bluuebunny/crossref_metadata_2025_split huggingface dataset:
Natural‐convection heat transfer in regions of maximum fluid density
Authors: Schechter R. S. , Isbin H. S. 
Published: June 2004

AbstractOne of the important factors affecting the rate of heat transfer by natural convection is the temperature‐density relationship of the convecting fluid. The importance of this factor is amplified when the heat is being transferred to a medium which has a maximum density.This investigation consisted of measuring the heat transfer rates, velocity gradients, and temperature profiles when heat is transferred from a flat vertical plate to water in the region of 4°C. In some experiments the flow in the boundary layer was observed to be downward while at other conditions of plate and fluid temperature a dual motion (both up and down) was noted, thus establishing a basic difference in the heat transfer mechanism and precluding a unified theory. Theoretical consideration is given to each mechanism and a criterion is derived to predict the flow regime which will prevail at fixed conditions of plate and bulk temperatures.An analogue computer was used to establish theoretical velocity and temperature profiles. The theoretical values agree reasonably well with the measured values; however, the experimental temperrature gradients near the wall were not sufficiently accurate to be extrapolated to determine a point heat transfer coefficent.
Velocity profile for fully developed turbulent flow in a pipe
Authors: Hanratty Thomas J. , Flint Duane L. 
Published: June 2004

AbstractAn equivalent Poiseuille's Law is derived for a homogeneous isotropic turbulent field. The derivation is based on an analogy between momentum transfer and heat and mass transfer, three coefficients being used to characterize the exchange process: (1) the molecular viscosity µ, (2) an intensity parameter to characterize the magnitude of the turbulent velocity fluctuations ν2, and (3) a scale parameter to characterize the scale of the turbulence T.
Mathematical development of tube loading in horizontal condensers
Authors: Kern Donald Q. 
Published: June 2004

AbstractEquations were derived by Nusselt for condensation on a vertical bank of horizontal tubes employing several questionable assumptions. His theoretical results indicate that the average condensing coefficient for a tube in ann‐tube vertical bank should ben−1/4times the single‐tube coefficient. An empirical modification for turbulence previously suggested by the present author changed the factor ton−1/6. To facilitate further experimental studies and design calculations, precise equations are developed for condensate loading for the different common tube layouts bounded by a circle. These equations use a generalized factorn−1/swhere a value of s/4 > 1.0 becomes an index of turbulence.
Individual film coefficients of mass transfer in liquid‐liquid extraction
Authors: Smith G. C. , Beckmann R. B. 
Published: June 2004

AbstractA study has been made of the individual film coefficients of mass transfer for two binary liquid‐liquid systems of differing physical properties, namely methyl isobutyl carbinol‐water and methylethyl ketone‐water, in a 4‐in. diam. extraction column operated as a spray column and with 1/2‐in. Raschig ring packing. The value of Ht for the dispersed phase was found to be a constant, C1 for a given system in a given column. The Ht values for the continuous phase could be correlated by the equation,

Values of the constants C1, C2, and n are tabulated along with the values found by earlier investigators for other systems and column packings. The Ht values have been reduced to area base coefficients by the expression for droplet surface area proposed by Gaylor and Pratt (3).Presaturation of either phase was found to have no effect on mass transfer rates. There appears to be relatively little difference in the efficiency of spray and packed columns for systems of low interfacial tension, but for high interfacial‐tension systems packed columns are considerably more efficient than spray columns.While no definitive correlations for the effect of physical properties are proposed, there are some indications that n is a function of the viscosity ratio of the two liquid phases and that C2 is a function of the 1/4 power of the groups (dΔργ/μ2c)(μc/μa) and (NS c)c. No correlation was found for the effect of physical properties on (Ht)d.
Kinetics of nitrogen tetroxide absorption in water
Authors: Wendel M. M. , Pigford R. L. 
Published: June 2004

