bluuebunny/crossref_metadata_2025_split huggingface dataset:
Longitudinal gas dispersion in transitional and turbulent flow through a straight tube
Authors: Flint L. F. , Eisenklam Paul 
Published: March 2009

AbstractLongitudinal dispersion data are reported for a straight tube (internal dia. 1¼′ (2.77 cm)). Three binary gas systems were examined over the regime 3 × 102 < Re < 104 with special emphasis on the transition from laminar to turbulent flow. Effect of Schmidt number is studied in detail over the transition regime, and practical variation with Sc for the lower turbulent regime is compared with the predicted effect based on existing theories of turbulence. In the laminar regime results are reported which diverge from Taylor's theory at Re lower than the normally accepted value for the onset of turbulence.
Structural properties of packed beds — A review
Authors: Haughey D. P. , Beveridge G. S. G. 
Published: March 2009

AbstractSome structural properties of packed bed systems on both the local and overall scales which are available in the literature and of interest in chemical engineering applications are discussed. Regular and random packings of uniformly sized spheres are initially analyzed as a basis for the later examination of the more general case of random packed beds containing particles of various sizes and shapes, with or without restraining surfaces.
Mixing in anchor agitated vessels
Authors: Peters D. C. , Smith John M. 
Published: March 2009

AbstractFlow patterns and velocity profiles have been studied in anchor agitated vessels. The flow paths around the mixer blade in a Newtonian fluid may be characterized satisfactorily in terms of the blade tip Reynolds number and the blade width/wall clearance ratio. Calculations of the dispersion produced by the blade within a horizontal plane are not in agreement with experimentally determined (and therefore three‐dimensional) mixing times. This suggests that the vertical secondary flow is the more important mixing mechanism. Such vertical flows are shown to be more pronounced in visco‐elastic systems and the horizontal plane velocity profiles are substantially modified. A mechanism is suggested for this.
Generalized polynomial programming
Authors: Blau Gary E. , Wilde Douglass J. 
Published: March 2009

AbstractConventional design procedures use physical reasoning to construct equations describing the system. To find the optimal design for some specified performance criterion, it is desirable to change these equations into inequalities so that generalized polynominal programming, a highly nonlinear optimization technique, can be used. For illustration, a chemical reactor system optimal design problem with 11 variables and 8 constraints is formulated as an equality constrained optimization problem, then transformed into an inequality constrained generalized polynominal program and finally solved on the computer.
Analysis of stratified laminar flow of immiscible liquids in circular and non‐circular pipes
Authors: Achutaramayya G. , Sleicher C. A. 
Published: March 2009

AbstractA numerical analysis has been made of laminar stratified flow of two immiscible Newtonian liquids in circular and certain non‐circular pipe configurations. Solutions are given far viscosity ratios of 10, 100, and 1000 and for various volumetric flow rate fractions. Five pipe configurations are studied. In each case volumetric flow rate factors and power reduction factors are computed. It is shown that the circular pipe is the best pipe configuration for the two‐phase flow having a viscosity ratio of about 10 or less. A flat bottomed pipe configuration is found to give higher volumetric flow rate factors as well as higher power reduction factors than the circular pipe when the viscosity ratio is about 100 or more.
Suspension of solids by bubble agitation
Authors: Narayanan S. , Bhatia V. K. , Guha D. K. 
Published: March 2009

AbstractUsing fundamental aspects of the fluid mechanics of a single particle, a relation for the velocity of liquid necessary to suspend solid particles in a shallow depth column is derived. This liquid velocity is developed by the movement of the gas bubbles inside the column with the potential energy dissipated by the bubble during its ascent taken as the gain in the kinetic energy of the liquid. This energy brings about sufficient liquid motion to suspend the particles. The corresponding superficial gas velocity to suspend all the particles present in the column is theoretically estimated and compared to experimental values of superficial gas velocities obtained for various solids concentrations. A set pattern of deviation is observed, and empirical correlations are suggested for predicting the superficial gas velocity to suspend a given amount of solid particles in liquid.
Theoretical patterns of selectivity in aging catalysts with special reference to the catalytic cracking of petroleum
Authors: Campbell D. R. , Wojciechowski B. W. 
Published: March 2009

