bluuebunny/crossref_metadata_2025_split huggingface dataset:
Effect of carbon monoxide in causing nonuniform gasification of graphite by carbon dioxide
Authors: Austin L. G. , Walker P. L. 
Published: June 2004

AbstractExisting theories on the effect of mass transport on the rate (uniformity) of chemical reaction within a porous solid assume that the reaction is of integer order. However the carbon‐carbon‐dioxide reaction has the kinetic rate form, rate = k1p/(1 + k2pCO + k3p). For conditions where the retarding effect of carbon monoxide is very pronounced, the buildup of small concentrations of carbon monoxide within the porous graphite can lead to appreciable nonuniformity of gasification. Thus the criteria normally used to predict uniformity of gasification break down. A numerical integration of the combined differential equation of mass transport and chemical reaction has been performed, with rate constants for the carbon‐carbon dioxide reaction taken from the literature. The results indicate that extreme nonuniformity of reaction can exist even when the change in carbon dioxide concentration from the exterior of the sample to the interior is small. The results are similar to experimental determinations of non‐uniformity of gasification, obtained by determining the porosity of reacted graphite samples as a function of depth from the reacting face. Experimentally nonuniformity of reaction was observed for gasification rates a hundredfold lower than the usual Thiele criteria would predict, probably because of carbon monoxide inhibition.
Limitations on a generalized velocity distribution
Authors: Brodkey Robert S. 
Published: June 2004

AbstractThe usefulness of the Pai power series representation for the velocity distribution has been limited because of the lack of knowledge about the functional dependence of the empirical integer constant on the Reynolds number. Correlations are given for this constant for both Newtonian and non‐Newtonian materials; however, certain limitations are found as a result of actual velocity distribution calculations.The equation represents the distribution over most of the turbulent core at all Reynolds numbers, but deviates widely at about a y+ of 75 for Reynolds numbers greater than 100,000. Below this, the equation provides a satisfactory representation over the entire flow field.
Continuous propagation of microorganisms
Authors: Fredrickson A. G. , Tsuchiya H. M. 
Published: June 2004

AbstractMicroorganisms undergo a cycle of maturation during their life‐span in a proliferating culture. This gives rise to a distribution of degrees of cellular maturation in the culture. The gross rate of any metabolic process carried on by the culture is therefore an average over all degrees of maturation present.Equations embodying the life‐cycle concept are developed for cultures of organisms which proliferate by binary fission and do not form spores. The equations are solved for the age distribution in the special case of a continuous, steady state fermentation. Expressions for calculating gross metabolic rates and cell size distributions are derived. Finally, the stability of the steady state fermentor is discussed.
An analysis of slug flow heat transfer in an eccentric annulus
Authors: Snyder William T. 
Published: June 2004

AbstractA solution is presented for the temperature distribution in a fluid flowing in an eccentric annulus formed with circular cyclinders under the assumption of slug flow. The flow is assumed to be fully developed thermally with constant thermophysical properties. The outer surface is assumed to be adiabatic and the inner surface temperature is assumed to be independent of circumferential position. General expressions and numerical results for a typical set of conditions are presented for the quantities, local heat flux, local heat transfer coefficient, adiabatic surface temperature distribution, and average Nusselt number. The application of the present results to the prediction of turbulent heat transfer to liquid metals is indicated, and a comparison with other liquid metal heat transfer analyses is presented.
Prediction of vapor‐liquid equilibria with the Benedict‐Webb‐Rubin equation of state
Authors: Lin Min‐Shuey , Naphtali Leonard M. 
Published: June 2004

