bluuebunny/crossref_metadata_2025 huggingface dataset:
Application of modern estimation and identification techniques to chemical processes
Authors: Wells Charles H.
Published: June 2004

This 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

Similarity 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

Four 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.
Formation of organic drops in water
Authors: de Chazal L. E. M. , Ryan J. T.
Published: June 2004

Drop formation from submerged nozzles was studied using liquid‐liquid systems of widely varying properties. The data were correlated using a momentum balance and a two‐stage process of drop formation. The average agreement between data and correlation was 6.3%.
Thermal conductivity of a nonequilibrium chemically reacting gas
Authors: Bodman S. W. , Brian P. L. T. , Chang T. C.
Published: June 2004

Thermal 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

An 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

The 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

Experimental 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

The 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

Gas 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

Experimental 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

The 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

Exposing 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

A 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

Conditions 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.
Elongational flow of polymer melts
Authors: Stevenson James F.
Published: June 2004

Elongational flow experiments with viscous polymeric material were conducted at a constant elongation rate on a modified tensile testing machine. Steady elongational and shear viscosity data and elongational stress growth data are presented for an isobutylene‐isoprene copolymer at 100°C. S‐shaped elongational stress growth curves are reported for cis‐1,4‐polyisoprene at 80°C.

The stresses necessary to maintain a cylindrical specimen in steady elongational flow are indicated by a calculation which includes the effects of inertia, gravity, and interfacial tension.

Interrelations among several elongational flow material functions are given for a constitutive equation based on the theory of linear viscoelasticity.
Ecological aspects of combustion devices (with reference to hydrocarbon flaring)
Authors: Swithenbank J.
Published: June 2004

Some fundamental factors controlling the emission of pollutants by an industrial combustion system are illustrated by reference to gaseous hydrocarbon flare stack combustion. The formation of smoke (soot), radiation, and nitric oxide may be controlled by limiting of the premixed fuel air ratio to moderately rich mixtures. The factors which determine the design of a suitable Canada mixer are shown to be area ratio, density ratio, and pressure ratio. An important pollutant for large burners is the combustion roar. Fuel type and mixture ratio only affect the combustion noise output by about 5 db. The dominant factor in the generation of this noise is the burner turbulence, which can be controlled to reduce the combustion roar by up to 20 db.

Burner cost considerations lead to the current use of simple flare tips; however, the eventual use of more technically sophisticated low pollution units is inevitable.
Nonisothermal laminar contracted flow
Authors: Christiansen E. B. , Kelsey S. J.
Published: June 2004

Temperature and velocity profiles and pressure losses were computed for laminar, temperature‐dependent Newtonian flow from a stream tube through an abrupt contraction into and through the entrance region of a smaller coaxial tube, in which the fluid was cooled or heated at constant wall temperature. The equations of motion and energy, including axial diffusion and viscous dissipation, were solved numerically for diameter ratios of one and two, a practical temperature range, and NPe and NRe up to 100. Entrance temperatures and velocities are far from uniform, and pressure losses are greater than those computed using simplified equations and uniform entrance temperatures and velocities.
Asymptotic solutions of Hopf's equation for turbulent chemical reactions
Authors: Petty C. A. , Reed X. B.
Published: June 2004

Hopf's formalism is extended to chemically reactive turbulent systems, and weak mixing and convective mixing asymptotic forms are considered. The former recovers Corrsin's isotropic decay law for an isothermal first‐order, irreversible reaction; the latter extends Hopf's result to equipartition of mechano‐chemical energy.
Nucleation kinetics of the potassium sulfate‐water system
Authors: Randolph Alan D. , Cise Michael D.
Published: June 2004

