ISSN:0001-1541    

DOI:10.1002/aic.690190202

出版商:American Institute of Chemical Engineers    

年代:1973

数据来源: WILEY

摘要:

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 discus

ISSN:0001-1541    

DOI:10.1002/aic.690190203

出版商:American Institute of Chemical Engineers    

年代:1973

数据来源: WILEY

摘要:

AbstractFlow rate‐pressure gradient measurments have been performed on 15 different test capillary tubes, each of which consisted of short, alternating segments of two different diameters. The Reynolds number range covered extended from 2 to 700, based on the conditions in the narrower capillary segment. Darcy's law was found valid up to aboutRe= 30‐50, whereas the Forchheimer equation described the data over the entire range ofRecovered. The Forchheimer equation has been obtained from a nondimensional form of the volume averaged momentum equation by using the averaging theorem due to Slattery and to Whitaker. The parameters α and β have obtained precise hydrodynamic definitions. The experimental data have been treated in terms of the Forchheimer equation: the parameters α and β have been calculated using various definitions for the area of flow. Dimensionless permeability, equal to the ratio of measured‐to‐Poiseuille permeability has been found to be a minimum‐type function of small‐to‐large capillary diameter ratio. Dimensionless inertial parameter β* has been found to be a maximum‐type function of the capillary diameter ratio, if the calculation was based on the area of flow equal to the cross sectional area of the narrower capillary segment, in every case. The maximum occurred at the same value of the capillary diameter ratio as the minimum for the dimens

ISSN:0001-1541    

DOI:10.1002/aic.690190204

出版商:American Institute of Chemical Engineers    

年代:1973

数据来源: WILEY

摘要:

AbstractThe hydrodynamics of countercurrent flow of liquids with a high density difference cannot be predicted reliably from correlations developed with data on fluids having low densities (usually water and organic solvents). Dispersed‐phase holdup, flooding rates, and pressure drop during countercurrent flow of mercury and water were studied with several packing materials. Results show that, for a given packing, flooding rates and holdup can be correlated in terms of a single parameter, the superficial slip velocity. For the mercury‐water system, this parameter is shown to be proportional to the packing diameter and packing void fraction for Raschig rings and solid cylindrical pack

ISSN:0001-1541    

DOI:10.1002/aic.690190205

出版商:American Institute of Chemical Engineers    

年代:1973

数据来源: WILEY

摘要:

AbstractCorrelations of the excess Gibbs function and the activity coefficients of a binary, liquid‐phase system at constant temperature depend on reduction ofP‐x‐ydata taken for the system in vapor‐liquid equilibrium. It is shown that use of a fullP‐x‐ydata set is for all practical purposes based on just theP‐yvalues. Alternative procedures require onlyP‐xorP‐ydata. In any case, effective use of a fullP‐x‐ydata set can be made only if redundent experimental values ofPx,yorPare compared for consistency with calculated values. This cannot be accomplished by means of the popular area test for ther

ISSN:0001-1541    

DOI:10.1002/aic.690190206

出版商:American Institute of Chemical Engineers    

年代:1973

数据来源: WILEY

摘要:

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 syste

ISSN:0001-1541    

DOI:10.1002/aic.690190207

出版商:American Institute of Chemical Engineers    

年代:1973

数据来源: WILEY

摘要:

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.

ISSN:0001-1541    

DOI:10.1002/aic.690190208

出版商:American Institute of Chemical Engineers    

年代:1973

数据来源: WILEY

摘要:

AbstractA model describing the development of specific surface area, volume, porosity, and mean pore radius of a porous solid with extent of gasification is developed based on consideration of pore size growth, initiation of new pores, and coalescence of adjacent pores. Use of population balances and formulation of the properties as moments of the pore size distribution leads to a mathematically simple, closed set of equations for kinetically controlled gasification. The model successfully predicts maximums in specific surface area and number of pores observed by Kawahata and Walker (1962) in the activation of devolatilized anthracite by CO2in a fluidized bed.

ISSN:0001-1541    

DOI:10.1002/aic.690190209

出版商:American Institute of Chemical Engineers    

年代:1973

数据来源: WILEY

摘要:

AbstractGasification model developed in Part I is extended to allow for mass transfer of oxidant to the particle and for intraparticle diffusion. For this extension, a moving boundary problem results which is solved numerically in conjunction with a two‐point boundary value problem for the oxidant concentration profile in the particle. The extended model predicts, as expected, that mass transfer stifles gasification and intraparticle diffusion shifts gasification to the outer surface of the particle. For the conditions and parameters used in Part I, particle Thiele moduli above 10 result in particle shrinkage with negligible change in the solid properties, whereas if this modulus is less than 0.1, gasification is kinetically controlle

ISSN:0001-1541    

DOI:10.1002/aic.690190210

出版商:American Institute of Chemical Engineers    

年代:1973

数据来源: WILEY

摘要:

AbstractFor drying and moistening processes in batch fluidization and fluidization in a horizontal exchanger, the overall mathematical model describing simultaneous heat and mass exchange is given. On this basis, the problem of finding the optimal temperatures of inlet gas is formulated and investigated for the case when inlet gas humidity is constant. It is explained that when unit economical values of gas and solid phases are linear with regard to unit available energies (exergies), the economical problem of minimum costs is equivalent to the thermodynamical problem of minimum available energy (exergy) dissipation. Therefore, the performance index expression in exergy terms is formulated as a functional of the Bolza form. The dynamic programming method is used to obtain results of optimal trajectories and decisions. The dependence of optimal process time on apparatus price, which is characterized here by a Lagrangian multiplier λ, is pointed out.The results indicate that the constant gas inlet temperature policy commonly applied to the processes considered here prevents attainment of the process optimum. In fact, increasing inlet temperature until an admissible gas temperature is attained is the optimal policy

ISSN:0001-1541    

DOI:10.1002/aic.690190211

出版商:American Institute of Chemical Engineers    

年代:1973

数据来源: WILEY