bluuebunny/crossref_metadata_2025_split huggingface dataset:
Crystal size distribution dynamics in a classified crystallizer: Part I. Experimental and theoretical study of cycling in a potassium chloride crystallizer
Authors: Randolph Alan D. , Beckman James R. , Kraljevich Zlatica I. 
Published: June 2004

AbstractCycles in particle size and slurry density were experimentally observed in a mixed suspension, potassium chloride crystallizer equipped with a fines dissolver and having nonrepresentative product withdrawal. Cycling behavior was achieved with a product crystal elutriator but was also observed with changes in the orientation of the product removal tube, indicating that instability was induced by product classification. Simulation of the unstable runs with a dynamic model showed crystal size distribution (CSD) limit cycles of similar period using nucleation kinetics and process conditions measured experimentally. The computer simulation showed no tendency towards cycling for the stable runs.
Mechanisms and idealized dissolution modes for high density (ρ > 1), immiscible chemicals spilled in flowing aqueous environments
Authors: Thibodeaux L. J. 
Published: June 2004

AbstractA plausible spill mechanism is proposed and idealized dissolution modes are developed for the prediction of lifetime and downstream cup‐mixing concentration of spilled liquids. Four models are developed which reveal that detailed knowledge of the quantity and distribution of geometric shapes that make up the bottom residing interface between the spillage and the overlaying water are the independent variables of primary importance.
Simulated binary isothermal adsorption on activated carbon in periodic countercurrent column operation
Authors: Klaus Roland , Aiken Richard C. , Rippin David W. T. 
Published: June 2004

AbstractSimulation studies are presented of single‐ and two‐component adsorption in periodic, countercurrent, multicolumn systems. It is demonstrated that long adsorption profiles are likely to occur in the adsorption of organic contaminants from wastewater onto activated carbon, thus favoring the use of multicolumn rather than single‐column systems. For two‐component adsorption in a multicolumn system, it is shown that more switching periods are needed than in the single‐column case before the profiles stabilize, that the stabilized profiles can differ substantially from those found in a single‐column system, and that their shape is strongly influenced by the relative concentrations of the components in the feed.
The chemical engineering side of nuclear fusion power
Authors: Johnson Ernest F. 
Published: June 2004

AbstractIt is widely recognized that chemical engineering has important roles to play in the development of national and worldwide energy resources through optimal utilization of fossil fuel reserves. It is much less appreciated that there are crucial chemical engineering problems in the development of energy production from other sources. In particular, the successful development of nuclear fusion power generating systems will require the solution of many problems that are uniquely suited to chemical engineers.This paper presents a brief overview of the fusion development program for magnetically confined fusion power reactors and an identification of the major technological problems remaining to be solved.
An improved corresponding states method for polar fluids: Correlation of second virial coefficients
Authors: Tarakad Ramanathan R. , Danner Ronald P. 
Published: June 2004

AbstractAn improved four‐parameter corresponding states method that includes polar fluids has been developed. The four parameters are the critical temperature, the critical pressure, the radius of gyration, and a newly developed polarity factor based on the second virial coefficient. These parameters have been used to empirically correlate pure and interaction second virial coefficients of a variety of fluids.
Dispersion in layered porous media
Authors: Moranville M. B. , Kessler D. P. , Greenkorn R. A. 
Published: June 2004

AbstractExperimental data on directional dispersion coefficients in transversely isotropic media, a special case of anisotropic media, were determined in models consisting of alternating layers of sintered glass and unconsolidated glass beads. Values of appropriate parameters to relate the velocity to the directional dispersion coefficient were determined for a variety of permeabilities and angles. Sensitivity of these parameters with respect to angle was determined, and results are presented which will permit estimate of when this effect is significant.
Stochastic models of algal photosynthesis in turbulent channel flow
Authors: Sheth Mayur , Ramkrishna Doraiswami , Fredrickson Arnold G. 
Published: June 2004

