bluuebunny/crossref_metadata_2025_split huggingface dataset:
The mixing of solid particles in a motionless mixer—a stochastic approach
Authors: Chen S. J. , Fan L. T. , Watson C. A. 
Published: June 2004

AbstractA Markov chain model was used to model the axial mixing of solid particles in a motionless mixer having no moving parts. One step transition probabilities were determined experimentally for the model. Based on these transition probabilities, the model was able to predict spatial distribution of tracer particles up to seven steps of the Markov chain, which was equivalent to seven consecutive passes of the mixture through the mixer. Experimental results were in good agreement with those predicted from the Markov chain model.
Dissociation of oxygen in a radiofrequency electrical discharge
Authors: Bell Alexis T. , Kwong Kam 
Published: June 2004

AbstractAn experimental investigation was made of oxygen dissociation in a radiofrequency discharge. The conversion and yield were examined as a function of power, pressure, and gas flow rate. These measurements were supplemented by measurements taken with catalytic and noncatalytic thermocouple probes in order to determine the local gas temperature and atomic oxygen concentration. An interpretation of the results is given in terms ofa theoretical model of the reactor.
Measured enthalpy changes for a simulated natural gas mixture and their prediction using a modified BWR equation
Authors: Sood Sotander K. , Haselden Geoffrey G. 
Published: June 2004

AbstractA new method of incorporating binary interaction data into the BWR equation is proposed. It is developed to predict phase equilibria and enthalpies for multicomponent mixtures using interaction data for 18 binaries.A calorimeter is described, together with experiments made upon it, for a 6‐component simulated North Sea Gas mixture at three pressure levels from 18 to 36 bar, and over a temperature range from 373 to 188K. The experimental enthalpy results are claimed to have an accuracy of ± 0.9%. These results are compared with the predictions of the modified BWR equation. The average deviation is 1.1%, the values being negative at about 18 bar and generally positive for the higher pressures tested.
Interpretation of overall area tests for thermodynamic consistency: The effect of random error
Authors: Samuels Michael R. , Ulrichson Dean L. , Stevenson F. Dee 
Published: June 2004

AbstractMethods are developed and illustrated for determining the amount of nonsatisfaction of the overall area (integrated Gibbs‐Duhem equation) test for vapor‐liquid equilibrium data that is to be expected on the basis of random experimental uncertainties. Data which satisfy the overall test within these limits, as well as the local area test, are said to be consistent within the bounds established by their experimental uncertainties, while data which do not are said to show significant systematic error and hence are termed inconsistent.
Momentum, heat, and mass transfer for fixed and homogeneous fluidized beds
Authors: Hughmark G. A. 
Published: June 2004

AbstractThe Carman channel model for flow in packed beds is shown to apply for the minimum fluidization velocity and homogeneous fluidized beds. The channel model also provides correlations for mass transfer in the laminar flow region and heat and mass transfer for turbulent flow in a packed bed. Tube bundle data for pressure drop and heat transfer are also evaluated as a packed bed with the channel model.
The shape of a fluid drop trapped between two horizontal surfaces
Authors: Wood S. M. , Hartland S. 
Published: June 2004

AbstractIn a close packed dispersion, a drop experiences forces from the surrounding drops which affect its shape and rate of coalescence. The geometry is complicated, but a simple model which may help clarify the phenomenon is that of a drop trapped between two horizontal surfaces under the action of an applied force.The differential equations governing the shape of the surface of such a drop have been solved numerically and the predicted drop dimensions checked experimentally by applying known forces to a drop and recording the shape photographically.
Damping coefficient design charts for sampled‐data control of processes with deadtime
Authors: Luyben W. L. 
Published: June 2004

AbstractDesign charts that give the value of the gain of a proportional sampleddata controller for various closed loop damping coefficient specifications are presented. Charts for first‐ and second‐order processes with various deadtimes are given over a range of sampling rates.Typical root locus plots in the z plane are also presented to illustrate how increasing deadtime (as an integer multiple of the sampling period) increases the order of the system in the z domain.
Resource recovery: A new field for technology application
Authors: Abert J. G. , Zusman Morris J. 
Published: June 2004