AbstractThe catalyst decay theory of Wojciechowski(1) is applied to a simplified theoretical mechanism of catalytic gas oil cracking. The resulting patterns of selectivity are presented and general conclusions drawn. It is shown that selectivity in gas oil cracking is bounded by optimum and minimum performance envelopes which confine the range of possible product distributions.
Studies on cocurrent gas‐liquid flow in helically coiled tubes. I. Flow patterns, pressure drop and holdup
Authors: Banerjee Sanjoy , Rhodes Edward , Scott Donald S. 
Published: March 2009

AbstractThe effects of tube diameter, coil diameter, helix angle and liquid viscosity on flow patterns, pressure drop and holdup for cocurrent gas‐liquid flow in helically coiled tubes have been investigated. Nine coils of varying coil diameter and helix angle have been used with liquids of three different viscosities and air at varying pressures. The effect of tube diameter on pressure drop and holdup was determined by using tubes of diameters up to 2‐in.Flow patterns were adequately predicted for all the systems by Baker's plot. Small helix angles were found to have no effect on pressure drop or holdup in coiled tubes. Both pressure drop and holdup could be adequately correlated using the Lockhart‐Martinelli approach with modified correlating parameters.
Free convection boundary‐layer flow over horizontal plates and discs
Authors: Rotem Zeëv , Claassen Lutz 
Published: March 2009

AbstractFree convection flows near horizontal surfaces are discussed for those cases in which a similarity solution can be obtained. Particular cases considered are those of asymptotically large and vanishingly small Prandtl numbers. The solution for the relevant velocity, temperature and pressure functions has to be carried‐out numerically. For the particular cases when the Prandtl number is either sufficiently large, or sufficiently small, this integration would yield general functions, no longer dependent on the Prandtl number. Numerical data are included.
Liquid‐liquid‐vapor equilibria in the nitrogen‐methane‐ethane system
Authors: Yu Paul , Elshayal I. M. , Lu Benjamin C.‐Y. 
Published: March 2009

AbstractLiquid‐liquid‐vapor equilibrium compositions were measured for the nitrogen‐ethane binary and the nitrogen‐methane‐ethane ternary systems from –255° to –219.8°F and at pressures up to 591 psia. A forced‐recirculation apparatus was employed for the determinations. Experimental results were interpreted and correlated. Optimum operating temperature for nitrogen separation has been suggested.
The kinetics and mechanism of the hydration of magnesium oxide in a batch reactor
Authors: Smithson G. L. , Bakhshi N. N. 
Published: March 2009

AbstractThe kinetics of the reaction between water and MgO powders has been investigated at 9°, 18°, 28° and 38°C in a stirred batch reactor. Six commercial samples of MgO prepared from Mg(OH)2 plus two of unknown origin, with specific surface areas of 12 to 80 mg/g, were studied. After correcting for particle size distribution, the rate of reaction was found to be directly proportional to the surface area contained in a shell at the surface of the particles. The activation energy is 14.1 ± 0.2 kcal/g‐mole indicating chemical reaction as the rate controlling process. A reaction mechanism has been proposed./
Granulation of superphosphate in a rotary drum
Authors: Linskson P. B. 
Published: March 2009

AbstractUsing water as a binding agent, some of the factors affecting the preparation of superphosphate granules have been investigated. The amount of water added to the material completely dominates the other physical variables in determining the characteristics of the granules formed. An optimum water content was found for which the proportion of granules within a specified size range (–4 + 14 Tyler mesh) was at a maximum.Granulation with simultaneous drying showed that an increase in the drying rate results in a decrease in the rate of granule growth. The speed at which the granulator is rotated to obtain the correct “tumbling action” is influenced by the internal surface of the drum and the presence and design of internal flights.The mechanical strength of superphosphate granules depends on the quantity of binding agent used in the granulation process and the degree of agitation. The dry strength of the granules formed is considerably greater than the wet strength.
Design of settling basins with allowance for residence time distributions
Authors: Silveston P. L. 
Published: March 2009