AbstractModels have been formulated and analyzed for photosynthesis by algae in turbulent, channel flow. Analytical and computational for results for different stochastic, kinematic models of algal motion have been obtained for two different rate mechanisms. The results indicate that turbulent mixing can achieve an increase in the rates and efficiencies of photosynthesis by realizing the intermittency effects. Optimum levels of turbulence are shown to exist in turbulent channel flow for the mass cultivation of algae. The methodology of this paper is relevant to photochemical reactions in general.
The effect of surfactants on the stability of fluid interfaces during phase transformation
Authors: Palmer Harvey J. 
Published: June 2004

AbstractThe influence of surface active solutes on the stability of fluids during phase transformation is examined both experimentally and theoretically. Experiments on the interfacial stability of triethanolamine as it steadily evaporates into a partial vacuum verifies that for high surface tension fluids, spontaneous convection induced by differential vapor recoil is stabilized by the addition of surfactants and that the degree of stability increases with the surface activity of the surfactant. The hydrodynamic stability of surfactant solutions undergoing phase transformation is then examined using linear stability analysis. Results reveal that surfactants have a marked stabilizing effect on the differential vapor recoil mechanism but have essentially no effect on the fluid inertia and moving boundary destabilizing mechanisms. Consequently, the maximum stabilizing effect of surface active solutes on liquids evaporating under vacuum is determined by the criterion for fluid inertia instability.
Equilibrium staged parametric pumping: II. Multiple transfer steps per half‐cycle and reservoir staging
Authors: Grevillot Georges , Tondeur Daniel 
Published: June 2004

AbstractThe limit regimes of equilibrium staged batch parametric pumps are studied. The half‐cycle comprises several equilibrations at each temperature, each followed by a discrete transfer of fluid. The concentration distribution of the effluent of each half‐cycle is conserved by a cascade of reservoirs. The concepts, methods, and McCabe‐Thiele representation are first introduced on the example of the (one‐stage, two transfer) pump. The generalization to the (one stage, n transfer) pump leads to a limit regime represented by a staircase construction between the two isotherms, the number of steps of the staircase being equal to the number of transfer steps. The limit regime of the general (N stage, n transfer) pump is then analyzed in terms of the properties of the (one stage, n transfer) pump considered above and of the (N stage, one transfer) pump discussed in the preceding paper of this series. An analytical solution for the separation factor is given in the case of linear isotherms. The importance of conserving the effluent concentration distribution is illustrated by graphical and numerical comparisons with pumps where this is not done.
Two‐phase downflow through catalyst beds: Part II. Pulsing regime pressure drop
Authors: Talmor E. 
Published: June 2004

AbstractSurveys of local and overall pressure drop in partially pulsing 29.2 cm diameter beds show the overall pressure drop steady but elevated, while local pressure drops across various sections of the bed oscillate in correspondence with the local pulse frequency. The increase in overall pressure drop due to pulsing varies between 0 and 100%, depending on the extent of pulsing and liquid holdup within the bed.In foaming systems, the overall bed pressure drop can be higher than for pulsing alone, depending on liquid holdup and (apparently) the type of foam and its intensity. In some cases, pulsing appears to be the starting point for low frequency foaming pressure drop surges which are associated with cyclic foam formation and breakup within the bed.
Analytical model reduction of large scale linear dynamic systems
Authors: Edgar T. F. , Schwartz J. S. 
Published: June 2004

AbstractA class of dynamic model approximation techniques based on a frequency domain Taylor series expansion is presented. These methods yield low‐order models and are analytical rather than computational in nature; that is, one can retain important parameters (which may be time varying) from the original model in functional form in the low‐order model. This feature is very attractive for on‐line updating of the simplified model and subsequent control of the process. An example for a tenth‐order original model has shown that the analytical low‐order models provide excellent approximations to the step response of the original system.
Combined pressure and diffusional transition region flow of gases in porous media
Authors: Alzaydi Ayad A. , Moore Charles A. , Rai Iqbal S. 
Published: June 2004

