bluuebunny/crossref_metadata_2025_split huggingface dataset:
Flow mechanism of adsorbate through porous media in presence of capillary condensation
Authors: Tamon Hajime , Okazaki Morio , Toei Ryozo 
Published: June 2004

AbstractThe flow mechanism of adsorbable gas through the porous adsorbent in the presence of capillary condensation is interpreted, and a new transport model is derived by separately taking into account the hopping behavior of adsorbed molecules in the adsorbed phase and the viscous flow of capillary condensate. Surface flow coefficients including the contribution of capillary flow calculated with this model agree with published experimental data.
SO2 absorption into aqueous solutions
Authors: Chang C. S. , Rochelle G. T. 
Published: June 2004

AbstractThe absorption rate of SO2 from a gas mixture of SO2 and N2 into pure water, HCl, and NaCl solutions has been measured at 25°C in a continuous stirred vessel with an unbroken gas‐liquid interface. The rates of the liquid‐phase mass transfer are accurately modeled by the theory of surface renewal with the instantaneous, reversible hydrolysis of dissolved SO2. The theory and results are applicable to SO2 absorption from waste gases.
Laminar condensation heat and mass transfer to a moving drop
Authors: Chung J. N. , Ayyaswamy P. S. 
Published: June 2004

AbstractThis paper presents numerical solutions to the nonlinear, coupled boundary‐layer equations governing laminar condensation heat and mass transfer in the vicinity of the forward stagnation point of a spherical cold water droplet translating in a saturated mixture of three components. The environment surrounding the droplet is composed of a condensable (steam), a noncondensable and nonabsorbable (air), and a third component which is noncondensable but absorbable (Elemental Iodine, for example). The dispersed and the continuous phases have been treated simultaneously. Results obtained here show excellent agreement with experimental results where available. An important conclusion is that for laminar condensation on a freely falling droplet, for a given thermal driving force and noncondensable gas concentration in the bulk, the dimensionless heat transfer decreases with increasing saturation temperature of the outside medium.
A single, particle‐size model for sulfur retention in fluidized bed coal combustors
Authors: Lee D. C. , Georgakis Christos 
Published: June 2004

AbstractA reactor model is presented to calculate the sulfur retention and SO2 emission of a fluidized‐bed coal combustor with absorption of SO2 by limestone or dolomite. It is based on the two‐phase theory of fluidization and a two parameter simplified rate expression for the sulfation reaction. Both parameters can be determined by experimental reaction rate measurements. In the overall reactor model, an average size is assumed for all the stone particles in the bed. Sulfur retention is found to be dependent on only three dimensionless parameters. Comparisons with experimental measurements indicated that the model predicts satisfactorily the dependence of sulfur retention on the Ca/S ratio, sulfur content of the coal, excess air, gas residence time, and sorbent type.
Liquid‐Liquid dispersion in turbulent couette flow
Authors: Leonard R. A. , Bernstein G. J. , Pelto R. H. , Ziegler A. A. 
Published: June 2004

AbstractA dimensionless dispersion number was developed to characterize liquid‐liquid dispersions created in turbulent Couette flow with respect to their subsequent coalescence in a settling zone. For a given solvent pair and continuous phase, the dispersion number is relatively constant over a wide range of operating and dimensional parameters. Because of this, the dispersion number can be used for the design and scale‐up of liquid extraction equipment with discrete stages.
Convective solids settling induced by a buoyant phase
Authors: Fessas Y. P. , Weiland R. H. 
Published: June 2004

AbstractQuantitative measurements of the effect of a third phase of buoyant solid particles on the settling rates of suspensions of heavy particles are reported. It is found that for a wide range of concentration of both buoyant and heavy particles, the settling rates of both solid phases are greatly increased. If the phases are dilute, the settling velocities of both are retarded. The total settling time of heavy particles can be halved, but only under conditions that the light phase is unaccelerated. This suggests that small gas bubbles would form a more satisfactory buoyant phase. The high concentrations of thickened suspensions which result from the acceleration process are also reported.
Effects of perforated partition plate on mixing characteristics of horizontal stirred vessel
Authors: Ando Koji , Shirahige Minoru , Fukuda Takashi , Endoh Kazuo 
Published: June 2004

