bluuebunny/crossref_metadata_2025_split huggingface dataset:
Flow patterns in agitated vessels
Authors: Metzner A. B. , Taylor J. S. 
Published: June 2004

AbstractThe flow patterns obtained when viscous fluids are agitated inside baffled cylindrical tanks have been studied in both Newtonian and non‐Newtonian systems. The experimental technique consisted of observing the motions of small tracer particles in highly illuminated, narrow beams of light.The results may be broken down into two major categories. The first was a qualitative comparison between the flow patterns obtained in non‐Newtonian and Newtonian fluids of the same general viscosity levels. This part of the study included observation of changes in the flow fields as one moves from laminar into turbulent conditions for both fluid systems.The second portion of the paper deals with quantitative determinations of local flow velocities, shear rates, and power‐dissipation rates in various parts of the vessel. The following conclusions may be drawn from these measurements.1. Local fluid shear rates were found to be directly proportional to impeller speed, in both Newtonian and non‐Newtonian systems. As would be expected, the shear rates decreased more rapidly with increasing distances from the impeller in pseudoplastic non‐Newtonian fluids than in Newtonian systems.2. The rates of local power dissipation decreased rapidly with distance from the impeller.3. The fluid velocities in the horizontal plane of the impeller varied almost linearly with rotational speed in the Newtonian systems, in accordance with prior observations. On the other hand, movement in pseudoplastic systems increased exponentially with impeller speed. This effect, like the dampening of shear rates, is caused by the cumulative effects of local velocity and viscosity changes in these systems. (Increases in velocity decrease the fluid viscosity, which in turn causes further increases in velocity, etc.)This work serves to define pertinent problems which are of importance in determining mixing rates, on a microscopic scale. Efforts may now perhaps be turned more profitably than before toward macroscopic fluid‐mixing studies.
A corresponding‐states correlation for higher molecular‐weight liquids
Authors: Bondi A. , Simkin D. J. 
Published: June 2004

AbstractA corresponding‐states correlation for the liquid‐state properties of higher molecular‐weight substances is presented which contains as reducing parameters the readily measurable (and correlatable) energy vaporization and van der Waals volume instead of the often inaccessible critical constants. One additional parameter characterizing molecular flexibility is introduced.A single curve of the new reduced density ρ* vs. the new reduced temperatureT* is shown to represent the atmospheric‐pressure‐density‐temperature relations of paraffinic, naphthenic, and aromatic hydrocarbons with 10 or more carbon atoms per molecule to within ±1% between their melting and their atmospheric boiling points. The reduced surface tension is shown to be a unique function of ρ± for many compounds, thus permitting prediction of surface tension over wide ranges of temperature. The heat‐capacity difference between liquid and vapor proved to be easily correlatable with ρ±. Finally the compression of numerous hydrocarbons proved to be well correlated in terms ofT*, ρ±, andP*. Extensive group data forVwandE° have been assembled in the appendix in order to enable others to use the proposed method without effort.
Critical temperatures and pressures of organic compounds
Authors: Forman Charles J. , Thodos George 
Published: June 2004

AbstractThe approach presented for the prediction of critical temperatures and pressures for hydrocarbons from the van der Waals' constants a and b (1) has been extended to permit the estimation of these constants for other organic compounds. Analogously, contribution values for a number of functional groups have been established, and the majority were found to depend on the size of the organic molecule. Information presently available in the literature (4) has permitted the establishment of values for functional groups in organic compounds of the following types: alcohols, phenols, ethers, ketones, carboxylic acids and esters, amines, nitriles, and halides. These functional group contributions, in conjunction with the values previously developed for the hydrocarbons, now make possible the calculation of both van der Waals' constants from only structural considerations. Once these van der Waals' constants have been established, the critical temperature and pressure are readily calculated.With the approach developed in this investigation critical temperatures and pressures for eighty‐one organic compounds have been calculated and when compared with literature values produced average absolute deviations of 1.36% for the critical temperature and 2.32% for the critical pressure.
Heat transfer to liquid streams in a packed tube containing large packings
Authors: Chennakesavan Balapa 
Published: June 2004