Secondary nucleation in the potassium sulfate‐water system occurs by micro‐attrition processes over the entire 1.3‐26 μ size range of this study. Experimental nucleation rates were correlated with power‐law kinetics expressions in terms of supersaturation, the fourth moment of the parent seed‐crystal distribution, and stirring rate. Such kinetics expressions are similar to those used to correlate MSMPR data; however, the secondary nucleation rates of this paper are two orders of magnitude greater than those reported in previous MSMPR studies of the same system. An upper bound on growth rate of these nuclei was calculated based on a population balance analysis; maximum growth rates of these nuclei was markedly size‐dependent in the 1.3‐26 micron size range of measurement, decreasing with decreasing size. The apparent descrepancy between these nucleation rates and MSMPR values can be explained by nuclei washout during the low growth rate period. Anomalous MSMPR kinetics (low or even negative supersaturation power‐law dependence) can be explained by this growth phenomenon.
A heuristic method for the inversion of certain Laplace transforms to produce initially valid approximations
Authors: Semerciyan Mikayel , Thodos George
Published: June 2004

Based on a Lagrangian interpolation, a heuristic scheme is developed for the inversion of certain types of Laplace transforms and is applied to the solution of problems of interest to chemical engineers for which the exact solution is either very difficult or impossible to obtain. The solutions thus obtained are in good agreement with exact values, when available, for initial values of the transformed independent variable and may therefore be used as approximations. Three illustrative examples are presented.
Mass transfer to a rotating fluid: Part I. Transport from a stationary disk to a fluid in bödewadt flow
Authors: Smith Kenneth A. , Colton Clark K.
Published: June 2004

Solutions are developed for mass transfer between a fluid undergoing solid body rotation and a coaxial disk which is located on a stationary infinite surface. The fluid mechanics corresponds to a laminar Bödewadt boundary layer. The overall mass transfer is dominated by the outer portion of the disk, a result of the high transfer rate associated with a leading edge. The concentration field near the axis of rotation extends to great axial distances as a long narrow plume. Approximate analytical solutions are given for each of these regions, and a numerical solution is provided for the entire concentration field.
Stability of rotational couette flow of polymer solutions
Authors: Sun Zu‐Shung , Denn Morton M.
Published: June 2004

The onset of secondary flow between rotating cylinders (Taylor vortices) was observed for a dilute polymer solution whose viscometric flow properties were characterized rheogoniometrically. The critical Taylor number (flow onset) was predicted accurately by linear stability theory with a stress constitutive equation describing viscometric behavior. The cell spacing differed significantly from that predicted by linear theory. A nonlinear analysis shows that Linear theory will predict the ultimate cell size only for an inelastic liquid. For an elastic liquid a larger wave number (closer spacing) is a lower energy configuration than the linear theory spacing. This is consistent with experiment.
Intermolecular repulsions and the equation of state for fluids
Authors: Carnahan Norman F. , Starling Kenneth E.
Published: June 2004

This investigation demonstrates the advantages of an improved expression for intermolecular repulsions in equations of state. A highly accurate equation of state for the rigid‐sphere fluid is used as the model of repulsion behavior in real fluids. A method for general usage of this new rigid‐sphere equation in real fluid models is presented via reformulation of van der Waal's equation using the accurate new rigid‐sphere equation to describe repulsion effects. To test this reformulation, properties of methane, ethane, propane, n‐butane, isobutane, hydrogen sulfide, nitrogen, ethylene, acetylene, methyl chloride, cyclohexane, pentane and octane have been calculated. The advantage of using the accurate rigid‐sphere equation was demonstrated by the general improvement in calculated properties relative to the original van der Waals and Redlich‐Kwong equations. Calculations of enthalpy departures for mixtures of nitrogen and methane, propane and methane, pentane and cyclohexane, and pentane and octane also indicated the desirability of using the accurate rigid‐sphere equation to describe repulsion effects in mixtures.
Hydrodynamic stability and natural convection in Ostwald‐de Waele and Ellis fluids: The development of a numerical solution
Authors: Ozoe Hiroyuki , Churchill Stuart W.
Published: June 2004

An algorithm was developed for the finite‐difference computation of hydrodynamic stability and natural convection in non‐Newtonian fluids heated from below. Test calculations were carried out for fluids whose viscosity characteristics are described by the Ostwald‐de Waele (power‐law) and Ellis models and for roll‐cells with both rigid and dragless vertical boundaries. The effects of time‐step and grid‐size were tested thoroughly. The results were found to be independent of the assumed initial state. The computed values of the Nusselt number and the critical Rayleigh number for Newtonian fluids agree well with prior experimental results. The computations for the Ostwald‐de Waele model indicate that the approximate solution of Tien, Tsuei, and Sun may underestimate the critical Rayleigh Number.
Synthesis in the design of chemical processes
Authors: Hendry J. E. , Rudd D. F. , Seader J. D.
Published: June 2004