AbstractExpressions were derived for combined pressure and diffusional transition region flow of gases in porous media. Experimental systems were developed to verify the applicability of the equations for packed columns of Kaolinite clay and quartz sand with methane and carbon dioxide flowing into nitrogen.
Scaling laws and the differential equations of an entrained flow coal gasifier
Authors: Kane Ronald S. , Mc Callister Robert A. 
Published: June 2004

AbstractA formal order of magnitude analysis was applied to the differential equations describing mass, momentum, and energy transport in an axially translating, vortex flow field and used to determine the importance of various terms. Significant dimensionless parameters, suitable for establishing scaling laws, appear naturally from the equations. Among the important parameters are the swirl number, geometric scale ratio, Froude number, and particle loading ratio. These parameters were combined to establish rules for complete similarity between a model and a prototype gasifier.
A formulation for ϵM and ϵH based on the surface renewal principle
Authors: Thomas Lindon C. 
Published: June 2004

AbstractThis paper presents a simplified formulation for ϵH for low to moderate Prandtl number fluids and for ϵM that utilizes the surface renewal model, but which also accounts for the fact that eddies do not reach the surface. The predicted trend in Prt obtained on the basis of the present analysis suggests an opposite dependency on Pr to that predicted by many of the other analyses.
Bubble nucleation in viscous material due to gas formation by a chemical reaction: Application to coal pyrolysis
Authors: Attar Amir 
Published: June 2004

AbstractMost coals swell when heated, and their plastic properties change. These phenomena are explained qualitatively and semiquantitatively using a theory which combines classical nucleation theory and chemical kinetics.Classical bubble nucleation theory is modified to include cases where gases are formed in a liquid as a result of a chemical reaction. Part of the gas that is formed in the liquid escapes through the surface. However, the concentration of gas that remains in the solution increases until a critical concentration is reached. When the critical concentration of gas in the solution is reached, bubbles will begin to nucleate.The value of the rate of nucleation has a critical upper limit which is determined by the thermodynamic properties of the solution. However, the kinetics of the heat, momentum, or mass transfer may reduce the thermodynamic rate.The criteria to decide which transport mode limits the kinetics of the nucleation were derived and applied to melting coal. In coal, the rate of bubble nucleation appears to be limited by the rate of momentum transfer in the melt.The size of the melting coal particle determines the ratio of surface area to volume and thus affects the kinetics of the accumulation of gaseous reaction product in the melt. Thus, smaller rates of bubble nucleation will be observed in smaller coal particles (very viscous melts).Kinetic equations are derived and used to estimate the time that is required for bubbles to appear inside a coal particle. A general method is proposed to calculate the time‐temperature contour at which nucleation will occur. The effect of the particle size on the time of nucleation is calculated. The results of the calculations yield values which compare very well with experimental results on coal.
An observation of the effect of integral scale on drag reduction
Authors: Berman Neil S. , Griswold Susan T. , Elihu Shahram , Yuen John 
Published: June 2004

AbstractDrag reduction pipe flow experiments using random coiling polymers have been dominated by the small scales of turbulence. An experiment is reported using polyelectrolytes DNA and collagen, which have extended conformations in solution that shows a relationship between the large scales and drag reduction. Turbulent or molecular interactions can explain the observed increase in drag reduction with an increase in pipe diameter.
Real‐time estimation of aerobic batch fermentation biomass concentration by component balancing
Authors: Zabriskie Dane W. , Humphrey Arthur E. 
Published: June 2004

AbstractReal‐time estimates of biomass concentration and growth rate in fermentation processes were obtained by performing a material balance on oxygen and employing a kinetic model for molecular oxygen utilization. A model containing yield and maintenance terms was satisfactory in fermentations where only the EMP and TCA pathways were utilized for glucose metabolism. However, model alterations based on metabolic energetics were required before accurate estimates were obtained for a metabolically complex fermentation producing bakers yeast.
Bounds and approximate solutions to linear problems with nonlinear boundary conditions: Solidification of a slab
Authors: Glasser David , Kern Jochen 
Published: June 2004