AbstractThis review paper surveys the state‐of‐the‐art of resource recovery from municipal, primarily residential, refuse. Unfortunately, progress in effecting the actual installation of full‐sized recovery facilities has been minimal. The work that has been done has been beset with technical, and more often, economic difficulties. However, the rising cost of traditional means of disposal may allow new systems to become economically competitive. Past research development efforts hold out promise of success and the nation may see the application of efficient technological solutions that in some localities will actually reduce the cost of refuse disposal below that of traditional means.
The utilization of expert opinion in decision‐making
Authors: Klee Albert J. 
Published: June 2004

AbstractThis is a review of the state‐of‐the‐art of rational and primarily quantitative approaches to the utilization of expert opinion in the inexact sciences, among which the engineering sciences must be included. Of primary concern is the decision‐maker's utilization of one or more experts, and the criteria and scoring rules used to evaluate their performance. Also reviewed are certain game‐theoretic strategies used by experts to maximize their own goal satisfaction. With this review, it is hoped that chemical engineers, when acting as decision‐makers, will be able to utilize expert opinion more effectively and will better understand the function of experts when it is necessary for them to adopt such roles themselves.
Modal analysis of convection with axial diffusion
Authors: Cohen William C. , Loeb Alfred M. , Weston Kenneth 
Published: June 2004

AbstractThe one‐dimensional model for convection with diffusion and with a source term for mass or energy generation or interchange is analyzed for the eigenvalues and the corresponding spatial eigenmodes as a function of the Peclet number. It is shown how the modal analysis of the source case, when the source coefficients for heat exchange and chemical reaction are spatially independent, is directly related to the no source solution. Numerical examples of determining the source term coefficient are included. These solutions form a base to discuss dynamic characteristics and stability and to which solutions for spatially dependent coefficients can be compared.
The optimal control of a periodic adsorber: Part I. Experiment
Authors: Kowler Daniel E. , Kadlec Robert H. 
Published: June 2004

AbstractCyclic pressure variations in a fixed bed adsorber can cause significant separation of gaseous mixtures. Feed pressure changes are the driving force in this parametric pumping process. The optimal feed sequence is maximum (maximum flow in) pressure, zero flow (variable pressure), maximum flow out (minimum pressure). For the nitrogen‐methane feed gas at 168 k N/m2 and a 1.22 m bed of adsorbent, the optimal cycle time is 3 seconds, and feed is sustained 50% of the time. The zero flow mode is unnecessary if product purity is the sole objective.
The optimal control of a periodic adsorber: Part II. Theory
Authors: Kowler Daniel E. , Kadlec Robert H. 
Published: June 2004

AbstractThe fixed bed binary gas adsorber, when alternately fed and exhausted at one end, produces a purified product from the other end. Coupled partial differential equations in pressure and composition, representing total mass and component balances with local equilibrium, describe the operation. The Maximum Principle is applied to determine the optimal cyclic unsteady feed policy for the balanced objectives of product purity and quantity. The sequence (maximum feed, no flow, maximum exhaust) is optimal. The experimental optimum is close to the calculated optimum. Dimensional analysis is used to determine parametric effects.
Calculation method for the response time to step inputs for approximate dynamic models of distillation columns
Authors: Weigand W. A. , Jhawar A. K. , Williams T. J. 
Published: June 2004

