bluuebunny/crossref_metadata_2025 huggingface dataset:
Mass transfer to particles: Part I. Suspended in agitated tanks
Authors: Harriott Peter
Published: June 2004

Mass transfer coefficients were measured for particles suspended in agitated, baffled tanks. The coefficients for a given particle size and a given fluid vary with the 0.10 to 0.15 power of the power dissipated per unit volume. The coefficients, which cover a one hundred fold range, are about 1.5 to 8 times those predicted from the correlations for fixed particles if the terminal vilocity is used to calculate the particle Reynolds number. The measured effects of particle diameter, diffusivity, viscosity, and density difference cannot be described by a simple expenential equation or by previous empirical correlations. The effects of these variables can be explained by using a slip‐velocity theory combined with a modified penetration theory.
An experimental study of liquid‐phase turbulent diffusion: Part I. Fluid mechanical data
Authors: Sparks Robert E. , Hoelscher H. E.
Published: June 2004

Results from an investigation of the fully developed turbulent wake of a circular cylinder are presented. The study was conducted in the liquid phase, in the controlled flow field of a water tunnel. A technique was developed for measuring the intensity of turbulence in water. The decay of turbulence intensity downstream from a series of fine‐mesh wire screens was measured and compared with aerodynamic decay laws. Profiles of the turbulence intensity in the cylinder wake were also obtained. This paper is Part I of a study of liquid phase turbulent mass transfer in the wake of a cylinder. The mass transfer results are reported in Part II.
Gas absorption accompanied by chemical reaction: A study of the absorption of carbon dioxide in aqueous solutions of monoethanolamine
Authors: Emmert R. E. , Pigford R. L.
Published: June 2004

Experiments were conducted on the absorption of carbon dioxide in aqueous solutions of monoethanolamine in a very short wetted‐wall column.

When the absorption was effected from pure carbon dioxide streams, the results conformed to a theoretical relation for absorption combined with very fast second‐order reaction. This is in accordance with expectations based on the probable mechanism and rate of the reaction. The data indicate that there is no appreciable effect of nonequilibrium at the interface for this particular reaction system over the range of exposure times studied.

When mixed gas streams were used, it was necessary to resort to empiricism to correlate the data, although the correlating expression arose from theoretical considerations.
Kinetics of the catalytic dehydration of primary alcohols
Authors: Miller Donald N. , Kirk Robert S.
Published: June 2004

The catalytic dehydrations of n‐butanol, n‐propanol, and ethanol to produce water and the respective olefins were studied for the temperature range 400° to 700°F. and over the pressure range 1 atm. to 100 lb./sq. in. gauge. Silica‐alumina catalyst in bead form was used. Dehydration rates were found to be consistent with a single‐site surface reaction‐controlled mechanism in which was superimposed a mass transfer effect internal to the catalyst pellets. Rate constants for the three reactions are presented. The significances of their relative values and their temperature and pressure dependencies are discussed.
Experimental determination of critical temperatures and pressures of mixtures: The methane‐ethane‐n‐butane system
Authors: Forman J. Charles , Thodos George
Published: June 2004

An experimental unit has been designed and constructed for the study of critical phenomena in multicomponent systems. This unit has been built to utilize a new visual PV̇T cell capable of operating at temperatures up to 300°F. and pressures to 10,000 lb./sq. in. abs. This cell is of the liquid piston type with mercury as the pressurizing fluid and affords unobstructed visual observation of its contents. The dependability of the unit has been tested on two mixtures of ethane and n‐butane. Phase equilibria data were obtained, which in turn were used to establish the critical temperture and pressure.

Critical temperatures and pressures have been determined for six different compositions of the methane‐ethane‐n‐butane system. These mixtures consisted of two series, each of three compositions differing only in methane content. The data obtained from them, in conjunction with previously reported critical values for the binaries of this system, have been utilized to generate the complete critical locus for the ternary system. The results for the six mixtures of this study have been compared with critical values predicted by methods available in the literature.
Thermal conductivity of gas mixtures
Authors: Cheung Henry , Bromley Leroy A. , Wilke C. R.
Published: June 2004

Thermal conductivities of ten gases and selected binary and ternary mixtures of them were measured in a concentric silver cylinder cell over the temperature range from 100° to 540°C. The gases were helium, argon, nitrogen, oxygen, carbon dioxide, methyl ether, and methyl formate.

Correlations based upon empirical equations derived from kinetic theory have been developed for the thermal conductivity of gas mixtures. For mixtures of polyatomic molecules the energy transport is considered in two parts, that is one portion transferred by collision and the other by diffusion. When compared with the experimental data for 226 binary mixtures over temperatures from 0° to 774°C., the conductivity equation proposed in this work shows an average deviation of 2.1%.
Axial solid distribution in gas‐solid fluidized beds
Authors: Fan Liang‐Tseng , Lee Chau Jen , Bailie Richard C.
Published: June 2004

Γ‐ray attenuation method was applied to determine the axial fluidizing bulk density profile for an air‐solid aggregative fluidized bed. Except for beds fluidized at very high air velocities two distinct density zones were noted. The density of the bed in the lower portion of the column was relatively constant for a particular set of operating conditions and did not vary with bed height. The density in the top portion of the bed fell rapidly with bed height.

