bluuebunny/crossref_metadata_2025 huggingface dataset:
Charged membrabe ultrafiltration of inorganic ions in single annd multi‐salt systems
Authors: Bhattacharyya D. , McCarthy J. M. , Grives R. B.
Published: June 2004

An experimental study of the ultrafiltratin of several ionic inorganic soluted, using a negatively‐charged membrane, is detailed. Both single salt and multi‐salt systems are investigated in a continuous flow, thin chappel unit, with and average transmembrane pressure difference of 2.76 × 105N/m2 and a channel Reynolds number of 2800, The solute rejection is predictable to some extent in terms of Donnan ion exclusion theory, and the water flux is dictated by the combined effects of osmotic pressure and membrane‐cation interaction.

In the single salt experiments, the anion rejections can be related to the inlet (feet) concentration by power functions of the form: rejection = 1 − K Cia, in which 0 < a < 1.0. The power a is 0.4 chloride salts 0.25 fo monovalent oxyanion salts, and 0.1 fir divalent oxynion salts, but a is indepedent of the cationn present (Na+, Ca2+, or La3+). The constant K is generally a function of both the anion (except in the case of SO42−, HPO42−, and CrO42−) and the cation, being determined by such factors as sistance to water flux is found to depend on cation charge and cation radius. For systems containing two or more salts, the presence of a divalent anion decreses the rejection of the monovalent anion. For multi‐salt systems, a rejection of Ca2+ plus Mg2+ of 0.82 and a water flux of 12.9 × 10−4 cm/s (27.2 gal/ft2‐day) are achieved at a transmembrane pressure difference of 4.10 × 105 N/m2 (4.1atm), indicating that the process has considerable potential for industrial water softening.
Molecular rheology of polymer solutions: Interpretation and utility
Authors: Williams Michael C.
Published: June 2004

Molecular theories of polymer rheology are reviewed with emphasis on predictions of the more familiar properties: non‐Newtonian viscosity and normal stress in steady shear, complex viscosity in oscillatory shear, and elongational viscosity in extensional flow. Both dilute and concentrated solutions are discussed, with emphasis on the former. An important objective is clarification of polymer modeling strategies and how they are related to polymer structure. The intended readership consists of those engineers familiar in a general way with continuum polymer rheology, but with no special expertise in polymer physical or theoretical chemistry.
Porous‐electrode theory with battery applications
Authors: Newman John , Tiedemann William
Published: June 2004

Developments in the theory of flooded porous electrodes are reviewed with regard to simulation of primary and secondary batteries, adsorption of ions and double‐layer charging, and flow‐through electrochemical reactors.
A dynamic method for catalyst diffusivities
Authors: Dogu Gulsen , Smith J. M.
Published: June 2004

It is shown that a pulse‐response technique can be used with the Wicke‐Kallenbach type of diffusion cell to determine effective diffusivities in catalyst pellets. The diffusivity is a function of the retention time of the pulse of diffusing gas in the pellet. Experimental values obtained with an alumina pellet agreed well with expected results for this type of material.
Flexible solutions to linear programs under uncertainty: Equality constraints
Authors: Friedman Y. , Reklaitis G. V.
Published: June 2004

This paper presents a framework which allows uncertainties in the matrix elements of an equality constrained linear program to be taken into account without requiring detailed knowledge of the statical characteristics of these uncertainties. The results are derived using the model of the linear program with flexibility previously introduced for the inequality constrained case. However, because a feasible region common to all perturbed constraint sets does not exist in the equality constrained case, a flexibility set which intersects all perturbed sets individually rather than jointly is defined. The flexibility set is constructed by identifying a finite subset of all perturbed constraint sets which need to be investigated. Three cases for the equality constrained problem are considered: independent variations in the array elements, column dependent variations, and row dependent variations. In each case the problem is solved using a possibly large but decomposable linear program. In the first two cases, this program needs to be solved only once; while in the row dependent case an iterative but finite solution procedure is required.
Thermodynamics of aqueous solutions containing volatile weak electrolytes
Authors: Edwards Thomas J. , Newman John , Prausnitz John M.
Published: June 2004

A thermodynamic framework has been established to calculate equilibrium vapor‐liquid compositions for dilute aqueous solutions of one or more volatile weak electrolytes: ammonia, carbon dioxide, hydrogen sulfide, sulfur dioxide, and hydrogen cyanide, in the temperature range 0° to 100°C and for liquid‐phase concentrations from 10−4to 1 or 2 molal.