AbstractThe prediction of vapor‐liquid equilibria with the Benedict‐Webb‐Rubin (BWR) equation of state has been restudied. It was found that the suitability of the equation of state to represent fully the behavior of the constituents is the main factor which affects the accuracy of the prediction. To improve the representation of the pure component data by means of equation of state it is necessary to modify the present form of the BWR equation of state. A tentative form of modification of the BWR equation of state has been chosen. Although the modified equation is still subject to further evaluation and refinement, satisfactory results have been obtained for the prediction of four binary systems containing nitrogen and carbon dioxide (nitrogen‐methane. methane‐carbon dioxide, propane‐carbon dioxide, and n‐butane‐carbon dioxide).The method of nonlinear estimation has been used to fit the coefficients in the equation of state to either vapor‐pressure data or P‐V‐T data.
Formation of moderate‐size bubbles
Authors: Mahoney John F. , Wenzel Leonard A. 
Published: June 2004

AbstractBubbles were formed in water when air was passed through a single square‐edged orifice which had been drilled in a glass plate. The glass plate was 0.05 in. thick, and the orifice diameter was 1/8 in. The air chambers above the liquid surface and below the orifice plate were varied. The extreme values of these volumes were 0.00975 and 0.195 cu. ft. The air rate through the orifice, Q was as great as 200 × 10−5 cu. ft./sec. Bubble frequencies, f, were as great as 16 sec.−1Both the upper and lower chamber volume influenced markedly the relationship between f and Q. A relationship that predicts sets of upper and lower chamber volumes that result in the same f vs. Q relation is given. A two‐parameter equation that gives f as a function of Q is presented.Wettability of the orifice plate and the liquid depth over the orifice plate were also considered as independent variables.
Analytical solution of equilibrium‐stage operations—application to rectification with varying saturated enthalpies and to liquid‐liquid extraction
Authors: Martin Joseph J. 
Published: June 2004

AbstractA complete analytical solution is developed for the number of equilibrium stages in separations processes for which operating and equilibrium lines are not necessarily straight. The resulting equations are solutions of a Riccati difference equation and are applied to liquid‐liquid extraction and the distillation of a binary mixture where the liquid and vapor flows are not constant because of the variation of the saturated liquid and vapor enthalpies with concentration. A specific example is given for the separation of ethyl alcohol and water in which the equilibrium curve is highly nonlinear and where a large number of plates are required in a pinch region. Another example is given for the extraction of methylcyclopentane from its solution in n‐hexane using aniline as a selective solvent.
Nuclear radiation‐induced cracking of n‐hexadecane
Authors: Guernsey Edwin O. , Shaw Henry , Smith William E. 
Published: June 2004

AbstractA representative paraffin hydrocarbon in the gas oil range, n‐hexadecane, has been irradiated in the Industrial Reactor Laboratories' 5 mw. nuclear research reactor. In the vapor phase radiation‐induced cracking proceeded efficiently, and G values for radiation conversion of n‐hexadecane were 200 to 1,200 at temperatures near 750°F. Total conversions of n‐hexadecane were less than 3 wt. % and were due only in part to the radiation effect. The distributions of products which were obtained were similar to those which result from thermal cracking of n‐hexadecane. There were however significant increases in the yields of hydroger., reductions in the yields of very light hydrocarbons and small yields of high molecular weight products. At temperatures above 850°F. extensive thermal cracking obscured the effects of radiation.In liquid phase radiation‐induced cracking at 750°F. conversions of n‐hexadecane up to 15 wt. % have been obtained at liquid spaces velocities near 4 v./hr./v. In many exposures nearly one‐half of this conversion was attributed to the direct utilization of radiation. The corresponding G values were 30 to 60. The products obtained have been accounted for by adding together the products which would be expected from a radiation‐induced reaction producing primarily dimer, from radiation‐initiated chain propagated cracking, and thermally initiated chain cracking. The product distribution from these reactions can be changed by variation of the cracking temperature and/or radiation dose.
Characterization of multiple variable linear systems from random inputs
Authors: Angus R. M. , Lapidus Leon 
Published: June 2004

