bluuebunny/crossref_metadata_2025_split huggingface dataset:
Second virial coefficients of polar fluids and mixtures
Authors: Halm Roland L. , Stiel Leonard I. 
Published: June 2004

AbstractRelationships have been developed for the calculation of second virial coefficients of polar fluids from the critical constants, acentric factor w, and fourth parameter x of the substance. Coefficients for the expansion of the reduced second virial coefficient in w and x are presented for 0.64 ≤TR ≤ 0.94. Comparisons with available experimental data indicate that good results are obtained by the method of this study for most polar fluids. The second virial coefficient for water is found to exhibit anomalous behavior. Procedures have also been established for extending the relationships for pure fluids to the second virial coefficient of mixtures containing nonpolar or polar components.
Diffusion in sodium mordenite
Authors: Satterfield Charles N. , Margetts William G. 
Published: June 2004

AbstractThe rates of diffusion of CH4, nC4H10, iso‐C4H10, and C4F10 into well‐characterized single crystals of sodium mordenite were studied at 25°C to 100°C., using a rapidly responding constant‐volume system. The diffusion coefficients are of the order of 10−8 to 10−9 sq. cm/sec. and exhibit a maximum value with time, probably due to an initial temperature increase caused by the heat of sorption. The implications to catalysis of these and other studies of diffusion in zeolites are discussed.
Entry region mass transfer in turbulent pipe flow
Authors: Wasan D. T. , Jones W. O. , Von Behren G. L. 
Published: June 2004

AbstractA general treatment is presented for mass transfer in turbulent pipe flow with special emphasis on the mass transfer entry region and the role of interfacial velocity on the rate of mass transfer. This study includes numerical solutions of the convective diffusion equation with an entering fully developed flow. Solutions for constant properties and a constant wall boundary condition are presented over a wide range of Reynolds numbers, Schmidt numbers, and aspect ratios.An expression was developed for predicting the entry region mass transfer coefficient in both gaseous and liquid systems at ordinary fluxes with negligible interfacial velocities and at small aspect ratios. The proposed equation for a binary system is

Experimental concentration profiles have been reported on the vaporization of acetone into a turbulent air stream within a short cylindrical test section. Data are also reported on concentration measurements in an air‐carbon dioxide gaseous mixture with a large interfacial velocity at the inner surface of a porous pipe test section.The numerical solutions of the diffusion convection equation have been compared with the experimental data in the mass transfer entry region, and a pronounced effect of the interfacial velocity on the mass transfer coefficient was found.
Phase equilibria in the methane‐ethane‐propane‐n‐pentane‐n‐hexane‐n‐decane system
Authors: Vairogs Juris , Klekers A. J. , Edmister W. C. 
Published: June 2004

AbstractAn experimental facility for vapor‐liquid equilibrium measurements at high pressures (100 to 15,000 lb./sq. in. abs.) and ordinary temperatures (100° to 300°F.) on multicomponent mixtures is described. The vapor‐liquid phase behavior of a six‐component hydrocarbon mixture, which simulated a natural gas and a condensate, was studied with this apparatus. Measurements were made at 150° and 250°F. and pressures ranging from 100 lb./sq. in. abs. to the single‐phase pressures for these systems and temperatures.
Transfer of surface‐active agents across a liquid‐liquid interface
Authors: England Dennis C. , Berg John C. 
Published: June 2004

AbstractAnalytical solutions are obtained for the transfer of an adsorbing solute across a liquid‐liquid interface taking into account the effects of molecular diffusion in both bulk phases, adsorptive accumulation at the interface, and energy barriers to adsorption and/or desorption. These solutions show that while adsorptive accumulation alone affects the transfer rate but little, the presence of an adsorption or desorption barrier can significantly affect the bulk concentration profiles and decrease the mass transfer rate. The presence of a desorption barrier is shown to cause the dynamic interfacial tension to pass through a minimum below the steady state value. For some systems it is conceivable that the interfacial tension minimum would be sufficiently low that a slight agitation would result in spontaneous emulsification.Dynamic interfacial tension data for oil‐water systems with interface ages from 0.05 to 1.5 sec. are obtained using a laminar contracting liquid jet. The data indicate the presence of a small net desorption barrier to the transfer of normal and isobutyric acids from oil to water and large barriers to both the adsorption and desorption of 1,5 pentanediol.
Separation of nitrogen and methane via periodic adsorption
Authors: Turnock Philip H. , Kadlec Robert H. 
Published: June 2004