AbstractIn solidification, one is primarily interested in the movement of the solid‐liquid interface and not in the details of the internal temperature distribution. This is parallelled in many other processes of practical interest. Because of the linearity of the governing equation, one may readily obtain an integral relationship between the system variables, as expressed by the moment equations. By further introducing physically reasonable assumptions, one obtains bounding or approximate solutions, some of which are simple but accurate analytic expressions.
Mixing and mass transfer at high liquid rates in the steady state counterflow operation of packed columns
Authors: Hatton T. Alan , Woodburn Edward T. 
Published: June 2004

AbstractCarbon dioxide absorption profiles have been measured for high liquidgas ratios in an absorption column operated at atmospheric pressure under steady state counterflow conditions. Mixing and mass transfer parameters were extracted from these profiles using an extension of the technique described by Brittan (1967). The flow ranges covered are 15 < Res < 100 and 300 < ReL < 1 600.The dispersion data reflect the same trends as shown by dynamic testing methods (Woodburn, 1974). However, with decreasing liquid‐gas ratios the effect of dispersion on steady state mass transfer becomes less significant than would be inferred from dynamic testing results.Under reverse gas flow conditions, the mass transfer coefficients corrected for the effects of axial dispersion show the same functional dependency on liquid rate as given by the Sherwood and Holloway (1940) correlation and provide a quantitative explanation for the anomalous behavior exhibited by their results in this liquid range.
Interfacial resistance to interphase mass transfer in quiescent two‐phase systems
Authors: Brenner Howard , Leal L. Gary 
Published: June 2004

AbstractInterfacial resistance to solute mass transfer between two unstirred immiscible fluids is theoretically calculated. Solute molecules are modeled as Brownian particles, bathed by homogeneous fluid continua when wholly immersed in either fluid, or else by heterogeneous fluid continua when instantaneously straddling the interface. These diffusing particles are assumed to be subjected to either repulsive or attractive conservative forces exerted on them by the interface. Additionally, their mobility is supposed affected by proximity to the interface. Circumstances are found to exist under which the interface may offer significant resistance to interphase transport. Surprisingly, conditions also exist in which the interface may actually offer a negative resistance to such solute transfer. In such cases, the presence of the interface enhances the overall interphase mass transfer rate.
The homogeneous nucleation of bubbles in superheated binary liquid mixtures
Authors: Holden Bruce S. , Katz Joseph L. 
Published: June 2004

AbstractIt is shown how to apply homogeneous nucleation theory to predict the limits of superheat of multicomponent liquid mixtures. Measurements of such limits for n‐pentane‐n‐hexane, n‐hexane‐cyclohexane, benzene‐cyclohexane, and benzene‐n‐hexane mixtures as a function of composition are presented and compared with theory.
Performance of slurry and trickle‐bed reactors: Application to sulfur dioxide removal
Authors: Goto Shigeo , Smith J. M. 
Published: June 2004

AbstractMethods are developed for predicting the performance of different types of three‐phase reactors for removal of a gaseous reactant by catalytic reaction. The removal is assumed to occur by mass transport of reactant from gas‐to‐liquid and liquid‐to‐catalyst particle and then by intraparticle diffusion and reaction in the liquid filled pores. The method is applied to the oxidation of sulfur dioxide at 25°C and 1 atm using activated carbon, in the presence of water, as a catalyst. Slurry, trickle‐bed, and counterflow packed‐bed reactors are compared in terms of the key variables affecting the fraction of sulfur dioxide reacted.
Analysis of three‐phase packed‐bed reactors
Authors: Goto Shigeo , Smith J. M. 
Published: June 2004