Binary electrolyte‐water parameters are obtained from reduction of experimental data for single‐solute solutions. Additional parameters required for multi‐solute systems are estimated from correlations. These parameters, coupled with chemical equilibria, are used to predict multicomponent vapor‐liquid equilibria. At a fixed temperature, either liquid‐phase or vapor‐phase compositions may be calculated if the composition of the other phase is known. Although the framework has no adjustable parameters for multisolute systems, predicted and observed equilibria are in good agreement for two ternary systems: ammonia‐hydrogen sulfide‐water and ammonia‐carbon dioxide‐water.
Diffusion and partitioning of macromolecules within finely porous glass
Authors: Colton Clark K. , Satterfield Charles N. , Lai Chung‐Jung
Published: June 2004

Measurements of diffusion and partitioning of nearly monodisperse polystyrene, having molecular weights of from 600 to 670,000, in chloro‐form and dichloroethane and of two proteins in aqueous solution were made with leached borosilicate glass cubes having a narrow pore size distribution and pore radi of from 2.5 to 47.6 nm. With increasing ratio of molecular to pore size, the partition coefficient for all solutes decreased; the ratio of effective to bulk diffusivity decreased for the proteins but remained constant for polystyrene. This suggests that polystyrene behaved like a free‐draining macromolecule under the conditions of this study.
Steady state multiplicity of adiabatic gas‐liquid reactors: I. The single reaction case
Authors: Hoffman Lee A. , Sharma Shanmuk , Luss Dan
Published: June 2004

A model of an adiabatic continuously stirred‐tank reactor in which a single exothermic second order‐gas liquid reaction occurs has been developed. The interactions between the rate of the chemical reaction, the diffusional resistances, and the solubility may cause the occurrence of up to five steady state solutions, even though no more than three solutions can be attained when the same reaction is carried out in a sinle phase CSTR. A parametric study is used to examine the sensitivity of the model to the value of several parameters. Topological arguments are used to obtain a simple instability criterion.
Reduction and removal of SO2 and NOx from simulated flue gas using iron oxide as catalyst/absorbent
Authors: Clay David T. , Lynn Scott
Published: June 2004

Iron oxide supported on alumina is a promising catalyst/absorbent for use in the simultaneous removal of NOx and SOx from power plant stack gases. A dry‐contacting process is under development which would operate under net reducing conditions at temperatures of 370° to 540°C. Iron oxide is converted to the ferrous state, NO is reduced to N2 or NH3, and SO2 is removed as ferrous sulfide or sulfate. Regeneration with air produces SO2 and reforms Fe2O3.

The reduction of SO2 by CO and H2 was studied in fixed‐bed reactors to determine the effects of temperature and of the other reactive components of flue gas (excepting fly ash) on the rate of reaction and the products formed. H2S and COS react with FeO to form FeS. Under readily attainable conditions, virtually complete removal of sulfur compounds was achieved for gas‐phase residence times of about 1 to 10 ms. NO and O2 were also reduced. Conditions under which oxygen poisons the catalyst were determined.
Stability of moving surfaces in fluid systems with heat and mass transport III. Stability of displacement fronts in porous media
Authors: Miller Clarence A.
Published: June 2004

Two effects not considered in previous work can significantly influence stability of moving displacement fronts in porous media. They are transport near the front and expansion or contraction accompanying phase change or chemical reaction at the front. It is shown that both effects act to stabilize a moving front at which steam condenses and displaces water. Available experimental data confirm that such a front is more stable than would be expected based on previous work. The effects should be important in steam drive and underground combustion processes for improving oil recovery and in processes involving moving reaction fronts in packed beds.
Penetration of vertical jets into fluidized beds
Authors: Merry J. M. D.
Published: June 2004

An expression has been derived for predicting the penetration depth of vertical jets into fluidized beds based on the experimental observations of several workers. The expression correlates a wide range of data with reasonable accuracy and is suggested as a useful working equation for design purposes.
Ternary mass transfer in liquid‐liquid extraction
Authors: Standart G. L. , Cullinan H. T. , Paybarah A. , Louizos N.
Published: June 2004

Isothermal mass transfer was studied in a stirred cell with movable baffles using a ternary system with partially miscible solvents (water‐acetone‐glycerol). The measurements were extended from the binary solvent pair to the vicinity of the critical point. It was found that the straight line composition paths in the homogeneous regions on extensions of the equilibrium tie lines characteristic of the critical region applied over the ternary diagram. The results could not be explained even qualitatively by assuming mass transfer without driving force interactions. The principles of irreversible thermodynamics were used to explain the observations and to evaluate the appropriate mass transfer coefficients.
Analysis of time‐delay systems by series approximation
Authors: Mutharasan Rajakkannu , Luus Rein
Published: June 2004

A new method of analyzing the behavior of dynamic systems containing time delays is presented. The method, which is based on the construction of a subsidiary system where the delayed state variables are approximated by Taylor series expansion, is simple and easy to apply. The stability and the region of stability of the subsidiary equation correspond closely to that of the original system.
Transport of mass in ternary liquid‐liquid systems. Part II. Mass transfer and interfacial studies
Authors: Sethy Anil , Cullinan Harry T.
Published: June 2004

The objective of this work is to experimentally examine mass transfer during liquid‐liquid extraction in the system acetonitrile‐benzene‐n‐heptane. The interfacial characteristics of the system are simultaneously investigated. (Part I deals with the diffusion properties of the system).

The mass transfer experiments are conducted in a stirred extraction cell of the Lewis type. The transfer between an unsaturated and nearly saturated phase is studied. The mass transfer coefficients for the partially miscible binary system, and for those ternary experiments in which the slope of the operating line was negative are found to be independent of the driving force. A photographic investigation, which employed the schlieren technique, indicates that Marangoni‐type instabilities are absent in such experiments. However, in ternary experiments, in which the slope of the operating line is positive and above a certain critical value the mass transfer coefficients decreases as equilibrium approached. The schlieren results confirm the presence of interfacial turbulence for this case.

