bluuebunny/crossref_metadata_2025 huggingface dataset:
Effect of radial temperature variation on axial mixing in pipes
Authors: Hawthorn R. D.
Published: June 2004

In a pipe reactor axial mixing results in a distribution of residence times of fluid elements in the reactor. Taylor and others have discussed methods of predicting the extent of axial mixing for isothermal flow in pipes; however, in a reactor the heat of reaction and its supply or removal at the wall can cause significant radial variation of temperature and temperature‐dependent physical properties. Thus the velocity profile in a reactor may differ from that in a pipe through which fluid flows at constant temperature.

This paper presents an analysis of the effects of radial temperature variations on effective axial diffusion coefficients. In laminar flow it is found that radial temperature variation may increase or decrease the effective diffusivity two‐ to threefold from that calculated for isothermal flow. At Reynolds numbers greater than 10,000 the diffusivity calculated for constant temperature flow does not differ significantly from that for flow through a reactor tube (with radial temperature variation) at the same Reynolds number, calculated with the viscosity evaluated at the wall temperature. In turbulent flow at Reynolds numbers less than 10,000, the effect of radial temperature variation is important but can be estimated only roughly.
Effect of uniformity of fluidization on catalytic cracking of cumene
Authors: Gomezplata Albert , Shuster W. W.
Published: June 2004

The effect of uniformity of fluidization on the catalytic cracking of cumene, with a silicaalumina catalyst, was studied in a 3‐in.–diameter reactor operated at 800°F. Superficial gas velocities were varied from 0.06 to 0.24 ft./sec. for bed heights of 1.5, 3, 5, and 8 in. The percentage conversion in a fluidized bed was found to be lower than in a fixed bed and to be dependent on the type of catalyst support used. A porous plate support was up to 30% more efficient than a screen support, which is attributed to its better gas‐distribution characteristics and to its ability to introduce the discontinuous phase as smaller gas bubbles. Indications are that the first few inches of bed are very effective in bringing in contact the continuous and discontinuous phase, and therefore most of the conversion due to the interaction of the two phases takes place here. This can be explained in terms of the rapid growth of gas bubbles as they proceed through the bed.
A scintillation method for determining liquid ‐ liquid interfacial areas
Authors: Mitsis George J. , Plebuch Richard R. , Gordon Kenneth F.
Published: June 2004

In stirred beakers the interfacial area between xylene containing a scintillator and tritiated water was measured as a function of stirrer speed by a scintillation counting technique. Because of the 6 μ average range of the tritium betas the rate at which flashes are detected by a phototube is a function of the interfacial area. A calibration curve of count rate against known interfacial area for unstirred phases in containers of various diameters gave a numerical estimate of the interfacial area for ten configurations.
Mass transfer with interfacial adsorption methyl chloride into water
Authors: Chiang S. H. , Toor H. L.
Published: June 2004

The rate of transfer of a surface‐active solute across an interface may be either greater or less than the rate which would be obtained if the interface had no abnormal properties. Studies of the absorption of methyl chloride, a surface‐active gas, by a laminar water jet show that for contact times of 1 msec. or greater the absorption rate is the same as would be predicted for a system with no abnormal interfacial properties. This is in accord with theory which indicates that an abnormally high rate caused by a positive surface excess could only be observed for contact times considerably shorter than those used here.
Unsteady multicomponent diffusional evaporation
Authors: Hsu Hsien‐Wen , Bird R. Byron
Published: June 2004

The unsteady diffusion‐controlled evaporation of a pure fluid into a multicomponent mixture is studied by a boundary‐layer method. An expression is obtained for the volume of vapor produced by the evaporating species as a function of time. It is shown that the result can be interpreted in terms of an effective diffusivity of the type proposed by Wilke and by Stewart. It is further demonstrated that the boundary‐layer method predicts a sweep‐diffusion effect.
Macroscopic mixing in fluidization
Authors: Cairns E. J. , Prausnitz J. M.
Published: June 2004

Mixing studies were performed in beds of lead and glass particles fluidized with water. A salt solution was injected from a point source, and electrical conductivity cells were used to determine time average and fluctuating salt concentrations at various points downstream from the point of injection. The frequency distribution of the fluctuations was determined, and correlation coefficients were measured for the fluctuations at two points separated by a known distance.

The mixing data for the central portion of the bed yield radial eddy diffusivities and scales and intensities of turbulence. At the same fraction void the eddy diffusivity and scale of turbulence are larger for lead than for glass particles, but the velocity fluctuations appear to be independent of the density of the particles. Minimum Peclet numbers are observed at a fraction void of about 0.7. Scales based on correlation coefficients exceed those calculated from Peclet numbers, indicating that in a fluidized bed there are large‐scale eddies whose size is much larger than a particle diameter. The interpretation of the mixing data is coupled with visual observations of fluidized bed flow patterns.
Second virial coefficients of the acetonitrile‐acetaldehyde system
Authors: Prausnitz J. M. , Carter W. B.
Published: June 2004

The low‐pressure compressibilities of acetonitrile, acetaldehyde, and their mixtures were measured in the temperature range 40° to 100°C. From these data second virial coefficients were determined for the pure components and for the mixture. The absolute value of the coefficient B12, characteristic of interaction between dissimilar molecules, was considerably larger than that for B11 or B22, which are characteristic of interactions between similar molecules. As a result it was not possible to predict the properties of the mixture with only data for the pure components. Calculations based on the Stockmayer potential and with conventional mixing rules gave seriously incorrect results for the second virial coefficient B12.