The average density of the lower zone was correlated as a function of the operating variables. The density in the top zone was represented by a one‐tail normal distribution curve. A somewhat better correlation was obtained by a two‐parameter equation at high air velocities. The effects of operational variables, such as air velocity, static bed height, particle size, and particle‐size distribution on these correlations were investigated.

Friction‐factor correlations based on two different definitions of bed height were also obtained.
Laminar and turbulent flow of unstable liquid‐liquid emulsions
Authors: Cengel J. A. , Faruqui A. A. , Finnigan J. W. , Wright C. H. , Kundsen J. G.
Published: June 2004

Liquid‐liquid dispersions containing various volume fractions of a petroleum solvent dispersed in water have been studied in laminar and turbulent flow conditions. If one assumes that the dispersion behaves as a single‐phase fluid, measured friction factors may be used to calculate an effective viscosity of the mixture.

In laminar flow, viscosities were found to be a function of capillary diameter, possibly due of the formation of a thin film of continous phase adjacent to the capillary wall. The thickness of this film was determined to be of the order of 10 to 25 μ, which is probably of the order of the average size of the droplets.

Up to 20% solvent, the relative fluidity (or viscosity) of the dispersions was the same in laminar, vertical turbulent, and horizontal turbulent flow. In the laminar flow case viscosity decreased somewhat with flow rate and became essentially constant at a Reynolds number of about 1,000.

In vertical turbulent flow all dispersions behaved as Newtonian fluids, and a single curve (Figure 6) is presented to predict fluidities. The 35 and 50% dispersions in horizontal flow exhibited non‐Newtonian characteristics and had effective fluidities considerably less than the same dispersion in vertical flow but agreed with the horizontal turbulent flow results of Baron, et al. The apparent non‐Newtonian behavior could be due to phase separation in the horizontal tube.

Corrected laminar flow fluidities for dispersions with 35 and 50% solvent deviated from the vertical turbulent flow results. Reasons for this are unexplained. In laminar flow also, tube orientation affected the viscosity of the 50% dispersion.
Coalescence and entrainment: Phenomena on sieve trays
Authors: Teller A. J. , Rood R. E.
Published: June 2004

Evaluation was made of the effect of hole spacing for 3/16‐in. diameter perforations on a sieve tray, on the magnitude and size distribution of entrainment. The study utilized high‐speed photography and entrainment measurements. The magnitude and average particle size of entrainment appears to be related to the degree of bubble coalescence in the liquid continuous phase and increases rapidly with decrease in hole spacing. Bubble bursts do not contribute significantly to entrainment in multiple perforation geometry; the major contribution occurs from shear of the liquid wall by vapor flumes.
Prediction of vapor‐liquid equilibrium for polar‐nonpolar binary systems
Authors: Finch R. N. , Van Winkle Matthew
Published: June 2004

This paper presents a method of calculating the van Laar constants for binary vapor‐liquid systems. The basis of the method is the van Arkel modification of the van Laar (Scatchard‐Hildebrand) equations which utilize the concept of internal pressure. A generalized method of predicting the apparent internal pressure was developed and described. The experimental van Laar constants and those calculated by the proposed method are compared for twelve polar‐nonpolar binary systems.
The laminar‐turbulent transition in nonisothermal flow of pseudoplastic fluids in tubes
Authors: Hanks Richard W. , Christiansen E. B.
Published: June 2004

Ryan and Johnson's treatment of the transition from laminar to turbulent flow is extended to include the heated flow of pseudoplastic liquids in smooth tubes. A limitation is pointed out for the case of Bingham plastic fluids.

The theoretical results of the present investigation are compared with experimental data obtained for a large number of pseudoplastic fluids having widely variant rheological properties. It is found that the theoretically predicted flow rates corresponding to the inception of turbulence agree with the observed values to within ±6.7%. The theoretical critical wall shear stresses agree within ±3.87% with experiment.
Prediction of vapor‐liquid equilibria from the corresponding states principle
Authors: Leland Thomas W. , Chappelear Patsy S. , Gamson Bernard W.
Published: June 2004

A new ideal K value is defined which does not depend on the Lewis and Randall ideal solution rule but is derived only from composition dependent pseudo criticals and the corresponding states principle. Properties of the liquid and vapor mixtures are evaluated from either experimentally measured properties of closely related pure substances or from generalized tables of thermodynamic properties. A derivation of an improved pseudocritical expression applicable to liquids which may be approximated by simple spherical molecules is presented. The derivation illustrates the assumptions involved and points the way for a possible extension of the technique to more complex molecules.