AbstractA calculation method to determine the response time to be used for approximate mathematical models is developed for the dynamic behavior of distillation columns. Previous work has shown that the concept of Inventory time can be successfully used to approximate the response time, that is, the 60% point of the step response, of distillation columns operating at a high degree of separation. A modified version of the inventory time method, based on the minimum change of storage, has been developed to predict the response time for other ranges of separation within reasonable bounds of error, ± 10%. Only steady state and design data were used. A rigorous nonlinear simulation generates the steady state and transient data upon which the approximate models are based.While the modified inventory time method developed cannot handle every possible operating condition with the desired degree of accuracy, it has been shown to apply over a much wider range of operating conditions than the original inventory time method.
Determination of friction factors for pulsatile flow of water in distensible tubes
Authors: Ahn John S. , Hershey Daniel 
Published: June 2004

AbstractTheoretical models for computing velocity profiles and friction factors for sinusoidally pulsing laminar flow in linearly elastic tubes were derived from the Navier‐Stokes equations, a modified Fanning equation, and the pressure‐tube wall movement relationship. The theoretical results were checked experimentally for NRe and λ = ωR2/v values up to 2000 and 57, respectively. It was found that the theoretical friction factors predicted the experimental values to within less than 13%. Also the results showed that the energy losses in elastic tubes were greater than in rigid tubes.
Separation in a thermoelectrogravitational electrophoresis column without reservoirs: Part I. Theoretical development of the transport equation and its application to the analysis of steady state batch operation
Authors: Crosser O. K. , Powers J. E. , Prabhudesai R. K. 
Published: June 2004

AbstractThe thermoelectrogravitational electrophoresis column without reservoirs has been conceived following the principle of the Clusius‐Dickel thermal diffusion column. The transport equation approach in thermal diffusion developed by Jones and Furry to explain the behavior of a conventional thermogravitational thermal diffusion column has been applied to describe the electrophoretic separation in the thermoelectrogravitational electrophoresis column. Equations have been established for a system in which one single or one hypothetically single component is mobile and the other species are at their isoelectric points.Theoretical calculations for the velocity profiles, temperature distribution, and the steady state batch separation factors have been made with field strength, temperature difference, membrane spacing, and electric mobility as variables, and expected trends of the results are discussed using the steady state solution of the transport equation for batch operation.
Theoretical recoveries in filter cake reslurrying and washing
Authors: Tomiak A. 
Published: June 2004

AbstractTheoretical equations and graphs are presented for filter cake reslurrying and washing with linear solute sorption.In the case of washing, the filter cake was represented by a model consisting of a number of mixing cells in series. Due to the complexity of the model, explicit algebraic solutions could not be obtained for countercurrent washing, but numerical data were generated using a computer.Practical application of the above is outlined.
Fully developed viscous flow in coiled circular pipes
Authors: Austin Larry R. , Seader J. D. 
Published: June 2004

AbstractThe Navier‐Stokes equations in stream‐function/vorticity form were solved numerically by over‐relaxation for the case of steady state, fully developed, isothermal, incompressible viscous Newtonian flow within a rigorously treated toroidal geometry. Solutions were obtained for curvature ratios ranging from 5 to 100 and for Dean numbers as low as I and as high as 1000. The Dean number was demonstrated to be the principal parameter to characterize toroidal flow; however, a second‐order dependence upon the curvature ratio above that expressed in the Dean number was observed. Comparisons of the numerically computed axial‐velocity profiles were made with experimental data. The cross‐sectional pressure distribution was calculated, and a correlation is presented for a diametral pressure drop in terms of the Dean number.
Effect of mixing on nonuniformly initiated polymerization by radiation
Authors: Kawakami Waichiro , Machi Sueo 
Published: June 2004

AbstractAn analytical study was carried out on the effects of mixing on radiation‐induced polymerization in which the species initiating the polymerization were not uniformly produced because of a nonuniform dose rate distribution. The analysis is based on the periodic irradiation of fluid elements circulating in a stirred‐tank reactor having a high dose rate region and a very low dose rate region. It is shown that the rate of polymerization increases with agitation speed and that the bimodal molecular weight distribution of the polymer formed at low agitation speed moves to a unimodal distribution as the agitation speed increases.
A new method of parameter estimation in linear systems
Authors: Gavalas George R. 
Published: June 2004

