bluuebunny/crossref_metadata_2025_split huggingface dataset:
The permeation of gases through hollow silicone rubber fibers: Effect of fiber elasticity on gas permeability
Authors: Stern S. A. , Onorato F. J. , Libove Charles 
Published: June 2004

AbstractThe permeation of oxygen, nitrogen, argon, and synthetic air through hollow silicon rubber fibers was studied between 0° and 40°C and at gauge pressures of up to 3.45 × 105 N/m2 (50 lb/in.2 abs). The study was conducted in a permeator module in which the hollow fibers were pressurized externally. Strain measurements with single fibers showed this mode of operation to be preferable to internal pressurization. The gas permeation rates were markedly affected by dimensional changes of the hollow fibers under external pressure. These changes were predicted satisfactorily by a modification of Varga's (1966) deformation analysis of thick‐walled elastic tubes. The extent of air separation achieved in the permeator was in agreement with that calculated from theoretical models. It is conjectured that the performance of such a permeator may be improved in certain cases if the fibers are under suitable initial tension.
Multiple steady states in an isothermal, integral reactor: The catalytic oxidation of carbon monoxide over platinum‐alumina
Authors: Hegedus L. Louis , Oh Se H. , Baron Kenneth 
Published: June 2004

AbstractStable isothermal multiplicities were observed during carbon monoxide oxidation in an integral reactor, filled with alumina supported platinum catalysts. The multiplicities were investigated in the conversion‐temperature, conversion‐inlet carbon monoxide concentration and conversion‐mass flow rate domains.The region of multiplicities was found to widen significantly upon catalyst aging which enhanced the pellets' diffusive resistances.Several intermediate stable steady states were found between the highest and lowest steady states, both experimentally and theoretically.All the above phenomena could be well interpreted by the interactions of the kinetics of carbon monoxide oxidation with intrapellet diffusion resistances.
Vacuum‐spray stripping of sparingly soluble gases from aqueous solutions: Part II. Stripper design using jet impingement nozzles
Authors: Simpson Stuart G. , Lynn Scott 
Published: June 2004

AbstractExperimental data on vacuum‐spray stripping of sparingly soluble gases from aqueous solution using hydraulic nozzles were presented in part I of this communication. Mass transfer was shown to occur primarily from the thin liquid sheet issuing from the nozzle tip in semiquantitative accordance with an analytical model based on laminar flow behavior.Jet impingement hydraulic nozzles offer the advantages of simplicity and low operating cost in vacuum‐spray stripping. An empirical model for the turbulent flow regime has been developed to facilitate incorporating jet impingement nozzles into a vacuum stripper design. The results of an economic analysis comparing other types of industrial vacuum strippers with the proposed design of a jet impingement vacuum stripper show the latter process to compare very favorably in terms of estimated equipment size and cost and in expected operating cost.
Dispersed phase mass transfer during drop formation under jetting conditions
Authors: Skelland A. H. P. , Huang Y‐F 
Published: June 2004

AbstractA recent design procedure for perforated plate extraction columns requires extension to include jetting conditions at each perforation. For this purpose, correlations are obtained for jet length, jet contraction, drop size, and mass transfer coefficients in disperse phase controlled liquid‐liquid systems. Experimental variables include nozzle size, flow velocity, and physical properties.
Elongational flow behavior of viscoelastic liquids: Part I. Modeling of bubble collapse
Authors: Pearson Glen , Middleman Stanley 
Published: June 2004

AbstractA spherically collapsing gas bubble will create a uniaxial extension of the fluid surrounding it. This flow may be readily analyzed, and it is possible to relate observed experimental parameters such as the pressure inside the bubble and the bubble collapse rate to the predictions of viscoelastic constitutive relations. This study compares the predictions of the Newtonian fluid and a viscoelastic model to observed bubble collapse in three fluids: one Newtonian fluid and two viscoelastic polymer solutions. Good agreement between data and the model was observed for the Newtonian experiments. The viscoelastic solutions, however, yielded rates of collapse which were greater than the Newtonian predictions based on equal zero‐shear viscosity. Subsequent modeling with a modified corotational Maxwell fluid yielded good agreement with the data for the transient elongational response in the viscoelastic solutions.
Multivariable computer control of a butane hydrogenolysis reactor: Part II. Data collection, parameter estimation, and stochastic disturbance identification
Authors: Jutan Arthur , MacGregor J. F. , Wright J. D. 
Published: June 2004