There are some advantages to this approach. It does not require the troublesome extrapolation of liquid properties into regions where no liquid can exist, a fact which is characteristic of K value calculations from the ideal solution rule. It is especially useful for systems in which an equation of state is not available for all of the components present. It avoids the difficulties in defining combination rules for complicated equations of state. Even for systems including very complex or moderately polar molecules it provides a base for subsequent empirical modification. This base follows the correct isotherm of In K vs. In P up to the actual critical of the system without the difficulties associated with defining a convergence pressure or evaluating the extremely large activity coefficient corrections to the ideal solution rule in the critical region. For mixtures of simple molecules the calculated ideal K value is within about 10% of the experimental value in both the low pressure and in the critical region. The entire calculation may be expressed completely analytically for use on a digital computer and may be coupled with an equilibrium flash calculation so that the ideal K values may be determined from a given overall composition, temperature, and pressure.
A theoretical investigation of natural convection effects in forced horizontal flows
Authors: Gill William N. , Del Casal Eduardo
Published: June 2004

It is shown that viscosity variations and temperature differences between the upper and lower walls can significantly increase or decrease the tendency toward instability. It was found that low Prandtl number fluids are most sensitive to gravitational field effects because they are characterized by a thicker thermal boundary layer.
A study of consecutive competitive reaction systems
Authors: Friedman M. H. , White R. R.
Published: June 2004

Experimental kinetic data are most conveniently correlated by the integrated form of the differential rate equations which the reactions are presumed to obey. A new method of obtaining an approximate integral solution of the differential equations is described and applied to a set of three consecutive competitive reactions.

The approximate integral solution is used to correlate experimental data on systems whose stoichiometry would indicate a consecutivecompetitive mechanism. The compositions of the reaction mixes are predicted with a standard error of estimate of less than 4% of the original concentration of the initiating reactant, in most cases less than 2%. The estimates of the rate constants, found by fitting the approximate solution to the data, are within experimental error of the values obtained by differentiation of the published results.
A diffusion model for rinsing
Authors: Tallmadge John A. , Buffham Bryan A. , Barbolini Robert R.
Published: June 2004

The removal, by immersion in water, of solute from a solution adhering to a 14.7‐cm. wide flat plate has been experimentally investigated at about 80°F. over a 3.5 to 1,000 sec. range of contact time. Diffusivity was varied over a sixfold range (from 0.5 to 3.0 by 10−5 sq.cm./sec.) by the use of two dilute solutions, pontamine blue dye and 0.09 N nitric acid. Equations relating the effects of film thickness, contact time, and diffusivity on the mass fraction of solute which was not removed during rinsing were developed from a diffusion model, under the assumption that the adhering solution was present throughout as a stagnant film of uniform thickness.

The experimentally determined effects of time and diffusivity agreed with those indicated by the idealized model. The agreement of these effects and the magnitude of unremoved solute gave strong indication that diffusion may be considered the controlling mechanism. The experimental dip and rinse method used offers potential as a technique for studying natural convection at transient conditions in the region where diffusion is also important, because it offers the advantage of allowing independent selection of initial fluid densities.
Heat transfer in the nitrogen dioxide‐nitrogen tetroxide system
Authors: Furgason R. R. , Smith J. M.
Published: June 2004

Local heat transfer coefficients were carefully measured for the nitrogen dioxide‐nitrogen tetroxide system in well‐developed turbulent flow in an electrically heated, 0.194‐in. I.D. tube. The average probable error determined from reproducibility tests was less than 2%.

The modification of the Deissler analogy presented earlier (8) was found to predict coefficients which agreed well (0 to 19% deviation) with the observed results. Some of this deviation may be due to uncertainties in the viscosity data. Brokaw's viscosity information (1) gives results that were higher than the experimental values, but that of Thievon et al. (11) would have given low values.

The data were also compared with a simpler Colburn type of analogy in which a heat transfer coefficient based upon enthalpy was employed. The deviations here were larger.
Surface effects in a pulsed, packed column
Authors: Jackson M. L. , Holman K. L. , Grove D. B.
Published: June 2004

Mass transfer rates and flooding limits are basic to the use of packed columns for liquid‐liquid extraction. The input of pulsing energy increases transfer rates and promotes counterflow of the two phases. The wetting characteristics of the packing influence performance.

The toluene‐benzoic acid‐water system was used to observe the performance of a 2‐in. diam. column containing ceramic (hydrophilic) rings, polyethylene (hydrophobic) rings, or a sieve‐plate cartridge. The packed columns showed lower flooding limits than the plate column, but polyethylene packing gave highest transfer rates and capacities. The pulsing energy input was much lower for the plastic packing to effect a higher transfer rate.

Flooding limits for the pulsed, packed columns were lower than for packed columns which were not pulsed. Columns packed with rings so that the ratio of diameter to packing size was 4:1 gave higher flooding limits and better performance than a ratio of 8:1. The use of the two types of packing in alternating bands resulted in a performance intermediate between that of each packing employed separately, and no advantage was indicated in reference to flooding limits or transfer rates.
Reaction kinetics in the absorption of chlorine into aqueous media
Authors: Spalding Charles W.
Published: June 2004

It was established that chlorine reacts with both water and hydroxyl ions. At a short reaction time when the pH was less than 3 the reversible reaction of chlorine and water controlled the absorption rate. From pH 3 to 10.5 the forward reaction predominated and yielded an apparent first‐order rate constant of 20.9 sec.−1 at 25°C. Between pH 10.5 and 12.5 the reaction of chlorine with hydroxyl ions occurred simultaneously with the chlorine‐water reaction. Above pH 12.5 the second‐order reaction between chlorine and hydroxyl ions became controlling and the reaction‐rate constant was evaluated to be in the order of 106 liters/(mole)(sec.) at 25°C.

