摘要:

AbstractVarious ways of building quasi‐Newton matrix approximations that satisfy the special form of the Gibbs‐Duhem equation are studied. Partition symmetry, the separability of the functions in γ and in ϕ, and the method of iterated projections are used in order to develop thermodynamically consistent matrix approximations with good secant information. Many examples are presented which show that exploiting the special form of the Gibbs‐Duhem equation results in improved numerical performance. Ways of exploiting the Gibbs‐Helmholtz equation in addition to the special form of Gibbs‐Duhem equation, and thus the isobaric form of the Gibbs‐Duhem equation, are a

ISSN:0001-1541    

DOI:10.1002/aic.690320702

出版商:American Institute of Chemical Engineers    

年代:1986

数据来源: WILEY

摘要:

AbstractA low‐order modeling technique for separation processes is developed by considering a staged column as a compartment system in which a number of stage are lumped to form an equivalent stage. This method leads to low‐order models of separation processes directly and without linearization. Moreover, the resulting models have state variables and parameters that are physically significant. In contrast to alternative model reduction methods, compartmental analysis guarantees preservation of both material balances and steady states for arbitrary changes in the input variables.A comparison of compartmental analysis to a recently proposed technique based on orthogonal collocation, both methods incorporating an equimolal overflow assumption, shows the efficiency and robustness of the compartmental met

ISSN:0001-1541    

DOI:10.1002/aic.690320703

出版商:American Institute of Chemical Engineers    

年代:1986

数据来源: WILEY

摘要:

AbstractA scheme for rapidly computing the chemical equilibrium composition of hydrocarbon combustion products is derived. A set of ten governing equations is reduced to a single equation that is solved by the Newton iteration method. Computation speeds are approximately 80 times faster than the often used free‐energy minimization method. The general approach also has application to many other chemical system

ISSN:0001-1541    

DOI:10.1002/aic.690320704

出版商:American Institute of Chemical Engineers    

年代:1986

数据来源: WILEY

摘要:

AbstractA restricted diffusion model is developed to study the immobilization of enzyme in porous solid supports. Simulation studies have been carried out for various combinations of process variables and parameters of the immobilization system. The model has also been used to develop a method for estimating the intrinsic rate constant of immobilization when enzyme diffusion into the support is restricted. Results of experiments in which glucose oxidase was immobilized in porous glass supports are consistent with model simulations.

ISSN:0001-1541    

DOI:10.1002/aic.690320705

出版商:American Institute of Chemical Engineers    

年代:1986

数据来源: WILEY

摘要:

AbstractA continuous, staged‐feed column crystallizer was investigated to obtain enlarged product size distribution in precipitation from solution. Stage population balances, in moment form, were solved analytically for several single‐feed configurations. It was found that internal staging permits control of the solids concentration profile, and if collision nucleation is unimportant then countercurrent operation yields the greatest product size enlargement. Nucleation kinetic parameters for a given salt indicate the potential product size improvement, compared to product from an MSMPR crystallizer of equal vol

ISSN:0001-1541    

DOI:10.1002/aic.690320706

出版商:American Institute of Chemical Engineers    

年代:1986

数据来源: WILEY

摘要:

AbstractNumerical solutions to the unaveraged mass balance equation for the case of a flat mobile interface reveal that both high‐ and low‐frequency velocity fluctuations can contribute to mass transfer. This is in contrast to transport to a solid boundary where only low‐frequency fluctuations, normal to the wall, are important. The average mass transfer coefficient is found to depend on Schmidt number to the −0.5 power, in agreement with classical theories. It is related to the velocity field in the liquid primarily through the mean‐square value of the gradient of normal velocity fluctuations at the

ISSN:0001-1541    

DOI:10.1002/aic.690320707

出版商:American Institute of Chemical Engineers    

年代:1986

数据来源: WILEY

摘要:

AbstractA model that describes fractionation with condensation and evaporation in a plate‐fin device has been formulated. It is capable of evaluating profiles of composition, temperature, and flow rate for both liquid and vapor streams in an extended surface device. The device may be adiabatic or nonadiabatic and the surface may be incompletely wetted. Compared to experimental measurements, the model predictions showed ± 1 number of transfer unit deviation along the length of the device. The predictions of the top and bottom flow rate ratio showed a 5–10% deviation for adiabatic and condensation runs and a 25% deviation for evaporation

ISSN:0001-1541    

DOI:10.1002/aic.690320708

出版商:American Institute of Chemical Engineers    

年代:1986

数据来源: WILEY

摘要:

AbstractThe composition and temperature dependence of the mutual diffusion coefficient near the liquid‐liquid critical point of methanol–n‐hexane mixtures has been determined by Gouy interferometry. The critical exponent was found to be 0.685. Constant‐temperature extrapolation to zero diffusivity located the spinodal curve. Spinodal loci calculated from the NRTL model are inconsistent with the experimentally determined

ISSN:0001-1541    

DOI:10.1002/aic.690320709

出版商:American Institute of Chemical Engineers    

年代:1986

数据来源: WILEY

摘要:

AbstractThe mechanism of potassium‐catalyzed C/CO2reaction is studied by a temperature and concentration programmed reaction (TCPR) technique. The proposed redox mechanism contains three surface complexes: –CO2K, –COK, and –CK. The oxide groups are the intermediates during C/CO2gasification. The completely reduced form, –CK, is the end product of catalyst reduction and is the precursor for K loss. The stoichiometries of these surface groups are confirmed by oxygen and potassium

ISSN:0001-1541    

DOI:10.1002/aic.690320710

出版商:American Institute of Chemical Engineers    

年代:1986

数据来源: WILEY

摘要:

AbstractA recently developed error‐in‐variables method of calculating regression parameters was applied to the modeling of gas‐solid adsorption equilibria. The method accounts for error in all experimental variables in the regression calculations. Regression coefficients from pure component data calculated by the new method were used to predict multicomponent equilibria. The multicomponent predictions using pure component parameters calculated by the error‐in‐variables method were more accurae than predictions using parameters calculated by conventional least‐squares

ISSN:0001-1541    

DOI:10.1002/aic.690320711

出版商:American Institute of Chemical Engineers    

年代:1986

数据来源: WILEY