AbstractA state space model, developed for multivariable control studies on a pilot plant packed‐bed reactor for the hydrogenolysis of butane, is fitted to experimental temperature and concentration data collected under unsteady state conditions. The parameters estimated are the fundamental transport parameters of the packed‐bed reactor and a catalyst activity parameter. A discrete stochastic model for the process disturbances is also identified, and a principle component type of procedure is used to reduce its dimensionality and to gain insight into the nature of these distrubances.
Calculation of phase equilibria for ethylene/low‐density polyethylene mixtures
Authors: Harmony Stephen C. , Bonner David C. , Heichelheim Hubert R. 
Published: June 2004

AbstractWe have used recent ethylene/low‐density polyethylene gas sorption data to calculate phase equilibria for ethylene/polyethylene mixtures from 0 to 30.3 MN/m2 (0 to 300 atm), the pressure range normally used in the flash separation step in low‐density polyethylene manufacture. The computations show significant differences from results obtained by extrapolation of the results of a previous study to the relatively low pressure range considered here.
Mean temperature difference: A reappraisal
Authors: Gardner Karl , Taborek Jerry 
Published: June 2004

AbstractThe derivation of the mean temperature difference in heat exchangers is based on a number of assumptions or idealizations, the most important ones being that the heat transfer coefficient is constant throughout the exchanger; that the temperature of either fluid is constant over any cross section of its nominal path, that is, complete mixing, no stratification or bypassing; and that an additional assumption for shell and tube exchangers, which has not always been fully recognized, is that within one baffle crossing the shell fluid temperature change is small with respect to its overall change, (that is, number of baffles is large). In actual exchangers, any of the above assumptions are frequently subject to various degrees of invalidation. This paper examines the effects of deviating from the first two assumptions and presents a new solution to the third.
Effects of temperature on the crystallization of potassium nitrate by direct measurement of supersaturation
Authors: Helt James E. , Larson Maurice A. 
Published: June 2004

AbstractA laboratory continuous mixed‐suspension, mixed‐product‐removal crystallizer was used to study the effects of temperature on the kinetics of crystallization of potassium nitrate. A differential refractometer was used to continuously monitor the supersaturation permitting the measurement of supersaturation levels of order 10−3Kg solute/Kg water. The nucleation rate exhibited an inverse relationship with temperature.
A solid/liquid separation process based on cross flow and electrofiltration
Authors: Henry Joseph D. , Lawler Lee F. , Kuo C. H. Alex 
Published: June 2004

AbstractThe cross flow/electrifiltration process combines migration of particles in the presence of electrical and shear fields to increase filtration rates. A mathematical model and the experimental data are presented for both a kaolin clay suspension and an oil in water chemically stabilized emulsion. When the filter is operated in a regime above the critical voltage, filtration rate‐electric field strength dependence becomes linear, and both electroosmosis in the filtration medium and electrophoresis in the liquid film are the controlling mechanisms of transport. Both experimental data and the mathematical model indicate that the fluid circulation rate tangential to the filtration media does not necessarily increase filtration rate depending on the regime of operation. The model is used in conjunction with the experimental data to separate the liquid film resistance adjacent to the filter cake which is determined by fluid shear and electric field from the cake and filter medium resistances which are influenced by electroosmosis.
Two‐phase downflow through catalyst beds: Part I. Flow maps
Authors: Talmor E. 
Published: June 2004

AbstractFlow regimes for nonfoaming and foaming two‐phase downflow through catalyst beds are correlated in terms of the superficial volumetric gas‐to‐liquid ratio and a force ratio relating inertia plus gravity forces to viscous plus interphase forces. In the pulsing flow regime, the frequency of pulses leaving large (29.2 cm) and small (6.58 cm) diameter beds is correlated with the flow map coordinates.
Model of the constricted unit cell type for isotropic granular porous media
Authors: Payatakes A. C. , Neira Mariano A. 
Published: June 2004