AbstractThe periodic process utilizes a rapid pressure swing cycle in an adsorbent bed to effect the separation of gas mixtures. During the first portion of a cycle the compressed gas mixture flows into the adsorbent‐filled column. Next, while the feed gas is restrained, an exhaust orifice is opened at the feed end of the column providing depressurization. The product stream is enriched in the component exhibiting the lowest coefficient of adsorption.A mathematical model based upon the assumption of instantaneous equilibrium between the gas phase and the adsorbed gas was formulated and solved to simulate the periodic, adsorption process. The measured nitrogen content of the product gas stream was found to correlate with the ratio of the product gas rate to the feed gas rate.At 24°C. the calculated pressure response, feed gas flow rate, and product gas composition correspond favorably with related experimental measurements for all values of the feed gas pressure, cycling frequency, and product gas flow rate within the ranges investigated.
Computation of near‐optimal control policies by trajectory approximation: Hyperbolic‐distributed parameter systems with space‐independent controls
Authors: Parkin Elliot S. , Zahradnik R. L. 
Published: June 2004

AbstractTrajectory approximations have been used to compute near‐optimal control policies for a number of lumped‐parameter systems. In this paper the technique is generalized to distributed‐parameter systems. The essence of the method is the approximation of the state and adjoint variables of the problem by a linear combination of spatially dependent trial functions and time‐dependent mixing coefficients. Application of the method of weighted residuals to the spatial variations reduces the problem to one involving a system of ordinary differential equations for the mixing coefficients.Results are presented of an application of the algorithm to the determination of nearoptimal control policies for a tubular plug‐flow heat exchanger with uniform wall flux forcing. The results compare favorably with the optimal solutions and indicate that the method could be of considerable value in implementing optimal control for a wide class of systems.
Vapor‐liquid and liquid‐liquid vapor phase behavior of the carbon monoxide‐propane and the carbon monoxide‐ethane systems
Authors: Trust D. B. , Kurata Fred 
Published: June 2004

AbstractLow‐temperature vapor‐liquid phase data are reported for the carbon monoxide‐propane and the carbon monoxide‐ethane systems. The data for the carbon monoxide‐propane system are reported at eight temperatures ranging from −125°C to +50°C., with pressure up to 2,000 lb./sq. in. abs., those for the carbon monoxide‐ethane system are reported at four temperatures from −100°C to 0°C., with pressures ranging up to the critical locus. Liquid phase immiscibility was observed at low temperatures in both the carbon monoxide‐ethane and the carbon monoxide‐propane systems. The pressure‐temperature loci for these two systems in liquid‐liquid vapor equilibrium were determined.
Molecular thermodynamics of gases in mixed solvents
Authors: O'connell J. P. 
Published: June 2004

AbstractThe general thermodynamic relation between Henry's constant for a solute in a mixed solvent and Henry's constants for the solute in the pure solvents is discussed in terms of limiting activity coefficients. The inadequacy of several common excess free energy expressions is shown, and results are presented for a form of Kirkwood‐Buff solution theory based on pair distribution functions. Several unknown integrals in the theory are approximated by an empirical function of solvent composition and of solvent properties which generally predicts experimental data for gases in both simple and complex binary solvents with good accuracy. Prediction of fugacities of gaseous components in ternary and higher solvents and in nonideal solutions is considered.
Radiation‐induced polymerizations in continuous stirred‐tank reactors
Authors: Chen H. T. , Hill F. B. 
Published: June 2004