The data were interpreted with the aid of an association theory. Dimerization equilibrium constants and enthalpies and entropies of formation were computed for the pure‐component dimers and for the complex. The heat of formation for the complex was significantly larger than that for the dimers; comparison with energy terms calculated from electrostatic theory suggest that the structure of the complex is different from that of the pure‐component dimers.
Kinetics of mixed‐bed deionization: I
Authors: Frisch Norman W. , Kunin Robert
Published: June 2004

Mixed‐bed deionization of 0.0002 to 0.01N sodium chloride solutions at flow rates in the range of 3 to 70 gal./(min.) (sq. ft.) with bed depths of 0.25 to 3.2 ft. was investigated. The rate of ion exchange was found to be limited by a liquid‐film mass transfer mechanism in the high purity water range (< 1 μ micromho/cm. effluent conductivity).

The magnitude of the temperature effect in the range 15° to 45°C. is given. Methods for prediction of effect of both changes in particle size distribution and incomplete regeneration of the component ion exchange resins are presented. A tentative correlation is given which estimates the effect of solute and solvent species.
Local shell‐side heat transfer coefficients and pressure drop in a tubular heat exchanger with orifice baffles
Authors: Lee K. S. , Knudsen J. G.
Published: June 2004

By means of a moveable sensing probe previously described2 local shell‐side heat transfer coefficients and friction losses were measured on a model tubular heat exchanger containing orifice baffles. The heat exchanger shell was 6‐in. nominal I.D. and 45 in. in length and contained four tubes in triangular arrangement passing through orifice baffles. Baffle hole diameters of 1‐/16, 1–2/16, 1–3/16, and 1–5/16 in. and baffle spacings of 4.0 and 9.0 in. were studied. Data were taken at several air flow rates for each of the four baffle hole diameters.

The average heat transfer coefficient for the region between two central baffles was correlated with an empirical equation based on only two baffle spacings.

An increase in the baffle‐to‐tube clearance caused a decrease in heat transfer. An increase in the baffle spacing also resulted in a decrease in heat transfer. Four flow zones in the baffle space are postulated from the analysis of Nusselt number distribution along the tube. The heat transfer characteristics in each of the four flow zones were analyzed in terms of the mechanism of the fluid flow.

The pressure‐drop data were correlated in terms of an annular orifice coefficient of discharge and an orifice‐pressure‐drop function. As a result of this study a method was developed by which one can predict the average of the local coefficients at the baffle position from the knowledge of pressure drop across a single baffle.
Thermal conductivity: Reduced state correlation for ethylene and its application to gaseous aliphatic hydrocarbons and their derivatives at moderate pressures
Authors: Owens E. James , Thodos George
Published: June 2004

By means of a procedure similar to that used for the inert gases (19) and methane (20) a reduced thermal conductivity correlation was developed for ethylene from experimental data available in the literature (2, 3, 4, 9, 13). The resulting correlation permits the prediction of thermal conductivities for gaseous and liquid ethylene in the temperature rangeTR= 0.4 toTR= 6.0 and for pressures up toPR= 50. For pressures belowPR= 0.5 this correlation was found to apply to gaseous aliphatic hydrocarbons and their derivatives but not to cyclic compounds. For these aliphatic hydrocarbons and their derivatives the relation between thermal conductivity at atmospheric pressure and temperature isk*/k= 0.364T.

Experimental thermal conductivities of ethylene in the liquid state and dense‐phase region were compared with values predicted by the reduced‐state correlation. The average deviation for thirty‐six experimental points was 1.8%. Gaseous‐state data at atmospheric pressure of alkanes, alkenes, alkynes, alcohols, ethers, halogenated derivatives, esters, aldehydes, ketones, amines, nitriles, and other aliphatic compounds were also compared with values predicted by this correlation. For 414 experimental points the average deviation was 1.63%.
Agitation of viscous Newtonian and non‐Newtonian fluids
Authors: Metzner A. B. , Feehs R. H. , Ramos Hector Lopez , Otto R. E. , Tuthill J. D.
Published: June 2004

Viscous fluids are frequently agitated by multiple impellers and in vessels only slightly larger than the impeller. This paper presents data for both Newtonian and non‐Newtonian fluids agitated under such conditions. The large decreases in power requirements (at a given level of mixing rate in the non‐Newtonian system) which are possible by use of low tank diameter, impeller diameter ratios and/or two impellers, have been quantitatively studied.

