bluuebunny/crossref_metadata_2025_split huggingface dataset:
Mixing and product distribution for a liquid‐phase, second‐order, competitive‐consecutive reaction
Authors: Paul Edward L. , Treybal Robert E. 
Published: June 2004

AbstractMixing effects for the homogeneous, liquid‐phase, second‐order, competitive‐consecutive reaction of iodine (B) with L‐tyrosine (A) to form 3‐iodo‐L‐tyrosine (R) and 3,5‐diiodo‐L‐tyrosine (S) were determined for the following conditions: vessel volume, 5 and 36 liters (baffled and unbaffled); turbine diameter (2 to 6 in.) and speed (95 to 1,600 r.p.m.); feed inlet locations (3), addition rate (0.25 to 18 min.), and distribution; temperature (11° to 43°C.); initial A concentration (0.1 to 0.4 g.‐mole/liter); and kinematic viscosity (0.765 to 6.35 centistokes). A was initially charged to the reactor and an equimolar quantity of feed B was added over a time period. Yields of R are less than that expected for perfect mixing owing to local regions of excess B concentration that exist for time periods during which R over‐reacts to S.Agitation power for a given yield is less in unbaffled vessels without an air‐liquid interface than for baffled vessels. The local fluctuating velocity u′ where feed is introduced correlates the mixing variables and predicts mixing requirements for maintaining yields of R on scale‐up. Regions of excess B concentration are related to a concept of partial segregation. The extent of reaction occurring under this condition is correlated by the dimensionless group (k1bτ) (a0/b), where τ is a microtime scale of mixing related to u′ and the characteristic length of a microscale eddy. The magnitude of this group provides a criterion for predicting the importance of mixing effects on other reaction systems.
Flow of dilatant (shear‐thickening) fluids
Authors: Griskey Richard G. , Green Richard G. 
Published: June 2004

AbstractThe conduit laminar flow of dilatant (shear‐thickening) fluids was investigated. It was found that such flow agreed with the Metzner‐Reed (friction factor‐modified Reynolds number) correlation previously verified only for pseudoplastic fluids. The agreement was found to hold even for cases where the flow behavior index was 2.0 or greater, which caused the velocity term V in the modified Reynolds number Dn′ V2−n′/gc8n−1 K′ to be raised to the zero or a negative power. It was also demonstrated that conduit laminar flow for dilatant (shear‐thickening) fluids could be described solely with the Metzner‐Reed correlation and rheological data taken with a small‐scale laboratory viscometer. Studies of flow through fittings (90‐deg. elbows, globe valves, and couplings) showed a definite effect for non‐Newtonian fluids contrary to previous reports for pseudoplastics which indicated essentially Newtonian behavior.
Effect of dissipation and compression work on the eddy conductivity calculated from experimental temperature data for gases
Authors: Blanco Jose A. , Gill William N. 
Published: June 2004

AbstractThe effect of dissipation and compression work on the eddy conductivity calculated from experimental temperature distribution data for gases is examined in detail, and it is shown that these effects are significant even in relatively low Reynolds number flows, say greater than 30,00. The inclusion of dissipation and compression work in the energy equation for gaseous flows is shown to lead to the determination of symmetrical eddy diffusivities from experimental data.
Experimental heats of mixing for gaseous nitrogen and methane
Authors: Klein R. R. , Bennett C. O. , Dodgge B. F. 
Published: June 2004

AbstractThe excess enthalpy of binary gas phase mixtures has been measured by direct experiment, using a continuous flow, isothermal colorimeter. Heat of mixing data are presented for the methane‐nitrogen system for compositions of 25 to 80 mole % methane in nitrogen, at temperatures of 40°, 0°, −20°, −40°, −60°, and −78°C. and pressures from 250 to 1,50 lb./sq. in. abs. These data are in agreement with the literature to within the experimental uncertainty of this work, 4%.The experimental results agree well with values predicted using the Benedict‐Webb‐Rubin and the Redlich‐Kwong equations of state. The virial equation of state truncated after the third coefficient fits the low density data only. The liquid theories of Scott predict the enthalpies of the mixtures in a qualitative way.
Langmuir‐hinshelwood kinetics of the dehydration of methanol catalyzed by cation exchange resin
Authors: Gates B. C. , Johanson L. N. 
Published: June 2004