AbstractThe rate of absorption of nitrogen peroxide into water at 25° and 40°C. has been found to be a linear function of the concentration of nitrogen tetroxide in the gas phase and directly proportional to the interfacial partial pressure of the same species.The rate of absorption is independent of gas velocity over a range of ReG from 170 to 350. The results plotted as absorption rate divided by interfacial partial pressure of nitrogen tetroxide show no effect of liquid rate or contact time between gas and liquid over a tenfold range of contact time from 0.03 to 0.3 sec. This indicates that the rate‐controlling step during nitrogen dioxide absorption into water is the rate of hydrolysis of nitrogen tetroxide.The absorption rate decreases with increasing temperature from 25° to 40°C., owing to the shift of the equilibrium in the gas phase away from the reacting species nitrogen tetroxide toward nitrogen dioxide and owing to the the decreased solubility of nitrogen tetroxide in water. The effect of these factors on absorption more than offsets the effect of the increase in reaction rate and higher diffusivity on absorption at 40°C.The reaction rate constant for the hydrolysis of nitrogen tetroxide has been determined and the solubility of dissolved but unreacted nitrogen tetroxide in equilibrium with gaseous nitrogen tetroxide has been found.
Pulsations in sieve‐tray and bubble‐cap distillation towers
Authors: McAllister R. A. , Plank C. A. 
Published: June 2004

AbstractA periodic pulsation of the frothing mass of liquid and vapor on a sieve tray and a bubblecap tray is reported. An equation is proposed which relates the frequency of the oscillation to the velocity of sound, the physical dimensions of the systems, and the flow rates of the gas and liquid. The equation is a modification of the acoustical analogy to the classical Helmholtz resonance in electrical circuits having both capacitance and inductance. The oscillation is shown to decrease back‐mixing on the tray, and thus to result in an increase in the Murphree vapor efficiency.
II. The ammonia—isooctane system
Authors: Kay Webster B. , Warzel F. Morgan 
Published: June 2004

AbstractBecause of the paucity of data on the phase behavior of binary systems that form azeotropes, the P‐V‐T‐x relations of the ammonia‐isooctane system were determined at the liquid‐vapor boundaries from room temperature to the critical temperature of issoctane. Evidence of an azeotrope existing over a very limited pressure and temperature range was obtained. The sistem is unique in that the critical locus contains a minimum temperature point as well as a minimum and a maximum pressure point. These relations are shown to fit a general pattern of phase relations characteristic of binary systems that form azeotropes in the critical region. This pattern serves as an aid for the qualitative prediction of the P‐T‐x relations of such systems.
Local shell‐side heat transfer coefficients in baffled tubular heat exchangers
Authors: Ambrose T. W. , Knudsen J. G. 
Published: June 2004

AbstractAn experimental study of local heat transfer coefficients in a baffled tubular heat exchanger for five baffle spacings and two tube spacings (23/16‐in.‐pitch, four‐tube bundle, and 11/4‐in.‐pitch, fourteen‐tube bundle) is reported. Shell‐side air‐flow rate was constant for all runs. The variation of the local heat transfer coefficient around the tubes and along the length of the tubes for each tube spacing and baffle spacing was investigated. Average shell‐side heat transfer coefficients were evaluated from local values and were found to agree with average values reported in the literature. These average values varied with the six‐tenths power of the mass velocity in the heat exchanger. The average Nusselt number and the pressure drop across the exchanger each increased at about the same rate as the number of baffles was increased from two to ten. The average heat transfer rate decreased with decreased tube spacing. This effect was evident from the local heat transfer coefficients, and it is explained on the basis of the mechanism of flow around tubes. An eddy flow zone was detected between the baffles. Average heat transfer rates in the eddy and crossflow zones were almost equal and were about 15% below the average rate in the longitudinal‐flow zone. The variation of the average heat transfer coefficient along a tube definitely showed the effects of baffles. High coefficients occurred in the baffle holes and in the baffle windows.
Electrolytic methods for measuring water velocities
Authors: Ranz William E. 
Published: June 2004