The driving‐force dependence of the turbulent mass transfer coefficients is explaine using a surface renewal model. The model provides a correlation for the results of ternary experiments in which interfaical turbulence is present.
Non‐Newtonian heat transfer in the thermal entrance region of uniformly heated, horizontal pipes
Authors: Bassett Charles E. , Welty James R.
Published: June 2004

Experimental data were obtained for laminar forced flow in the thermal entry region of a uniformly heated pipe with fluids exhibiting a range of non‐Newtonian behavior. The Graetz number range was between 240 and 38,000. Contributions to heat transfer made by non‐Newtonian fluid behavior, temperature‐dependent fluid properties, viscous heating, and secondary flow due to buoyancy were evaluated.

Results indicate that heat transfer is controlled by local wall shear rates. Local wall shear is affected much more by temperature variation of fluid rheological properties than by the degree of pseudoplasticity. Viscous heating was not detected in any of the tests. Natural convection effects were apparent in all cases; however, the heat transfer rates showed contributions due to buoyancy only at the lowest flow rates with low viscosity fluids.
Hydrogenation of acetone in a vibrating slurry reactor
Authors: Lemcoff N. O. , Jameson G. J.
Published: June 2004

The behavior of a vibrating column of liquid as a slurry reactor and the dependence of the mass transfer resistances on the frequency of oscillation and liquid temperature were studied. The hydrogenation of liquid acetone over Raney nickel was chosen as the model reaction. The tortuosity factor of the catalyst was determined from measurements with two different particle sizes.
Method of evaluation and reduction of vapor‐liquid equilibrium data of binary mixtures
Authors: Fabries Jean‐François , Renon Henri
Published: June 2004

A new method to reduce vapor‐liquid equilibrium data of binary mixtures and to evaluate a thermodynamic model is presented. It is based on the principle of maximum likelihood. Deviations between all measured and predicted quantities are calculated and confidence limits in model parameters are evaluated from the given estimates of experimental errors. Many examples illustrate the practical applications of the method.
Instability of film coating of wires and tubes
Authors: Lin S. P. , Liu W. C.
Published: June 2004

The stability problem of the free coating of wires and tubes by withdrawal is formulated and solved. The necessary condition for the stability of the film coating is given explicitly in terms of the Reynolds number, wave number, the Weber number, and implicitly in terms of the withdrawal velocity. The outcome of the competition between the destabilizing capillary pinching and the stabilizing capillary restoring force associated with the film thickness variation is shown to dictate the stability of the film. The comparisons between the present theoretical results and the known experimental results for falling films and creeping annular threads of viscous liquids are good. A possible application of the present results to some aspects of the qualitative design of a coating process is given.
Enzyme separation by parametric pumping
Authors: Shaffer A. G. , Hamrin C. E.
Published: June 2004

Affinity chromatography and parametric pumping were combined to reduce trypsin concentration in an aqueous solution. The trypsin inhibitor, chicken ovomucoid, was covalently bonded to Sepharose 4B beads. A solution was cycled over this packing in a column at a low pH in one direction followed by a high pH in the other direction. Trypsin retention was favored at the high pH and elution at the low pH. The decrease in trypsin concentration at one end of the column was fitted to an equation derived from the equilibrium parametric pumping model and was a function of the pH limits imposed on the column. Separation was much less than predicted by equilibrium data, but the equation based on trypsin reduction agreed with the α‐chymotrypsin‐trypsin separation.
Bubble nucleation in liquids
Authors: Blander Milton , Katz Joseph L.
Published: June 2004

Theoretical and experimental aspects of homogeneous and heterogeneous bubble nucleation are reviewed. Recent developments in nucleation theory, which include hydrodynamic and diffusion constraints, gas phase nonidealities, and heterogeneous nucleation are discussed. A large number of the measured limits of superheat of pure components are close to 88 to 90% of the critical temperature. Where calculations can be made, these measurements are in agreement with predictions from classical nucleation theory. Measurements of the limits of superheat of mixtures are useful for understanding one proposed mechanism for the dangerous phenomena known as contact vapor explosions.
An analogy for heat transfer with wavy/stratified gas‐liquid flow
Authors: Davis E. James , Hung Scott C. , Arciero Steven
Published: June 2004

The von Karman analogy between heat transfer and momentum transfer in turbulent fluids is shown to apply to heat transfer through wavy liquid films in horizontal, stratified, gas‐liquid flow. Nusselt numbers predicted from the analogy are shown to be in good agreement with experimental data for air‐water flows involving three‐dimensional wavy films and large‐amplitude roll waves. The Nusselt numbers encountered with these turbulent water films are found to be in the same range as those associated with condensation of organics in horizontal tubes under stratified flow conditions.
Dissipation effects in hydrodynamic stability of viscoelastic fluids
Authors: Bonnett W. S. , McIntire Larry V.
Published: June 2004