AbstractA theoretical study of the performance characteristics of continuous stirred‐tank reactors when used to conduct radiation‐induced polymerizations is presented. The effects on conversion and molecular weight distribution of the interaction of radiation attenuation, chemical kinetics, and mixing are examined for initiation by ultraviolet light and by Co60 gamma radiation.
Application of modern estimation and identification techniques to chemical processes
Authors: Wells Charles H. 
Published: June 2004

AbstractThis paper describes a new application of modern estimation theory to nonlinear chemical processes. A particularly convenient form of the extended Kalman estimator is presented and its applications are discussed. The method described may be used to compute nonmeasureable process states and system parameters in real time with an on‐line process control computer. An application of the extended Kalman filter to a six‐dimensional nonlinear well‐stirred reactor is discussed in detail. The results clearly indicate the feasibility of on‐line application of this technique. In some cases these computations could eliminate the requirement for an on‐line analysis.
Similarity solutions for the converging or diverging steady flow of non‐newtonian elastic power law fluids with wall suction or injection. Part I: Two‐dimensional channel flow
Authors: Balmer R. T. , Kauzlaich James J. 
Published: June 2004

AbstractSimilarity solutions are determined for the steady flow of an incompressible elastic power law fluid in a two‐dimensional channel with nonparallel walls. The possibility of wall suction or injection is considered. Solutions are found to exist only for power law indices of unity. A method is developed for estimating the pressure drop in the naturally converging flow field before the entrance to a capillary. In diverging flows a singularity is found to arise due to the elasticity of the fluid. The singularity corresponds to a Deborah number of unity. It is postulated that the singularity is, for the constitutive equation used here, a possible source of the flow instability commonly referred to as melt fracture.
Polymerization in expanding catalyst particles
Authors: Schmeal W. R. , Street J. R. 
Published: June 2004

AbstractFour models are presented to describe polymerization in expanding catalyst particles. The globules are presumed to be expanding with accumulating polymer, and catalytic reaction sites are dispersed throughout the polymer matrix which is forming about them. Monomer must diffuse through the polymer to polymerize at the catalyst sites.The Thiele modulus (α), \documentclass{article}\pagestyle{empty}\begin{document}$ R\sqrt {kl/D} $\end{document}, is a ratio of characteristic diffusion time to reaction time which is a measure of the importance of diffusion relative to reaction. Polymerization rates are predicted by the models which are generally dependent on the controlling mechanism. Broad molecular weight distributions are predicted for cases of diffusion control (large α) for those models in which catalyst sites are not equally accessible to monomer.Polymerization rates decline toward an asymptotic final value as the particles expand in diffusion‐controlled cases. Most of the decline which would be readily observable in a laboratory experiment would have occurred by the time the particle radii had increased to about three times their original value.
Thermal conductivity of a nonequilibrium chemically reacting gas
Authors: Bodman S. W. , Brian P. L. T. , Chang T. C. 
Published: June 2004

AbstractThermal conductivity measurements were made for the dissociating system 2 NO2 ⇋ 2NO + O2. Experiments were made at temperatures from 548° to 792°K. and pressures from 1 to 30 atm. Under these conditions the chemical reaction is in a nonequilibrium state, and the rate of energy transport is limited by the rates of the forward and reverse reactions. Experimental results agreed very well with a theoretical model based on a linearized reaction rate expression. Using the thermal conductivity results, it was also possible to determine the chemical kinetic constants for the reaction.
Application of empirical rate expressions and conservation equations to photoreactor design
Authors: Ragonese Francis P. , Williams John A. 
Published: June 2004

AbstractAn empirical rate expression was obtained for the photolysis of tetrachloroplantinic acid (TCPA). The data used to evaluate the parameters of the rate expression were obtained in an elliptical photoreactor operated at high recycle rates in order to maintain a uniform reactant concentration within the photoreactor. A low‐pressure mercury lamp provided light at a wavelength of 2,537Å. The light was assumed to enter the reactor radially and uniformly with respect to both the axial and angular directions.This rate expression was incorporated in a reactant conservation equation which was solved to obtain the predicted conversion of TCPA in an elliptical photoreactor operating in the laminar regime. Solutions of the conservation equation were obtained for photoreactors of two different diameters and for three different lengths.Experimentally observed conversions of TCPA in the laminar regime agreed well with the theoretical solutions except at conversions above 55%, where a solid precipitate apparently caused the lack of agreement.
Optimal startup control of a jacketed tubular reactor
Authors: Hahn D. R. , Fan L. T. , Hwang C. L. 
Published: June 2004