AbstractRates of the dehydration of methanol to dimethyl ether catalyzed by cation exchange resin (polystyrenesulfonic acid) were measured with a differential flow reactor and gas chromatographic analysis. Reaction temperature was 119°C., pressure was 1 atm., and feeds were methanol and mixtures of methanol with argon, dimethyl ether, and water.Rata data for the methanol reaction as well as the previously investigated ethanol dehydration reaction are well represented by Langmuir‐Hinshelwood kinetics with adsorption parameters in the rate equations approximately equal to corresponding values of Langmuir adsorption equilibrium constants estimated from or available in the literature. The reaction model is consistent with previous conclusions regarding mechanism. Its pertinence suggests that at reaction conditions the ion exchange resin offers a nearly homogeneous array of catalytic sites.
Invariant imbedding, iterative linearization, and multistage countercurrent processes: III. Estimation and the overdetermined system
Authors: Lee E. S. , Noh J. C. 
Published: June 2004

AbstractIn the design of distillation processes, it is frequently necessary to obtain a specified purity of certain product from a given feed mixture by the use of an existing column. The only variable within the designer's control is the reflux ratio. This design problem cannot be solved easily by existing computational methods. In general a trial‐and‐error approach is used. To avoid this difficulty, this problem is solved as an estimation problem by the use of the quasilinerization approach. To show the effectiveness of this approach, several problems are solved. In general, a four‐digit accuracy is obtained in four iterations with very approximate initial approximations. Furthermore, this approach can treat the overdetermined system in a straightforward manner by the use of least squares criterion and minimization. Only the cases with constant total flow rates of the vapor and liquid streams within each section of the column are considered. The relative volatilities are also taken to be constant throughoutthe column.
Dispersed phase mass transfer during drop formation and coalescence in liquid‐liquid extraction
Authors: Skelland A. H. P. , Minhas Sardul S. 
Published: June 2004

AbstractRates of mass transfer during drop formation and coalescence were investigated for three dispersed phase‐controlled liquid systems, one binary (ethyl acetate‐water) and two ternary (acetic acid‐chlorobenzene‐water and acetic acid‐50% by volume mixture of carbon tetrachloride and nujol‐water). A calculation procedure was devised to isolate these end effects. The measured rates during drop formation were in general greater than predicted by various theoretical models, including those by Heertjes et al. and Ilkovic; and measurements during drop coalescence were in general lower than predicted by the simplified penetration theory model of Johnson and Hamielec. The results were statistically correlated with average absolute deviations of 26.2 and 25.4%, respectively, for drop formation and coalescence.
The suboptimal control of nonlinear systems using liapunov‐like functions
Authors: Schlossmacher E. J. , Lapidus Leon 
Published: June 2004

AbstractA technique which calculates approximate solutions to optimal control problems is developed in this work. The technique, which uses an empirically found weighted quadratic Liapunov function to transform the original n‐dimensional optimization problem into a scalar optimization problem, is applied to a number of optimal control problems typical of those encountered in chemical engineering practice. The problems considered include both linear and nonlinear, lumped and distributed systems with minimum time, and quadratic and final value type performance indices. The solutions of these control problems show that the Liapunov‐like suboptimal method, in general, requires less computer time and storage than that required by iterative and noniterative optimal methods currently used to solve optimal control problems. The reduction in computer storage and time enables the Liapunov‐like technique to handle large dimensional control problems with relatively little effort.
A corresponding states correlation of saturated liquid volumes
Authors: Gunn R. D. , Yamada Tomoyoshi 
Published: June 2004