The types of impellers used in the non‐Newtonian work and the ranges of conditions over which power requirement correlations were developed are summarized as follows:

D
T/D
n
NRe

Marine propeller
0.42‐1.0
1.4 ‐4.8
0.16‐1.0
0.67‐1320

Fan turbine
0.33‐0.67
1.3 ‐3.0
0.21‐1.4
6.6 ‐160

Flat‐Bladed turbine: one impeller
0.17‐0.67
1.3 ‐5.5
0.20‐1.5
2.0 ‐1800

two impellers per shaft
0.33‐1.00
1.023‐3.5
0.14‐1.00
0.15‐620

The results generally confirm an approach developed earlier, for the broader ranges of variables listed above. For the non‐Newtonian fluids of primary interest in this study, that is purely viscous materials having flow behavior indexes of less than unity (pseudoplastics, Bingham plastics), the prediction of power requirements has been developed to nearly the same level of perfection as for Newtonian fluids.
Heat transfer characteristics of porous rocks: II. Thermal conductivities of unconsolidated particles with flowing fluids
Authors: Kunii Daizo , Smith J. M.
Published: June 2004

Experimental heat transfer studies were carried out in beds of unconsolidated glass beads and sand through which fluids were flowing. The scope of the measurements included four fluids, helium, air, carbon dioxide, and water liquid at atmospheric pressure in beds packed with four sizes of glass beads, 110, 370, 570, and 1,020 μ and with two sizes of sand, 110 and 240 μ. Flow rates ranged form 1 to 26 lb./(hr. sq.ft.) in a direction parallel and countercurrent to energy flow.

The data were interpreted in terms of apparent, effective thermal conductivities of the bed. The values of ke increase significantly with mass velocity of fluid.

By considering the mechanism of heat transfer in porous media a relationship was developed between ke and the heat transfer coefficient between fluid and particle. Treatment of the experimental data in this fashion, combined with available information for larger particles, results in a correlation of Nusselt and Reynolds numbers for air that covers the range N = 10−1 to 104.
A quantitative treatment of the forgotten effect in liquid thermal diffusion
Authors: Baldeschwieler John D.
Published: June 2004

The influence of the concentration gradient on the density gradient in a thermal‐diffusion column is called the forgotten effect. A modification of the theory developed by Furry, Jones, and Onsager is proposed to include the effect of the horizontal concentration gradient. A sample calculation with the system toluene‐cyclohexane shows that the equations predict the proper behavior for a forgotten‐effect system.
Fluid ‐ particle mass transfer in a packed bed
Authors: Bradshaw R. D. , Bennett C. O.
Published: June 2004

Mass transfer coefficients have been measured for air flowing through a bed of naphthalene pellets. Results were obtained for ⅜‐in. spheres and for ½, ⅜, and ¼‐in. cylinders in a bed 4 in. in diameter and packed to heights varying from 5 to 10 in. Radial concentration profiles were obtained for some conditions, from which the radial variation of the mass transfer coefficient was determined. The point‐values of kg follow an equation of the form kg = a Gb. From mixed outlet concentrations, values of kgav and jd, corrected for the effect of axial diffusion, have been obtained for all the pellet sizes as functions of mass velocity and Reynolds number, respectively.
The effect of acoustic vibration on forced convective heat transfer
Authors: Lemlich Robert , Hwu Chung‐Kong
Published: June 2004

In an effort to study the effect of acoustic vibration on forced convective heat transfer, sound at resonant frequencies of 198, 256, and 322 c./sec., as well as sound at nonresonant frequencies, was imposed on air flowing at Reynolds numbers of 560 to 5,900 in the core of a horizontal, double pipe, steam to air, heat exchanger. Increases in Nusselt number of up to 51% in the nominally laminar region and up to 27% in the nominally turbulent region were obtained. The improvement peaked sharply at resonance and increased with both amplitude and resonant frequency. A qualitative dual mechanism is suggested, and correlations for the experimental results are presented.
The P.V.T.‐behavior of diatomic substances in their gaseous and liquid states
Authors: Byrne Robert , Thodos George
Published: June 2004

The critical compressibility factor has been used as a criterion for the correlation of the P.V.T.‐behavior in the gaseous and liquid states for the diatomic gases, nitrogen, oxygen, carbon monoxide, nitric oxide, chlorine, and hydrogen chloride. Reduced densities for these substances have been calculated from available literature data. These are presented as functions of reduced temperature and reduced pressure to produce extensive density correlations for nitrogen, oxygen, and carbon monoxide. These correlations exhibit similar behavior as expected from their similar critical compressibility factors.

The validity of the critical compressibility factor as a correlating parameter has been verified by the favorable comparison of the P.V.T.‐behavior of substances other than diatomic gases including argon, krypton, xenon, and methane. These results indicate that the P.V.T.‐behavior of substances having critical compressibility factors of approximately 0.291 can be predicted from the reduced state correlation developed in this study as long as polarity effects are absent.
The thermal conductivity of hydrocarbon gases at normal pressures
Authors: Misic Dragoslav , Thodos George
Published: June 2004

Dimensional analysis has been applied for the correlation of the thermal conductivity of a gas to its temperature, molecular weight, heat capacity, and critical constants. This approach indicates that the groupk*λ/Cpshould be a function ofzcandTR, where λ =M1/2Tc1/6/Pc2/3. Experimental thermal conductivities of hydrocarbons at normal pressures (approximately 0.2 to 5 atm.) have been used to develop two relationships. The first is applicable to all types of hydrocarbons for 0.6 <TR< 3.0 with the exception of methane and the cyclic hydrocarbons belowTR= 1.0, for which the other relationship is applicable. These two relationships have been used to calculate thermal conductivities for twenty‐eight gaseous hydrocarbons for which experimental data are available. Calculated values for normal paraffins, isoparaffins, olefins, diolefins, acetylenes, naphthenes, and aromatics produce an average deviation of 2.4% from experimental values for 154 points considered.
Dispersed‐phase holdup in a rotating disk extraction column
Authors: Kung E. Y. , Beckmann R. B.
Published: June 2004