AbstractThe time constant of a continuous stirred‐tank reactor and the transfer function of a simulated second‐order system with two random inputs were determined. In the first case the experimental result agreed within 11% of the known value; in the second case the results agreed with those predicted from a theoretical analysis. To determine the transfer matrix of a fifth‐order system an impractical amount of medium speed computer time was required; the results were not considered satisfactory. However the length of calculation compares favorably with other methods of total identification for processes which have extraneous noise associated with them. Because of this the application of the present technique in adaptive control systems appears to be favorable.
The role of porosity in filtration: VI. New definition of filtration resistance
Authors: Tiller F. M. , Shirato Mompei 
Published: June 2004

AbstractThe definition of filtration resistance is re‐examined in view of the new theory (12) of the variation of flow rate with respect to distance through a filter cake. In the new definition it is shown that the filtration resistance depends upon slurry concentration as well as applied pressure. A correction factor modifying the specific filtration resistance previously defined by Ruth (5, 6) is developed.Where the hydraulic pressure variation within a cake is known, methods are presented for calculating the variation of flow rate with respect to distance and the change of filtration resistance in relation to slurry concentration.
The mechanism of liquid‐phase resistance to gas absorption in a packed column
Authors: Vivian J. Edward , King C. Judson 
Published: June 2004

AbstractThe desorption of five sparingly soluble gases from water into air in a packed tower was studied at five different flow conditions. At 25°C. these systems represent a range of liquid‐phase diffusivity from 1.4 × 10−5 to 6.3 × 10−5 sq. cm./sec. The mass transfer coefficient was found to vary as the 0.5 power of liquid‐phase diffusivity in all cases. This result, obtained through the variation of diffusivity alone, is in agreement with the predictions of penetration theory and strongly suggests a penetration mechanism based on molecular processes and independent of eddy processes during a surface lifetime. A discussion of the nature of the diffusion and surface renewal process in flow over packing is included.
Transport characteristics of suspensions: Part IX. Representation of periodic phenomena on a flow regime diagram for dilute suspension transport
Authors: Thomas David G. 
Published: June 2004

AbstractFour different flow regimes may be identified during transport of dilute suspensions of solid particles through horizontal pipes by liquids in turbulent flow as the velocity is varied. The regimes may be characterized by the distribution of solids in the channel. In two of the regimes the bulk of the material is immediately adjacent to the bottom of the channel and is clumped up either into transverse waves (dunes or islands) with a reproducible periodicity or into longitudinal waves (long stria). The definition of the other two regimes is somewhat more arbitrary but may qualitatively be described as heterogeneous or homogeneous flow. Extensive studies of the conditions under which transverse and longitudinal waves occurred, when combined with results of previous studies, showed that all four of these flow regimes may be conveniently represented on a single diagram in which the terminal‐settling velocity divided by the friction velocity and the Reynolds number on particle diameter and friction velocity are the coordinates. Because the particle Reynolds number based on the terminal‐settling velocity can be uniquely defined as an additional parametre on such a diagram the particular flow behavior for any given combination of system and particle characteristics can be readily determined.
Optimization by Pontryagin's maximum principle on the analog computer
Authors: Lee E. Stanley 
Published: June 2004

AbstractA computational method has been developed for obtaining the solution to a class of optimization problems by the combined use of the maximum principle and a maximum (or minimum) seeking technique on the analogue computer. Various maximum seeking techniques can be used for this method. However if the random search technique is used, this computational method has the advantage of being able to investigate a large number of operating (or controlling) variables.The calculation procedure is essentially a trial‐and‐error procedure which is alternately integration and maximum seeking operations. The variables over which the system is to be optimized are approximated by a finite number of straight line segments n. Thus the maximum (or minimum) of the Hamiltonian function which is obtained by the maximum principle need only be obtained at n + 1 points along the optimization path (or trajectory).To illustrate the use of the method the optimum operating variable profiles (or gradients) in a tubular chemical reactor were computed.The present method, in addition to making it easier to investigate systems with a moderate number of state variables, can be used to solve problems with almost any kind of constraints and performance index encountered in ordinary optimum design problems. It offers some possibilities for on‐line optimizing control of a process. A special purpose analogue computer could be built for this use.
Laminar flow in the inlet section of parallel plates
Authors: Wang Y. L. , Longwell P. A. 
Published: June 2004

