bluuebunny/crossref_metadata_2025_split huggingface dataset:
Lateral transport in a fluidized‐packed bed: Part II. Heat transfer
Authors: Gabor John D. , Stangeland Bruce E. , Mecham William J. 
Published: June 2004

AbstractEffective thermal conductivities for lateral heat transfer were measured in a fluidized‐packed bed. An analysis of the mechanism of heat transfer was made by comparison with previously determined rates of solids mixing. A general correlation was made of the fluidized‐packed bed thermal diffusivities with the size of the fixed packing and the minimum fluidization velocity in a manner similar to the correlation for lateral solids mixing diffusivities in a fludizied‐packed bed.
Analysis of phase‐boundary motion in diffusion‐controlled processes: Part I. Solution of the diffusion equation with a moving boundary
Authors: Griffin J. R. , Coughanowr D. R. 
Published: June 2004

AbstractThree general methods are developed for solving moving‐boundary problems which are governed by diffusional processes such as heat and mass transfer. Examples of such problems include melting, evaporation, and ablation. A method based upon a Riemann‐Volterra integration of the diffusion equation leads to nonlinear integrodifferential equations for the boundary motion that are in terms of definite integrals involving Green's functions. An analytical method, which is more convenient for problems involving phase motion, is based on the method of intermediate integrals. A numerical method based on finite difference approximations is implemented on the differential analyzer (analogue computer).
The thermal conductivity and diffusivity of gases for temperatures to 10,000°K
Authors: Mathur G. P. , Thodos George 
Published: June 2004

AbstractA generalized method has been developed for the prediction of the diffusivity and thermal conductivity of nonpolar gases for temperatures up to 10,000°K. This method is applicable to monatomic gases and to diatomic gases existing in their molecular and dissociated states. Dimensional analysis has been used to obtain relationships for self‐ and mutual diffusivities and for the translational contribution to the thermal conductivity of these substances. For the internal contribution to thermal conductivity, a modified Eucken‐factor relationship is presented. Furthermore, relationships have been developed for the calculation of these transport properties for the equilibrium mixture of a dissociating gas.
The friction factor–Reynolds number relation for the steady flow of pseudoplastic fluids through rectangular ducts. Part I. Theory
Authors: Wheeler John A. , Wissler Eugene H. 
Published: June 2004

AbstractA finite difference technique is used to calculate the velocity profile, maximum shear stress, and friction factor‐Reynolds number product for a power‐law, pseudoplastic fluid flowing through a cylindrical duct of rectangular cross section. It is assumed that the motion is rectilinear. A very simple friction factor‐Reynolds number correlation is obtained for the special case of a square duct.
Mixing of viscous non‐Newtonian fluids in packed beds
Authors: Hassell H. L. , Bondi Arnold 
Published: June 2004

AbstractRadial mixing of concentrated solutions of rubber dissolved in a light aliphatic hydrocarbon was studied in beds packed with glass spheres or York mats. The degree of mixing in the bed of spheres was significantly better, that is the Peclet number much smaller, than predicted from Wilhelm's correlation.Pressure drop associated with the flow of rubber cement through packed beds is well represented by existing correlations, provided the effective viscosity is obtained from a shear rate vs. shear stress diagram for the fluid.
Generalization of gas‐liquid partition chromatography to study high pressure vapor‐liquid equilibria of multicomponent systems
Authors: Koonce K. Terry , Deans H. A. , Kobayashi Riki 
Published: June 2004