A study has been made of the effect of column geometry and flow condition upon the dispersed‐phase holdup in an rotating disk type of extraction column. Variables investigated were stator opening, disk diameter, compartment height, rotor speed, and flow rates of the dispersed and continuous phases. The toluene‐water system, with the toluene dispersed, was used throughout the study. The radio‐isotope technique was used to measure the dispersed‐phase holdup.

Results of this study as well as those of earlier investigators have been used to expand upon the design equations proposed by Logsdail, Thornton, and Pratt for estimating flooding rates and dispersed‐phase holdup in rotating disk columns. Modifications to increase the accuracy of prediction of these equations have also been suggested, while possible limitations in their application have been indicated.
The utilization of fission fragment energy for the fixation of nitrogen
Authors: Steinberg Meyer , Green Leon , Powell J. R.
Published: June 2004

The principles involved in designing a process for the production of fixed nitrogen by the direct use of fission fragment recoil energy are reviewed. The problems concerned with the radiation chemistry, development of fuel element, reactor design, and chemical process design are pointed out. Possible solutions to these problems incorporated in a complete plant design are presented. An economic evaluation, comparing the chemonuclear process with other conventional processes, is made. The conclusion is reached that at the present state of knowledge there does not seem to be any clear‐cut advantage over conventional processes, even based on a nuclear economy. However moderate research efforts should continue for further evaluation of this process.
Compressibility of real binary gas mixtures
Authors: Busch Joseph S. , Canjar Lawrence N.
Published: June 2004

The P‐V‐T‐x properties of binary gas mixtures and their dependence on reduced temperature and pressure have been reviewed in detail.

A modified form of Kay's original method for estimating P‐V‐T‐x properties of mixtures is suggested for purposes of engineering calculations.
Liquid‐vapor equilibria in the hydrogen‐nitrogen and deuterium‐nitrogen systems
Authors: Maimoni Arturo
Published: June 2004

A recirculation type of apparatus with a novel liquid‐sampling system was used to obtain liquid‐vapor equilibrium data for the hydrogen‐nitrogen and deuterium‐nitrogen systems at 90° and 95°K. and pressures up to 1,000 lb./sq. in. abs. The data obtained show an average scatter in liquid compositions of the order of 0.01%, thus proving the feasibility of the new liquid‐sampling system. The vapor samples are shown by thermodynamic analysis to scatter less than 0.1%. Deuterium is slightly more soluble in liquid nitrogen than hydrogen; the relative volatility is 1.198 at 90°K. and about 1.177 at 95°K. The relative volatility is practically independent of pressure; thus at 90°K. the relative volatility decreases from 1.198 at 100 lb./sq. in. abs. to 1.196 at 1,000 lb./sq. in. abs., but this range of values is well within the experimental error.
Some observations on the mechanics of drops in liquid‐liquid systems
Authors: Elzinga E. R. , Banchero J. T.
Published: June 2004

Data on the rate of rise and distortion of drops in several liquid‐liquid systems have been collected. These are compared with correlations developed by other investigators, and in some cases discrepancies between observed and predicted values are noted which do not seem to be related to any easily measured physical property. However evidence is given showing that they are most likely due to the presence of surface‐active materials. Photographs and shadowgraphs showing the nature of the flow around and behind moving drops are also included. The point of boundary‐layer separation on the drop surface as indicated by these photographs has been related to the internal drop circulation. It is the shift in this point of separation which is the primary cause for the reduction in drag of liquid drops as compared with solid spheres. A previous theory for the breakup of rain drops explains the existing data for drop breakup in liquid‐liquid systems.
Turbulent flow ballistics facility for particle momentum transfer studies
Authors: Torobin L. B. , Gauvin W. H.
Published: June 2004

This paper describes the calibration and use of an experimental installation which was specifically designed for the quantitative measurement of the drag coefficient of single particles moving with a turbulent fluid. The installation consisted of an 8‐in. I.D. wind tunnel with an 18‐ft. test section, preceded by an inlet grid arrangement designed to provide a flow with a symmetrical mean velocity profile and a flat central core having a nonperiodic spectrum of turbulence. The particles were launched at controlled entrance velocities into the core in a nonrotating manner by means of a particle accelerator, and axial motion was obtained. A hot‐wire anemometer was used to measure the flow turbulence parameters at two Reynolds numbers by means of probes inserted at various distances above the inlet grid section. These measurements included the radial and axial intensities, the axial turbulent energy spectrum, and the macro and microscales. An accurate record of the particle velocity history was provided by a new radiotracer velocity measurement technique. This information was then processed by an IBM‐650 program which supplied the drag coefficient as well as the instantaneous particle velocity, acceleration, rate of change of acceleration, Reynolds number, and relative turbulence intensity from the time‐distance data. The experimental facility was found to be well suited for general studies of momentum transfer phenomena in particulate systems at high relative intensities.
On the steady flow of a non‐Newtonian fluid in cylinder ducts
Authors: Schechter Robert S.
Published: June 2004