In this paper an analysis is made of the hydrodynamic stability of a Boussinesq viscoelastic fluid undergoing plane Couette flow with a superposed temperature gradient. Of special interest is the effect of including the dissipation term in the energy equation. This term is shown to destabilize the fluid for most values of disturbance wave number and material parameters and to cause overstability for all values of the Brinkman number. At a critical Weissenberg number of 1, a rheological instability is developed which is essentially independent of the Reynolds, Prandtl, and Brinkman numbers.
Self‐generated oscillations in continuous crystallizers: Part II. An experimental study of an isothermal system
Authors: Song Y. H. , Douglas J. M.
Published: June 2004

An experimental study was undertaken to verify the theoretical predictions that for a certain range of operating conditions an isothermal crystallizer would produce oscillating outputs even when the inputs were maintained constant. An interesting feature of the results is that even though a power‐law model and Volmer's model for nucleation kineties provided equivalent descriptions of the steady state data, predictions of transient responses based on Volmer's equation were much better than the power‐law results, and the observed behavior of the oscillating system was described well with Volmer's expression, whereas the power‐law equation predicted that the system would not oscillate.
Flow phenomena in stirred tanks. Part I. The impeller stream
Authors: Günkel Alfred A. , Weber Martin E.
Published: June 2004

Flow parameters were measured in a baffled, turbulent, stirred tank agitated by a six‐blade, disk style turbine. The working fluid was air. Mean and fluctuating velocities were measured between the blades of the impeller with a probe mounted on the spinning impeller. Mean velocities, turbulent velocities, one‐dimensional energy spectra, and Eulerian autocorrelation functions were measured in the impeller stream by using the shielded hot‐wire anemometer of Gunkel et al. (1971) which permits the measurement of turbulence parameters in flows of very high turbulence intensity. Reliable impeller pumping capacities were obtained yielding Qrad/ND3 = 1.0 at the impeller periphery. An energy balance on a control volume containing the impeller and the impeller stream showed that the energy put into the tank via the impeller appeared as a net efflux of kinetic energy leaving the control volume. Therefore, most of the energy input to the tank is dissipated in the bulk of the tank.
Nonlinear theory of free coating onto a vertical surface
Authors: Esmail M. Nabil , Hummel Richard L.
Published: June 2004

The work of Landau and Levich (1942) initiated detailed theoretical and experimental study of the flow of the thin liquid film entrained by a steady withdrawal of a sheet from a bath of liquid. The existing theories, which differ considerably, are all based on linearization of the problem and give single relationships between film thickness T and a capillary number Ca. The present paper demonstrates theoretically that differing physical properties for each liquid result not in a single curve but in a family of curves for T vs. Ca and that the complete set of previous experimental work required and fitted the family of curves. Previous theories could fit only a portion of this experimental data.

The solution requires a nonlinear theory to include inertial terms and two‐dimensional flow and thus treat the parameter of liquid physical properties. This is obtained by applying a nonlinear approach based on the direct method of Galerkin. Owing to the nonlinear character of the solution, the new theory has the advantage of accurately determining the shape and size of the upper meniscus profile. Excellent agreement with the complete set of available experimental data is obtained.
Numerical treatment of laminar flow in helically coiled tubes of square cross section. Part I. Stationary helically coiled tubes
Authors: Joseph B. , Smith E. P. , Adler R. J.
Published: June 2004

Numerical solution of steady laminar flow in helically coiled tubes of square cross section for Dean numbers from 0.8 to 307.8 reveal two regimes of secondary flow. Up to Dean number of 100, the expected secondary flow pattern appears with twin counterrotating vortices. Above Dean numbers of 100, a new secondary flow regime, reported here for the first time, appears with four vortices. Flow visualization and pressure drop experiments confirm the transition.
Drug permeation through human skin: Theory and invitro experimental measurement
Authors: Michaels A. S. , Chandrasekaran S. K. , Shaw J. E.
Published: June 2004

The penetration of drugs and other micromolecules through intact human skin can be regarded as a process of dissolution and molecular diffusion through a composite, multilayer membrane, whose principal barrier to transport is localized within the stratum corneum. A mathematical model of the stratum corneum as a two‐phase protein‐lipid heterogeneous membrane (in which the lipid phase is continuous) correlates the permeability of the membrane to a specific penetrant with the water solubility of the penetrant and with its lipid‐protein partition coefficient.

Experimentally measured permeabilities of human skin to a variety of drugs have been found to conform to this model. The extraordinarily low permeability of skin to most micromolecules appears to arise from the very low diffusivity of such molecules in the intercellular lipid phase.
Thermal cracking of propane and propane‐propylene mixtures: Pilot plant versus industrial data
Authors: Van Damme P. S. , Narayanan S. , Froment G. F.
Published: June 2004

The product distribution and kinetics of the thermal cracking of propane and propane‐propylene mixtures were investigated for a temperature range of 700° to 850°C, exit total pressures from 1.2 to 2 atm. absolute, and steam dilutions of 0.4 and 1.0. The reaction kinetics were determined by two methods. The first uses the equivalent reactor volume concept to reduce the data to isothermicity before attempting the kinetic analysis. The second determines the parameters directly from the nonisothermal data by means of a search routine. Both methods led to a reaction order of 1. The effect of propylene addition was also investigated. Finally, a detailed molecular reaction scheme was derived from a nonisothermal and nonisobaric simulation of the cracking experiments. This scheme was used in the simulation of an industrial cracker and led to excellent agreement, in particular of the product distribution.
Group‐contribution estimation of activity coefficients in nonideal liquid mixtures
Authors: Fredenslund Aage , Jones Russell L. , Prausnitz John M.
Published: June 2004

A group‐contribution method is presented for the prediction of activity coefficients in nonelectrolyte liquid mixtures. The method combines the solution‐of‐functional‐groups concept with a model for activity coefficients based on an extension of the quasi chemical theory of liquid mixtures (UNIQUAC). The resulting UNIFAC model (UNIQUAC Functional‐group Activity Coefficients) contains two adjustable parameters per pair of functional groups.