AbstractTo reduce backmixing in the flow‐type horizontal stirred vessel, a perforated partition plate was attached and the effects of shape of plate on the mixing characteristics were studied under various operating conditions. Results were analyzed in terms of mixing models to evaluate the extent of preventing backmixing. It enabled us to estimate the extent of back flow at the perforated partition plate from power consumption.
Employment of vapor pressure data in the description of vapor‐liquid equilibrium with direct method
Authors: Morbidelli Massimo , Carrà Sergio 
Published: June 2004

AbstractA procedure for inserting vapor pressure data in the equations of state is presented. It provides a straightforward scheme for the extension of direct methods to the study of phase equilibria of polar mixtures and of solutions containing nonvolatile electrolytes. Some examples of application are also given.
Design of advanced process controllers
Authors: Palmor Z. J. , Shinnar R. 
Published: June 2004

AbstractThis paper deals with defining the relation between modeling of process units and controller design. In the process industries, it is often difficult to obtain accurate process models. It is shown that advanced algorithms such as dead‐time compensators require more detailed process information for design than do with PI and PID controllers. A method is described to systematically evaluate the relation between process identification and controller design, stability, and performance. It is shown that conventional gain and phase margins do not provide proper safety margins for dead‐time compensators and optimal controllers. Methods for safe design of dead‐time compensators are derived, and the approach could be useful in a wide class of problems.To illustrate the approach presented, the design of PI controllers by conventional methods is analyzed. The conditions, as well as the exceptions, are specified in which methods such as described by Ziegler and Nichols or Cohen and Coon will give good results. It is shown that for any stable nonlinear system with an input/output function y = G*p(u), a linearized design function G′pd can be constructed and identified that guarantees stability and reasonable performance of the controller (Eqs. 21 and 22 and Figures 4–7) over a wide range of operating conditions. A rigorous framework for identifying the exceptions and understanding the reason why such methods work is presented.
A semi‐empirical adsorption equation for single component gas‐solid equilibria
Authors: Sircar Shivaji , Gupta Ramesh 
Published: June 2004

AbstractA semi‐empirical adsorption equation is derived and tested against published equilibrium sorption data on various types of systems. The equation is designed to satisfy the constraints imposed by the physics and the thermodynamics of the adsorption systems. It can describe the Type I and the Type III isotherms as well as their combinations. The model does not restrict the nature of the isosteric heat of adsorption to simplified forms such as a constant or a linear function of the surface coverage. This restriction is primarily responsible for limited applications of the published theories. Empirical equations relating the isosteric heat of adsorption and the surface excess variable are proposed.
Influence of turbulence on mass transfer between a liquid and a solid sphere
Authors: Sandoval‐Robles J. G. , Delmas H. , Couderc J. P. 
Published: June 2004

AbstractElectrochemical measurements of overall mass transfer rates from a single sphere have been performed in a highly turbulent liquid. The increase in mass transfer rate due to turbulence has been shown to be more important at high Reynolds number and high turbulence intensity. Various equations of correlation have been proposed between the overall Sherwood number, the Reynolds number and turbulence intensity, the simplest one beingA correct agreement has been found with previous heat or mass transfer results between a gas and a sphere.
Evaluation of liquid‐solid contacting in trickle‐bed reactors by tracer methods
Authors: Mills P. L , Dudukovic M. P. 
Published: June 2004

AbstractThe use of dynamic (tracer) methods for the evaluation of liquid‐solid contacting and holdup in trickle‐bed reactors is illustrated. It is shown that both the fraction of external catalyst area wetted and the fraction of total catalyst wetted by liquid can be obtained. External contacting efficiency and dynamic liquid saturation are correlated in terms of the appropriate dimensionless groups over the range of variables typical for trickle‐flow operation. The relationship between catalyst contacting efficiency and catalyst utilization is outlined.
A temperature swing process for hydrogen isotope separation
Authors: Hill F. B. , Wong Y. W. , Chan Y. N. I. 
Published: June 2004