AbstractA convection‐controlled mass transfer process in which the rate of mass transfer results in an electrical signal should have certain advantages as the working principle for a velocity‐and turbulence‐measuring device. The velocity can be read at a remote place as a calibrated electrical signal. Compensation for phase shift and amplitude attenuation of a fluctuating signal should be small because the measuring probe would have no capacity for the transferred quantity. In water, such processes are possible whenever electrolysis occurs under conditions ofconcentration polarization, and they exist in relatively uncomplicated from as thelimiting currentsof polarographic analysis. The investigation reported here was intended as a survey and evaluation of electrolytic methods for measuring water velocities.The series of experiments that was performed showed that a working instrument could be designed on the principle of convection‐controlled electrolysis, but that the chemical reactions involved were unreliable for consistent trouble‐free results. Practical instruments appear to be possible only after long development and considerable study of chemical mechanisms.
The formation of interfacial area in immiscible liquids by orifice mixers
Authors: Scott L. S. , Hayes W. B. , Holland C. D. 
Published: June 2004

AbstractThis paper deals with the dispersion of one immiscible liquid in another (water in kerosene) by means of an orifice mixer. The degree of mixing was determined by measuring the area per unit volume of the dispersed phase. The area was measured with a photoelectric device, which had been calibrated photographically. The interfacial area formed at high Reynolds numbers (10,000 to 45,000, based on the diameter of the orifice) was found to increase with increases in both the volume fraction of water in the water‐kerosene mixture and the change in kinetic energy across the orifice. In addition, other aspects such as the rate of coalescence of the dispersed phase downstream from the orifice are treated.
An improved experimental reactor for applied kinetic studies
Authors: Perkins Thomas K. , Rase Howard F. 
Published: June 2004

AbstractA recirculation type of reactor has been designed and tested on a rapid reaction which characteristically causes difficult temperature‐control problems and high diffusional resistances (hydrogenation of propylene on nickel catalyst). Descriptions of the reactor and its operation are given, together with an assessment of errors and the advantages and disadvantages of the recirculation technique. A rate equation and rate constants are determined so that the data will be more readily comparable with the work of other investigators.
Liquid‐phase adsorption equilibria
Authors: Stuart Edward B. , Coull James 
Published: June 2004

AbstractA correlating equation for liquid‐phase adsorption equilibria, including the effects of temperature and pore diameter, is presented, together with a derivation of the equation ascribing the equilibration process of physical adsorption to van der Waal's forces. The derivation is based on the effect of temperature and surface configuration on the concentration of adsorbate at the surface. The correlating equation was tested with experimental data for the benzene‐cyclohexane‐silica‐gel system and the toluene‐isooctane–silica‐gel system. Temperatures ranged between 23.9° and 99°C. and the pore diameters between 20.7 and 149.5 Å.
On phase equilibrium at the gas‐liquid interface during absorption
Authors: Scriven L. E. , Pigford R. L. 
Published: June 2004

AbstractThat phase equilibrium exists at the gas‐liquid interface during gas absorption is usually assumed in the analysis and design of absorption equipment, but the validity of this assumption has been in doubt since Higbie's pioneering gas‐absorption studies. Accurate measurements are reported herein of the absorption rates at 25°C. of carbon dioxide into short water jets in which the liquid was in laminar flow. The jets issued from circular nozzles of about 1.5‐mm. diam., flowed intact downward through an atmosphere of carbon dioxide at average velocities of from 75 to 550 cm./sec. over distances of 1 to 15 cm., and were collected in a receiver slightly larger in diameter than the nozzles. The measured absorption rates are in excellent agreement with predictions based on unsteady state diffusion theory, when one assumes interfacial equilibrium. It is concluded from these results and those of other investigators that equilibrium prevails at a freshly formed, relatively clean, carbon dioxide–water interface and that the same statement probably applies to the absorption of other slightly soluble gases in water.Evidence is discussed which indicates that an accumulation of minute quantitities of surface‐active materials may seriously reduce the rate of gas absorption, either by affecting the hydrodynamic characteristics of the system or perhaps by offering resistance to the transfer of solute molecules across the interface.
A theoretical‐empirical approach to the mechanism of particle entrainment from fluidized beds
Authors: Zenz F. A. , Weil N. A. 
Published: June 2004