AbstractThe optimal startup policy of a jacketed tubular reactor, in which a first‐order, reversible, exothermic reaction takes place, is presented. A distributed maximum principle is presented for determining weak necessary conditions for optimality of a diffusional distributed parameter system. A numerical technique is developed for practical implementation of the distributed maximum principle. This involves the sequential solution of the state and adjoint equations, in conjunction with a functional gradient technique for iteratively improving the control function.
Experimental evaluation of dynamic models for a fixed‐bed catalytic reactor
Authors: Hoiberg J. A. , Lyche B. C. , Foss A. S. 
Published: June 2004

AbstractExperimental observations of a reactor's frequency response when compared with mathematical models of the reactor revealed the need for accurate modeling of heat generation, heat exchange, and heat storage processes. The experiments were performed in a laboratory reactor with the exothermic reaction between hydrogen and oxygen catalyzed by platinum on granules of silica gel. This system permitted observation of several nonlinear effects.One‐ and two‐dimensional, locally linear, plug‐flow models of the continuum type were used for the comparison. One of the models included the effects of intraparticle diffusion of reactants. However, models that neglected intraparticle dynamic effects were found suitable here because the decay time for the diffusion process within the catalyst was short compared to the reactor's major thermal time constant. A two‐dimensional model was found to give an excellent representation of the very complex movement of concentration and temperature waves in this type of reactor, while a one‐dimensional model was found to serve well when radial gradients are small.
Mass transfer in drag reducing fluid systems
Authors: Sidahmed Gomaa H. , Griskey Richard G. 
Published: June 2004

AbstractThe effect of drag reducing agents on mass transfer in fluid systems was studied. The mass transfer was determined by an electrochemical technique which involved transport of mass from the fluid to the tube wall. It was found that the drag reducing agents retarded mass transfer in turbulent but not in laminar systems. The effect on mass transfer was shown to be comparable to that on heat transfer. The Wells correlation for heat ransfer was shown to be comparable to that on heat transfer. The Wells correlation for heat transfer reducing systems was empolyed for mass transfer. In addition, correlations for Stanton number were determined for mass transfer in drag reducing systems.

Role Indicator
Terms

D
Drag reducing agents

E
Drag reduction

H
Mass transfer

J
Electrochemical technique

D
Polyox solutions

H
Turbulent systems

H
Laminur systems

H
Schmidt number

H
Prandtl number

H
Momentum transfer

H
Heat transfer

H
Stanton number

H
Mass transfer entry region
Turbulence phenomena at free surfaces
Authors: Davies J. T. 
Published: June 2004

AbstractGas absorption by eddies at the free surface of a strongly turbulent liquid is interpreted quantitatively in terms of the Levich approach. The mass transfer coefficient is calculated to vary as Re to a relatively high power (1.3 to 1.5).Experiments on free turbulent jets of liquids in gas are in general accord with this theory. For turbulent films of liquids flowing over large roughness elements in “wake‐interference” flow, the turbulence is anomalously efective in promoting gas absorption.Traces of surface‐active agents suppress the surface renewal. This is analyzed theoretically: the results compare favorably with gas‐absorption for stirred cells and flow experiments over smooth plates. For “wake‐interference” flow over rough plates, the reduction in the rate of gas absorption by surface‐active material is more pronounced than predicted for ordinary turbulence. But even in the presence of a surface‐active agent, the roughness still gives an advantage in mass transfer rates as compared with smooth plates.
An Experimental and theoretical study of the transient response of an isothermal tubular reactor with recycle
Authors: McKinstry K. A. , Stermole F. J. , Dunn R. L. 
Published: June 2004