AbstractEquations are developed for the performance of settling basins where hydraulics are characterized by residence time distributions. An illustrative calculation for a typical basin design using literature settling data and a residence time distribution predicts a reduction in solids removed of only about 10% over that predicted for an ideal basin where plug flow is assumed. This calculation suggests that the effect of residence time distribution on basin performance for realistic conditions may be just modest.
Drag reduction in large tubes and the behavior of annular films of drag reducing fluids
Authors: Seyer F. A. , Metzner A. B. 
Published: March 2009

AbstractTurbulent flow drag reduction is governed by elastic effects within the boundary layer of the flow. The effect of elasticity is to reduce the radial momentum transfer rates of large eddies that exist near the tube wall, and in so doing a reduction in the turbulent flow drag occurs. A recent theoretical analysis is used to formulate a general discussion of the significant features of drag reducing systems and is used to predict quantitatively the percentage reductions in drag for systems of practical significance. It is shown that little or no drag reduction can be expected in large tubes using polymeric materials that are presently available though micellar systems show effects of substantial magnitude which appear to be exploitable.An analysis is presented which indicates that laminar annular films of dilute polymeric fluids, used to enable the core fluid or a capsule to “slide” through a pipeline at reduced pressure drop, are of especial interest in that the normal stress field may generate forces which increase the concentricity of the core in the presence of major density differences. This exploitation of non‐Newtonian fluid properties, suggested some years ago by Lummus, does not appear to have been subjected to analysis before, nor do verifying experimental data appear to be available.
A lumped parameter approximation to a general model for catalytic reactors
Authors: McGreavy C. , Cresswell D. L. 
Published: March 2009

AbstractConsideration ig given to the solution of the highly exothermic fixed bed catalytic reactor problem taking into account heat and mass transfer resistances inside the catalyst pellets and across the external fluid film, as well as radial temperature and concentration gradients in the fluid phase. Even on large digital computers, the computation time is excessively long if the sets of differential equations are solved simultaneously. By considering the intra‐particle equations in detail, it is shown that they may be reduced to a lumped parameter form which permits rapid evaluation of an effectiveness factor. The functional dependence of this effectiveness factor is determined primarily by the external film resistance. While still retaining the characteristics of the general problem, the lumped parameter approximation may be solved in a substantially shorter time, thus permitting its use in optimization and control studies.
Prediction of flow patterns in horizontal two‐phase pipe flow
Authors: Al‐Sheikh J. N. , Saunders D. E. , Brodkey Robert S. 
Published: March 2009

AbstractA new concept of a sequence of plots is used for the separation of flow regimes in two‐phase flow. The empirical correlations themselves are based on extensive tabulations of flow‐type data from the AGA‐API Data Bank. Provided these data and the tabulations are accurate, the accuracy of the proposed method is better than 5%. The accuracy for any separation can easily be obtained from the information given.The probability of being able to separate flow types by the various correlations was determined and used to select the best correlations. In actual use, there will be times when a complete separation cannot be made. However, one will know this and be able to say that the flow is one of two or, rarely, more types.
Effect of dilute polymer solution injection on external boundary layer phenomena
Authors: Latto B. , Shen Chi Hung 
Published: March 2009

AbstractThis paper describes an experimental study of the effect of injecting dilute aqueous polymer solutions into a turbulent boundary formed on a flat plate. Using hot film anemometry, it was found that the momentum diffusivity was less than that for pure water, and that there was a reduction in the size range of the turbulent eddies. Furthermore, it was observed that the angle and velocity of injection of a polymer solution can have a pronounced effect on the local skin friction, which under certain conditions could be reduced by as much as 80% when compared to no injection conditions.
Mass transfer produced by laminar flow oscillations
Authors: Rice Richard G. , Eagleton L. C. 
Published: March 2009