AbstractThe use of chromatographic retention volume data to obtain vapor‐liquid equilibrium coefficients has been extended to a ternary system with all components present at finite concentrations in the liquid phase and essentially a light binary gas comprising the vapor phase. The data are obtained by observing the retention time of the solute of interest when that solute is eluted by a flowing gas stream through a column packed with an inert porous firebrick on which is impregnated a fixed, relatively nonvolatile liquid. The retention times are used to compute retention volumes which may be related to the K values of the solute.A previous mathematical description of the elution process is modified to include the case of an N component elution gas, all constituents of which are soluble in the fixed liquid phase. A general solution is derived for the multicomponent elution gas from which K values for each component may be calculated if retention volume data are taken for each, provided molecules of the solute samples used are distinguishable from others of the same species present in the eloution gas. For the case of indistinguishable sample molecules, the rate theory development of Stalkup and Deans is verified for a binary elution gas.Sufficient retention data were taken to completely define the concentration dependence of the K value for propane in the system methane‐propane‐n‐decane at −20°, 0°, 40°, and 70°F. from 20 to 1,000 lb/sq.in.abs. Six methane‐propane binary mixtures were used as elution gases, consisting of 2.08, 4.31, 6.90, 9.44, 13.09, 16.27 mole % propane. Retention data were also taken for methane under the same conditions. Distinguishability of sample molecules was achieved by using radioactive solute samples tagged with carbon‐14.Propane retention data were also obtained for the system methane‐propane‐n‐heptane at −20° and −40°F. from 100 to 1,000 lb./sq.in.abs. for propane at infinite dilution and for binary elution gases composed of 2.08 mole % propane at −40°F. and 4.31 mole % propane at −20°F.All K values determined chromatographically were either compared directly with published static equilibrium values or tested for consistency with such values and found to be in substantial agreement.
Film instabilities in two‐phase flows
Authors: Ostrach Simon , Koestel Alfred 
Published: June 2004

AbstractThe major types of instabilities which can alter a given two‐phase flow pattern or lead to the breakup of a liquid film are delineated, and their physical mechanisms are discussed. Existing stability criteria are correlated to these basic types, and their application and limitations with respect to actual problems are indicated. Basic areas requiring further study are outlined.A criterion for determining the breakup length of a liquid film is developed which gives an indication of whether a given instability will lead to low frequency and high amplitude pressure and inventory pulsations. Such phenomena may be undesirable.Two new aspects of importance to the problem of film instability are introduced which have not been previously studied. These are rotation of the fluids and large disturbances in the flow. Their possible influence on the problem is discussed.
Effectiveness factors for general reaction rate forms
Authors: Bischoff Kenneth B. 
Published: June 2004

AbstractThe great utility of the effectiveness factor concept to account for intraparticle diffusion lies in its simplicity of application. Unfortunately, the standard formulation leads to a separate relationship for each type of reaction rate form, which greatly complicates practical computations.A general asymptotic solution is given here which leads to the definition of a general modulus somewhat different in form from the standard one. The use of this general modulus tends to approximately bring together all of the various curves.To illustrate its use, a few new exact solutions for simple order reactions are derived and combined with existing solutions for both simple order and adsorption reaction rate forms. It is seen that all of the curves lie within a relatively narrow range. Thus the general modulus permits one to estimate the effectiveness factor for any arbitrary reaction from the existing curves.
Longitudinal dispersion in pulsed perforated‐plate columns
Authors: Miyauchi Terukatsu , Oya Haruhiko 
Published: June 2004

AbstractExperimental measurements have been performed for pulsed perforated‐plate columns of different sizes and geometry to obtain longitudinal dispersion coefficients for continuous and dispersed phases and size and holdup of liquid droplets dispersed in the columns. These quantities are correlated with operating conditions and column design, including the data published by different authors. Longitudinal dispersion coefficients for the continuous phase are shown to follow the backflow model. A superficial number of stages in series in each compartment is shown to come from inherent instability of fluid motion in the compartment. The longitudinal dispersion coefficient of the dispersed phase approaches that of the continuous phase with increasing pulse velocity. Holdup and mean size of droplets are correlated mainly on the basis of the rate of energy dissipation in the column fluid. Inclusion of dispersed‐phase viscosity is shown to correlate the holdup data successfully for different liquid‐liquid systems.
Coalescence of liquid droplets in two‐component–two‐phase systems: Part I. Effect of physical properties on the rate of coalescence
Authors: Jeffreys G. V. , Hawksley J. L. 
Published: June 2004