AbstractThe constricted unit cell model for isotropic granular porous media developed by Payatakes, Tien, and Turian (1973) is extended here to take in account the random orientation of the flow channels. In the proposed model, each unit cell corresponds to a pore (cavern) and has two coaxial constricted inlet and outlet ports (throats). The unit cells have random dimensions and orientations, the distributions of which can be determined from simple experimental measurements. The flow through a unit cell is assumed to be identical to that through a segment of the corresponding periodically constricted tube. The model is applied to the case of creeping Newtonian flow. The solution to the flow problem is obtained by a collocation method. Permeabilities of typical packings are calculated without use of any adjustable parameters (such as tortuosities, etc.) and are found in excellent agreement with experimental values.
Aeration and mixing in deep tank fermentation systems
Authors: Jackson Melbourne L. , Shen Chia‐Cheuh 
Published: June 2004

AbstractOxygen transfer characteristics for three sizes of equipment, from 76 mm to 7.6 m in diameter and for liquid depths from 4 to 21 m, correlate well and permit scaling of fermentation systems in size. Simple orifice inlets for gas flow, uniformly distributed over a tank bottom, effect rapid mixing and permit very high oxygen demands to be met. Supersaturation provides dissolved gases for the flotation and solids separation as an inherent processing procedure. Nearly uniform bulk liquid composition and a linear decrease of gas phase composition with depth permit a proper, integrated value of the oxygen saturation driving force to be employed. Results provide the design basis for large scale aeration systems which offer potential savings in both capital and energy.
Mass transfer characterization of Donnan dialysis
Authors: Lake Michael A. , Melsheimer Stephen S. 
Published: June 2004

AbstractDonnan dialysis is a relatively new ion exchange process using ion exchange membranes to permit continuous operation. Potential applications exist in many areas where traditional columnar ion exchange, requiring a regeneration cycle, is currently used. A mathematical model was developed. Mass transfer parameters for the model were determined from laboratory data and correlated with the system operating variables.
A generalized correlation for Henry's constants in nonpolar binary systems
Authors: Yorizane Masahiro , Miyano Yoshimori 
Published: June 2004

AbstractA generalized correlation for Henry's constant is developed from a three‐parameter corresponding states theory for fluid mixtures. Two characteristic parameters are required in each binary system. These parameters are determined for thirty‐eight nonpolar binary systems containing quantum gases for solutes. The overall average deviation for calculated Henry's constants is relatively small, about ± 2.5%.
Critical points of mixtures: An analogy with pure fluids
Authors: Moldover Michael R. , Gallagher John S. 
Published: June 2004

AbstractThe thermodynamic properties of vapor‐liquid equilibrium (VLE) states near the critical locus of mixtures are correlated in very close analogy with the techniques used to correlate the properties of pure fluids near a critical point. The only mixture parameters used in the correlation are the values of pressure, volume, temperature, and mole fraction (PVTx) along the physical critical locus. We illustrate the power of the present approach by correlating the rather extensive PVTx data that exist near the critical loci of the binary mixtures: CO2C2H6, SF6C3H8, and C8H18C3H8. Nearly all the data within 10% of the critical temperature may be described within their accuracy despite the occurrence of critical azeotropy or large regions of retrograde condensation.
Liquid distribution in trickle‐bed reactors: Part I. Flow measurements
Authors: Herskowitz Mordechay , Smith J. M. 
Published: June 2004

AbstractRadial liquid distribution was measured for concurrent downflow of air and water through beds packed with catalyst particles. The experimental results can be predicted by a theory involving two parameters, a spreading factorSand wall factorf. Criteria are presented for predicting operating conditions (particle size and shape and tube diameter) for which the equilibrium distribution will be uniform and packed‐bed depth required to attain equilibrium liquid distribution.
Dispersion measurement in clogged filter beds: A diagnostic study on the morphology of particle deposits
Authors: Pendse Hemant , Tien Chi , Rajagopalan R. , Turian R. M. 
Published: June 2004