AbstractMass transfer produced by laminar flow oscillations was studied theoretically and experimentally. A hollow tube was caused to oscillate between two constant volume reservoirs with a constant concentration difference. Experimental axial mass transfer rates of hydrochloric acid in water were found to be from 20 to 1100 tmies that of ordinary diffusion for a Reynolds number range of 0.07 to 0.84. The coupled momentum‐mass transfer equations were solved and show excellent agreement with the experimental work. The average deviation from theory for all experiments was 6.44%. The theoretical results show that the mass transfer increase is proportional to the square of amplitude and depends, in a complex way, on the Reynolds and Schmidt numbers.
The dynamics of extraction processes: Part III. The determination of steady state and transient concentration profiles
Authors: Pollock G. G. , Johnson A. I. 
Published: March 2009

AbstractTechniques for determining concentration profiles during the transient and final steady state operation of a countercurrent extraction column are described and evaluated. The column is mechanically agitated and the stages are separated using Teflon sieve trays. The paper discusses numerical procedures for analyzing the behaviour of such columns, and the errors introduced by the measurement techniques studied. Mass transfer coefficients for the column under study are reported, and there is a discussion of the effect of concentration (or position along the column) on their value.
The dispersion of solute in turbulent pipe flow of non‐newtonian fluids
Authors: Wasan D. T. , Dayan J. 
Published: March 2009

AbstractThe dispersion of solute in turbulent pipe flow of power law fluids is investigated theoretically. Results in terms of the intensity of dispersion are compared for the non‐Newtonian and purely viscous Newtonian fluids over a wide range of Schmidt numbers. The computed results indicate that the intensity of dispersion at a constant Schmidt and Reynolds number increases with increasing flow behavior index.
Kinetics and reactors — The engineer's dilemma
Authors: Smith J. M. 
Published: March 2009

AbstractScaleup of catalytic reactors is often unrewarding because of the incompatibility of chemical and physical similarity requirements. Hence, a rational design procedure usually requires experimental study of global rates of reaction, as well as kinetics of the chemical steps at a catalyst site.This paper examines the role of laboratory and pilot‐plant reactor data in the design procedure. Recent developments in laboratory reactors, and the potential for ultimately eliminating the need for global rate measurements, are considered.
Evaluation of the three phase transport reactor
Authors: Pruden B. B. , Weber M. E. 
Published: March 2009

AbstractA high aspect ratio chemical reactor for reacting a liquid with a gas in the presence of a finely divided catalyst was tested. The gas was sparged into the bottom of a tubular reactor with the slurry of liquid and catalyst flowing countercurrent to the gas. The liquid phase hydrogenation of alpha‐methylstyrene to cumene on a Pd. catalyst was studied in semibatch operation of the reactor with slurry recycle. The reacor was 1 1/2‐in. I.D. by 6‐ft. long. The following variables were studied at a temperature of 28°C and a pressure of 1 atm: superficial gas velocities of 1.1 to 3.3 cm/sec., and catalyst loadings from 0.4 to 2.0 gm. catalyst per liter. A model of the reactor was developed and successfully compared with the data.
Statistical methods in model discrimination
Authors: Reilly P. M. 
Published: March 2009

AbstractParticularly in the chemical kinetic field but also in others in chemistry and engineering there has been much recent attention on the use of statistics in discriminating between rival models. There are two related basic problems. The first is to design experiments which will be most informative in determining which of several possible mathematical models is the “correct” one. Simple illustrations are given of the solution of this problem by different methods, such as the criteria of Roth, Box and Hill and of others, including some work done by R. S. Hawkins and the author on expected entropy change. The second problem is to analyze the data when received. A sampling of likelihood and Bayesian approaches to this problem is described with examples.
Mathematical models for the transient behavior of a packed bed Reactor
Authors: Feick J. , Quon D. 
Published: March 2009

AbstractA mathematical model of a packed bed reactor was developed to include radial and axial diffusion within the reactor as well as film and pore resistances to both heat and mass flows. The non‐linear partial differential equations which are coupled by a generalized reaction rate expression were finite‐differenced and integrated in the time domain. The performance of the detailed model was compared with those predicted for two simpler models: a homogeneous reactor model and a surface resistance reactor model. The range of variables over which these considerations are important is also indicated.
Mass transfer within oscillating liquid droplets
Authors: Brunson Roy J. , Wellek Robert M. 
Published: March 2009