AbstractWall‐area heat transfer coefficients based on bulk‐mean temperatures of the liquids flowing upward in a steam‐jacketed packed tube (4 ft. long and 2.25‐in. I.D.) were determined. The tube was randomly packed in each of the experiments with spherical glass packings of uniform size (with diameters between 3/4 and 5/32 in.). The liquids used were water, toluene, 45% aqueous glycerine, and nitrobenzene.Analogous correlations were developed for the heat transfer coefficients and for pressure drop, the dimensionless groups in the above being the same as for open tubes. The two relationships are applicable for the range inDT/DPratio from 14 to 3 and inNRefrom 40,000 to 300. The first is satisfactory within ±15% for heating of liquids in the above packed tube, the second within ±10% for most of the data of packed tubes reported so far.
Natural convection inside a horizontal cylinder
Authors: Martini William R. 
Published: June 2004

AbstractThe two vertical halves of the wall of a 4.3‐in. I.D. cylinder were maintained at different uniform temperatures. The rate of circulation of air inside the cylinder and the local rate of heat transfer between the wall and air were derived from measurements of the velocity and temperature fields in the air for wall‐temperature differences from 3.5° to 367°F. The overall rate of circulation was found to increase quite rapidly and then to decrease slowly as the wall‐temperature difference was increased. The over‐all Nusselt number based on the wall‐temperature difference was found to have an approximately constant value of 7.0.Numerical solution of the partial differential equations describing the conservation of mass, momentum, and energy for this system was investigated with an IBM‐650 magnetic drum computer. Instabilities in the computational procedure and limitations of this computer prevented solution of the general problem. However specification of the velocity field obtained from experiment yielded a numerical solution for the temperature field in good agreement with the experimental measurements.
The thermal entrance region in fully developed turbulent flow
Authors: Abbrecht Peter H. , Churchill Stuart W. 
Published: June 2004

AbstractThe temperature profile and the local rate of heat transfer from the wall were measured at 0.453, 1.13, 4.12, and 9.97 tube diameters downstream from a step increase in wall temperature for air in fully developed turbulent flow at Reynolds numbers of 15,000 and 65,000 in a 1.52‐in. tube. The velocity profile and the pressure were also measured at these lengths.Radial and longitudinal temperature gradients, radial heat fluxes, and eddy diffusivities for heat and momentum transfer were computed from the measurements. The longitudinal temperature gradients at all radii were found to differ significantly from the mixed mean temperature gradient. Although the radial heat flux was a maximum at the wall, the radial heat‐flux density, in terms of which the eddy diffusivity for heat transfer is usually defined, was found to go through a maximum near the wall and then to decrease almost linearly across the thermal boundary layer. The eddy diffusivity for heat transfer was found to be independent of length in the thermal entrance region and hence a function only of the fluid motion, as previously hypothesized.
Mass transfer coefficients for solids suspended in agitated liquids
Authors: Barker James J. , Treybal Robert E. 
Published: June 2004

AbstractThe mass transfer coefficient in covered, right‐cylindrical tanks full of liquid, turbulently agitated at various speeds by turbines with six flat blades, was measured by the rate of solution suspended solids in water and in 45% sucrose solutions.Screened crystals in the following U. S. mesh sizes were used: boric acid: 18/20, 16/18, 16/20, 14/16, 12/14, 10/12, 8/10, 6/8; rock salt: 6/8, 4/6. Pellets were benzoic acid: 0.126 in. long by 0.218‐in. diam.; salt: 0.565‐in. diam. by 0.531‐in. long (over rounded ends). Tanks were 6, 12, 18, and 30 in. Turbines were 2, 3, 4, 6, 9, and 12 in. in diameter, centrally located. Four full‐length baffles 10% of the tank diameter wide were spaced at 90 deg. A few runs were made without baffles.The coefficient of mass transfer was found to be independent of particle size and Schmidt member (NSc = 735 to 62,000) and could be correlated with turbine Reynolds number in each tank, with larger tanks yielding smaller coefficients at the same NRe. An empirical equation which fits all the data from the baffled tanks within about 4% (in the range 0.1 < k < 2) is