AbstractA means of calculating the rate of entrainment of solids from commercial‐size continuously operating fluidized beds was developed from the combined results of a theoretical and an empirical approach which through different channels arrived at the same fundamental mechanism. The calculation method shows agreement with data obtained from an apparatus simulating flow characteristics in large‐scale equipment and compares favorably with smaller scale tests reported in the literature at pressures up to 200 1b./sq. in. gauge.
Density: Reduced‐state correlations for the inert gases
Authors: Hamrin Charles E. , Thodos George 
Published: June 2004

AbstractThe principle of corresponding states has been adopted to the correlation of densities and found to be applicable for nonopolar substances when the critical compressibility factor is introduced as an independent parameter. For the inert gases, densities available in the literature for the gaseous and liquid states have been referred to their critical densities to produce reduced‐state correlations which are identical only when their corresponding critical compressibility factors are the same. As a result, a consolidated reduced density correlation forzc= 0.291 has been developed from experimental data for argon, krypton, and xenon. Although thezcvalues for helium and neon are essentially alike, different reduced‐state correlations for these substances were found to exist. This behavior is expected in view of the radical nature of helium, which can be accounted for by its excessive quantum deviation. Therefore the reduced density correlation for neon (zc= 0.307) is selected as representative of that class of substances having similarzcvalues.The validity of both correlations has been extended beyond the monatomic gases to include substances having comparable critical compressibility factors. With the generalized chart forzc= 0.291 gaseous densities at elevated temperatures and pressures have been calculated for nitrogen, oxygen, carbon monoxide, and methane to produce an average deviation of 1.4% from reported values in the literature. For these substances the average deviation becomes 1.5% for densities in the liquid state. With the reduced density chart for neon (zc= 0.307) densities calculated for hydrogen (zc= 0.305) in the gaseous region produced an average deviation of 2.5% and covered pressures in excess of 500 atm. and temperatures as high as 500°C.
Compressibility of n‐hexane
Authors: Griskey Richard G. , Canjar Lawrence N. 
Published: June 2004

AbstractAlthough a considerable amount of work has been done on the compressibility of n‐hexane, it has been impossible until now to compare or evaluate the work of the various investigators. There has also been a serious lack of information in the region above the critical temperature. It is the purpose of this work to make an extensive study of temperatures of 240° to 300°C. and of pressures up to 225 atm. in order to provide the lacking information and to overlap with the work of other investigators so that a proper evaluation of their work may be made.
Low‐temperature vapor‐liquid equilibria in ternary and quaternary systems containing hydrogen, nitrogen, methane, and ethane
Authors: Cosway Harry F. , Katz Donald L. 
Published: June 2004

AbstractExperimental data are presented for three ternary systems and the quaternary at pressures of 500 and 1,000 1b./sq. in. abs. and at temperatures of −100° and −200°F. These data along with information in the literature were correlated to give charts of equilibrium ratios as a function of temperature, pressure, and composition.
Sublimation from sharp‐edged cylinders in axisymmetric flow, including influence of surface curvature
Authors: Christian William J. , Kezios Stothe P. 
Published: June 2004

AbstractAn experimental investigation was performed on the mass transfer by sublimation from the outer surfaces of hollow naphthalene cylinders, 0.75 and 1.00 in. in diam., in parallel air streams at velocities between 20 and 120 ft./sec. Local mass transfer rates on the cylinders were obtained by a profilometric technique consisting of accurate determinations of changes in radii of the subliming surfaces at points along elements of the cylinders.Local coefficients of mass transfer obtained with laminar boundary layers for Reynolds numbers (based on axial length) between 12,000 and 100,000 were found to be up to 8% greater, because of surface curvature, than corresponding values for flat surfaces. Moreover comparison of the mass‐transfer data with a theoretical prediction for laminar skin friction on circular cylinders indicates an effect of surface curvature on the Chilton‐Colburn anology between momentum and mass transfer amounting to as much as 6% in the range of air velocity employed. For turbulent boundary layers obtained by artificial triggering of turbulence at the leading edges of the cylinders no effect of surface curvature was found. The results obtained for Reynolds numbers of 40,000 to 1,000,000 are lower than previously published correlations of turbulent heat, mass, and momentum transfer, when compared by the Boelter, Martinelli, and Jonassen form of the analogy.
Theoretical plate concept in chromatography: Part II
Authors: Said A. S. 
Published: June 2004