The flow of a power law fluid in cylindrical ducts is considered, with a variational principle evolved from minimum entropy considerations used. This principle is applied to flow in rectangular ducts and between two flat plates with the method of Ritz and Galerkin to determine the velocity profiles used. These velocity profiles are used to determine the relationship between the friction factor and the Reynolds number.
Effects of superheated vapor and noncondensable gases on laminar film condensation
Authors: Sparrow E. M. , Eckert E. R. G.
Published: June 2004

A boundary‐layer analysis of laminar film condensation on a vertical plate has been carried out to study the effects of superheated vapor and noncondensable gases. For a pure, superheated vapor the effects of superheating on the surface heat transfer are accounted for by a simple modification of previously available results for saturated vapors. For a given temperature difference between the plate surface and the liquid‐vapor interface, superheating increases the heat transfer to the surface, but only to a modest extent for most practical situations. Although free convection was not included in the analysis, its role has been estimated to be small. For noncondensable gases the analysis shows that the presence of a few per cent of noncondensable in the bulk of the vapor causes a great reduction in the surface heat transfer. The fact that the predicted reduction is substantially larger than that found experimentally indicates that free convection, which is not included in the analysis, plays an important role when noncondensables are present.
A study on linear process control
Authors: Iinoya Koichi , Altpeter R. J.
Published: June 2004

Critical limits of controller parameters (PID) and critical cycling periods are derived for several linear processes. A method for determining the approximate dynamic characteristics of a process is developed. A pressure control system is analyzed by this method and its behavior interpreted.
Initiation of roll waves
Authors: Hanratty Thomas J. , Hershman Arnold
Published: June 2004

The theory proposed by Jeffreys to explain roll‐wave transition on a liquid surface is applied to the concurrent flow of a gas and liquid. Data are presented for the concurrent flow of air with water‐glycerine solutions, water‐butanol solutions, and water‐sodium lauryl sulfate solutions. Agreement is obtained between theory and experiment.
Kinetics of carbon deposition in a fluidized bed
Authors: Oxley Joseph H. , Secrest Arthur C. , Veigel Neil D. , Blocher John M.
Published: June 2004

Rate data have been obtained for the deposition of carbon films from methane and acetylene in fluidized beds of alumina, uranium dioxide, uranium monocarbide, uranium dicarbide, and a solid solution of uranium‐thorium dicarbide powders. These carbon films have been shown to provide excellent protection for the powdered fertile material against attack by hot concentrated nitric‐acid solutions. The coated uranium‐thorium dicarbide particles were also shown to be stable in humid air.
Transient studies of product distribution from a packed bed reactor
Authors: Kapner R. S. , Hoelscher H. E.
Published: June 2004

The distribution of reactants and products from a simulated fixed‐bed catalytic reactor has been studied. The concentration of both reactant and product in the effluent stream as a function of time has been measured following a sudden change in inlet concentration. The effect of various types and sources of holdup in the bed is discussed. This study is preliminary to further experimental investigations of the mechanism and the rate of exchange of product between a catalyst surface in a fixed‐bed reactor and the free stream.
Immersion sampling of spray droplets
Authors: Tate R. W.
Published: June 2004

Nearly all process involving sprays or aerosols are strongly affected by droplet size. The measurement of droplet size has therefore been attempted by numerous methods, including direct high‐speed photography, light absorptionor scattering, droplet cooling or freezing, and collection of droplets on coated slides or immersion cells. Although no method is entirely satisfactory, the immersion sampling technique has been successfully used both in research and industrial testing of atomizing devices. This method entails collection of dyed‐water droplets in sampling cells containing solvent or a similar immersion fluid. Photomicrographs of the droplets are then obtained for manual or automatic counting.

Although immersion sampling has several recognized advantages, it is limited by the tendency of large, high‐velocity droplets to shatter and by the failure of very small droplets to impact on the cell. Another problem is interference by the shutter used to expose the spray. To help overcome these limitations the mechanics of sampling hollow or solid‐cone sprays was analyzed, and procedures were developed for selecting optimum cell and shutter configurations, sampling distance, and exposure time. Extension of the method to sprays comprised of two liquid streams and to sampling of oil droplets is also discussed.
High temperature pile irradiation of the n‐heptane‐hydrogen system
Authors: Miley George H. , Martin Joseph J.
Published: June 2004

A pilot unit for the high‐temperature irradiation of flowing reactants was designed for the beam port of a nuclear reactor. Radiation‐thermal cracking of the n‐heptane‐hydrogen system was studied with molal H2/C7 ratios from 0 to 5 at 250 lb./sq. in., 600° to 750°F., 2 to 8 min. residence time, and up to 3,600 rep./min. Although conversions were low, the decomposition rate was significantly increased by radiation giving G values > 103. Product distributions were not significantly altered by radiation. These results, while different from low‐temperature data, appear consistent with other published high‐temperature results. Radiation yields were found to be reasonably linear with total dose from 0 to 14 krep., but a twofold increase was observed in passing from a molal H2/C7 ratio of 0 to 0.5.
The effect of rate of sampling on the transient behavior of thermogravitational thermal diffusion columns without reservoirs
Authors: Vichare G. G. , Powers J. E.
Published: June 2004

In experimental investigations of the transient behavior of batch thermogravitational thermal diffusion columns it is expedient to obtain more than one sample from the column during a single run. Such sampling modifies the true batch nature of the column and thereby influences the experimental measurements to some degree. A combined theoretical and experimental investigation was carried out to determine the extent of the influence of sampling rate and thereby provide a means of predetermining a suitable sampling rate.