These ionic reactions of chlorine were further interpreted through the collision and transition state theories. Certain important quantities with regard to the reaction characteristics were derived from the experimental data.
Kihara parameters and second virial coefficients for cryogenic fluids and their mixtures
Authors: Prausnitz J. M. , Myers A. L.
Published: June 2004

The volumetric properties of sixteen fluids of interest in cryogenic engineering have been used to calculate second virial coefficients over as large a temperature range as possible. These coefficients were then fitted to theoretical expressions based on the Kihara potential function. For helium, hydrogen, and neon quantum corrections were applied. For nitrogen, carbon dioxide, and acetylene corrections for quadrupole interactions were made. It was found that the theoretical expressions give an extremely good fit of all reliable experimental datu. The theoretical expressions may therefore be used with confidence to predict volumetric behavior at very low temperatures where data are frequently unavailable.

With the aid of semiempirical mixing rules the theoretical expressions may be used to predict second virial coefficients for mixtures. Agreement with the very limited amount of experimental mixture data is satisfactory. Finally it is shown that calculations based on the Kihara potential may be employed to make useful predictions of phase equilibria such as the solubility of a solid in a compressed gas.
The critical pressures of multicomponent hydrocarbon mixtures and the critical densities of binary hydrocarbon mixtures
Authors: Grieves Robert B. , Thodos George
Published: June 2004

A method of predicting the critical pressures of multicomponent hydrocarbon mixtures of known composition has been developed. These mixtures include ternary, quaternary, and quinary systems consisting of normal and isoparaffins, olefins, acetylenes, naphthenes, and aromatics. The method, based upon the mole fraction of the low‐boiling component in the mixture, graphically presents the ratio of the actual critical pressure to the pseudocritical pressure as a function of a boiling parameter. For mixtures of more than two components the pseudocritical pressure is based on the critical pressure of the pure low‐boiling component and on the actual critical pressure of the mixture consisting of all the remaining higher‐boiling components. From an analysis of twenty‐seven binary systems (139 compositions) the average deviation of calculated values from reported values is 1.27%. For thirty‐four mixtures containing from three to seven components the average deviation is 1.64%.

Based upon a similar approach graphical relationships are presented for the estimation of the critical molar density of binary hydrocarbon mixtures of known composition, which also may contain normal and isoparaffins, olefins, nuphthenes, and aromatics. The same boiling point parameter is used to correlate the ratio of the critical density to the reciprocal of the molar average critical volume for nonmethane systems and the product of the critical pressure and the critical volume for methane systems. From an analysis of fifteen binary systems (eighty compositions) the average deviation of calculated values form reported values is 1.54%.
Transfer processes in the flow of gases through packed and distended beds of spheres
Authors: McConnachie J. T. L. , Thodos George
Published: June 2004

Simultaneous mass, heat, and momentum transfer was experimentally investigated for the flow of air through packed and distended beds of spheres saturated with water. The porous spheres were approximately ⅝ in. in diameter. The void fraction of the packed bed was ϵ = 0.416, and the distended beds, whose spheres were positioned in a body‐centered cubic arrangement, had respective void fractions of ϵ = 0.576 and 0.778. The distended beds were formed by separating the spheres and connecting them with short lengths of fine rigid wire.

Similar relationships for the packed and the distended fixed beds were obtained when the transfer factors were related to the modified Reynolds number. The relationship obtained for mass transfer in packed and distended beds was found to apply to data reported for fluidized beds of spheres.

Pressure drop measurements were made which were not exacting but which indicate that the Ergun relationship for packed beds can be used to relate the friction factor to the modified Reynolds number for both the packed and distended beds investigated.
Mass transfer in drops under conditions that promote oscillation and internal circulation
Authors: Constan G. L. , Calvert Seymour
Published: June 2004

Single drops supported on hypodermic tubing have been studied in a wind tunnel to determine the effect of drop oscillation on mass transfer. The systems studied for the case where internal resistance controls consisted of absorption of sulfur dioxide gas by drops of glycerine, propylene glycol, and ethylene glycol. The results may be expressed in terms of effective diffusivity.

No significant effect was noted in glycerine, whereas the glycols gave effective diffusivity values two to eight times greater than theoretically calculated values of molecular diffusivities.

Frequencies, amplitudes, and internal circulation velocities in the drops were studied by cinematography.

The effect of oscillation on external mass transfer coefficients was studied by sublimation of naphthalene spheres in air. In the cases where the vibrational velocity was less than the stream velocity, no effect was noted; this is in agreement with heat transfer studies.