where l2=0.8235−1.544V1/3+0.115V2/3The variance of estimate for this expression i s 0.0383, in units of [ln(10 k)]2.For extrapolation outside the experimental range of vessel sizes it is recommended that l1 = 0.676 − 1.266 V1/3 be used in place of I2. NRe = T2n/v. The results indicate that power per unit volume for a given k goes through a maximum, with the following relative values for the 6‐, 12‐, 18‐ and 30‐in. tanks: 1, 1.73, 1.78, 0.62.A treatment of the data according to dimensionless groups provides another correlation:kd/D=0.02NNt is shown that for the systems used 1/D is essentially proportional to N, and so the effect of diffusivity here is only apparent.
Continuous‐throughput rectification of organic liquid mixtures with thermal‐diffusion columns
Authors: Longmire David R. 
Published: June 2004

AbstractExperiments were carried out with cylindrical thermal‐diffusion columns in which the separation chambers were sufficiently narrow so that curvature effects might be ignored. For both open and closed operation, results were obtained for the two binary systems benzene‐carbon tetrachloride and n‐heptane–benzene as well as the ternary mixture n‐heptane–methylcyclo‐hexane‐toluene. For the binary systems, correlations are given in terms of dimensionless combinations which arise when the equations of conservation are placed in dimensionless form. The thermal‐diffusion coefficients used in the correlations are literature values determined in steady‐state–cell (no convection) measurements.
Correlating criteria for liquid‐phase adsorption
Authors: Jones Herbert L. , Stuart Edward B. 
Published: June 2004

AbstractA correlating equation for selective adsorption in the liquid phase has been extended to predict accurately the benzene‐cyclohexane equilibrium data on silica gel. Gel pore diameters range from approximately 25 to 150 Å. and temperatures between the boiling and freezing points of the pure components.
Calculation procedures for binary batch rectification
Authors: Huckaba Charles E. , Danly Donald E. 
Published: June 2004

AbstractA rigorous mathematical description, consisting of differential‐difference equations, is presented for binary batch rectification in the plate type of column. Two approaches are taken to solving these equations for the condition of constant reflux ratio: an integration by numerical means employing an IBM 650 computer, and a hand calculation procedure that involves trial‐and‐error computation of batch‐rectification curves, which is of interest primarily where high‐speed computing equipment is not available.Enthalpy balances are used to avoid assumption of equal rate of overflow in the tower; weight units are used instead of mole units; means for accounting for holdup in the condenser‐accumulator system are described. Criteria of convergence and stability of the numerical solution are presented. The validity of the results of the proposed calculation procedures is substantiated by the close agreement of experimental and calculated batch‐rectification curves.
Ion exchange kinetics for systems of linear equilibrium relationships
Authors: Tien Chi , Thodos George 
Published: June 2004

AbstractThe mathematical equations describing the kinetic behavior of ion exchange processes have been solved analytically for systems having linear equilibrium relationships of the type q* = K1 + K2C*. The concentration ratios of the effluent to the influent solution for these cases are found to depend on parameters involving time, position, and relative resistances of the liquid and resin phases. Numerical results have been obtained and are presented in tabular and graphical forms. Furthermore expressions for the constant pattern breakthrough curve for two special cases have also been worked out.
The dual nature of a catalytic reaction: The dehydrogenation of sec‐butyl alcohol to methyl ethyl ketone at elevated pressures
Authors: Thaller Lawrence H. , Thodos George 
Published: June 2004

AbstractA detailed analysis of initial rate data obtained for the catalytic dehydrogenation of sec‐butyl alcohol to methyl ethyl ketone in the presence of brass reveals that the controlling step of the reaction changes and depends on the operating conditions. To take advantage of the unique characteristics of initial rate equations, the experimental phase of this work has been carried out with a differential reactor and covered the temperature range 550° to 700°F. for pressures up to 15 atm. Feed compositions containing sec‐butyl alcohol and mixtures with methyl ethyl ketone and hydrogen were used.These studies show that the desorption of molecularly adsorbed hydrogen ceases to be the controlling step in favor of a dual‐site surface reaction depending on the operating variables. In view of these observations it now becomes necessary to calculate reaction rates with both over‐all rate equations and to select the lower rate as representative of the controlling step of the reaction.
A study of sieve‐tray efficiencies
Authors: Hay J. M. , Johnson A. I. 
Published: June 2004