AbstractPart A of this paper is essentially a continuation of a previous paper on the theoretical plate concept in chromatography (4). It deals with some special cases of eluting conditions and zone shapes. A more general equation, which combines both elution and deposition, is derived, and methods for approximating a continuous zone by means of a discontinuous one are discussed.Part B discusses the effect of the finite size of samples and the dead free volume at the bottom of the column on the shape of elution curves. The effect of representative sample volumes is calculated, and the deviation between the experimental and the true elution curves is illustrated.A simple expression for the number of theoretical plates utilizing the ratio between the maximum concentrations at the top and bottom of the column is derived and corrected for the effect of the finite size of samples.
Liquid viscosities of methane and propane
Authors: Swift G. W. , Christy J. A. , Kurata Fred 
Published: June 2004

AbstractThe theory and calibration procedure for a cylindrical falling body viscometer is presented.Experimental viscosity data are given for liquid methane from −150°C. to the critical point and for liquid propane from −185° to +90°C. The maximum experimental error for methane data is ±8% and for propane data ±5%.
Mass transfer at low flow rates in a packed column
Authors: Dorweiler V. P. , Fahien R. W. 
Published: June 2004

AbstractMass transfer in packed columns has been investigated for a variety of column and packing sizes but at flow rates restricted to fully developed turbulent conditions. The present work was undertaken to investigate mass transfer at flow‐rate conditions in the transition and laminar regions.A dual treatment of experimental data required a knowledge of the variation of concentration and velocity with radial position. A tracer‐injection technique was employed which consisted in the introduction of a tracer gas into the center of a bulk gas stream and the measurement of the tracer‐gas concentration at various radial positions downstream. The velocity distribution for the packed column was determined by means of a five‐loop, circular, hot‐wire anemometer. The test column was a vertical 4‐in, pipe. packed with 1/4‐in. spherical, ceramic catalyst‐support pellets.Mass transfer diffusivity and Peclet number were determined from two solutions of the differential‐diffusion equation applied in previous investigations. An analytical solution in terms of Bessel functions was used to calculate values of average diffusivity and Peclet number and a seminumerical solution in terms of homogeneous linear‐difference equations to calculate values of point diffusivity and Peclet number.Variation of diffusivity and Peclet number with radial position is shown, average diffusivity and Peclet number being correlated with Reynolds number. The interaction of molecular and eddy mass transfer mechanisms with decreasing mass velocity is illustrated by defining a molecular and an eddy Peclet number and correlating with Reynolds number. Eddy diffusivity is correlated as a function of local flow conditions.
Solubility of liquids in compressed hydrogen, nitrogen, and carbon dioxide
Authors: Prausnitz J. M. , Benson P. R. 
Published: June 2004

AbstractThe vapor‐phase solubilities of carbon tetrachloride, iso‐octane, toluene, and n‐decane were measured in compressed hydrogen, nitrogen, and carbon dioxide at 50° and 75°C. and at various pressures between 20 and 90 atm. The virial equation of state was used to describe the volumetric properties of the vapor mixtures, and the second virial cross coefficients were evaluated from the solubility data. The results indicate that the vapor phase departs from ideality very quickly for these systems as the pressure increases, particularly at pressures greater than 10 atm.
Turbulent flow of pseudoplastic polymer solutions in straight cylindrical tubes
Authors: Shaver Robert G. , Merrill Edward W. 
Published: June 2004

AbstractExperimental studies are described concerning the fluid dynamics, particularly in the turbulent region, of dilute solutions of free‐draining, nonassociating, linear polymers; sodium carboxymethylcellulose, ammonium alginate, polyisobutylene, and carboxypolymethylene, all of which are pseudoplastic. These solutions were run in laminar, transition, and turbulent flow in a pipeline flow apparatus designed to permit measurement of dynamic pressure drop and impact pressure by radial traverse.Photographic studies with dye injection used at the tube wall and at the tube center showed that turbulent flow of these pseudoplastic fluids has the following characteristics compared to Newtonian fluids: poor over‐all radial mixing, thicker nonturbulent layer at the wall, and decreased rate of formation of horseshoe vortices at the wall.