Until recently, the subject of chemical process synthesis was largely ignored in the chemical engineering literature despite its importance in chemical engineering practice. However since 1968, attention to the subject has greatly increased and important progress has been made. This review article critically surveys the readily accessible literature in chemical process synthesis from two points of view: theory and applications. It is concluded that a number of effective synthesis tools are now available for application in industrial chemical process design. However, much more remains to be done, particularly with regard to the development of synthesis procedures which can lead to novel processing system structures.
Prediction of transport processes within porous media: Diffusive flow processes within an homogeneous swarm of spherical particles
Authors: Neale Graham H. , Nader Walter K.
Published: June 2004

A geometric model for an homogeneous and isotropic porous medium composed of spherical particles is proposed. This model requires a minimum of geometric simplifications and lends itself to the study of hydrodynamic as well as diffusive flow processes, permitting in each application a mathematically rigorous and fully predictive analysis leading to mathematical representations of the respective flow parameters.

This particular investigation seeks to evaluate, and to provide physical insight into, diffusive flow processes occurring within an homogeneous swarm of spherical particles.
Dropwise and filmwise condensation of water vapor on gold
Authors: Wilkins David G. , Bromley Leroy A. , Read Stanley M.
Published: June 2004

A pure gold tube was found to give filmwise condensation in the absense of organic contamination in a flow sitution simulating that found in seawater conversion plants. A sensitive test for the presence of organic contamination has been developed. The gold tube, promoted by paraffinic thio‐silane or mercaptan, gave 100% excellent dropwise condensation. Overall heat transfer coefficients are reported for filmwise and dropwise condensation. The steamside heat transfer coefficient with dropwise condensation was estimated to be over 0.2 MW/m2‐°C (35,000 B.t.u./hr‐ft2‐°F) at the 95% confidence level.

Gold plated tubes

Supplied by P. Tomalin and S. Mulford of the Office of Saline Water, USDI.

gave 95% filmwise condensation after one week of operation in a clean, once‐through system.
Suboptimal feedback control of distributed systems: Part II. Discussion of test systems and numerical results
Authors: Vermeychuk J. Gregory , Lapidus Leon
Published: June 2004

The suboptimal control algorithms developed in Part I are tested on four example problems to obtain some indication of their performance. Results are presented and compared with results obtained from the application of classical open‐loop optimal control synthesis algorithms to the same test problems.

The suboptimal feedback control algorithms are found to give acceptable performance on both linear and nonlinear systems at the expense of very little computational effort.
Vapor‐Liquid equilibrium: Part I. An appraisal of data reduction methods
Authors: Van Ness Hendrick C. , Byer Stanley M. , Gibbs Richard E.
Published: June 2004

Correlations of the excess Gibbs function and the activity coefficients of a binary, liquid‐phase system at constant temperature depend on reduction of P‐x‐y data taken for the system in vapor‐liquid equilibrium. It is shown that use of a full P‐x‐y data set is for all practical purposes based on just the P‐y values. Alternative procedures require only P‐x or P‐y data. In any case, effective use of a full P‐x‐y data set can be made only if redundent experimental values of Px,y or P are compared for consistency with calculated values. This cannot be accomplished by means of the popular area test for thermodynamic consistency.
Gasification: Part II. Extension to diffusion control
Authors: Hashimoto Kenji , Silveston P. L.
Published: June 2004

Gasification model developed in Part I is extended to allow for mass transfer of oxidant to the particle and for intraparticle diffusion. For this extension, a moving boundary problem results which is solved numerically in conjunction with a two‐point boundary value problem for the oxidant concentration profile in the particle. The extended model predicts, as expected, that mass transfer stifles gasification and intraparticle diffusion shifts gasification to the outer surface of the particle. For the conditions and parameters used in Part I, particle Thiele moduli above 10 result in particle shrinkage with negligible change in the solid properties, whereas if this modulus is less than 0.1, gasification is kinetically controlled.
Infinite dilution diffusion coefficients in liquids
Authors: Vadovic C. J. , Colver C. P.
Published: June 2004