AbstractVelocity distributions, pressure gradients, and overall pressure drops are presented. A definite concavity was found in the velocity profile near the entrance for case I. In case II, which is more realistic physically, very definite effects are transmitted upstream, and the velocity distributions downstream show little concavity.
Lateral solids mixing in fludized‐packed beds
Authors: Gabor John D. 
Published: June 2004

AbstractA study was made of the mixing of particulate solids fluidized in the voids of a packed bed of larger nonfluidized bodies. In such a system heat transfer rates are dependent on the movement of fluidized particles. Recently application has been made of inert fluidized particles in chemical reactor systems to improve the removal of the heat generated by the exothermic reaction of the larger particles. A measure of the particle movement was achieved in this study by the determination of diffusion coefficients for the rates of solids mixing in the lateral direction when metal shot is fluidized in the voids of spherical and cylindrical packing. Experimental data showed that the particle mixing was related to the void structure of the packed bed by a random walk model. A general correlation was made for fluidized‐solids diffusivity in spherically packed beds.
Correlation of thermodynamic properties of amine‐water solution with molecular structure
Authors: Davison R. R. , Hood D. W. , Harris W. D. 
Published: June 2004

AbstractThe solutions of amines and water are in several respects among the most interesting that have been studied. They give some of the most perfect examples of lower consolute temperatures with fast breaking, almost flat solubility curves near the critical solution point. Their heat and entropy of solution are very high, and with few other solutions do the thermodynamic properties show greater sensitivity to molecular structure.The activity coefficients for these solutions are inordinately difficult to fit with equations such as the Margules, Redlich‐Kister, etc., requiring as many as six constants. It has been found however that some of the properties can be correlated in terms of structural parameters which are measures of the steric and inductive contribution of the substituent groups. A very good correlation of the heat of solution at infinite dilution of amines in water is given. An equation of the Margules type employing orthogonal polynomials is given for which the constants are similarly correlated. Five six‐carbon atom amines at 10°C. are included in the latter correlations, and the activity coefficients of all of these are represented in terms of two structural parameters.
An experimental investigation of the inherent uncertainty in pool boiling critical heat fluxes to saturated water
Authors: Gambill Wallace 
Published: June 2004

AbstractThe inherent uncertainty of the critical heat flux in saturated pool boiling has been inconclusively debated for some time. In an effort to ascertain this uncertainty a series of 234 tests was conducted at atmospheric pressure with saturated water outside horizontal, a.c. heated, 0.234‐in. O.D., A‐nickel tubes in an open 6 × 6 × 9‐in. deep pool. Approximately fifty tests were conducted with each of four test sections which were protected from physical burnout by a detector circuit which terminated the applied current before the wall temperature exceeded approximately 450°F. The maximum relative uncertainty in the derived values of critical heat flux was ±3%.For all the tests the minimum, average, and maximum critical fluxes were 0.201 × 106, 0.436 × 106, and 0.596 × 106 B.t.u./hr. sq. ft., respectively, and the average critical wall superheat was 41°F. The surface roughness of the test sections remained essentially unchanged during the program. The data show that there is an inherent uncertainty or scatter band in the critical heat flux under conditions of minimum surface variability, and that solely hydrodynamic theories of burnout do not fully represent the phenomenon, since surface condition can constitute a significant influence.
A kinetic study of sulfur dioxide in aqueous solution with radioactive tracers
Authors: Wang J. C. , Himmelblau D. M. 
Published: June 2004