The theoretical analysis was made by approximating the intermittent sampling as a continuous flow through the column. The transport equation of Furry, Jones, and Onsager was applied in the analysis, and an analytical solution was obtained for small separations of equicomposition binary solutions. The series solution is presented in the form of a graph. Experimental data were obtained in two thermogravitational columns with different plate spacings to test the theory. The effect of sampling rate was investigated, and theory and experiments were found to be in good agreement. It is concluded that the theory is entirely adequate to permit the prediction of sampling rates which will yield the maximum number of samples without disturbing the true batch behavior of the column.
Interfacial area in liquid‐liquid mixing
Authors: Rodriguez Ferdinand , Grotz L. C. , Engle D. L.
Published: June 2004

In predicting interfacial area in liquid‐liquid systems there are several published reports which give different results. Differences in methods of measurement of interfacial area and impeller design and location account for some of these discrepancies.

For one pair of liquids, 40 parts by volume of ethylhexanol and 60 parts water, it was found that over wide ranges of impeller size to tank size ratio (0.27 to 0.67) that equal power per unit volume gave equal interfacial area per unit volume.
Kinetic data from nonisothermal experiments: Thermal decomposition of ethane, ethylene, and acetylene
Authors: Towell Gordon D. , Martin Joseph J.
Published: June 2004

A rigorous method was developed to account for nonuniform temperature distributions in the analysis of kinetic data. The rate constants cannot be determined directly since they are functions of temperature, so equations were derived and solutions developed for the substantially temperature independent kinetic parameters, activation energy, and pre‐exponential factor. A digital computer was used to evaluate numerically various integrals involved in the solution of the equations. The method developed here will be useful in all laboratory kinetic studies where limitations of heat transfer do not permit an isothermal experiment and in the analysis of kinetic data obtained from commerical or pilot plant units where the temperature distribution is nearly always nonuniform.

Kinetic studies were made of the thermal decompositions of ethane, ethylene, and acetylene, all of which are high temperature fast reactions. The experimental conditions covered highly nonuniform temperature distributions with peaks from 730° to 1,330°C., a total pressure of 1 atm., varying amounts of nitrogen dilution, and residence times in the millisecond range.
Prediction of pressure drop in two‐phase single‐component fluid flow
Authors: Hatch M. R. , Jacobs R. B.
Published: June 2004

Data on pressure drop in two‐phase, single‐component fluid flow, both with and without heat transfer, are presented in terms of the Lockhart and Martinelli correlation parameters. The fluids used were trichloromonofluoromethane and hydrogen.

The results are compared with the correlation curve recommended by Martinelli and Nelson and give frictional pressure drops that are about 40% lower than the curve. The reasons for the deviations are discussed in terms of the effects of friction factors, the existence of metastable equilibrium, accuracy of data and instrumentation, and calculation procedures.

It is concluded that the Martinelli and Nelson correlation and a simple momentum pressure drop computation can be superposed to predict roughly the total pressure drop in tubes containing steady state, two‐phase, single‐component fluid flow with appreciable vaporization.
Mass, heat, and momentum transfer in the flow of gases past single spheres
Authors: Yen Yin‐Chao , Thodos George
Published: June 2004

The transfer of mass, heat, and momentum past a single sphere, 2.02 in. in diameter, was experimentally investigated for the turbulent flow of air between NRe = 1,750 and NRe = 8,922. The data resulting for the vaporization of water from the spherical surface verify the existence of the analogy between mass and heat transfer.

Measurements were made to account for the total drag and form drag of the sphere. The total drag was obtained by directly accounting for the force exerted, while the form drag was determined from static pressure measurements around the surface of the sphere. The resulting friction factors for total drag f and for form drag fp were found to be of the same order of magnitude, thus making it impossible to account for the friction factor due to shear drag at these Reynolds numbers. Consequently it is not possible to determine if the analogy between mass and heat transfer can be extended to include the transfer of momentum for flow past single spheres at these conditions, although the results of this study cast considerable doubt on such an extension of this analogy.
Mass transfer to particles: Part II. Suspended in a pipeline
Authors: Harriott Peter
Published: June 2004

Mass transfer coefficients are reported for particles of boric acid and benzoic acid dissolving in water in a 2‐in. pipeline. For water velocities of 1 to 4 ft./sec. the coefficients are 1.2 to 2 times the values predicted for freely falling particles. The coefficients are slightly less than those obtained in agitated tanks at the same power per unit volume.
Thermodynamic properties of polar gases in the dilute phase
Authors: Eubank P. T. , Smith J. M.
Published: June 2004

A procedure is proposed, based in part on theory and in part on experimental data, for predicting the effect of polarity on the thermodynamic properties of polar, organic gases in the dilute phase. This correlation was used to predict compressibility factors Z, and the change of enthalpy with pressure, in the vapor phase.