The extension of the Enskog theory by Tham and Gubbins for the calculation of diffusivities is applied to the prediction of infinite dilution diffusion coefficients in binary organic systems. The resulting expression is a function only of the size and mass of the diffusing species. Excellent agreement is obtained for nonassociating n‐alkane mixtures as well as for associated systems. Extension of the expression to alcohol and aqueous systems is shown to require Only an empirical correction factor. It is also shown that the quantity Dij∞ ηj Mj/ρjT is independent of temperature for all systems.
Convergence properties of systems of algebraic equations—explicit loops
Authors: Friedman Francois , Ramirez W. Fred
Published: June 2004

Techniques are developed for using the structural information contained in algebraic equation sets to aid in the study of convergence properties of iterative equation loops.

The concept of inverse mapping is applied directly in order to study convergence properties of sequences. For problems in which there exist both a direct and inverse path for the computation of iterative loops, direct substitution techniques will converge via one path and diverge via the other path. When an inverse path existed, the direct substitution method was superior to simultaneous solution techniques for the problems studied. Not all iterative loops have an inverse path. For problems in which inverse paths do not originally exist, rearrangement of the equations of an iterative loop can result in a modified loop for which an inverse path does exist. The digraph representation of an iterative loop aids in deciding whether rearrangements are feasible for a particular problem. When inverse paths cannot conveniently be obtained, direct substitution cannot be successfully used and simultaneous solution techniques such as quasi‐linearization are recommended.
Real‐time control of air pollution
Authors: Kyan Chwan P. , Seinfeld John H.
Published: June 2004

The problem of determining real‐time (episode) air pollution control strategies for an urban airshed is posed as selecting those control measures from among all possible such that air quality is maintained at a certain level over a given time period and the total control imposed is minimum. The real‐time control is based on meteorological predictions made over a several‐hour to several‐day period. A computational algorithm is developed for solving the class of control problems that result. The theory is applied to a hypothetical study of the effect of implementation of the optimal control on September 29, 1969, in the Los Angeles basin.
Gas‐solid fluidized systems: Average mass transfer potentials of shallow beds
Authors: Yoon Poong , Thodos George
Published: June 2004

An experimental investigation has been conducted on the direct establishment of mass transfer driving forces for the vaporization of n‐decane from Celite particles fluidized by air. Ranges of particle sizes and reactor diameters were employed.

Concentration profiles of n‐decane were determined and were integrated to obtain the actual average concentration difference for the entire bed. The ratio of the actual driving force to the corresponding log‐mean value has been correlated with the average particle size, the fluidized bed height, and the modified Reynolds number to produce two relationships capable of predicting these ratios to within 2.5% (83 runs). The results for these mass transfer studies should also be applicable to comparable studies on heat transfer in fluidized beds.
Thermodynamics of concentrated polymer solutions containing polyethylene, polyisobutylene, and copolymers of ethylene with vinyl acetate and propylene
Authors: Newman R. D. , Prausnitz J. M.
Published: June 2004

Gas‐liquid chromatography is used to measure polymer‐solvent interactions in polymer solutions where the solvent is at infinite dilution. Experimental data are presented for 24 binary polymer‐solvent systems in the temperature range 50° to 150°C. A simple relation exists between the experimental retention volume data and the infinite dilution volatility; this volatility can be used to calculate the solvent vapor pressure over the polymer solution up to about 0.1 weight fraction solvent. Using concepts from the Prigogine‐Flory theory of polymer solutions, Flory‐HugginsXparameters for some polymer‐hydrocarbon systems were correlated with the hydrocarbon's normal boiling temperature.
Experimental liquid mixture densities for testing and improving correlations for liquefied natural gas
Authors: Rodosevich James B. , Miller Reid C.
Published: June 2004

Liquid molar volumes and excess volumes have been experimentally determined for some methane‐rich binary and ternary mixtures containing ethane, propane, isobutane, and nitrogen between 91 and 115 K. A gas expansion type system calibrated against pure methane densities was used to make the necessary pure fluid and mixture measurements.