A technique has been developed for studying the effect of internal circulation on effective diffusivity by the use of forced circulation through a drop suspended on hypodermic tubing. A pseudofilm thickness is determined as a function of circulation velocity and presents a means of predicting effective diffusivities for the systems studied. This technique has been demonstrated, giving results in fair agreement with the correlation of Garner and Lane.
Partial enthalpies of components in gas mixtures via Redlich‐Kwong equation of state
Authors: Edmister Wayne C. , Thompson Richard E. , Yarborough Lyman
Published: June 2004

Enthalpies of components in ideal gas mixtures can be computed from existing data. However the isothermal effects of pressure and composition on partial enthalpies of mixture components have not been completely characterized. An investigation of the application of the Redlich‐Kwong equation of state to the calculation of partial enthalpies is reported here. Methods are developed for convenient hand calculations and for computations on the IBM‐650.

Calculated partial enthalpies are compared with values derived from experimental P‐V‐T‐C data for binary hydrocarbon mixtures. The calculated values agree fairly well with the derived data for pressures up to 2,500 lb./sq. in. abs. Best agreement is generally obtained when the mixture is well above the critical temperature of the more abundant component. No consistent bias was indicated however.
A computer model of the fixed bed catalytic reactor: The adiabatic and quasi‐adiabatic cases
Authors: Carberry James J. , Wendel Martin M.
Published: June 2004

A digital computer model of the adiabatic‐fixed bed catalytic reactor is developed which includes axial dispersion of heat and mass, interparticle heat and mass transport, and intraparticle diffusion of reacting species. The influence of these transport processes upon conversion and yield is discussed. The model is readily extended to nonisothermal, nonadiabatic cases in the absence of radial gradients.

The technique of computer solution avoids the inherent instability problem associated with explicit techniques as applied to flux boundary condition problems which involve flow, diffusion, and reaction.
Dispersed phase mixing: I. Theory and effects in simple reactors
Authors: Curl R. L.
Published: June 2004

When drops in a two‐liquid phase chemical reactor are able to mix with one another by coalescences and redispersions, any spread of concentration among the drops tends to be averaged out. This phenomenon can affect average reaction rate and selectivity in non first‐order reactions or mass transfer rate controlled reactions in the dispersed phase. It was found that for mass transfer rate controlled reactions, or the equivalent zero‐order reaction, quite large dispersed phase mixing rates are required to bring conversions close to the level obtained with complete mixing.
The dynamics of a packed gas absorber by frequency response analysis
Authors: Gray Robert I. , Prados John W.
Published: June 2004

The unsteady state behavior of a packed‐column gas absorber was investigated by comparing the results of experimental frequency response tests with theoretical frequency responses determined for several postulated flow models.

Carbon dioxide was absorbed in water from air‐carbon dioxide mixtures in a 6‐in. I.D. Pyrex pipe, packed to a depth of 5.12 ft. with 5/8‐in. ceramic Raschig rings. A sinusoidal variation in inlet gas‐phase carbon dioxide concentration was produced by a specially designed linear valve, driven at frequencies of 0.1 to 15 cycles/min. Inlet and outlet gas‐phase concentration sinusoids were measured continuously with specially designed high‐speed thermal conductivity cells. Liquid flows from 0 to 222 lb. moles/hr.‐sq. ft. and gas flows from 1 to 20 lb. moles/hr.‐sq. ft. were investigated. Separate frequency response tests on inlet and outlet mock‐ups permitted determination of the frequency response of the packing section alone. Results were expressed graphically as Bode plots.

Theoretical frequency response curves were calculated based on three different flow models: no axial mixing, axial mixing described by a series of perfectly mixed cells, and axial mixing described by an effective longitudinal diffusivity. Neither of the three models gave completely satisfactory agreement with the experimental magnitude‐ratio curves above about 1 cycle/min., although the slug flow model appeared somewhat better than the others. The theoretical phase‐shift curves were almost indistinguishable for the three models and agreed well with the experimental curves.
Two‐phase critical flow of steam‐water mixtures
Authors: Faletti Duane W. , Moulton R. W.
Published: June 2004

Critical flow of two‐phase steam‐water mixtures in annuli has been studied, with a cylindrical test section 0.574 in. in diameter with an axially centered rod, 0.137 or 0.375 in. O.D., as a pressure probe. Pressure taps on the wall and the center rod permitted an accurate determination of the pressure profile over the entire length of the section, and, in cases where a movable probe was used, a short distance into the downstream exhaust chamber. Results were correlated by plotting the ratio of the observed critical mass velocity to the theoretical critical mass velocity for homogeneous flow as a function of quality.