AbstractExperiments on the separation of hydrogen isotopes were conducted using vanadium hydride in a temperature swing process. Process behavior followed trends predicted by an equilibrium theory of process operation, but was modified by a kinetic isotope effect and by finite rates of hydrogen absorption and isotope exchange.
Purification of phenolic wastewater by parametric pumping: Nonmixed dead volume equilibrium model
Authors: Costa C. A. V. , Rodrigues A. E. , Grevillot Georges , Tondeur Daniel 
Published: June 2004

AbstractA new process for purification of phenolic wastewaters by parametric pumping is presented.An equilibrium (linear) model for nonmixed dead volumes thermal direct mode parametric pumping is developed and the influence of bottom and top dead volume magnitudes on transient separation is analyzed.Analytical solutions for batch, continuous and semicontinuous operations are presented.Experimental data on the system phenol/water‐Duolite ES861 include equilibrium isotherms at 20°C and 60°C and parapump runs for the cases mentioned above.
Photopolymerization in an isothermal and continuous stirred tank reactor: Concentration stability
Authors: Chen H. T. , Kuan C. N. , Lin D. J. 
Published: June 2004

AbstractAn investigation of photopolymerization in an isothermal and continuous stirred tank reactor (CSTR) was made. The existence of multiple steady states induced by gel effects was demonstrated theoretically and experimentally. This multiple steady state problem is presented in relation to reactor stability and control. Also, the relative behavior of the batch and CSTR systems is discussed.
Studies of mold filling and curing in the reaction injection molding process
Authors: Castro J. M. , Macosko C. W. 
Published: June 2004

AbstractA model is developed for pressure rise, extent of reaction and temperature changes during filling and curing in thin rectangular molds for the reaction injection molding (RIM) process. The predictions of the model are shown to be in good agreement with experimental results obtained for several intrumented molds using polyurethane RIM chemical systems. The relevant dimensionless groups are identified. Criteria for good mold filling are developed.
Prediction of diffusion coefficients for polymer‐solvent systems
Authors: Duda J. L. , Vrentas J. S. , Ju S. T. , Liu H. T. 
Published: June 2004

AbstractA revised version of a recently proposed free‐volume theory of polymer‐solvent diffusion is introduced and evaluated using experimental diffusivity data collected over wide temperature and concentration ranges. The theory accurately predicts the large temperature and concentration variations typically observed for polymer‐solvent diffusion coefficients.
Effect of micelle formation on chromatographic movement of surfactant mixtures
Authors: Harwell J. H. , Helfferich F. G. , Schechter R. S. 
Published: June 2004

AbstractSolutions are presented for equations which describe the chromatographic transport of binary surfactant mixtures. The formation of micelles in the bulk fluid is taken into account. The effects of micellization on the behavior of surfactant pulses are illustrated by solutions for specific cases. Schemes are presented for offsetting the tendency of surfactant pulses to undergo chromatographic separation because of preferential adsorption of the surfactants on the solid substrate. These schemes take advantage of the effects of micelle formation. Generalizations for n‐component surfactant systems are outlined.
Influence of vapor entrainment on distillation tray efficiency at high pressures
Authors: Hoek P. J. , Zuiderweg F. J. 
Published: June 2004

AbstractA recent publication of Fractionation Research Inc. (FRI) (Sakata and Yanagi, 1979) provides experimental evidence that tray efficiency initially rises with increasing pressure, reaches a maximum value, and then decreases again at very high pressures. It is shown in this paper that at these high pressures, significant amounts of vapor can be entrained with the downflowing liquid, e.g., abt. 50 mol per 100 mol liquid at 2,760 kPa. A new model is developed to determine the effect of vapor entrainment on tray efficiency. It is shown that the experimentally observed loss of tray efficiency corresponds with the entrainment rates found at high pressures.
Local drag reduction due to injection of polymer solutions into turbulent flow in a pipe. Part I: Dependence on local polymer concentration
Authors: McComb W. D. , Rabie L. H. 
Published: June 2004