AbstractThree‐phase reactors involving a solid catalyst are normally used for production of product or removal of impurity. Equations are presented for these two measures of reactor performance for a first‐order, reversible or irreversible reaction in an isothermal reactor. The results are presented in terms of dimensionless groups of the pertinent mass transfer, kinetic, and equilibrium (solubility) properties, and the gas and liquid flow rates. From the equations given, it is possible to predict the relative performance of concurrent (trickle bed) and countercurrent flow reactors and also the effect of mixing in the gas or liquid streams on performance.
Parametric studies in industrial distillation: Part III. Design methods and their evaluation
Authors: Tedder D. William , Rudd Dale F. 
Published: June 2004

AbstractDistillation networks are described as sets of composition nodes which are used to estimate material and energy balances. Comparisons with equialent, equilibrium stage models indicate that these simplified design methods consistently result in small, but acceptable, overdesign, even when applied to complex, thermally coupled tower configurations.
A constitutive equation for a viscoelastic interface
Authors: Gardner J. W. , Addison J. V. , Schechter R. S. 
Published: June 2004

AbstractA constitutive equation has been developed to relate surface stresses to the deformational history of an interface. This equation is designed to provide a unified description of complex interfacial rheological phenomena. New and as yet unreported behavior such as surface normal stresses and viscoelastic contributions to the dynamic surface tension are predicted.A monolayer of poly(vinyl alcohol) adsorbed at an air/water interface has been studied using a deep channel surface rheometer and the observed viscoelastic behavior shown to be fitted by the model.
Liquid distribution in trickle‐bed reactors: Part II. Tracer studies
Authors: Herskowitz Mordechay , Smith J. M. 
Published: June 2004

AbstractAn aqueous solution of potassium chloride tracer was introduced at a central location in the water feed to a trickle bed, and the tracer concentration was measured at various radial positions and bed depths. From the model and parameters of liquid distribution proposed in Part I, tracer concentrations can also be predicted. The predicted and experimental concentrations usually agreed within a few percent, providing an independent evaluation of the flow distribution model.
Measurement of structured microbial population dynamics by flow microfluorometry
Authors: Bailey James E. , Fazel‐Madjlessi Jila , McQuitty Donald N. , Lee L. Y. , Oro James A. 
Published: June 2004

AbstractCommercial microbiological processes frequently contain dispersed microorganisms which are heterogeneous in their age, size, and composition. Relative protein and nucleic acid contents of individual bacteria in Bacillus subtilis submerged cultures have been measured experimentally using laser flow microfluorometry. Marginal and joint population composition density data and their complex patterns of evolution during batch growth provide an impetus and emerging basis for a new generation of potentially robust mathematical models of microbial systems.
Vapor‐liquid equilibrium measurements for the propane‐ethanol system at elevated pressures
Authors: Gomez‐Nieto Mateo , Thodos George 
Published: June 2004

AbstractVapor‐liquid equilibrium measurements have been carried out for the propane‐ethanol system at 325°, 350°, 375°, 400°, and 425°K. The pressures corresponding to these temperatures ranged from 569.5 kPa (82.6 lb/in.2abs) to 5 618.5 kPa (814.9 lb/in.2abs). Altogether, nineteen experimental determinations were made; one of these determinations at 425°K approached the critical state, and this measurement assisted in establishing the entire critical temperature and critical pressure profiles for this binary system. The information associated with these measurements enabled the construction of isothermal bubble point‐dew point relationships up to 500°K. These results made possible the establishment of isothermal relationships of K values vs. pressure for the components of the propane‐ethanol system. Calculated K values for this system using the BWR method and the SRK method were found to be in fair agreement with corresponding experimental values.
Countercurrent backmixing model for slugging fluidized‐bed reactors
Authors: Raghuraman Janakiraman , Potter O. E. 
Published: June 2004

AbstractA model is developed for slugging fluidized bed catalytic reaction which improves on the model of Hovmand and Davidson by incorporating the solids mixing. The model parallels the countercurrent backmixing model of Fryer and Potter. Solids mixing is accounted for by the model of Thiel and Potter which assumes the rising slug is followed by a well‐mixed wake into and out of which solids flow at a rate determined by the rise velocity of the slug. Comparison is made with experimental data reported by Hovmand and Davidson with good results.