By using group‐interaction parameters obtained from data reduction, activity coefficients in a large number of binary and multicomponent mixtures may be predicted, often with good accuracy. This is demonstrated for mixtures containing water, hydrocarbons, alcohols, chlorides, nitriles, ketones, amines, and other organic fluids in the temperature range 275° to 400°K.
Interactions between catalytic hydrodesulfurization of thiophene and hydrodenitrogenation of pyridine
Authors: Satterfield Charles N. , Modell Michael , Mayer Jerome F.
Published: June 2004

Pyridine hydrodenitrogenation (HDN) is more difficult than thiophene hydrodesulfurization (HDS), and there is a thermodynamic limitation on the first step of the HDN reaction mechanism which occurs, for example, at 5 to 11 bars, at temperatures above about 350°C. Pyridine inhibits the HDS reaction as previously reported, but sulfur compounds have a dual effect on HDN. At low temperatures, thiophene inhibits the reaction by competing with pyridine for hydrogenation sites on the catalyst. This retards the hydrogenation of pyridine to piperidine, reducing the overall reaction rate. At high temperatures the dominant effect is interaction of hydrogen sulfide, an HDS reaction product, with the catalyst to improve its hydrogenolysis (hydrocracking) activity. This increases the rate of piperidine hydrogenolysis, which is rate determining at the latter conditions, and enhances the overall rate of HDN.
A new technique for collecting binary vapor‐liquid equilibrium data without measuring composition: The method of intersecting isochores
Authors: Hall Kenneth R. , Eubank Philip T. , Myerson Allan S. , Nixon William E.
Published: June 2004

The Burnett coupled isochoric PVT experiment possesses many advantages for determining volumetric properties. In this study, we suggest that it also provides an excellent vehicle for determining VLE data. Incorporating a magnetic densimeter into the apparatus encompasses a VLE experiment in which the phases are not sampled to determine composition. Material balances allow composition calculation; the Gibbs‐Duhem equation is not necessary and thus remains available for consistency checks.
Electroosmosis and electrolyte conductance in charged microcapillaries
Authors: Koh Wei‐Hu , Anderson John L.
Published: June 2004

Interactions between the electrostatic double layer and transport rates in long capillary pores were investigated experimentally. Track‐etched mica sheets with extremely narrow pore size distribution and large length‐toradius ratio were used as model membranes to examine the electrokinetic phenomena enhanced conduction and electroosmosis as a function of pore size and electrolyte (potassium chloride) concentration. Of experimental significance was that the capillary pores were of radius comparable to or even less than the solution Debye length parameter even at moderate (10−4 – 10−3 M) electrolyte concentrations. Heparin, a negatively charged polyelectrolyte, was adsorbed to the pore wall to augment electrostatic effects. The data were compared with numerical calculations based on a diffuse double‐layer model, and the unknown pore wall charge densities were computed for each experiment. The results show that the classical analysis is somehow deficient and also that adsorption of the potential determining ion (heparin) is dependent on electrostatic potential at the pore wall.
Correlation and prediction of gas‐liquid holdups in inclined upflows
Authors: Greskovich E. J. , Cooper W. T.
Published: June 2004

A correlation is developed for predicting in‐situ (or true) liquid holdups for two‐phase, gas‐liquid slug flows in inclined pipes. The correlation is based on experimental data collected in pipes ranging from 2.54 to 7.94 cm in diameter with the air‐water system used.

The experimental data used to develop the correlation were collected at zero input liquid qualities, as previously discussed by Greskovich (1973), and extended over the entire range. These data revealed little diameter effect on holdup for diameters greater than 2.54 cm but a marked effect of angle of inclination. Predicted holdup values show good agreement with experimental data.
A model for predicting flow regime transitions in horizontal and near horizontal gas‐liquid flow
Authors: Taitel Yemada , Dukler A. E.
Published: June 2004

Models are presented for determining flow regime transitions in two‐phase gas‐liquid flow. The mechanisms for transition are based on physical concepts and are fully predictive in that no flow regime transitions are used in their development. A generalized flow regime map based on this theory is presented.
Solubilities of ethylene and other organic solutes in liquid, low‐density polyethylene in the region 124° to 300°C
Authors: Maloney D. P. , Prausnitz J. M.
Published: June 2004