AbstractAqueous solutions of drag‐reducing polymers were injected into turbulent water flow in a pipe. The injection point was situated where the flow was well‐developed. Thus, subsequent steamwise variations in pressure drop were due to the injected polymer spreading out across the pipe. The axial development of local drag reduction was monitored by a series of closely‐spaced pressure tappings. The corresponding radial dispersion of the injected polymer, as it travelled downstream, was assessed by sampling the flow at various points.Local drag reduction, due to either point injection at the centerline or injection through a slot in the wall, was found to increase with distance downstream. This increase was related to the streamline increase of polymer concentration in a narrow annulus near the pipe wall. It was tentatively concluded that the effective annulus was bounded by 15 ≤ y + ≤ 100, in agreement with previous deductions from less direct evidence.
Local composition model for excess Gibbs energy of electrolyte systems. Part I: Single solvent, single completely dissociated electrolyte systems
Authors: Chen Chau‐Chyun , Britt H. I. , Boston J. F. , Evans L. B. 
Published: June 2004

AbstractAn electrolyte local composition model is developed for excess Gibbs energy, which is assumed to be the sum of two contributions, one resulting from long range electrostatic forces between ions and the other from short range forces between all the species. The validity of the model is demonstrated for systems emcompassing the entire range from molecular liquid to fused salt.
Holographic and photographic studies of high‐quality steam‐water critical flow
Authors: Ju Yi‐Hsu , Moulton R. W. , Garlid K. L. 
Published: June 2004

AbstractHigh‐quality (95%) steam‐water critical flow through a straight pipe was studied using high‐speed photographic and holographic techniques. The results indicate that most of the water exists as a discontinuous or continuous thin film which flows along the wall with a speed much slower than that of the steam. This results in slip ratios higher than those reported before. Although a separated flow model would seem to describe the actual flow situation more closely than other models, the assumption of thermal equilibrium between phases and the fact that the flow is not separated except close to the exit plane are probably explanations for differences in slip ratios obtained in this study from those predicted.
Correlation of phase‐separation data for coal‐conversion systems
Authors: Watanasiri Suphat , Brulé M. R. , Starling K. E. 
Published: June 2004

AbstractA multiparameter corresponding‐states correlation is applied to describe fossil‐fluid vapor/liquid‐equilibrium behavior needed to design separation and other process units in coal‐liquefaction plants. Data for both defined and undefined fluids pertinent to coal liquefaction are utilized in correlation development. The procurement of these data requires a thorough evaluation and study of the needs for additional data to improve correlations. These needs are systematically outlined in the context of the level of predication capability that can be achieved using the currently available data base.A conformal‐solution model is applied to describe the behavior of many defined binary and ternary coal‐solvent systems. The correlation is then extended to undefined systems such as those encountered in the Exxon Donor Solvent process. Correlation results are reported and correlation limits are assessed.
Batch extraction with liquid surfactant membranes: A diffusion controlled model
Authors: Ho W. S. , Hatton T. A. , Lightfoot E. N. , Li N. N. 
Published: June 2004

AbstractA model of diffusion controlled mass transfer in liquid surfactant membranes is developed for uniform emulsion globules having no internal circulation. The solute is assumed to react instantaneously and irreversibly with the internal reagent at a reaction surface which advances into the globule as the reagent is consumed. A perturbation solution to the resulting non‐linear equations is presented. In general, the zero‐order, or pseudo‐steady state solution alone often gives an adequate representation of the process. Experimental data on the batch extraction of phenol from waste water are in good agreement with the model predictions.
Thinning of a liquid film as a small drop or bubble approaches a fluid–fluid interface
Authors: Lin Cheng‐Yuan , Slattery J. C. 
Published: June 2004

AbstractWhen a small drop or bubble approaches a fluid–fluid interface, a thin liquid film forms between them, drains, until an instability forms and coalescence occurs. A hydrodynamic theory is developed for the first portion of this coalescence process: the drainage of the thin liquid film while it is still sufficiently thick that the effects of London‐van der Waals forces and electrostatic forces can be ignored. The time rate of change of the film profile is predicted, given only the drop radius and the required physical properties. Comparisons are offered with the limited experimental data available.
Interaction second virial coefficients and binary interaction parameters for the CO2  C2H6 systems between 250 and 300 K
Authors: Holste J. C. , Young J. G. , Eubank P. T. , Hall K. R. 
Published: June 2004