AbstractExperimental coalescence time and time distribution studies of the coalescence of a single droplet at a plane interface are presented for four two‐component–two‐phase systems. The results have been analyzed by dimensional analysis and statistical analysis, and a correlation of coalescence time and coalescence time distribution with the physical properties of the system is proposed.
Significance of pressure gradients in porous materials: Part II. Diffusion and flow in porous catalysts
Authors: Otani Seiya , Wakao Noriaki , Smith J. M. 
Published: June 2004

AbstractDiffusion and flow rates through porous catalysts were measured under the conditions of finite pressure gradients for single‐ and two‐component systems. For large pore (low density) alumina pellets the diffusion rate counter to the pressure gradient was severely depressed, while for small pore Vycor the pressure gradient had little effect.The equations developed in Part I for flow and diffusion in a single capillary were extended to porous catalysts. The resulting prediction methods contain no parameters which require transport data for their evaluation, but pore size and void fraction information is needed. For the catalysts investigated, both the permeability and diffusion rates varied several thousand‐fold. The calculated results predict the same extensive range and show the same effects of pressure gradient and pore properties. Also the quantitative agreement between calculated and experimental results is such that the theory provides a useful method of predicting transport rates through certain types of porous media.
Vapor‐liquid equilibria in hydrogen‐benzene and hydrogen‐cyclohexane mixtures
Authors: Thompson Richard E. , Edmister Wayne C. 
Published: June 2004

AbstractA new vapor‐liquid equilibrium experimental facility has been built for and operated on light gas‐hydrocarbon systems. The range of operating conditions are 3 to 1,000 atm. and 25° to 400°C. A dynamic flow type of equilibrium cell is used. This and most of the other apparatus are from designs by Michels. Solubilities of hydrogen in benzene and in cyclohexane were obtained at 150° and 250°F. and at pressures up to 10,000 lb./sq.in.abs.Compositions of the equilibrium vapor phases were determined so the vapor‐liquid K ratios could be derived. Thermodynamic consistency tests were applied to the data with the conclusion that the new data are consistent with volumetric properties, predicted by other methods.
A study of perfectly mixed photochemical reactors
Authors: Harris Paul R. , Dranoff Joshua S. 
Published: June 2004

AbstractThe performance of a perfectly mixed photochemical reactor has been analyzed for systems having low light absorption coefficients. The analysis has been tested by an experimental study of the decomposition of hexachloroplatinic acid in dilute aqueous solution. Results tend to verify the analysis, but indicate the need for additional experimental work.
Turbulence effect on direct‐contact heat transfer with change of phase: Effect of mixing on heat transfer between an evaporating volatile liquid in direct contact with an immiscible liquid medium
Authors: Sideman Samuel , Barsky Zvi 
Published: June 2004

AbstractThe concept of local isotropy in turbulent agitation together with the particular characteristics of volatile drops evaporating while in dispersion were used to derive a simple and practical correlation relating the specific power input with the temperature driving force and the heat flow rates for all conceivable mixing regimes. The correlation was verified by experiments which indicate that dilute evaporating dispersions are controlled by viscous shear stresses.The generality of the proposed correlation is demonstrated by its application to pilot plant and laboratory data obtained over a wide range of turbulent mixing intensities. At its lower limit the correlation reduces to the well‐known relationship of surface‐boiling heat transfer.
Analytical and numerical solutions for laminar flow of the non‐Newtonian ellis fluid
Authors: Matsuhisa Seikichi , Bird R. Byron 
Published: June 2004

AbstractBecause of the apparent success in the use of the three‐constant Ellis model to describe a wide variety of experimental data, a summary is given of analytical and numerical solutions for this model. The solutions include isothermal flow between flat plates, in tubes, in films, in annuli (axial, tangential, and radial) and nonisothermal flow in tubes with constant wall temperature and with constant heat flux at the tube wall.
Local parameters in cocurrent mercury‐nitrogen flow: Parts I and II
Authors: Neal L. G. , Bankoff S. G. 
Published: June 2004