AbstractA corresponding states correlation is presented for the prediction of saturated liquid volumes. Parameters required are the critical temperature, the acentric factor, and a scaling volume. The correlation is valid over the entire useful range of reduced temperatures from 0.2 to 1.0. The full temperature range has not been covered by previous corresponding states correlations. Average absolute deviations in predicted liquid volumes is one‐quarter of 1% for 26 compounds. The correlation is also useful for calculating critical temperatures, pressures, and volumes when experimental critical data are lacking. The proposed method also provides a convenient means for calculating rapidly and accurately the statistical mechanical parameters used in the cell model correlation developed by Renon, Eckert, and Prausnitz.
A single‐parameter equation for isothermal vapor‐liquid equilibrium correlations
Authors: Tassios Dimitrios 
Published: June 2004

AbstractThe Wilson equation is modified so that it contains only one adjustable constant per binary system. In describing binary behavior the new equation is inferior to the original Wilson but superior to the Van Laar equation. In developing ternary behavior from binary data, the new equation seems to be comparable to the original Wilson but definitely superior to the Van Laar equation.Binary and ternary vapor‐liquid equilibrium behavior has been successfully predicted from one γ° value per binary only.
Hydrodynamic measurements for imperfect mixing processes: Newtonian Fluids
Authors: Hubbard Davis W. , Patel Harish 
Published: June 2004

AbstractThe response of a continuous flow mixing system to a step change in an input variable is discussed from the standpoint of dimensional analysis. This idea is presented as an alternative to using zone models for predicting residence time distributions in systems where imperfect mixing occurs.Mixing experiments were performed in a cylindrical flat bottomed tank geometrically similar to tanks commonly used for industrial processes. The response of the system to a step change in feed concentration was observed. Initially the tank contained a salt solution. At the start of an experiment, a stream of salt‐free diluent was introduced at the top of the tank and a stream of the salt solution was drained from the bottom, keeping the liquid volume in the tank constant. The salt concentration in the output stream was measured continuously after the start of the experiment.The experimental results are correlated in terms of dimensionless variables, and the variables affecting the mixing process most strongly are determined. The results show that variations in throughput rate or in impeller shape or rotational speed affect the mixing process much more than does impeller position. The data are also compared with models proposed by other authors, and the model constants are evaluated.
A generalized method for predicting vapor‐liquid equilibrium
Authors: Lee Byung‐Ik , Edmister Wayne C. 
Published: June 2004

AbstractVapor‐liquid equilibrium distribution ratios for hydrocarbons can be computed by the new equations presented in this work with higher accuracy than is possible by previous generalized methods. In this proposed new method, the three coefficients of the combination Viγi/ϕi are newly developed and generalized functions.The vapor‐phase fugacity coefficient ϕi was formulated via a new generalized equation of state, and the liquid‐phase activity coefficient γi is predicted via a proposed new equation that contains three generalized binary interaction coefficients for each binary set in a mixture. These interaction coefficients were developed from experimental K value data. Two expressions are employed in predicting the liquid fugacity coefficient Vi, one for the real liquid state and one for the hypothetical liquid state, the latter being developed empirically from experimental K value data also. These two Vi equations are also generalized.This new K value prediction method gave an average absolute deviation of 5.25% on a total of 3,504 data points on 19 hydrocarbons in binary and ternary mixtures, these data points being selected so that they cover the range of pure component Tr = 0.5 and up and pressures up to 0.9 of the true mixture critical pressure. Inclusion of nonhydrocarbon‐hydrocarbon systems in the evaluation gave an overall absolute deviation of 6.33% for 4,290 K value data points on 23 components.
Flow of viscoelastic fluids through a rectangular duct
Authors: Han Chang Dae 
Published: June 2004

AbstractA study is carried out on the flow of polymer melts in a rectangular duct. As the theoretical study a three‐constant Oldroyd model is used to derive expressions which correlate the rheological properties of materials with the distributions of wall shear rates and wall normal stresses in the rectangular duct. As the experimental study, a die of rectangular cross section having an aspect ratio of 6 is designed, and then melt extrusion experiments are performed with high density polyethylene. In the experiments wall normal stresses are measured along two adjacent walls of the rectangular duct as a function of the axial position. The measurements permit one to obtain the normal stress differences at the duct exit, and then to calculate the distributions of shear rates at two adjacent walls of the rectangular duct, by use of the theoretically derived expressions. Also measured is the extrudate swell, showing trat more pronounced extrudate swell occurs at the long side of the rectangular duct than at the short side. This behavior of extrudate swell correlates with the exit pressure measurements at two adjacent walls of the rectangular duct.
Diffusion of inert and Hydrogen‐bonding solutes in aliphatic alcohols
Authors: Lusis M. A. , Ratcliff G. A. 
Published: June 2004