AbstractExperimental and theoretical transient response data are presented for a tubular reactor with recycle, illustrating the distributed nature of this feedback system. The transient concentration response of an isothermal tubular reactor with recycle was studied experimentally and theoretically for inlet concentration and flow upsets. The reaction studied experimentally was the second order homogeneous liquid phase saponification of methyl acetate with sodium hydroxide.Theoretical models using residence time distribution (RTD) techniques have been developed. The fact that the theoretical model (RTD) predicts the dynamic response data for the recycle reactor with and without reaction in the recycle line for both single flow and concentration upsets verifies that this model is satisfactory for simulation of recycle tubular reactor dynamics.
Analysis of activation energy of grouped parallel reactions
Authors: Golikeri Sudhir V. , Luss Dan 
Published: June 2004

AbstractThe effect of temperature on the reaction rate of grouped species which are consumed by parallel nth order irreversible reactions is investigated. It is shown that when the activation energies of the individual reacting species is aboput equal the temperature effect can be described by an Arrhenius expression. However, when the activation energies of the various reactions are widely spread the Arrhenius dependence may not be adequate unless one assumes that the activation energy of the lump may be temperature and conversion dependent. Unter these conditions the Arrhenius temperature dependence is at best a rough approximation and it is very important to define exactly the experimental method of determining the activation energy. Widely different activation energies for the pseudocomponent may be obtained from different experimental techniques which yield the same value for a single reactant.
Dynamics of diffusion and adsorption in a single catalyst pellet
Authors: Suzuki Motoyuki , Smith J. M. 
Published: June 2004

AbstractExposing one face of a catalyst pellet to a pulse of tracer gas and analyzing the response at the opposite and provides a dynamic method for measuring the effective diffusivity of porous catalysts. The first and second moments of the response peak are shown to be a function of only De and the geometry of the pellet and detector chamber for a nonadsorbing, tracer‐carrier system. Data obtained for alumina pellets of different densities ilustrate the method.For an adsorbing tracer, the first moment is a function of both De and the adsorption equilibrium comstant. Measurements for an unconsolidated assembly of nickel/Kieselguhr particles, using the D2‐H2 system, show that first‐moment data are sufficient to calculate reasonably accurate values of the equilibrium adsorption. However, it appears to be difficult to obtain adsorption rate constants by this method.
Salt effects in vapor‐liquid equilibrium: Testing the thermodynamic consistency of ethanol‐water saturated with inorganic salts
Authors: Jaques D. , Furter W. F. 
Published: June 2004

AbstractA semi‐empirical test for the thermodynamic consistency of isobaric liquid‐vapor equilibrium data for ethanol‐water saturated with a salt is proposed. The test is based upon an adaptation of the Herington method (1) in which the ternary system is treated as a special binary. The test is applied both to full concentration range data and to data which are incomplete at the high alcohol end. For data which are incomplete at the high water end, a less severe test is employed.Literature data for 23 systems composed of ethanol, water, and an inorganic salt at saturation were tested. By the criterion of the proposed test, fourteen were deemed consistent, six were borderline, and three were pronounced inconsistent.
Prediction of breakthrough curves in packed beds: I. Applicability of single parameter models
Authors: Jeffreson C. P. 
Published: June 2004

AbstractConditions under which simplified, single parameter models may be used to predict breakthrough curves in linear, packed bed adsorbers and thermal regenerators are examined with reference, in particular, to earlier conditions proposed by Handley and Heggs and by Babcock and co‐workers. It is found that for high values of heat capacity ratio the Schumann model provides a satisfactory description of packed bed dynamics where fluids axial dispersion and solids conduction effects are lumped into a single parameter the curve spread parameter σ*. For low values of heat capacity ratio, the equivalent conductivity model of Babcock and co‐workers should provide a more accurate description. The value of the Biot number Bi was found to provide the sole criterion for estimating the relative importance of the internal solids conduction. Empirical correlations are presented which allow rapid estimates of breakthrough curves to be made from the curve spread parameter and which facilitate analysis of experimental data from breakthrough curve experiments.