AbstractThe performance of sieve trays in the rectification of the methanol‐water system without entrainment or leakage from the perforations was studied in an 8‐in.–diameter five‐tray column. The trays had a 2‐in. weir height and 4‐in. length of liquid path. Three tray geometries were studied: 1/4‐in. diameter holes on 3/4‐in. triangular spacing, 1/8‐in. holes on 3/8‐in. triangular spacing, and 3/16‐in. on 7/16‐in. triangular spacing. The superficial vapor velocity was varied from 2.2 ft./sec. to the limit of stable operation, which for this apparatus was 4.4 ft./sec. The ratio LM/VM within the column was varied from 1 to 0.5. The Murphree plate efficiency varied greatly from 105% at low concentration to 82% at high concentrations of methanol. Variations of 10 or 12 efficiency % were noted owing to changing velocities and tray geometries. Measurements of concentration gradients, foam heights, and gas pressure drops are also reported. This paper proposes a method of calculating the point efficiency and the number of individual‐phase mass transfer units independent of the actual concentration gradient on the tray.The method is applied to the methanol‐water data, and calculated point efficiencies range from 50 to 65%. The value of 1/NL for the methanol‐water system is found to be small. The values of NG and the effect of the velocity on NG are believed to be the first in the literature for a tray in distillation operation. The effect of velocity is shown to be in agreement with the theory proposed by Gerster and co‐workers. It is shown that kG' aG decreases for increasing free area and increasing hole size. Finally variation in LM/VM is shown to have little effect on EMV.
Comparison of the specific resistances of cakes formed in filters and centrifuges
Authors: Valleroy V. V. , Maloney J. O. 
Published: June 2004

AbstractResistances to the flow of fluids through porous beds were determined in a compression‐permeability cell, a vacuum test filter, and an experimental centrifugal filter. The study was made on nearly incompressible beds composed of Lucite spheres having a given size distribution. The results show that liquid flow through the cakes in all three kinds of equipment can be described by a common basic equation, the terms of which are modified to reflect the type of operation. The centrifugal‐drainage data confirm the form of the centrifugal‐filtration equation. The specific resistances deduced from vacuum‐filtration and centrifugal‐drainage tests agree with permeability‐cell alphas within 16% at the same Δ P and within 2 to 3% at the same porosity.
A boundary‐layer model of fluid‐particle mass transfer in fixed beds
Authors: Carberry James J. 
Published: June 2004

AbstractThe process of fluid‐particle mass transfer in fixed beds at Reynolds numbers less than 1,000 is viewed in terms of transient molecular diffusion within a boundary layer which is developed and destroyed repeatedly as the fluid journeys through the bed. Literature data support the j factor derived from the premises of the model. The theory predicts a Schmidt number exponent of 2/3 for NSc ≧ 1; however this exponent should approach 1/2 for NSc < 1.
Performance of packed columns: VI. Mass transfer rates for dehumidification at high solute concentrations
Authors: Shulman H. L. , Robinson R. G. 
Published: June 2004

AbstractAir‐carbon tetrachloride gas streams were dehumidified with cold liquid carbon tetrachloride in a short 4.0‐in. diameter column packed with 0.5‐in. Raschig rings in an attempt to explain reported unsuccessful attempts to correlate dehumidification data obtained at high solute concentration.The data were in satisfactory agreement with a previously presented correlation if the Schmidt number was evaluated at average film conditions and interfacial conditions were employed with regorous calculation methods to evaluate the mass transfer coefficients.
Heat transfer and kinetics in a catalyst bed of rectangular cross section: Air oxidation of nitric oxide with silica gel
Authors: Jaffer J. H. , Bliss Harding 
Published: June 2004