AbstractThe diffusion of various inert and of hydrogen‐bonding solutes into aliphatic alcohols was considered. The diffusivities of benzene, p‐dichlorobenzene, biphenyl, and triphenyl methane in methanol, ethanol, n‐propanol, n‐butanol, n‐pentanol, and n‐heptanol were measured at 25°C. for low solute concentrations. An equation was developed for the limiting values of the binary mutual diffusion coefficient in complex‐forming mixtures. This equation, used in conjunction with the Wilke‐Chang correlation, gave a considerable improvement over existing predictive methods for the diffusivity of inert solutes, mono‐ and polyhydroxy alcohols, and water in aliphatic alcohols.
The role of porosity in filtration VII effect of side‐wall friction in compression‐permeability cells
Authors: Tiller Frank M. , Haynes Stewart , Lu Wei‐Ming 
Published: June 2004

AbstractThe effect of side‐wall friction on the uniformity of packing of beds in compression‐permeability cells is examined. A large portion of pressure applied to the top of a compressible bad is absorbed in wall friction, resulting in a nonuniformly packed bed. A simplified analysis of wall friction and its effect on porosity and permeability is presented.All experimenters involived in flow through porous media are urged to examine the effects of stress distribution on the structure and uniformity of the packing. In general, compressible beds of small particles will be strongly affected by the walls.
Flow attachment to solid surfaces: The Coanda effect
Authors: Panitz T. , Wasan D. T. 
Published: June 2004

AbstractThe phenomenon of flow attachment to solid surfaces, occurring with both liquids and gases, is the long‐known though inadequately understood Coanda effect.A flow visualization study was made using a birefringent milling yellow dye solutions flowing over a deflection surface consisting of flat plates. A two‐dimensional flow channel with transparent side walls was used. Photographic observations of the development of the Coanda effect reveal the method of flow attachment and confirm a number of literature predictions. One of the most interesting of these phenomena is the existence of a well defined mixing region along the deflection surface.A simplified model of the flow field has been proposed in order to described the mechanism governing the Coanda effect. The model is supported by experimental data consisting of pressure profiles obtained along the deflection surface and secondary flow entrainment measurements.
Predictive equations for self‐diffusion in liquids: A different approach
Authors: Dullien F. A. L. 
Published: June 2004

AbstractSimple relationships have been obtained which can be used to predict self‐diffusion coefficients of liquids with an average error of ±4%. In addition to the customary parameters, one of these equations contains the critical volume

whereas the other uses Lennard‐Jones potential parameters

Both relations were derived by using a general relation between transport coefficients of pure fluids and a molecular‐kinetic‐model of liquids. No use has been made either of the Stokes‐Einstein relation or the absolute rate theory.By applying the same relation between transport coefficients of pure fluids to gases, an equation has been obtained which can be used to calculate consistently molecular diameters in gases as a function of temperature, using Lennard‐Jones potential parameters.
Thermodynamics of nearly‐ideal systems
Authors: Ellis James A. , Chao Kwang‐Chu 
Published: June 2004

AbstractThe industrial importance of mixtures of closely similar substances is out of proportion to their relatively small numbers due to their frequent occurrence and the difficulty of their separations. A procedure specially designed for the general prediction of their properties, particularly relative volatility, over a wide range of state variables is needed.Such a procedure is developed in this work for convenient application to multicomponent systems with the use of generalized functions. The relative volatility of a nearly ideal system is decomposed into ideal solution factors and nonideality factors. The first order perturbation thory of Longuet‐Higgins is adopted for the calculation of the nonideality factor. The validity of the procedure for the quantitative description of real mixtures is demonstrated with the system propane/propylene for which extensive data are available.The required pure fluid properties for the general application of the procedure are reviewed. System parameters are evaluated for 15 binary systems of industrial interest.
On intrinsic errors in pressure‐hole measurements in flow of polymer melts
Authors: Han Chang Dae 
Published: June 2004