Exit pressures were found to be lower than most values previously reported. The ratioGO/GThwas found to be independent of the probe diameter, the manner of upstream steam‐water mixing, and, for test sections greater than 9 in. in length, the test section length. Since probe diameter had no observable effect onGO/GTH, the correlation may be applicable to full bore pipes near 1/2 in. in diameter. In the range of qualities from 2 to 15% the criticalGO/GTHratio was depressed with increasing exit (throat) pressure, but at other qualities no pressure dependency was noted. The effect of changing the downstream exhaust chamber pressure was found to influence the exit pressure but to have little effect on the observed critical mass velocity. Addition of surface active agents to the steam‐water mixture did not affect the mass velocity but did result in increased exit pressure.
A reduced equation of state for gaseous and liquid substances
Authors: Costolnick John J. , Thodos George
Published: June 2004

Experimental pressure‐volume‐temperature data available in the literature for argon have been utilized to produce relationships for the prediction of densities for reduced temperatures up to TR = 3.38 and reduced pressures up to PR = 50. A plot of reduced pressure vs. reduced temperature for constant reduced density was made for argon, in which each isochor terminates at the vapor‐pressure curve. This information was utilized to develop a third degree polynomial relationship between the normalized pressure and the normalized temperature for each isochor by the method of least squares. This method was also used to establish the dependence of the coefficients of the polynomials on reduced density.

The resulting relationships permitted the calculation of desities for argon from the critical constants, vapor pressure function, and the saturated vapor and liquid densities of the substance with a trial‐and‐error procedure. For fifty‐seven densities for the dense gaseous and liquid phases of argon an average deviation of 1.29% with a maximum value of 3.66% resulted between calculated and reported values. The relationships developed in theis study have also been found to be applicable to nitrogen, oxygen, carbon monoxide, and methane, whose critical compressibility factors are similar to that of argon.
Transport characteristics of suspensions VII. Relation of hindered‐settling floc characteristics to rheological parameters
Authors: Thomas David G.
Published: June 2004

Both the rheological and the hindered‐settling characteristics of small particle size suspensions (0.1 to 50 μ) are primarily determined by the degree of flocculation and the concentration of the suspension. Previous studies have shown that when the laminar shear diagrams are fitted by the Bingham plastic model, the parameters τy/ϕ3 and ϕ−1 In η/μ are constants which are proportional to the degree of flocculation

The present study showed that these rheological parameters were proportional to the value of α determined from the hindered‐settling measurements (α is defined as the ratio of the volume of fluid immobilized by the floc structure to the volume of solids in the floc structure). The materials studied included suspensions of thorium oxide in water and methanol and of titania, kaolin, alumina, and graphite in water. The particle size range was from 0.40 to 17.0 μ

Values of the attractive force between particles calculated from the rheological and hindered‐settling data were in good agreement with each other and with the theoretical values calculated from the Derjaguin‐Verwey‐Overbeek theory of colloid stability. The good agreement among the different values suggests that the present approach may be generally applicable to a variety of different systems.
The apparent chemical kinetics of surface reactions in external flow systems: Diffusional falsification of activation energy and reaction order
Authors: Rosner Daniel E.
Published: June 2004

If the temperature level or free stream reactant concentration is deliberately changed, the resulting change in the observed global reaction rate on a catalytic surface in a flow system will not necessarily reflect the true chemical kinetics at the fluid/solid interface. General expressions, reminiscent of those applicable to a static system, are derived for the relation between the diffusional falsification of activation energy and reaction order in terms of a logarithmic derivative of the isothermal diffusion correction (effectiveness factor). Approximate solutions are given for the case of the thin, nonturbulent diffusion layer which develops along an impermeable catalytic flat plate, for arbitrary values of the true reaction order and Prandtl number for diffusion (Schmidt number). Comparisons with exact solutions to the boundary‐layer equations and alternate approximate methods are given for the special case of first‐order surface reactions. Of the various quantities of interest in the diffusional theory of heterogeneous reactions in flow systems, it is shown that the accuracy of the Frank‐Kamenetskii quasi‐stationary method can become unacceptably poor for the calculation of these falsification parameters. The physicochemical conditions under which these errors are likely to be largest are discussed. Applications are given to the study of the chemical kinetics of fast surface reactions.
The effect of packing on a fluidized bed
Authors: Sutherland J. P. , Vassilatos George , Kubota Hiroshi , Osberg G. L.
Published: June 2004

A study has been made of the effect of fixed packing on the properties of a gas‐fluidized bed, including minimum fluidization velocity, pressure drop, and bed expansion. Experiments using a range of glass beads as fluidizing solid with smooth uniform spheres as packing indicate that both packing size and the ratio of particle to packing diameter are the main variables in correlating the results. Other solids of varying density and shape have also been used. In addition to smooth spherical packing, rough spheres and variously shaped packings such as Raschig rings, Berl saddles, and a cylindrical, open‐ended screen packing have received preliminary study. With the screen packing, which occupies only 5% of the column volume, it has been possible to operate a fluidized bed at a much higher gas throughput without slugging than is possible with a conventional bed.

A preliminary study has also been made of heat transfer rates, and the results indicate that the same factors are significant. With spherical packing, values of h of the order of 70% of that in a conventional bed have been obtained, while with screen packing values ranging up to 100% or greater have been observed.