AbstractThe results of an investigation of heat transfer and reaction kinetics in a fixed‐bed catalytic reactor of slab geometry are described. The particular reaction studied is the air oxidation of nitric oxide with silica gel. Conversions and catalyst‐bed temperatures were observed in the experimental, nonisothermal slab reactor, but only a sample of these data are reported and analyzed here.A mathematical analysis of the processes occurring in a slab reactor has been developed which leads to a design method for such reactors that permits prediction of catalyst‐bed temperatures and conversions from a knowledge of specific reaction rates and the physical properties of the system. The design method involves a step‐by‐step procedure but requires a small number of steps. To evaluate the accuracy of the design method and to illustrate its use, the specific reaction‐rate data together with published thermal‐conductivity data have been used with the method to predict the results of a run on the experimental nonisothermal reactor. Good agreement between calculated and observed temperatures and conversions was obtained.Specific reaction rates, derived from integral conversions in an experimental, isothermal reactor, are reported.
Multicomponent diffusion problems
Authors: Hsu Hsien‐Wen , Bird R. Byron 
Published: June 2004

AbstractAnalysis of four three‐component diffusion problems by means of the Stefan‐Maxwell equations is presented. In three of these problems heterogeneous chemical reactions are occurring at a catalytic surface. Characteristic curves are presented for the better understanding of the analytical solutions. The results of one of the exact solutions are compared with those by the effective diffusion‐coefficient approach.
The critical temperatures and pressures of binary systems: Hydrocarbons of all types and hydrogen
Authors: Grieves Robert B. , Thodos George 
Published: June 2004

AbstractA method of the prediction of the critical temperatures and pressures of mixtures has been developed, primarily on the basis of data for binary hydrocarbon systems available in the literature. These mixtures may contain aliphatic (normal paraffinic, isoparaffinic, and olefinic), naphthenic, and aromatic hydrocarbons as well as hydrogen. The mixtures may be of varying complexity, and, although this method has been tested chiefly on binary systems, it has been applied to a limited number of mixtures containing more than two components.This study introduces two dimensionless temperature parameters, γ and θ, which account for the composition of the mixture and for the nature of the components involved. These parameters are defined by the molar average boiling point, the boiling point, and the dew point, all at atmospheric pressure. For a given composition the ratios of the actual critical values to the pseudocritical values have been found to be functions of γ and θ. These relationships are presented graphically and permit the direct calculation of the critical temperature and pressure of the mixture.The validity of this method has been checked not only on the binary systems used to obtain these correlations but also on binary and ternary systems which have not been included in this development. Critical values for eighteen systems, consisting primarily of two components, have been calculated for ninety‐six compositions and have been compared with the experimental values presented in the literature. For temperature the average absolute deviation has been found to be 0.76% (based on degrees Rankine) and for pressure, 2.7%. The results for the majority of these systems have been compared with values calculated by the methods of Eilerts et al. (4), Organick and Brown (15), Kurata and Katz (11), Mayfield (12), and Smith and Watson (23).
Vapor pressures: Unsaturated aliphatic hydrocarbons
Authors: Smith Charles H. , Thodos George 
Published: June 2004

AbstractVapor‐pressure data available in the literature for olefins, diolefins, and acetylenes have been used to establish the constants of the Frost‐Kalkwarf equation (9). This equation requires the establishment of constants A, B, C, and D and defines accurately the vapor‐pressure function ever the complete range included between the triple point and the critical point. Constant D has been shown to be equal to a/2.303R2. Both van der Waals' constants can be predicted from the molecular structure (33), thus enabling the calculation of the critical temperatures and pressures for these unsaturated hydrocarbons. Constant B has been found also to depend on the molecular structure of these hydrocarbons.The normal boiling point of an aliphatic hydrocarbon in conjuction with its critical point and the values B and D calculated from structural considerations permit the calculation of constants A and C. All four vapor pressure constants were calculated for twenty‐seven monoolefins, nine diolefine, and five acetylenes for which reliable vapor‐pressure data are presented in the literature. Comparisons between calculated values and values reported in the literature produced an average percentage deviation of 0.63 for the monoolefins, 2.65 for the diolefins, and 1.13 for the acetylenes. For the forty‐one unsaturated aliphatic hydrocarbons considered in this investigation the average deviation was 1.14% for the randomly selected points of comparison.