AbstractA time domain method is given for estimating the matrix of related parameters in linear systems with constant coefficients and real eigenvalues. The method consists of a one‐dimensional search for the local minima of a scalar function μ(λ), which provide the eigenvalues of the system matrix and the matrix itself when observable. Applications are given to the determination of a transfer function and the estimation of the rate matrix of a monomolecular reaction system. Questions of accuracy, number, and type of measurements required are discussed.
Vapor‐liquid equilibrium: Part II. Correlations from P‐x data for 15 systems
Authors: Byer Stanley M. , Gibbs Richard E. , Van Ness Hendrick C. 
Published: June 2004

AbstractPressure versus composition data for 15 binary systems in vapor‐liquid equilibrium at 30°C form the basis for correlation of the excess Gibbs function and the activity coefficients for these systems.
A feasible‐point algorithm for structured design systems in chemical engineering
Authors: Debrosse Charles J. , Westerberg Arthur W. 
Published: June 2004

AbstractStructured design systems are systems in which the equations representing the equality and inequality constraints are sparse and highly precedenc orderable. An algorithm has been developed for such systems which is guaranteed, under certain assumptions, to arrive in a finite number of steps at a feasible point (that is, one which satisfies all the constraints) or to identify a subset of the constraints for which no feasible point can be found. The algorithm can be applied to a system with only inequality constraints or to a system with both equality and inequality constraints.The algorithm uses an indirect approach. It hypothesizes that a subset of constraints has no feasible region and then attempts to verify this conjecture. If successful, the subset is identified as infeasible and obviously no feasible point exists. If unsuccessful, either a new hypothesis can be generated or the algorithm has indirectly found a feasible point.Limited computational experience with the algorithm indicates that the number of steps required to find a feasible point for a system of constraints has been of the same order of magnitude as the total number of constraints in the system. For linear constraints, the efficiency of the algorithm has been comparable to phase one of the Simplex algorithm of Linear Programming.
An improved generalized equation of state
Authors: Yamada Tomoyoshi 
Published: June 2004

AbstractTwo forms of a generalized Benedict‐Webb‐Rubin Equation, BWR24 and BWR44, are proposed for dense gases which represent an improvement by a factor of about three in calculated pressures compared to reduced forms of this relationship in the literature. The method is also tested for accuracy in predicting enthalpy departures for pure components and mixtures. The proposed methods are marginally better than the best of other methods tested. Major advantages for the proposed equations are their relative simplicity, low computer storage requirements, and generality. No mixture interaction constants are required other than those already available in the literature.
A linear model for predicting the washout of pollutant gases from industrial plumes
Authors: Hales Jeremy M. , Wolf Marvin A. , Dana M. Terry 
Published: June 2004

AbstractA simplified method for predicting the washout of gaseous constituents from industrial plumes has been developed. This method is a linearized version of a more general treatment given previously. It is based upon an application of conventional mass‐transfer theory in conjunction with existing plume dispersion models and accounts for reversibility of the adsorption process and liquid‐phase mass‐transfer resistance. The method presented in this paper is sufficiently simple to permit hand calculation, if necessary.This model is recommended for calculation of washout of gases from plumes under conditions where the gas exhibits physical or pseudophysical adsorption behavior. It is expected to apply with reasonable accuracy for gases with linear solubility relationships; accuracy for situations involving other gases is expected to be less satisfactory, depending upon the degree of deviation from this idealized behavior.
Liquid‐Liquid contacting in unbaffled, agitated vessels
Authors: Weinstein Bruce , Treybal Robert E. 
Published: June 2004

AbstractDrop size and dispersed‐phase holdup were measured for liquid dispersions in covered, unbaffled agitated vessels with no gas‐liquid interface and hence no vortex for batch and continous flow. Vessel diameters of 0.245 and 0.372 m, turbine impellers of diameters 0.0762 and 0.127 m in two locations, four organic‐ and three water‐dispersed systems of a wide range of properties, and a wide range of operating conditions were studied. The data for average drop diameter and dispersed‐phase holdup, from which specific interfacial area may be computed, were successfully correlated through modification of the theories of maximum drop size in an isotropically turbulent fluid.
Approximation in control of nonlinear dynamic systems
Authors: Tsang A. C. C. , Luus Rein 
Published: June 2004