AbstractAn experimental study was made in a cocurrent vertical mercury‐nitrogen flow of local parameters, including local liquid velocity and gas fraction. In Part I the pertinent quantities are carefully defined and power‐law continuity expressions derived. A description is given of the apparatus, including a simple local liquid velocity probe. In Part II experimental velocity and void profiles are given for the mercury‐nitrogen flow. The regime is slug flow, but the slugs are not axisymmetrical, on account of the nonwetted walls. Intensities of density and liquid velocity fluctuations are computed for the first time and a comparison made with Levy's mixing‐length theory.
The effect of concentration level on the gas phase absorption coefficient
Authors: Vivian J. Edward , Behrmann William C. 
Published: June 2004

AbstractA theoretical and experimental investigation has been made to determine the effect of the concentration level on the rate of mass transfer of a solute from a nontransfering or inert carrier gas in turbulent flow.Diffusion theory predicts the gas phase mass transfer coefficient to be inversely proportional to the first power of the mean mole fraction of the nontransferring gas and to be a possible function of the rate and direction of mass transfer.The results of an experimental study of the absorption of ammonia from mixtures with nitrogen into distilled water and aqueous ammonia solutions in a short wetted‐wall column verified the predicted inverse relationship between the turbulent gas phase absorption coefficient and the first power of the mean inert mole fractions ranging from 0.068 to 0.934. The data also showed that for the range covered in this investigation there was no significant influence of the mass transfer rate on the product of the coefficient and the mean mole fraction of the inert carrier gas.
Second‐order chemical reactions in a nonhomogeneous turbulent fluid
Authors: Vassilatos George , Toor H. L. 
Published: June 2004

AbstractVery rapid, rapid, and slow second‐order reactions were studied in an isothermal turbulent flow reactor. The two aqueous reactant solutions were separately introduced through many alternate jets and the reaction took place in the resulting nonhomogeneous mixture. Very rapid reactions were diffusion controlled and were in agreement with earlier theory. All reactions followed second‐order rate laws based on time average quantities. The apparent reaction velocity constant was controlled by the mixing for very rapid reactions, by the chemical kinetics for slow reactions, and by both mechanisms for rapid reactions.
Determination of plate efficiencies from operational data: Part II
Authors: Davis Parke , Taylor D. L. , Holland C. D. 
Published: June 2004

AbstractA method for the determination of the plate efficiencies for existing conventional and complex columns is presented. Information, such as any combination of product distributions, plate temperatures, and plate compositions, which is in addition to that required to solve a problem for a fixed column is used to determine efficiencies.
Diffusion in the laminar boundary layer with a variable density
Authors: Hanna Owen T. 
Published: June 2004

AbstractThe problem of isothermal diffusion in a variable molecular‐weight binary gas mixture is considered for the case when the process occurs in a laminar boundary layer. Viscosity and diffusion coefficient are assumed constant. Solutions are given for both forced and free convection at large Schmidt numbers and large mass transfer rates toward the surface. Use of the molar average velocity considerably simplifies the results. These results suggest that the constant density solution in terms of mole fractions, evaluated at free stream conditions, may be a good approximation for variable density. This technique, improved by an approximate correction derived herein, is shown to agree reasonably well with the results of exact numerical solutions of the boundary layer equations.
Size distribution dynamics in a salting out crystallizer
Authors: Murray D. C. , Larson M. A. 
Published: June 2004

AbstractA laboratory continuous mixed suspension salting out crystallizer was designed and constructed to test the dynamic crystallization model proposed by Randolph and Larson. The model relates the crystal size distribution to nucleation and growth kinetics and operating conditions. The ammonium alum‐ethanol‐water system was selected because of its ease of operation and control.The results of this work were in agreement with the steady state model. Under the conditions of these experiments, it was found that the nucleation rate dNo/dt was related to the growth rate r by dNo/dt = k1r2. The crystallizer was also operated under unsteady state conditions which resulted from variations in the production rate. The theoretical model with experimentally determined parameters was simulated on an analog computer and solved for production rate changes. The results indicated that the model was in agreement with the dynamic data for production rate upsets.
Peak nucleate boiling fluxes for liquid oxygen on a flat horizontal platinum surface at buoyancies corresponding to accelerations between −0.03 and lgE
Authors: Lyon D. N. , Jones M. C. , Ritter G. L. , Chiladakis C. I. , Kosky P. G. 
Published: June 2004