Gas‐liquid chromatography was used to measure the solubilities of ethylene, n‐butane, vinyl acetate, n‐hexane, benzene, toluene, and n‐octane in three different samples of liquid, low‐density polyethylene. Solubilities in the different samples are similar. A correlation is presented for estimation of solubilities of nonpolar solutes in liquid polyethylene.
Solubility of gases and liquids in molten polystyrene
Authors: Stiel Leonard I. , Harnish Daniel F.
Published: June 2004

Experimental solubility data have been obtained for sixteen organic solutes in molten polystyrene by a gas chromatographic procedure for temperatures from 408° to 503°K and pressures to 4 atm. The effects of diffusion and adsorption of the solute on the substrate were considered. The Henry's law constants resulting from this study and those obtained by other investigators were related to the reduced temperature. The effect of pressure on the Henry's law constants is also discussed, and a relationship is presented for the heat of solution.
Convective instabilities in porous media with through flow
Authors: Homsy George M. , Sherwood Albert E.
Published: June 2004

The stability of a thermally stratified, saturated porous media through which mass is being ejected is considered theoretically. The stability parameter is a flow modified D'Arcy‐Rayleigh number and is a function of a single scalar variable, the dimensionless through‐flow strength. Results of both linear and energy theory are given, and it is seen that the fluid can lose stability by either a buoyantly driven mode or by a continuous analogue of the Saffman‐Taylor mode.
Surface reaction with combined forced and free convection
Authors: Chang Ching‐Yuan , Guin James A. , Roberts Loy D.
Published: June 2004

The influence of combined forced and free convection on the surface reaction of a laminarly flowing species in a rectangular channel is studied. The free convective motion, which is superimposed upon the main axial flow, arises from a transverse density gradient produced by the release of a reaction product, or heat, at the channel wall. A numerical stream function‐vorticity method is employed to solve the three‐dimensional conservation equations in the case of large Schmidt number. Effects of aspect ratio, diffusivity ratio, surface reaction rate, and Rayleigh number upon the overall reactant conversion rate and local Sherwood number are examined. Reasonable agreement is obtained with experimental data for a hydrochloric acid‐calcium carbonate surface reaction.
Drop size distributions and coalescence frequencies of liquid‐liquid dispersions in flow vessels
Authors: Coulaloglou C. A. , Tavlarides L. L.
Published: June 2004

A flash photomicrographic method and modified dye‐light transmittance technique are employed to measure size distributions and mixing frequencies in a turbulently agitated flow vessel. This liquid‐liquid dispersion is nearly spatially homogenous. Mixing frequencies are strongly dependent on impeller speed and moderately dependent on holdup fraction.
Practical realizations in process modeling: Part I. A new approach to practical realization
Authors: Jayaraman Krishnamurthy , Lapidus Leon
Published: June 2004

A new approach is presented for the construction of linear, low‐order stable, state‐variable, dynamic models from experimental pulse response data of process systems: the problem of practical realization. This problem is solved by deriving and implementing constraints in the estimation of Markov parameters which are input to a realization algorithm. This is accomplished sequentially by using an algorithm for recursive partial realization. Bounds on the Markov parameters are derived from qualitative information about the smoothness of the response curve and used in a stagewise regression procedure. The presente procedure identifies the faster modes first; hence the tail of the pulse response, if inordinately long and inaccurate, may be ignored while lower‐order partial realizations are constructed.
A multicomponent film model incorporating a general matrix method of solution to the Maxwell‐Stefan equations
Authors: Krishna Rajamani , Standart G. L.
Published: June 2004

Convenient expressions for calculating multicomponent gas phase mass transfer coefficients and transfer rates are obtained by use of an exact matrix method of solution to the Maxwell‐Stefan equations. The results are seen to be exact matrix analogues of classical binary relations and may also be applied as an approximation to describe liquid phase transport.
Evaluation of a rapid technique for measuring the diffusion coefficients of small molecules
Authors: Lemaguer Marc , Wolfe F. H. , Smyrl T. G.
Published: June 2004

The diffusion coefficients of sucrose, glycol, and glycine in water have been measured at 25.0°C by using the schlieren optical system of a preparative ultracentrifuge. The schlieren optical system was modified by the incorporation of a 35 mm single lens reflex camera. The values obtained were well within 2% of values found in existing literature and had an intrinsic precision of better than 2%.
A dual functional solid liquid separation process based on filtration and settling
Authors: Henry Joseph D. , Lui Alain P. , Kuo C. H.
Published: June 2004

The dual functional filter combines both the mechanisms of filtration and settling or decantation. The combined mechanisms of separation permit very high degrees of sludge dewatering; for example, slurries containing 0.2 wt. % gelatinous particles have been dewatered to produce a sludge of 35 wt. % particles. A mathematical model which includes both the effects of axial (vertical) variation of pressure driving force and cake compressibility effects is used in conjunction with experimental data to evaluate the dual functional filter performance.
Reaction of sulfur dioxide with limestone and the grain model
Authors: Hartman Miloslav , Coughlin Robert W.
Published: June 2004