AbstractA kinetic study was made of the homogeneous reactions in the sulfur dioxide‐sodium bisulfite‐water system, with a radioactive tracer technique. By operating this system at chemical equilibrium but at isotopic disequilibrium the influence of the diffusion of sulfur dioxide into and out of the aqueous solution could be divorced from the kinetic effects of the chemical reaction. It was then possible to follow the rate of reaction of this system by analyzing the radioactive sulfur‐35 in the form of gaseous sulfur dioxide, with the Bernstein‐Ballentine technique.Data were collected at temperatures of 0° to 20°C. and at pH ranges from 1.25 to 4.3. Analysis and correlation of the experimental data by different kinetic models demonstrated that the classical reaction SO2 + H2O ⇌ H+ + HSO3− represented the experimental data best from a macroscopic viewpoint. Because of the low pH conditions employed it was not possible to obtain rate data for the reaction SO2 + OH− ⇌ HSO3.Forward and reverse rate constants are reported for the first time for this system.
Virial coefficients for argon, methane, nitrogen, and xenon
Authors: Gyorog Donald A. , Obert Edward F. 
Published: June 2004

AbstractThe second, third, and fourth virial coefficients for argon, methane, nitrogen, and xenon have been established by various methods to satisfy experimental compressibility data and also to satisfy graphical computations of the property deviation relationships of Δuoand Δho.
Tube flow of non‐Newtonian polymer solutions: Part II. Turbulent flow
Authors: Meter Donald M. 
Published: June 2004

AbstractA correlation of turbulent tube‐flow friction factors for non‐Newtonian polymer solutions, based upon the fluid property τ1/2 defined in Part I, has been found to represent data taken on seven solutions of Natrosol hydroxyethylcellulose in ½‐ and 1‐in, I.D. smooth tubes, with an average accuracy of 10.8%. Also, for these seven solutions, this correlation gives somewhat more accurate predictions of the point of transition into turbulent flow than are made by the Ryan‐Johnson stability theory.The correlation must be considered only provisional, however, because it does not simplify to the limiting case of extremely dilute solutions. Plausible extensions based on models of steady‐flow non‐Newtonian viscosity behavior, and other possible correlation schemes utilizing viscoelastic fluid properties, are briefly discussed.
Analysis of phase boundary motion in diffusion‐controlled processes: Part II. Application to evaporation from a flat surface
Authors: Griffin J. R. , Coughanowr D. R. 
Published: June 2004

AbstractIn an earlier paper (1), three general methods of approaching the moving‐boundary problems were developed. In the present work, these three methods are applied in detail to the solution of the problem of evaporation from a flat surface into a vapor phase of infinite depth. While this particular problem has been solved before (2,3), it has been chosen as an example here because all three methods apply directly.
Thermal pressure applied to the prediction of viscosity of simple substances in the dense gaseous and liquid regions
Authors: Lennert David A. , Thodos George 
Published: June 2004

AbstractThe reduced thermal pressure‐temperature ratio has been used to relate residual viscosity modulus for argon, krypton, and xenon into a unique relationship applicable for the dense gaseous and liquid regions. For these monatomic substances the critical compressibility factor is zc= 0.291. Values of (∂PR/∂TR)pRvs. (μ —μ*)ζ on log‐log coordinates produced a linear relationship. For these simple substances, this relationship was used to predict viscosities with an average deviation of 3.0% for fifty eight experimental values. This relationship was also applied for the prediction of viscosities for nitrogen, oxygen and carbon dioxide.The approach developed in this study merits further examination with several additional substances. The lack of adequate thermal pressures in the dense gaseous and liquid regions of substances other than argon limits the use of this study to substances having critical compressibility factors zc= 0.291.
The influence of mass transfer on a countercurrent liquid‐liquid fluidized system
Authors: Dunn I. , Lapidus Leon , Elgin J. C. 
Published: June 2004

AbstractThe present work is concerned with an experimental study of the influence of mass transfer on the holdup of countercurrent liquid‐liquid fluidized systems and the effect of solute on droplet coalescence. Of particular importance in the results obtained is the dramatic demonstration that mass transfer greatly influences the holdup when solute is being extracted from the discontinuous phase loading to strong coalescence.