AbstractWe have determined the interaction second virial coefficients (B12) for the CO2  C2H6 system between 250 and 300K using a Burnett‐isochoric apparatus. The technique follows a procedure suggested by Hall and Eubank (1973) and extended by Holste et al. (1980). Combined errors for B12 are within 1.2 cm3/mol. In addition, values for the binary interaction parameter k12 calculated from our B12 values show difinite temperature dependence.
A thermodynamic approach to multicomponent distillation system synthesis
Authors: Naka Yuji , Terashita Masayuki , Takamatsu Tekeichiro 
Published: June 2004

AbstractThis paper shows a synthesis method of multicomponent distillation systems with heat integration based on the available energy concept. With this method, the problem of synthesizing the heat integrated distillation systems in which there are heat source and sink streams supplied from other processes can be solved so as to minimize the process utilities. Moreover, since the system synthesis is executed in the (1 – T0/T) vs. Q diagram, it is possible to visibly represent the physical meanings of the computing process.
Modeling of noncatalytic gas‐solid reactions
Authors: Ramachandran P. A. , Doraiswamy L. K. 
Published: June 2004

AbstractThis paper presents a critical review of the developments in the mathematical modeling of gas‐solid noncatalytic reactions with particular emphasis on recent trends in the subject. A number of models proposed for analyzing this class of reactions have been reviewed with a fairly detailed discussion of the methods of incorporating structural changes which occur in the solid with the progress of reaction. The present status on the modeling of various types of complex gas‐solid reactions is reviewed. Also the paper points out a number of areas in which future research may be needed. The review concludes with a critical discussion on the type of experimental data necessary for model verification and some comments on the choice of model for a given system.
Stripping of carbon dioxide from monoethanolamine solutions in a packed column
Authors: Weiland R. H. , Rawal M. , Rice R. G. 
Published: June 2004

AbstractA procedure using only fundamental physico‐chemical data is developed for the design and analysis of packed columns used for solvent recovery in gas purification processes involving chemical reaction. The results of 173 experiments on the mass transfer performance of a pilot‐scale regenerator stripping CO2 from loaded monoethanolamine solutions are reported and compared with model predictions. Anomolous responses of the overall mass transfer coefficient to changes in process conditions are observed and explained by the process model which is found to predict correctly both the magnitude of the coefficient and its response.
Optimum dimensions for pipeline mixing at a T‐junction
Authors: Forney L. J. , Lee H. C. 
Published: June 2004

AbstractConditions are identified which insure optimum pipeline mixing at a T‐junction. Analytical expressions, that result from detailed measurements of both near and far‐field momentum‐dominated jet trajectories in a crossflow, are renormalized in terms of pipe coordinates. It is demonstrated that a simple scaling law exists for the limiting geometry of either large or small jet‐to‐pipe diameter ratios. The scaling laws are shown to accurately correlate existing data for each limiting geometry.
Scrubbing of gaseous nitrogen oxides in packed towers
Authors: Counce R. M. , Perona J. J. 
Published: June 2004

AbstractNitrogen oxide removal efficiencies of up to 97% were obtained in tests using columns packed with Intalox saddles. These studies were conducted at atmospheric pressure with water as the scrub solution and nitrogen oxide feed concentrations of up to 10%. A mathematical model based on mass‐transfer, kinetic, and equilibrium data is presented; calculated removal efficiencies using this model agree very well with the experimental data.
Measurements of the rise velocities of bubbles, slugs and pressure waves in a gas‐solid fluidized bed using pressure fluctuation signals
Authors: Fan L. T. , Ho Tho‐Ching , Walawender W. P. 
Published: June 2004

AbstractThe rise velocities of bubbles, slugs and pressure waves in a fluidized bed have been measured on‐line through the use of pressure transducers coupled with the cross‐correlation technique. Sand and glass beads with different particle sizes were tested. Effects of the gas flow rate and column diameter on the rise velocities of bubbles and slugs were investigated. The results were correlated with two models developed in this work and were compared with the data obtained by other investigators.