AbstractThe type of system approximation in which the system state space x is mapped into a scalar domain V by a quadratic transformation

where Q is appropriately determined, is used to develop a suboptimal control procedure for unconstrained lumped parameter dynamic systems via the application of Pontryagin's Maximum Principle. The optimization problem in the scalar domain becomes an initial value problem when the scalar adjoint variable is held constant through out the course of control. The resulting computational scheme includes an effective and simple way to construct the transformation matrix Q and a straightforward minimum seeking approach to locate the best constant overall average scalar adjoint parameter. For the class of problems with quadratic performance index, system equation approximation further reduces the determination of Q to the solution of a matrix Riccati equation.The application of the proposed suboptimal control procedure to four chemical engineering systems shows that the procedure is simple direct, and efficient and works particularly well for problems where the final time is large.
Kinetics of crystallite sintering during heat treatment of supported metal catalysts
Authors: Ruckenstein E. , Pulvermacher B. 
Published: June 2004

AbstractModels are developed to describe sintering of metal crystallites during heat treatment. The growth rate of such crystallites is assumed to depend upon particle migration over the surface of the support as well as on the rate the colliding particles merge (sinter) into a single unit. The theory predicts that the rate of decay of exposed metal surface area S is given as in Equation (1a). The exponent n is related to the assumed size dependence of the diffusion coefficients or of the rate constant of the merging process. It varies from 4 to 8 for diffusion controlled decay and it is less than 3 for sintering controlled decay, that is, when the rate controlling step is the merging of two colliding particles. Diffusion control is associated with strong interactions between the metal and the support, but in sintering control there is a weaker metal‐support interaction.
Observer theory for lumping analysis of monomolecular reaction systems
Authors: Liu Y. A. , Lapidus L. 
Published: June 2004

AbstractA new approach for the lumping analysis of reversible and/or irreversible monomolecular reaction systems (MRS) with constant or time‐dependent rate coefficients in discrete and continuous mixtures is presented. The observer theory initiated by Luenberger is proposed and extended to obtain the necessary and sufficient conditions of exact and approximate lumping of such systems. Examples are given to illustrate the implications of lumping and to demonstrate the generality and promising aspects of the observer approach. It is shown that this theory is a unifying method for the lumping analysis of MRS. New insights on lumping analysis are discussed.
Computation of three‐dimensional viscous flow between convergent traveling surfaces
Authors: Hazbun Eddy A. , Churchill Stuart W. 
Published: June 2004

AbstractThe Marker‐and‐Cell numerical technique has been adapted to develop a method of solution for three‐dimensional, unconfined, isothermal flow of a highly viscous, Newtonian fluid in a region bounded by two, nonparallel traveling surfaces. Results are reported only for plane and elliptical surfaces, but the analysis is general enough to handle any shape of interest.A computer program was developed which can be used to generate and plot the flow and pressure fields. Numerical results were obtained for the special case of symmetrically opposed convergent surfaces for a wide range of conditions.
Impurity effects in continuous‐flow mixed suspension crystallizers
Authors: Liu Yih‐An , Botsaris Gregory D. 
Published: June 2004

AbstractThe crystallization of NaCl in the presence of Pb+ + as an Impurity in a continuous, mixed suspension, mixed product removal (CMSMPR) crystallizer was investigated. The results indicated that nucleation and growth rates as well as the dominant crystal sizes can be correlated by simple power functions of impurity concentration. The exponents are constants independent of the impurity concentration, thus permitting the prediction of nucleation rates, growth rates and size distributions at various concentrations of that impurity. This model was shown to apply also to other crystallizing systems.