bluuebunny/crossref_metadata_2025_split huggingface dataset:
The critical pressures of multicomponent hydrocarbon mixtures and the critical densities of binary hydrocarbon mixtures
Authors: Grieves Robert B. , Thodos George 
Published: June 2004

AbstractA 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

AbstractSimultaneous 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

AbstractSingle 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

AbstractEnthalpies 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

AbstractA 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

AbstractWhen 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

AbstractThe 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

AbstractCritical 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

AbstractExperimental 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

AbstractBoth 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 flocculationThe 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 μValues 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

AbstractIf 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

AbstractA 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

AbstractMass 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

AbstractThe 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

AbstractObservations 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

AbstractInterphase 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

AbstractA 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.
A selectivity factor in vapor‐phase hydrocarbon oxidation catalysis
Authors: Callahan J. L. , Grasselli R. K. 
Published: June 2004

AbstractTheoretical 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

AbstractEntrance‐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.