The best of the available density correlations predicts the experimental methane‐ethane molar volumes within ±0.2%, while larger systematic deviations are found for the methane‐propane and methane‐isobutane systems. Molar volumes for methane‐nitrogen and ternary mixtures containing nitrogen diverge strongly from the correlation predictions at 108 K and higher temperatures. An empirical scheme is proposed for predicting molar volumes of methane‐rich liquefied natural gases using reported methane‐ethane and methane‐nitrogen excess volumes. This method predicts all binary and ternary molar volumes from this investigation within ±0.1%.
Membrane ultrafiltration of a nonionic surfactant
Authors: Grieves R. B. , Bhattacharyya D. , Schomp W. G. , Bewley J. L.
Published: June 2004

Aqueous solutions 1.65 × 10−4 to 1.10 × 10−2 molar in the nonionic surfactant Triton X‐100 are subjected to membrane ultrafiltration over the temperature range of 22 to 50°C in a continuous flow, thin channel cell, with channel Reynolds numbers from 50 to 1175. Data for the ultrafiltrate flux through the optimum polyelectrolyte complex membrane (of the three tested) are correlated by an equation involving the in‐series resistances of the membrane and of the polarized boundary layer of the sufactant rejected by the membrane, with the latter resistance varied over a wide range. The correlations are used to estimate the required membrane area and resultant ultrafiltrate concentration of surfactant to achieve any specified water recovery using cells‐in‐series and cells‐in‐parallel operation. The gelation concentration and surfactant mass transfer coefficient are used to estimate water flux in the gel‐polarization region.
Stability of moving surfaces in fluid systems with heat and mass transport II. Combined effects of transport and density difference between Phases
Authors: Miller Clarence A.
Published: June 2004

Stability of interfaces moving as a result of phase transformation or mass transfer is considered. Effects of transport and of the density difference between phases known to significantly influence stability during solidification and combustion respectively are here studied theoretically in fluid systems. The analysis indicates that instability is possible during vaporization of liquids under vacuum and perhaps during growth of cavitation bubbles. But except when interfacial tension is very low, instability is unlikely during mass transfer in liquid‐liquid systems because the density difference between phases is small. A density difference can also produce cellular convection at an unstable interface during solidification.
A stochastic analysis of a nonisothermal packed bed reactor
Authors: Kado T. , Himmelblau D. M.
Published: June 2004

Monte Carlo techniques have been used to simulate the stochastic responses of the nonisothermal packed bed reactor. Random variables with specified ensemble means, ensemble standard deviations, and probability distributions (normal, uniform, or autocorrelated) were introduced as inputs and parameters into the model equations, and the equations were solved repeatedly to provide a sample of the outputs. Sample means and sample standard deviations both in the steady and unsteady state were evaluated and the probability distributions of the output temperature and concentration characterized. Confidence limits for a specified confidence coefficient have been determined from which overdesign factors could be computed.
Removal of liquid from a packed column of spherical beads under centrifugal force
Authors: Fricke Gordon H. , Rosenthal Donald , Welford George A.
Published: June 2004

Surface sulfonated copolymer beads and glass beads of various size distributions were used to study the removal of liquid from a packed column of spherical beads under centrifugal force. At low forces, from 1 G to approximately 20 G, the volume of liquid retained corresponds to the free volume between the packed beads. The liquid level varies with force from about 20 to 400 G. It is shown that the liquid level is a function of the force applied and the size distribution of the beads in the column. At forces from approximately 400 to 1200 G the weight of the liquid on the sample remains constant.
Chemical kinetics at a critical point
Authors: Snyder R. B. , Eckert C. A.
Published: June 2004

The rate of the Diels‐Alder reaction of isoprene with maleic anhydride has been measured in the vicinity of the upper critical solution points of two liquid‐liquid mixtures, and the rate of the Menschutkin reaction of ethyl iodide and triethylamine has been investigated near a lower critical solution point. Anomalous behavior has been observed, with the former reaction rate augmented by up to 40% and the latter apparently running 25–30% too slow. A possible explanation for these results is presented in terms of transition state theory and the abrupt behavior of the solution activities of dilute solutes near a critical point.
Self‐diffusion and viscosity of some liquids as a function of temperature
Authors: Ertl H. , Dullien F. A. L.
Published: June 2004