AbstractThe use of tracer dispersion measurements in conjunction with associated pressure drop data, as an indirect diagnostic technique for the determination of particle deposit morphology in deep‐bed filters, was investigated. The dispersion measurements consisted of the injection of an electrolyte tracer pulse at the inlet and the monitoring of the tracer peak as it traveled down the bed, while the pressure drop data consisted of the axial pressure gradient histories as deposition took place. These data are interpreted using dispersion and pressure drop theories established on the basis of assumed models of deposit morphology. The validity of this technique was confirmed experimentally.
Inferential control of processes: Part I. Steady state analysis and design
Authors: Joseph Babu , Brosilow Coleman B. 
Published: June 2004

AbstractMethods are presented for the design of a static estimator which infers unmeasurable product qualities from secondary measurements. The secondary measurements are selected so as to minimize the number of such measurements required to obtain an accurate estimate which is insensitive to modeling errors. Unlike previous work, the number of secondary measurements can be fewer than the number of unmeasured disturbances. If the statistics of the disturbances and/or measurement noise are available, this information can be incorporated into the design procedure to obtain an optimal static estimator.The design procedure is illustrated by application to a simulated industrial debutanizer. Data for the simulation were supplied by the Marathon Oil Company. Deviations in bottoms product quality are compared for the current control policy (maintenance of a stage temperature at its set point) and the inferential control system with the column subjected to representative feed composition disturbances. Results show that inferential control based on four, five, or six tray temperature measurements improves the steady state control performance by as much as 400%.
Inferential control of processes: Part III. Construction of optimal and suboptimal dynamic estimators
Authors: Joseph Babu , Brosilow Coleman 
Published: June 2004

AbstractMethods are presented for the construction of optimal and suboptimal estimators for inferential control systems. Optimal estimators are constructed with the aid of Kalman filtering techniques applied to linear systems driven by integrated white noise disturbances. The description of the disturbances as integrated white noise leads to optimal dynamic estimators which reduce to optimal static estimators for sustained disturbances. Suboptimal estimators are constructed by prespecifying the structure of the estimator and choosing estimator parameters so as to minimize the mean square error in estimation.Optimal and suboptimal estimators are compared by using them in an inferential control system which attempts to control the product composition of a simulated multicomponent distillation column. There is little difference in performance between optimal and suboptimal estimators which use temperature and flow measurements to estimate product composition. However, the inferential control system using a simple suboptimal estimator is significantly superior to the policy of maintaining a selected tray temperature constant through a standard feedback control system. The inferential control system is also superior to composition feedback control systems where the measurement delay is greater than 5 min.
Particle turbulent diffusion in a dust laden round jet
Authors: Yuu Shinichi , Yasukouchi Naoto , Hirosawa Yasuo , Jotaki Tomosada 
Published: June 2004

AbstractThe turbulent diffusion mechanism of particles in a round air jet are studied both theoretically and experimentally, with particular attention to the relative velocity between particles and fluid, overshooting effect of particles, and the distributions of fluid properties in space. The results indicate that the particle diffusivity decreases with the increase of the particle inertia. In general, the turbulent diffusivity of particles in an air jet is smaller than that of fluid scalar quantities. The particle inertia and the fluid large eddies, which are expressed by the Stokes number and the integral scale, respectively, play an important role in the transport mechanism of particles.
A modal approach to dynamics of nonlinear processes
Authors: Fisher Robert J. , Denn Morton M. 
Published: June 2004

AbstractApproximate process dynamics of certain nonlinear systems can be estimated by elementary quadratures using a modal approach. The transient response including quadratic nonlinearities is determined by the eigenvalues, eigenvectors, and adjoint eigenvectors of the linearized system equations. The only restriction is that the dominant eigenvalue of the linearized system must be widely separated from the next slowest mode. Several process models satisfy this requirement.The method is illustrated by application to a fourth‐order model of a fluidized bed. The dynamical response is in agreement with numerical solutions to the complete model equations, including estimates of finite regions of stability.
Prediction of multicomponent ion exchange equilibria for the ternary system SO‐NO‐Cl from data of binary systems
Authors: Smith Robert P. , Woodburn Edward T. 
Published: June 2004