AbstractIn order to investigate the possibilities of pressure‐hole errors in the measurement of wall normal stresses in the flow of polymer melts, a 2.280‐in. long slit die has been designed, having a slot with a rectangular cross section, 0.050 in. by 1.000 in. Three transducers were mounted on each of the two long sides of the rectangular slot along the longitudinal center line of the die and located so that each transducer was directly opposite another in the opposite side. The three transducers on one side were flush mounted. Those on the other side were mounted through pressure‐holes with different diameters (0.017, 0.034, and 0.050 in.) Measurements of wall normal stresse were made with high density polyethylene and polypropylene melts at 200°C., following the experimental procedure described in the author's earlier papers. The present study indicates that pressure measurements made through pressureholes are essentially the same as those made flush‐mounted instruments, and that there are no pressure hole errors in the measurements of wall normal stresses, insofar as polymer melts are concerned.
Distributed‐Parameter dynamics by correlation analysis
Authors: Ledbetter James B. , Bruley Duane F. 
Published: June 2004

AbstractThe experimental dynamic response of a distributed‐parameter, simulaneous heat and mass transfer system was investigated using correlation analysis. The system was a wetted‐wall column operating as a nonadiabatic humidifier with both liquid and gas phase in turbulent flow.The experimetnal frequency response results were compared to the values predicted by an existing mathematical model. The investigation also included a study of the effect of employing forcing functions having nonideal power spectra. Analog‐simulated, first‐order systems were tested to verify the computational procedure and to support the conclusions for the humidification system.System dynamic identifications, acceptable for most engineering purposes, were obtained from forcing signals having power spectra which differed significantly from ideality. For the reduction technique employed, a time‐domain record of approximately 2,500 pairs of input‐output data points was found to suffice for a satisfactory analysis. The correlation technique yielded reliable results over approximately the same range of frequencies as reported for previous pulse test studies based on a comparable forcing procedure. However, the results showed an upper frequency limit below that previously achieved by direct frequency forcing of the same system.
Non‐Newtonian behavior of a suspension of liquid drops in tube flow
Authors: Hyman W. A. , Skalak Richard 
Published: June 2004

AbstractThis paper present an analysis and computed results of the flow of deformable droplets of one Newtonian flow suspended in another Newtonian fluid. Surface tension is assumed to act at the interface of the two fluids. Non‐Newtonian characteristics of the suspension are demonstrated and are qualitatively similar to flow characteristics of blood in capillaries.The results show that the deformation of the drops may result in a significant reduction in the pressure gradient compared with that necessary for a suspension of rigid spheres or spherical (nondeformable) liquid drops. The decrease in the pressure gradient is velocity dependent. This constitutes a mechanism of non‐Newtonain behavior of the suspension as a whole, and is attributable to the flexibility of the suspended elements. The resultant shapes of the liquid drops are similar to the shapes of red blood cells that have been observed in narrow glass capillaries as well as in blood vessels.
The blending efficiencies of some impellers in batch mixing
Authors: Moo‐Young M. , Tichar K. , Dullien F. A. L. 
Published: June 2004

AbstractMixing times for the blending of viscous liquids with tracer materials have been measured in a mechanically agitated tank using two conventional agitutor types (turbine, helical ribbon) and a series of novel tubular‐type agitators. The range of conditions studied were: viscosity = 1 to 70,000 cP, agitator Reynolds number = 5 to 105, tank diameter = 11.5 in. It was found that in terms of agitator power requirement, the tubular agitators were generally more efficient for viscosities greater than 100cP than the others for the blending process.The effects of pseudoplastic non‐Newtonian fluid behavior, of tank‐baffles, and of tank size on mixing times have also been examined in several of the above cases.