bluuebunny/crossref_metadata_2025_split huggingface dataset:
Iron oxide sorbents for regenerative sorption of NOx
Authors: Leung Linus , Gidaspow Dimitri 
Published: June 2004

AbstractSupported ferric oxide can remove oxides of nitrogen from hot and cold gases, 20°C to 350°C, containing NO in the range of 50 to 1000 ppm when sufficient oxygen is present. Rates of sorption and capacities increase with oxygen concentration. The sorbent can be regenerated with air at 400° to 450°C an indefinite number of times.Reduced iron oxide sorbs nitric oxide more rapidly than the ferric oxide and has a higher capacity. It can be regenerated with hot reducing gases.
Corresponding states. III. Henry's constants for nonpolar binary mixtures
Authors: Gunn Robert D. , Yamada Tomoyoshi , Whitman David 
Published: June 2004

AbstractA Henry's constant correlation is developed from a macroscopic Corresponding states theory for fluid mixtures. The method requires three interaction parameters which are correlated for mixtures of paraffin with nitrogen, carbon dioxide, hydrogen sulfide, or another paraffin. Henry's constants can be calculated by this method to within experimental accuracy (about ± 5%) for the mixtures tested.
Models of secondary nucleation attributable to crystal‐crystallizer and crystal‐crystal collisions
Authors: Evans T. W. , Sarofim A. F. , Margolis G. 
Published: June 2004

AbstractThe rate of secondary nucleation of ice, assumed to be proportional to the product of collision frequency and impact energy, has been quantitatively modeled using idealized representations of collisions between crystals and either other crystals or surfaces in the crystallizer. The crystal‐crystallizer collisions were assumed to be driven by either steady or turbulent fluid motion and the crystal‐crystal collisions were assumed to be driven by either gravitational forces or turbulent eddies. The models predict to a good approximation the experimentally determined dependence of the secondary nucleation of ice on crystal size, ice concentration, and agitation power.
Convective instabilities in concurrent two phase flow: Part I. Linear stability
Authors: Gumerman Raymond J. , Homsy George M. 
Published: June 2004

AbstractThe linear stability of thermally stratified horizontal two‐phase Couette flow is analyzed for the case of a constant vertical temperature gradient. Instabilities driven by buoyancy, surface tension gradients, or shear are allowed for. It is shown that the instability can take three possible forms: streamwise oriented roll vortices, long interfacial waves, and short Tollmien‐Schlichting waves. It is shown that the stability limits for rolls are identical to those for plane, stagnant layers. A long wave expansion is presented and the stability limits for this mode are given algebraically. The nonexistence of a Squire's Theorem is demonstrated and some numerical experiments at moderate Reynolds numbers are described. Detailed comparisons with previous work are possible for only one fluid pair, but it is shown that reasonably accurate statements may be made to determine which mode may manifest itself in any given experimental situation.
A semimicro thermomechanical technique for characterizing polymeric materials: Torsional braid analysis
Authors: Gillham John K. 
Published: June 2004

AbstractAn overview of a nondestructive semimicro mechanical technique–pioneered, developed, and exploited by the author–which is used for characterizing phase transitions and transformations in polymeric materials is presented. Particular attention is given to literature published since January, 1972, which pertains to advances in automation, data acquisition and processing, and application to polymeric systems. The instrument has been consolidated as a powerful and convenient mechanical spectrometer in this short period.
Dense–bed column crystallizer: An experimental and analytical study
Authors: Moyers Charles G. , Olson Jon H. 
Published: June 2004

AbstractThe performance of a continuous, vertical, dense‐bed column crystallizer is evaluated by comparing experimental and predicted column temperature profiles and by examining product composition at various operating conditions. The separation obtained in an eutectic system is modeled by a component conservation equation coupled with a nonadiabatic energy balance equation. The critical parameter in the analysis is the axial dispersion coefficient and the measured values of this coefficient were similar in magnitude to those reported for ice washing columns. The dense‐bed column apparently achieves nearly ideal plug flow.
Interfacial effects in the entrapment and displacement of residual oil
Authors: Slattery John C. 
Published: June 2004

AbstractQualitiative theories are developed to explain the roles of surface tension and the two surface viscosities during the entrapment of residual oil by water and during the subsequent displacement of residual oil by surfactant solutions. The results are in agreement with available experimental data concerning the effects to be observed as the oil‐water surface tension is reduced. Limited data suggest an order of magnitude criterion for the critical surface tension above which no residual oil can be recovered. The two surface viscosities do not affect the entrapment of residual oil, but they are predicted to play a major role in the displacement of residual oil by surfactant solutions.
Mass transfer in a fixed‐bed gas‐liquid catalytic reactor with concurrent upflow
Authors: Snider James W. , Perona Joseph J. 
Published: June 2004

AbstractMass transfer coefficients for the hydrogenation of α‐methylstyrene were measured in a packed‐bed reactor with concurrent gas and liquid upflow. The packing was 0.29‐cm alumina spheres coated with palladium catalyst. Mass transfer coefficients increased as the 1/2 power of the liquid rate and increased with gas rate to a gas phase Reynolds number of about 50. The severe decrease for higher gas rates may be due to pulsing flow.
Charged membrabe ultrafiltration of inorganic ions in single annd multi‐salt systems
Authors: Bhattacharyya D. , McCarthy J. M. , Grives R. B. 
Published: June 2004

AbstractAn 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

AbstractMolecular 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.
A dynamic method for catalyst diffusivities
Authors: Dogu Gulsen , Smith J. M. 
Published: June 2004

AbstractIt 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

AbstractThis 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

AbstractA 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

AbstractMeasurements 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

AbstractA 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

AbstractIron 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

AbstractTwo 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.
Ternary mass transfer in liquid‐liquid extraction
Authors: Standart G. L. , Cullinan H. T. , Paybarah A. , Louizos N. 
Published: June 2004

AbstractIsothermal 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

AbstractA 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

AbstractThe 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

AbstractExperimental 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

AbstractThe 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

AbstractA 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

AbstractThe 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

AbstractAffinity 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

AbstractTheoretical 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

AbstractThe 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

AbstractIn 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.