AbstractA framework is developed which provides predictions of multicomponent ion exchange equilibria from binary data.Experimental data are reported for the ion exchange equilibria of the binary systems SO42−‐Cl−, SO42−‐NO3−, and Cl−‐NO3− on a strong base anion exchange resin. These systems exhibit nonideal characteristics in both phases, and the experimental characterization has been based on the reaction equilibrium constants and correlations for the activity coefficients in both phases. The exchanger phase activity coefficients are obtained from the well known Wilson (1964) modelThe predictions of the ternary system SO42−‐NO3−‐Cl− based solely on the binary data are consistent with the experimental data for this system.
A design oriented model of fines dissolving
Authors: Kraljevich Zlatica I. , Randolph Alan D. 
Published: June 2004

AbstractMass and population balances, together with nucleation kinetics of the potassium chloride system, were combined to present a design oriented model which describes the behavior of a fines destruction system (FDS) implemented in an MSMPR crystallizer. This model was tested in a well‐documented, bench scale, potassium chloride crystallizer and was found to be adequate to predict the effect of fines dissolving. Product size improvement was related to incremental cost incurred with an FDS.
Convective heat transfer in gas‐solid suspension flow through packed beds
Authors: Balakrishnan Arcot R. , Pei David C. T. 
Published: June 2004

AbstractA correlation for the convective heat transfer between a bed of metallic oxides and a flowing gas‐solid suspension was obtained experimentally. Four industrially important commercial catalysts with different physical, thermal, and transport properties were used as the bed materials. A wide range of air flow rates and solids to gas loading ratios were used. The correlating parameters, to estimate the convective Nusselt number, were found to be the Reynolds number, the Archimedes number, the solids loading ratio, and the shape factor of the packing materials. Impressive increases in heat transfer rates were observed with increased solids loading.
Reliability of optimization procedures for obtaining global optimum
Authors: Wang Bi‐Chong , Luus Rein 
Published: June 2004

AbstractThe importance of the starting point, the size of initial search region, and the search region reduction rate is examined with respect to the reliability of different direct search optimization procedures in being able to furnish the global optimum for nonunimodal systems. Although, in general, the reliability of an optimization procedure is problem dependent, it is nevertheless clear that reliability cannot be increased simply by selecting larger search regions or by reducing the rate of contraction of the search region. A more efficient means of increasing reliability is to embody a pseudo one‐dimensional search in the optimization procedure to enable the search to leave a local optimum and proceed to a better optimum.
Internal boiling and superheating in vaporizing multicomponent droplets
Authors: Law C. K. 
Published: June 2004

AbstractThe vaporization and combustion of a miscible multicomponent droplet in a quiescent atmosphere is analyzed by assuming transient‐diffusive transport within the droplet, quasi steady diffusive‐convective transport in the gas phase, and ideal solution behavior for the mixture. Results on the vaporization of a binary droplet show that owing to the significant liquid phase diffusional resistance, the vaporization process approximately consists of an initial transient regime, an intermediate, diffusion limited, almost quasi steady regime, and a final volatility limited regime. It is further demonstrated that the entrapment of the volatile components within the rapidly heated droplet interior may lead to the initiation of either homogeneous or heterogeneous nucleation, which can result in the fragmentation of the parent droplet with the internal pressure buildup.
Synthesis of heat exchanger networks: I. Systematic generation of energy optimal networks
Authors: Linnhoff Bodo , Flower John R. 
Published: June 2004

AbstractA thermodynamically orientated method is presented for the synthesis of heat exchanger networks. With this method, the problem is solved in two stages. In the first stage, preliminary networks are generated which give maximum heat recovery. In the second stage, the most satisfactory final networks are evolved using the preliminary networks as starting points. In this paper, emphasis is given to the synthesis of the preliminary networks. Two four‐stream examples are solved. In Part II, emphasis will be given to the synthesis of final networks.