Experimental measurements of the reaction of sulfur dioxide and oxygen with limestones have demonstrated substantial influence of the geologic origin of the stone, its porosity and particle size, gaseous concentration of sulfur dioxide, and temperature on the course of reaction and the conversion (that is, the degree of utilization of the limestone content of the particles as a sorbent for sulfur dioxide). A mathematical model including intraparticle transport and chemical reaction within the particles (grain theory) has been developed to simulate this sulfur dioxide sorption reaction.
Application of h‐transformation for the solution of multicomponent adsorption in fixed bed
Authors: Tien Chi , Hsieh J. S. C. , Turian R. M.
Published: June 2004

A procedure for the application of the so‐called h‐transformation in solving fixed‐bed multicomponent adsorption problems is developed. In order to apply this procedure, it is necessary to select an appropriate value for the transition‐motion factor ξ, and the criteria for making this selection are established in this work.
The static electrification of particles in gas‐solids pipe flow
Authors: Masuda Hiroaki , Komatsu Takahiro , Iinoya Koichi
Published: June 2004

Electrostatic characteristics in gas‐solids flow in a metal pipe are studied both theoretically and experimentally with particular attention to the collision between particles and pipe wall. Effects of gas velocity and particle diameter on the electrification are also examined.
Catalyst aging in a process for liquefaction and hydrodesulfurization of coal
Authors: Stanulonis J. J. , Gates B. C. , Olson J. H.
Published: June 2004

Aged CoO/MoO3/SiO2/Al2O3 catalyst pellets, used in a pilot plant for the single‐stage liquefaction and hydrodesulfurization of coal, were analyzed with an electron microprobe and scanning electron microscope. The results demonstrate the occurrence of catalyst aging processes which could lead to bed plugging and pore mouth blocking.
Coal devolatilization and hydrogastification
Authors: Anthony Donald B. , Howard Jack B.
Published: June 2004

The fundamental understanding of coal and its behavior under gasification conditions is far from complete, but significant insights into the complex chemical and physical phenomena have been achieved. This review of available fundamental information focuses on thermal decomposition of coal in inert gas and in hydrogen, with emphasis on the effects on yield of products exerted by time, temperature, heating rate, pressure, hydrogen partial pressure, and particle size, and on the development of chemical and transport models of engineering importance.
Turbulent drag reduction in dilute fiber suspensions: Mechanistic considerations
Authors: Kale D. D. , Metzner A. B.
Published: June 2004

Both fibrous and polymeric additives, used alone or in combination, appear to affect primarily the fluid in the sublayer region adjacent to a solid surface, contrary to previous predictions. An analysis of fluid deformation modes shows tentatively why drag reduction levels become less sensitive to system scale when fibrous additives are employed, and why polymeric and fibrous additives may be more effective in combination than when either additive is used alone.
Global minimization of a cooled reactor by using a posynomial lower bounding function
Authors: Wilde Douglass J.
Published: June 2004

The cost of a reactor‐heater system with an auxiliary cooler can have at least two local minima and a local maximum, with respect to the design variables: temperature and extent of reaction. This cost can be bounded below by a unimodal function which, being a posynomial (a sum of power functions), can be minimized efficiently by geometric programming. Construction of this lower bounding function is not obvious, since the cost involves both a definite intergral and economies of scale.
Basic concepts of spray dryer design
Authors: Gauvin W. H. , Katta S.
Published: June 2004

The major parameters in the design of spray dryers are discussed. A Lagrangian approach, combining experimental data with theoretical concepts, is proposed to develop design methods. Vortex flow patterns, obtained experimentally in a laboratory size chamber, are correlated and presented.

Based on this design methodology, computational methods are given to calculate droplet trajectories and hence to predict the optimum chamber dimensions and operating conditions for maximum thermal efficiency and/or minimum operating cost. Application of these basic principles is illustrated by the design of an industrial size, spray drying chamber for a specific feed solution and production rate.
An examination of the adaptive random search technique
Authors: Heuckroth M. W. , Gaddy J. L. , Gaines L. D.
Published: June 2004

Random search procedures have recently been successfully applied to the optimization of a variety of chemical engineering problems, including optimization of chemical processes by flow sheet simulation. These procedures represent the independent variables as random variables described by probability distributions. The adaptive random search procedure centers the distribution for each variable about the best search point found and examines this region for a better point. Thus, this technique has the ability of continuously moving the search region toward the optimum, which is particularly advantageous in following constraints.

This study examines the efficiency of the adaptive random search technique as applied to six different problems, which have been previously solved by various other techniques.
Sorption of oxygen, nitrogen, carbon monoxide, methane, and binary mixtures of these gases in 5A molecular sieve
Authors: Ruthven Douglas M.
Published: June 2004

Equilibrium data for the sorption of oxygen, nitrogen, carbon monoxide, and methane in 5A molecular sieve are analyzed in terms of a simple theoretical model isotherm. The model provides an excellent correlation of the single‐component isotherms over the entire concentration range, and it is shown that equilibrium data for sorption of binary mixtures of these gases are correctly predicted by the model using the parameters (Henry constants and molecular volumes) derived from analysis of the single‐component isotherms. The model predicts that mixtures of two sorbates with equal molecular volumes should show approximately ideal solution behavior in the adsorbed phase. The experimental data of Lederman for the sorption of nitrogen‐methane mixtures show the expected behavior over a wide range of pressures.
Particle attrition in shear flow of concentrated slurries
Authors: Karabelas A. J.
Published: June 2004