Possible applications of this technique and its limitations are also discussed.
Separation of liquids by mass diffusion
Authors: Shuck F. O. , Toor H. L.
Published: June 2004

Mass diffusion studies were carried out in a diaphragm diffusion cell with the liquid system methyl alcohol, n‐propyl alcohol, isobutyl alcohol. Experiments were conducted over a wide range of separating agent counterflow. The separation factor was approximately doubled and the yield decreased three orders of magnitude when the counterflow was increased one order of magnitude. Using the four ternary diffusion coefficients for the system and a diaphragm geometry based on previous calibration, the concentration and separation factors could be predicted within the range of experimental error. The theory indicates that at high counterflow considerably larger separation factors would be obtained if the diaphragm were uniform.
Gas‐liquid kinetics: The absorption of carbon dioxide in diethanolamine
Authors: Nunge Richard J. , Gill William N.
Published: June 2004

The absorption of carbon dioxide in pure diethanolamine was studied in a gas‐liquid stirred reactor at 85°, 95°, and 105°F. Over forty runs were made but only nineteen were reported here since several were invalidated by difficulties with the stirring mechanism and reaction‐temperature control. The absorption was followed by pressure‐time measurements with the carbon dioxide pressure ranging between 30 and 4 cm. of mercury. Experimental data were consistent and reproducible.

An equation describing the gas‐liquid absorption system was derived and then simplified by considering only the kinetic region. The experimental data were correlated with the simplified equation by both integral and differential methods and indicate that the reaction follows a third‐order rate equation: first order in carbon dioxide and second order in diethanolamine. A mechanism explaining the observed order is described.

Justification for assuming kinetic control of the absorption was demonstrated by doubling and tripling the stirring speed which produced no significant change in the absorption rate. Also, the temperature dependence of the pseudo‐rate constants was out of the range of ordinary mass transfer control. This agrees with the results of a theoretical model reported previously (6).
Diffusion in ion exchange resins
Authors: Hering Burton , Bliss Harding
Published: June 2004

Observations on the rate of ion exchange in Dowex 50W resins are reported. These measurements were made under conditions where solid diffusion was the governing phenomenon for six pairs of ions sodium‐zinc, sodium‐silver, silver‐aluminum, zinc‐copper, zinc‐aluminum, and aluminum‐cerium (trivalent). The effects of temperature and of resin cross‐linkage were studied with the first system. Exchange in both directions was studied for each pair except the last.

Interpretation with a Fick's law model was accomplished, and diffusion coefficients were obtained for each pair. Values were greatly dependent on the direction of the exchange as well as on the particular pair.

Interpretation with a Nernst‐Planck model was also accomplished and diffusivities for each ion were obtained. Values were greatly influenced by the nature of the second ion except in the case of sodium. The interpretation in this case required numerical solution of the flux equations. These solutions are presented for valence ratios of 1/3 and 2/3 with diffusivity ratios of 5, 10, and 20 and for valence ratios of 3 and 3/2 with diffusivity ratios of 1/5, 1/10, and 1/20.

Activation energies were found to be 4 to 6 kcal/g. mole for either model. Increasing the resin cross‐linkage from 4 to 12% decreased the diffusion values by approximately 80%.

The data were equally well represented with either model. In view of the simplicity of Fick's law, the use of this model is recommended for design purposes.
Interphase mass transfer for laminar concurrent flow of carbon dioxide and water between parallel plates
Authors: Tang Y. P. , Himmelblau D. M.
Published: June 2004

Interphase mass transfer between carbon dioxide gas and water has been investigated. The physical model used was the laminar concurrent flow of gas and liquid in a wide rectangular channel. Because of the high aspect ratio employed, the model was effectively one of parallel plates of infinite width.

Three methods of solving the equations of change—the eigensolution method, the boundary layer theory, and penetration theory—were used to compute the diffusion coefficient of carbon dioxide in water from the experimental data. Calculated values of diffusion coefficients from the penetration theory checked well with those from the eigensolution method, but the values computed from the integrated boundary layer equation were about 10% higher.

Results from the eigensolution agreed within 5% with the data of other investigators in the temperature range of 20° to 30°C.
Catalytic effectiveness in multicomponent and variable diffusivity systems
Authors: Butt John B.
Published: June 2004

A method of evaluating catalytic effectiveness in systems of variable diffusivity is proposed. These systems are encountered when catalysts with bi‐disperse pore‐size distributions are employed or when multicomponent mixtures are involved. The diffusivity is taken to be a linear function of length, and an effectiveness factor is defined for this case. Application of the method is discussed and a numerical example is given.
Direct analogy between mass and heat transfer to beds of spheres
Authors: Gupta Ashis Sen , Thodos George
Published: June 2004

No Abstrect.
A selectivity factor in vapor‐phase hydrocarbon oxidation catalysis
Authors: Callahan J. L. , Grasselli R. K.
Published: June 2004

Theoretical and experimental work is described which leads to a novel hypothesis for explaining the selectivity in heterogeneous vapor phase hydrocarbon oxidation catalysis. Two essential postulates of the hypothesis are:

The oxygen atoms must be distributed on the surface of a selective oxidation catalyst in an arrangement which provides for limitation of the number of active oxygen atoms in various isolated groups.