AbstractAll existing relations describing mass transfer within oscillating droplets were critically compared with experimental data in which resistance to transfer is predominantly inside the droplet. Several new relations are also developed to estimate oscillating droplet extraction efficiencies, one of which is recommended in view of its theoretical appeal, accuracy, and ease of application.The most accurate relation currently available is an empirical expression developed by Skelland and Wellek.
The influence of mixing on the distribution of copolymerization compositions
Authors: Mecklenburgh J. C. 
Published: March 2009

AbstractThe paper shows theoretically that the composition distribution in a copolymer depends on both the type of continuous reactor used in its production and the molecular and macroscopic mixing patterns within the reactor. Examples are given of the distributions to be expected from a plug flow reactor, a CSTR with either molecular or macroscopic scale mixing, a tubular reactor with backmixing and reactors with several regimes of mixing. The distribution curves are compared with those obtained by tracer injection. A short account is given of the experimental difficulties encountered in reproducing the composition distributions.
Interaction model for the critical pressures of aliphatic hydrocarbon mixtures
Authors: Akiyama Tetsuo , Thodos George 
Published: March 2009

AbstractAn interaction model is proposed for the prediction of the critical pressures of multicomponent aliphatic hydrocarbon mixtures which may include methane. This model utilizeg a series consisting of terms of increasing order which has been truncated beyond the fifth interaction term. After a number of algebraic manipulations, the excess critical pressure for these multicomponent mixtures has been represented as follows

The nonmethane interaction coefficients Aij, Bij, Cij and βijk and the methane interaction coefficients A1j, B1j, C1j, D1j and β1jk have been expressed as functions of the critical pressure parameter, πij. The resulting relationships permit the evaluation of these interaction coefficients for a multicomponent system and from its composition, the critical pressure of the mixture is calculated. The critical pressures of several binary and multicomponent aliphatic hydrocarbon mixtures have been calculated and have been compared with experimental values. For 99 binary methane‐free mixtures representing 11 systems, the average deviation is 3.23%. For 46 binary mixtures representing six methane systems, the average deviation becomes 4.41 %. For 36 multicomponent aliphatic hydrocarbon mixtures containing from three to six components, the average deviation is found to be 3.18%.
Bed expansion and bubble wakes in three‐phase fluidization
Authors: Rigby G. R. , Capes C. E. 
Published: March 2009

AbstractThe expansion characteristics of gas‐liquid fluidized beds have been measured for beds of glass ballotini and sand with particle sizes ranging from 120 to 775 microns. This data has been used in conjunction with recent measurements of bubble properties to predict the proportion of wake associated with bubbles rising through the bed using a modification of the theory proposed by Ostergaard to explain the contraction observed when gas is introduced into a liquid fluidized bed.Three‐pase fluidization has also been observed by photography in a two‐dimensional bed and the results are in substantial agreement with the calculations based on expansion behavior and bubble properties. The bubble wakes in a three phase system consist not only of a stable portion carried with the bubbles but also of vortices shed by the bubbles. A simplified model has been used to demonstrate that these vortices may contribute significantly to the observed contraction.
Local heat transfer coefficients in a model “falling film” scraped surface exchanger
Authors: Azoory S. , Bott T. R. 
Published: March 2009

AbstractUtilization of an accurate technique to measure the local heat transfer coefficient in thin falling film scraped surface exchangers yields results which indicate that the local heat transfer coefficient is dependent on N0.5 and, above a certain rotational speed, independent of axial flow rate. Both of these observations are in agreement with the theoretical penetration model. The results, however, are generally lower than would be expected from the theory, and as a result, heat transfer may be described by the penetration model in combination with an empirical factor, f. This term is based on the liquid physical properties and gives a measure of the intensity of cross sectional mixing within the liquid, i.e.

where f, is defined as