A first order kinetic formulation of brittle particle attrition is suggested. Experimental data show that it applies to coal particle attrition in Couette flow. These data reveal that particles are reduced by loss of surface protuberances, which are much smaller than their mean diameter. It is also shown how changes of the size spectrum, due to shearing, can be predicted.
Geothermal chemical engineering
Authors: Axtmann Robert C. , Peck Lawrence B.
Published: June 2004

A major, national program to exploit geothermal energy requires creative chemical engineering solutions to a wide array of difficult problems. With some overlap, most of the problems fall into these categories: resource development and management, energy extraction and utilization, power cycle design and optimization, environmental engineering, and corrosion and scaling of equipment. Reinjection of waste fluids, insofar as it proves feasible, will affect the shape of the solutions in all categories.

Convective hydrothermal reservoirs, the most accessible and well characterized of geothermal resources, are immense, permeable media in which heat and mass transport are coupled with chemical reaction. Despite decades of effort, no satisfactory physical or mathematical model exists for any reservoir. Even less is known about the hot rock and geopressured resources, which also may be utilized ultimately.

Electric power production receives primary emphasis in the United States, both in terms of current utilization and of research and development. Worldwide, however, the total power devoted to agricultural activities, space heating and cooling, and process heat applications is greater than that to electric power conversion.

Because hydrothermal reservoirs are low temperature (<350°C) sources of corrosive fluids, much current development effort aims at power cycles that promise enhanced efficiencies and that avoid some of the problems of corrosion and scaling. Among the candidates are several binary cycles which employ secondary working fluids, and the total flow concept, which utilizes two‐phase flow from the production wells.

Once thought to be all but negligible, the environmental effects of geothermal installations have recently been subjected to informed scrutiny and found nonnegligible. Among the problem areas are gaseous effluents including hydrogen sulfide, mercury, radon, ammonia, and H3BO3 and aqueous emissions that contain heavy metals. Reinjection of waste geothermal fluids would ameliorate many environmental impacts but could be complicated by silica deposition in equipment and in the underground reservoir.
Dynamics of aerosol coagulation and condensation
Authors: Ramabhadran T. E. , Peterson T. W. , Seinfeld J. H.
Published: June 2004

The dynamic behavior of aerosol size distributions under the influence of coagulation and growth by heterogeneous condensation of gaseous species is studied. Analytical solutions are obtained to the integro‐differential equation governing the aerosol size distribution density function. Two modes of coagulation (constant and linear coagulation constants) and two modes of condensation (growth independent of particle volume and linearly dependent on particle volume) are considered. The interaction of the two growth mechanisms on aerosol size distributions is elucidated.
A test particle approach to flow classification for viscoelastic fluids
Authors: Tanner Roger I.
Published: June 2004

The formulation of the Deborah and Weissenberg dimensionless numbers for viscoelastic fluids by means of a scheme based on the response of hypothetical tracer test particles having the form of elastic dumbbells is presented. By considering the dynamics of these test particles, we can classify flows as being either strong or weak. Consideration of the amount of stretching of a swarm of dumbbells in one relaxation time also provides a definition of the Weissenberg number. A simple workable definition of the Deborah number is given, and, finally, the ideas are applied to a viscoelastic lubrication case, to an inlet flow, and to the flow through porous media.
Separation sequence synthesis by a predictor based ordered search
Authors: Gomez M. Alejandro , Seader J. D.
Published: June 2004

A predictor based ordered search procedure is used to scan the graph representing all possible separation sequences for a given multicomponent separation process. The algorithmic procedure is expedited by utilizing an heuristic cost function to obtain lower bound estimates of the cost of separators not yet designed. Considerable reduction in search space occurs. Optimal and near optimal sequences are readily generated.
Application of the limiting current method to mass transfer in packed beds at very low reynolds numbers
Authors: Appel Peter W. , Newman John
Published: June 2004

The limiting current technique is used to obtain mass transfer coefficients at very low Reynolds numbers (Re < 0.1) in a packed bed consisting of stainless steel spheres. The data show that for Re < 0.015, the Nusselt numbers are below those predicted by existing empirical correlations. The results are discussed in the light of some mathematical models for packed beds reported in the literature and show semiquantitative agreement with the values predicted by Sorensen and Stewart (1974a).
The interfacial drag and the height of the wall layer in annular flows
Authors: Henstock William H. , Hanratty Thomas J.
Published: June 2004

A method to predict the height of the wall layer and the interfacial drag in annular flow under conditions that the flow rate of the entrained liquid is known is developed from measurements on air‐water flow in circular tubes. Flow conditions are found to be characterized by a generalized Martinelli flow parameter.
Mass transfer of dissolved gases through tubular membrane
Authors: Tang Thomas E. , Hwang Sun‐Tak
Published: June 2004

Mass transfer characteristics are studied theoretically and experimentally for dissolved oxygen and carbon dioxide in fully developed laminar flow through a gas permeable membrane tubing. The gas transfer rate is correlated with the liquid flow rate and tubing size. Membrane resistance together with liquid phase resistance determine the overall mass transport rate.