kinetics: Amorphous‐crystalline transformation of basic copper carbonates
Authors: Hsu Andrew C. T. 
Published: June 2004

AbstractThe transformation of amorphous basic copper carbonate precipitates into the crystalline form in aqueous solutions was experimentally studied. The unique blue‐to‐green color change and drastic volume reduction of the precipitates in transition made continuous observation and quantitative determination of the transformation process feasible. The transformation, which involves both nucleation and crystal growth proliferation, was autocatalytic. Experimental results are in good agreement with the rate equation formulated on the two‐stage kinetics model postulated for the system. Also studied were the effects of temperature and precipitate concentration on the rate of transformation. In the temperature range between 34° and 39°C., the apparent nucleation activation energy was 19.8 kcal./g.‐mole.
Optimal operation of a tubular chemical reactor
Authors: Newberger Mark R. , Kadlec Robert H. 
Published: June 2004

AbstractA theoretical and experimental study was conducted on the optimal steady state operation of a jacketed, tubular, liquid‐phase reactor in which consecutive second‐order reactions occurred in turbulent flow. To verify the proposed mathematical model, diethyl adipate was saponified with sodium hydroxide in aqueous solution. The 150 ft. long reactor jacket was divided into 5, 30 ft. sections. Hot water flow rates in the jacket sections were chosen to maximize the concentration of monoethyl adipate ion at the reactor exit. The plug‐flow model and a position‐dependent heat transfer coefficient accurately described temperature and concentration profiles. The Pontryagin maximum principle was used to choose idealized reactor temperature and wall heat flux profiles which would maximize the exit concentration of monoester. The maximum principle was shown to be an effective tool for this type of reactor optimization. A technique is given for optimizing more complex reaction systems.