Self‐diffusion coefficients of 15 liquids have been measured as a function of temperature between their melting and boiling points. The systems investigated were the benzenes, C6H5X where X = H, F, Cl, Br, and I, n‐paraffins, CnHn + 2 where n = 7, 9, 10, 12, 14, 16, and 18, acetone, acetic acid and water. The pulsed nmr technique was employed for the diffusion measurements. In addition, the viscosities of the halogenated benzenes have been measured between 20°C and their melting points.

The diffusion results obtained in this study have been found in excellent agreement with the best values available for benzene (Collings and Mills, 1970) and water (Longworth, 1960). The relation between the apparent molecular diameter d (d = 2.24(η VD/RT)1/2) and the critical volume as suggested by Dullien (1972) has been extended to include the temperature dependence of d. It is also shown that the temperature dependence of d is similar for all liquids studied here with respect to the reduced temperature. The increase of d for Tr < 0.46 shows the invalidity of the Stokes‐Einstein relation for this temperature range (Tr = T/Tc).

A normalized plot of d has been found very useful in checking the consistency of viscosity and self‐diffusion data. The relations proposed in this work can be used to predict self‐diffusion coefficients and viscosities over the normal liquid range.
On meeting the provisions of the clean air act
Authors: Kyan Chwan P. , Seinfeld John H.
Published: June 2004

A general structure is proposed for determining a set of long‐term (multi‐year) source control measures which achieve specified levels of air quality for an airshed at least cost. Such a structure is useful in evaluating alternative air pollution abatement strategies from the standpoint of air quality and total cost. The theory is applied to the problem of evaluating sets of control actions over the period 1973‐1975 in Los Angeles. Costs of achieving various levels of air quality in Los Angeles over this period are determined.
Molecular oxygen induced crystallite size effect in reduction of nitric oxide with ammonia ober supported platinum
Authors: Pusateri Robert J. , Katzer James R. , Manogue William H.
Published: June 2004

The effect of changing platinum crystallite size from 2.7 to 15.5 nm on the specific catalytic activity in NO reduction by NH3, with and without added O2, was studied over alumina supported platinum catalysts between 423 and 473°K. In the NO‐NH3 system both specific catalytic activity and selectivity to N2 are independent of crystallite size. In the NO‐O2‐NH3 system the specific catalytic activity of the 15.5 nm crystallites is about six times that of the 2.7 nm crystallites. The NO reduction rate shows dependence on NO to the first power and on NH3 to the one‐half power.
Pore and solid diffusion models for fixed‐bed adsorbers
Authors: Weber Thomas W. , Chakravorti Ranjit K.
Published: June 2004

Most models for fixed bed adsorbers have used either the homogeneoussolid or pore diffusion model for the pellets. When the adsorption isotherm is linear, the two models can lead to identical breakthrough curves. The conditions for this equivalence are presented here. It is shown that one of the bulk flow factors that was included in the formulation of one pore diffusion model will be significant only for feedstreams containing a relatively high concentration of adsorbate. The prosity factor of the pore model is shown to be very important, especially as the porosity decreases. The importance of the two diffusional models with respect to the predicted breakthrough curves is demonstrated. For comparable beds, it is shown that the breakthrough curve based on the homogeneous model is delayed with respect to that based on the pore model at early times, regardless of the shape of the isotherm. Finally, the various possible solutions for an irreverisble isotherm are reviewed for each of the models, and a solution is presented for the general case of a pore model with an outside film resistance.
An empirical correlation of second virial coefficients
Authors: Tsonopoulos Constantine
Published: June 2004

A new correlation of second virial coefficients of both polar and nonpolar systems is presented. It uses the Pitzer‐Curl correlation for nonpolar compounds, but in a modified form. The second virial coefficient of nonhydrogen bonding compounds (ketones, acetaldehyde, acetonitrile, ethers) and weakly hydrogen bonding compounds (phenol) is fitted satisfactorily with only one additional parameter per compound, which is shown to be a strong function of the reduced dipole moment. Two parameters are needed for hydrogen bonding compounds (alcohols, water), but for alcohols, one parameter has been kept constant and the other expressed as a function of the reduced dipole moment. The extension of the correlation to mixtures is satisfactory, direct, and involves only one coefficient per binary.
Diffusion in synthetic faujasite powder and pellets
Authors: Ma Y. H. , Ho S. Y.
Published: June 2004