By use of this correlation the computed compressibilities indicated an average absolute deviation of 1.0% from available experimental data, which includes reduced pressures up to 0.9 and temperatures to 1.0. Similar comparisons were made for the effect of pressure on enthalpy.
Bubble rise in a packed bed saturated with liquids
Authors: Gorring Robert L. , Katz Donald L.
Published: June 2004

Experimental data were determined for drag coefficients on fluid bubbles rising in a saturated packed bed and in clear liquids. Air and benzene were used to form bubbles in glycerine solution, water, and normal heptane. One‐inch diameter glass spheres in hexagonal, random, and cubic packings constituted the bed. The range in Reynolds number was from 0.1 to 1,000. It was found that the drag coefficients in the hexagonal and random arrays were from two to three times those in clear liquids, while the drag on bubbles rising in cubic packings was the same as that for clear liquids. The method of correlation involved the use of the minor diameter in the drag coefficient and the major diameter in the Reynolds number. This innovation improved the correlation for bubble rise in clear liquids.
Gas mixing in a square duct: II
Authors: Miller Eugene , Wohl Kurt
Published: June 2004

Instantaneous shadow photography is used to study the mixing of air flowing in a 2‐in. square duct with a secondary stream of carbon dioxide entering sidewise from an orifice. Mixing is described in terms of four mixing parameters measured from the shadow photographs, penetration distance, bulk mixing distance, macromixing distance, and the quality of micromixing, as a functon of sidestream: mainstream mass velocity and volume flow ratios, main duct velocity, and the average orifice shroud velocity component parallel to the air flow in the main duct.

The first three parameters are reported quantitatively as a function of the variables mentioned. The latter parameter is reported semiquantitatively by means of a scale of grading the micromixing which describes the condition of the schlieren at arbitrary duct lengths downstream from the entrance of the gases. Comparisons are made with previous results from studies of the secondary gas entering sidewise from a tube.

Orifice discharge coefficients are correlated as a function of the orifice diameter, orifice Reynolds number, main duct velocity, and orifice shroud velocity. These are presented to aid in the description of the mixing and to be used in the design of similar mixing configurations.
The effect of column length on separation in thermogravitational thermal diffusion columns
Authors: Crownover Carl F. , Powers John E.
Published: June 2004

A series of experiments was designed to test the phenomenological theory of thermogravitational thermal diffusion columns by obtaining data on the steady state separation and approach to equilibrium in a batch column as a function of column length. Data were obtained on the separation of an equimolar n‐heptane‐benzene solution at five different values of column length varying from 14.5 in. to 6 ft. All measurements were made in one concentric cylinder column in which the effective length was varied by controlling the liquid level in the annulus. Helium gas was used to displace the air in the annulus above the liquid in order to provide even temperature distribution throughout the column. The data were found to substantiate the effect of length predicted by application of the phenomenological theory and to be in very good agreement with other aspects of the theory.
Design and evaluation of a new body for falling cylinder viscometers
Authors: Lohrenz John , Kurata Fred
Published: June 2004

A new body with stabilizers removed from the cylindrical section was designed for falling cylinder viscometers. Experimental data to evaluate the new body were obtained with gases and liquids at varying temperatures and pressures.

Experimental results showed improved agreement with a theoretical model that assumes laminar flow friction along the cylindrical portion of the body and negligible additional frictional effects. Effects of temperature and pressure were accurately predicted by this theoretical model. The data were correlated on an improved viscometer plot.

The advantage of the new body design was a negligible frictional effect of the stabilizers. The entrance‐exit frictional effect was evaluated from the experimental data and correlated on a friction factor plot. Fluid flow in the annulus remained laminar throughout this study. The results of this investigation allow an improved prediction of the falling‐cylinder viscometer constant.
Pore diffusion in silver catalysts
Authors: Masamune Shinobu , Smith J. M.
Published: June 2004

Diffusion rates were measured at atmospheric pressure and room temperature for helium and nitrogen in pelleted silver catalysts. Pellets were prepared from three silver salts giving different micropore characteristics. The data showed that the diffusion was of the bulk type and that the micropores had no effect, indicating that mass transfer was predominantly in the macropore region. For each kind of material data were obtained for five pellet densities corresponding to macropore volume fractions from 0 up to 0.7.

Effective diffusivities and labyrinth factors ψ were evaluated and found to increase with macropore porosity. The linear relationship between ψ and void fraction proposed by Buckingham for diffusion through soils fitted the data at high void fractions. A generalized form of the Maxwell equation containing three constants was derived. A single‐constant form of this expression agreed reasonably well with the measured results over the entire range of macropore volume fraction.
Transport characteristics of suspensions: Part IV. Friction loss of concentrated‐flocculated suspensions in turbulent flow
Authors: Thomas David G.
Published: June 2004

Turbulent flow friction factors were determined for flocculated suspensions of thoria, kaolin, and titania in tubes 1/8‐ to 1‐in. diameter. The non‐Newtonian laminar flow data were arbitrarily fitted with the Bingham plastic model. With this model the range of yield stress values was 0.018 to 1.39 lb.f/sq. ft., with a maximum ratio of coefficient of rigidity to viscosity of suspending medium of 11.1. The volume fraction solids were varied from 0.042 to 0.23.