The metal‐oxygen bond energy of the active oxygen atoms, at the conditions of reaction, must be in a range where rapid removal (hydrocarbon oxidation) and addition (regeneration by oxygen) is assured.

Monte Carlo methods are used to illustrate the distribution of isolated sites on catalytic surfaces under the dynamic conditions of hydrocarbon oxidation reactions. Differences in catalyst and process requirements between oxidation processes operating in an overall oxidizing or reducing atmosphere are discussed.
Measurements of turbulent flow development in tubes and annuli with square or rounded entrances
Authors: Olson R. M. , Sparrow E. M.
Published: June 2004

Entrance‐region studies, based on static‐pressure measurements, were carried out with water flowing in annuli and a circular tube fitted with interchangeable square or rounded entrance sections. The tests covered the Reynolds number range from 16,000 to 70,000. For the annuli, the length of duct required to approach to within 5% of the fully developed pressure gradient was about 20 to 25 hydraulic diameters. This is in general accord with entrance length results for circular tubes and parallel‐plate channels but differs from prior results for the annulus which had indicated entrance lengths larger by a factor of ten. The results for the sharp entrance showed a definite effect of separation and were characterized by high loss coefficients. For the rounded entrance, the initial part of the flow development was laminar; the entrance‐region pressure drop did not substantially exceed (and in one case was less than) the corresponding fully developed pressure drop. Also for the rounded entrance, flow stability was improved and a monotonically decreasing pressure gradient obtained when a turbulent boundary layer was induced by means of a trip. Fully developed friction factors were calculated and compared with theory.
Vapor condensation in the mixing zone of a jet
Authors: Hidy George M. , Friedlander S. K.
Published: June 2004

Experimental studies were made of fog formation in free jets containing glycerine and dibutyl phthalate. Visual and photographic observations showed that condensation took place near the nozzle in the mixing zone between the jet and the ambient air. Fog formation began at a well‐defined location downstream from the nozzle depending on the initial velocity, temperature, and concentration of vapor. The location could be changed by inserting solid bodies or by adding foreign nuclei to the mixing zone. Measurements were made of mean temperature and concentration profiles in the mixing zone with noncondensable gases. These compared well with the predictions of turbulent boundary‐layer theory. Calculations were made of the supersaturation to be expected in the case of glycerine. Downstream of the point where condensation first occurred fog filled most of the region where the calculated supersaturation was above unity. Based on the experimental evidence a mechanism is proposed for condensation in a free jet.
Adsorption rate studies—significance of pore diffusion
Authors: Masamune Shinobu , Smith J. M.
Published: June 2004

Adsorption rates were measured by a transcient method for nitrogen on beds of porous Vycor glass particles. Nitrogen was adsorbed, from a low concentration in helium, at liquid nitrogen temperature.

Equations are presented for the concentration as a function of time and position in the bed, based upon surface adsorption, pore diffusion, or external diffusion controlling the overall process. Analysis of the data with these results indicates that the surface adsorption is a very rapid process and that pore processes determine the rate for particles larger than 0.01 cm. in radius. The effective pore diffusivity was determined to be 0.04 sq. cm./sec. The predominant contribution to the diffusivity is a surface mechanism rather than diffusion in the gas within the pores.
A numerical method for the solution of the energy equation for steady turbulent heat transfer
Authors: Strunk Mailand R. , Tao Frank F.
Published: June 2004

A method is presented for solving the basic energy expression for the temperature distribution for turbulent heat transfer in a circular conduit with a digital computer. The method assumes a knowledge of the velocity distribution, the eddy conductivity term as a function of the radial position, and a constant wall temperature. For illustrative purposes only a dimensionless expression is derived from Reichardt's relationship which gives the eddy conductivity term as a function of radial position with Reynolds and Prandtl numbers as parameters.

Incorporated in the computer program is Richardson's three‐point extrapolation formula which permits the determination of a more accurate eigenvalue from three previously computed values which were obtained by using three different values of the reduced radial increment. Agreement with the Crank‐Nicholson method is quite good, although the method with eigenvalues is considered to be superior. Eigenvalues determined from the analytical solution of the energy expression for the laminar flow case and those computed by the numerical method are in excellent agreement. This is indicative of the accuracy and reliability of the proposed numerical method.
A model building technique for chemical engineering kinetics
Authors: Hunter William G. , Mezaki Reiji
Published: June 2004

The object of much experimentation is to build or discover a suitable model for a given system. Unfortunately very little work has been published on what constitutes good strategies in these situations. This paper is an attempt to formulate an approach to this important problem of iteratively improving models in the area of chemical engineering kinetics. In this technique a statistical analysis is applied to the estimated parameters of a tentatively entertained theroretical model in such a way as to pinpoint its inadequacies, if they exist, so that it is possible to proceed in a logical manner to an appropriate modification of this model. This modified model is then analyzed in a similar way, and further modifications are suggested. In general the cycle is repeated as often as is necessary to reach an adequate model. This sequential method is illustrated by finding an adequate reaction model for the total catalytic oxidation of methane.