Transient sorption rates of allene and methylacetylene in synthetic faujasite (Linde 13X) powder and self‐bonded pellets are studied in a constant‐volume, constant‐pressure system at three temperatures. The intracrystalline diffusion coefficients are found to be in the order of 10−11 cm2/s and the activation energy for diffusion is 4.0 kcal/g‐mole.

A simple bipore distribution model for transient diffusion in macropores and micropores is presented. It agrees well with the experimental data and quantitatively predicts the macropore diffusion coefficients. The flow in the macropores is found to be in the Knudsen flow regime.
Comparison of parametric pumping with conventional adsorption
Authors: Gregory R. Alan
Published: June 2004

A continuous thermal parametric pumping system is compared to a conventional adsorption system with thermal regeneration. Well‐defined mathematical models are used to find the operating conditions which maximize the separation and throughput of each system.

Under practical operating conditions, the model equations indicate parametric pumping can process a larger volume feed stream at equivalent separations than conventional adsorption for the solute/adsorbent system studied. At equilibrium conditions equivalent results are obtained but parametric pumping requires more energy.
Drag reduction in the turbulent flow of fiber suspensions
Authors: Vaseleski R. C. , Metzner A. B.
Published: June 2004

An analysis of the velocity profile and pressure drop relationships for turbulent flow of fiber suspensions through smooth tubes was evaluated experimentally over a range of flow rates, tube sizes, fiber concentrations, and fiber geometries (aspect ratios). This work shows that drag reduction in these systems, in marked contrast to that in viscoelastic polymeric fluids, involves processes in the turbulent core of the velocity field. As a result the drag reduction achieved is independent of the scale of the system.

The implications of these results with respect to rates of heat and mass transport are considered in a preliminary way. The measurement of such transport rates, and of the turbulent velocity profiles in dilute suspensions, is seen to be of mechanistic interest.
Separation of multicomponent mixtures via thermal parametric pumping
Authors: Chen H. T. , Lin W. W. , Stokes J. D. , Fabisiak W. R.
Published: June 2004

A thermal continuous parametric pump for separating multicomponent mixtures was experimentally investigated using the model system tolueneaniline‐n‐heptane on silica gel adsorbent. A simple method for predicting separations is presented and is found to be in good agreement with the experimental results. The method, based on an equilibrium theory, invokes the assumption that a multicomponent mixture contains a series of pseudo binary systems. Each binary system consists of one of the solutes as one component and the common inert solvent as the other component.
Boundary‐layer skimming: Calculational curiosity or promising process?
Authors: Lee Ho‐Lun , Lightfoot E. N.
Published: June 2004

It is suggested that the productivity of ultra‐filtration and reverse osmosis can be increased substantially where the desired product is concentrated in the diffusional boundary layer adjacent to the membrane. This increase can be achieved by removing product preferentially from the boundary‐layer region. The possible concentration increase and yield of such a skimming process are predicted to be very significant for the constant‐property approximation and stagnation flow considered in this exploratory paper.
An experimental investigation of viscous heating in some simple shear flows
Authors: Sukanek Peter C. , Laurence Robert L.
Published: June 2004

Theoretical investigations of viscous heating in the flow of fluids with an exponential dependence of viscosity on temperature have shown that, for a given shear stress, two shear rates are possible. Above a critical value, the stress decreases as the shear rate increases.

The present work is an experimental study of this phenomenon in plane and circular Couette flows and in cylindrical Poiseuille flow. ArochlorR 1260, a high viscosity Newtonian fluid with an extremely sensitive viscosity‐temperature dependence is used as the test fluid. The results clearly show that two shear rates for Couette flow exist for one measured wall shear stress. Because of the viscosity‐pressure dependence of the fluid, the Poiseuille flow results are inconclusive.