Two types of behavior were observed depending on the value of the yield stress. For yield values less than 0.5 lb.f/sq. ft. the turbulent friction factors were always less than those for Newtonian fluids but tended to approach the Newtonian values as the Reynolds number was increased. For yield values greater than 0.5 lb.f/sq. ft. the friction factors were again less than those for New‐tonian fluids but tended to diverge from the Newtonian values as the Reynolds number was increased. Both sets of data were correlated with the Blasius relation with the coefficient and exponent given in terms of the laminar flow properties und the volume fraction solids.
Transport properties of gases in porous media at reduced pressures with reference to freeze‐drying
Authors: Harper John C.
Published: June 2004

Theory is outlined relative to the effect of pressure on permeabilities and thermal conductivities of gases in porous solids in the slip flow and free‐molecule flow regions, and experimental results are reported for several freeze‐dried food materials. Mean pore diameters for the porous materials calculated from permeability data were about 100 μ and were in agreement with microscopic observations. Thermal conductivities followed the predicted behavior of a constant value at high pressures, with a gradual decrease to another constant value at very low pressures. The results show that the usual operating pressure range of freeze‐dryers (0.1 to 1.0 mm. Hg) corresponds to the transition region between slip flow and free‐molecule flow.
An analytical study of heat transfer in laminar‐turbulent transition flow between parallel plates
Authors: Gill William N. , Lee Shaw Mei
Published: June 2004

With the results of a modification of Prandtl's mixing length theory, heat transfer in laminar‐turbulent transition flow is considered. An analytical study was made to obtain the eigenvalues, Nusselt numbers, and temperature distribution for transition region flows between constant temperature parallel plates. Reynolds numbers ranging from 4,800 to 43,000 and Prandtl numbers from 0.01 to 100 were investigated. Six to nine eigenvalues were obtained for each set of parameters. These values were used to compute local Nusselt numbers and thermal entrance lengths. The practicality of four numerical methods used for solving the associated Sturm‐Louville system is discussed.

It is shown how heat transfer effects change in the transition region. As expected, these changes are more rapid for higherNPrfluids where eddy diffusion is most effective.
Thermal and material transfer in turbulent gas streams: One‐inch spheres
Authors: Venezian Emilio , Crespo Manuel J. , Sage B. H.
Published: June 2004

As part of a study of the effect of conditions of flow upon macroscopic and local thermal and material transport from spheres, an investigation was made of the macroscopic and local transport from a silver and a porous sphere each 1 in. in diameter. The transport was measured in a turbulent air stream at Reynolds numbers up to 7,500, and the apparent level of longitudinal turbulence of the stream was varied between 0.013 and 0.15. In the case of the porous sphere the thermal and material transport were evaluated for the evaporation ofn‐octane.

The results indicate that the macroscopic Nusselt number is substantially larger for combined thermal and material transport than for thermal transport alone. The local Nusselt number varied by a factor of 5 around the silver sphere from stagnation to separation.
Absorption of ammonia by acetic acid solutions
Authors: Dhillonn Sharanjit S. , Perry R. H.
Published: June 2004

Absorption accompanied by rapid, second order, irreversible reaction was studied in disk column. The chemical system used involving absorption of ammonia by acetic acid has not been reported on before. Results confirm the prediction of two‐film and unsteady state theories for this class of two phase reaction; that is the liquid film absorption coefficient is a linear function of ratio of acid normality to interfacial concentration of ammonia. At high acid concentrations the liquid film resistance disappears. In preliminary studies an abrupt transition between laminar and turbulent liquid flow was noted, and as predicted by the unsteady state theory the liquid film coefficient in the laminar region was proportional to the 0.33 power of the liquid flow rate.
Nonequilibrium thermodynamic theory for concentration profiles in liquid extraction
Authors: Hennico Alphonse , Vermeulen Theodore
Published: June 2004

The pattern or profile of concentration change in each of the two countercurrent streams, within a packed extraction column involving a three‐component system, is generally assumed to follow either branch of the mutual‐solubility curve for the system. In the work reported here such concentration profiles have been computed for an idealized extraction. The results show that the raffinate will usually be carried into a metastable condition inside the equilibrium curve, but the extract composition remains appreciably outside the equilibrium curve.

In the calculations mass transfer coefficient ratios are held constant at any one steady state condition of operation (called a run), but are varied in different runs, in order to determine the direction and magnitude of their effects. A modified activity‐gradient, derived both for molecular diffusion and for penetration‐theory conditions, is postulated to govern mass transfer and is used in place of the usual concentration driving potential. Solute depletion, mainly, is found to explain the result for the raffinate phase in much the same way that temperature lowering leads to supersaturation in binary solutions. Solute enrichment is the cause of the extract‐phase behavior.