AbstractPeak nucleate boiling fluxes for liquid oxygen near 1 atm, have been measured on a 0.75‐in.–diameter flat polished horizontal platinum surface located in a known, variable magnetic‐field gradient that produced steady acceleration (which could be maintained indefinitely) on the oxygen acting in opposition to the earth's gravitation, gE. Measurements were made under condition ranging from net negative (directed away from the heated surface) accelerations of −0.03gE acting on the bulk liquid to the normal accelerations, 1.0gE. The results indicate that at zero g conditions for the bulk liquid, the peak nucleate boiling flux is ∼0.55 of the value at 1.0gE. For bulk‐liquid accelerations ranging from ∼0.25 to 1gE, the experimental results confirm the ¼ power dependence of peak flux on acceleration as predicted by various correlations. However, below 0.25gE the peak flux becomes insensitive to the acceleration, varying approximately in proportion to the 1/14 power of the net acceleration. At bulk‐liquid conditions of zero g (±0.005gE) the peak plux breaks sharply and falls by a factor of 10 between zero g and −0.03gE (for this apparatus).
Heat transfer to decomposing nitrogen dioxide in a turbulent boundary layer
Authors: Brian P. L. T. , Reid R. C. , Bodman S. W. 
Published: June 2004

AbstractHeat transfer coefficients were measured for the dissociating system 2 NO2⇋ NO + O2in turbulent flow. Heat transfer rates to this reacting gas are limited by the kinetics of the decomposition and recombination reactions. Experimental results agree to within 10% with a film‐theory solution for heat transfer accompanied by a nonequilibrium chemical reaction.
Forced convection mass transfer: Part II. Effect of wires located near the edge of the laminar boundary layer on the rate of forced convection from a flat plate
Authors: Thomas David G. 
Published: June 2004

AbstractThe local and the average rates of forced convection through laminar boundary layers on a flat plate were shown to be markedly increased by locating small cylinders near the outer edge of the boundary layer. The local rate of forced convection was strongly peaked directly beneath each cylinder; the magnitude of the effect depended upon the free stream velocity, the spacing between cylinders, and the gap between the cylinders and the plate. Under optimum conditions, local values of the rate of forced convection were increased as much as 340%, while the average values were increased by over 190%.
Laminar dispersion in capillaries: Part I. Mathematical analysis
Authors: Ananthakrishnan V. , Gill W. N. , Barduhn Allen J. 
Published: June 2004

AbstractSince 1953, when G. I. Taylor first considered the problem, numerous studies of the miscible displacement of fluids in capillaries have produced several approximate mathematical solutions which are purported to be valid under different conditions. Their form and ranges of applicability have been in conflict to some extent, since no exact solution is available to check these expressions.This study has resulted in exact numerical solutions to this problem with both axial and radial molecular diffusion accounted for. The range of parameters investigated is wide enough for comparison with all known analytical and empirical results and covers τ from 0.01 to 30 and NPe from 1 to 23,000. It is shown that for sufficiently large values of τ the Taylor‐Aris theory is valid and thus results for all τ and NPe of any practical interest are now known.Axial molecular diffusion is significant at lower values of the Peclet number but the magnitude of NPe at which this occurs depends on the value of τ. In general, axial molecular diffusion is important for Peclet numbers less than about 100.Present results show that there is no justification for Bailey and Gogarty's empirical modification which yields an exponent of 0.541 rather than 0.50 for τ in Equations (35) and (36). Also, for the system studied here, no justification was found for the conjecture of Bournia et al. that Aris' low NPe modification may not account for axial diffusion properly.Simple expressions given by Equations (48) and (50) were developed empirically and they give with good accuracy the average concentration distribution over wider ranges of NPe and τ than previously reported expressions.