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  • 201
    Electronic Resource
    Electronic Resource
    Structure of the stretching field in chaotic cavity flows (1994)
    Hoboken, NJ : Wiley-Blackwell
    AIChE Journal 40 (1994), S. 1273-1286 
    Details
    ISSN: 0001-1541
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Stretching of material elements in time-periodic cavity flows is investigated numerically. The spatial structure of the stretching field is determined not only by nonchaotic islands and by unstable manifolds of hyperbolic periodic points, but also by singularities of the flow field at the cavity corners. For the short time scales interesting to most mixing applications, regions of very high stretching (good local mixing) are determined by unstable manifolds that pass close to the corners of the cavity. Low stretching (poor local mixing) regions are usually found both inside and near islands. In some cases, however, the unstable manifolds wrap themselves around the islands, preventing the formation of segregated low stretching subregions within the chaotic region.
    Additional Material: 9 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/aic.690400802
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  • 202
    Electronic Resource
    Electronic Resource
    Pressure-dependent gas heat transport in a spherical pore (1994)
    Hoboken, NJ : Wiley-Blackwell
    AIChE Journal 40 (1994), S. 1287-1296 
    Details
    ISSN: 0001-1541
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: A mean free path gas kinetic theory is used to model the conductive heat transport of a gas within a void volume enclosed in a Fourier solid. A variational upper bound principle is derived for a void of arbitrary shape and applied to obtain a rigorous upper bound equation for the void gas conductivity in a spherical void. The variational void gas conductivity equation is exact in both the large and small Knudsen number (Kn) limits and provides a means to determine the accuracy of the reciprocal additivity interpolation formula as applied to thermal conductivity rather than diffusive mass transfer (maximum error 6% at Kn = 0.5 and α = 1). Temperature jump will occur even at atmospheric pressures and higher for sufficiently small thermal accommodation coefficients (α 〈 0.1). Experimental void gas heat conductivities vs. pressure data for H2, He, Ne, N2, CO2, and F12 in a polyurethane foam are compared with theoretical mean free path void gas conductivity vs. inverse Knudsen number curves drawn for various α. Estimates of the thermal accommodation coefficients for the gas- polyurethane surface exhibit a maximum with increasing molecular mass of the gas molecules, which qualitatively agrees with the predictions of Baule's classical theory. Results also point to a rather sharp shift of the S curve to higher pressures with decreasing thermal accommodation.
    Additional Material: 4 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/aic.690400803
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  • 203
    Electronic Resource
    Electronic Resource
    Modeling chemical processes using prior knowledge and neural networks (1994)
    Hoboken, NJ : Wiley-Blackwell
    AIChE Journal 40 (1994), S. 1328-1340 
    Details
    ISSN: 0001-1541
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: We present a method for synthesizing chemical process models that combines prior knowledge and artificial neural networks. The inclusion of prior knowledge is investigated as a means of improving the neural network predictions when trained on sparse and noisy process data. Prior knowledge enters the hybrid model as a simple process model and first principle equations. The simple model controls the extrapolation of the hybrid in the regions of input space that lack training data. The first principle equations, such as mass and component balances, enforce equality constraints. The neural network compensates for inaccuracy in the prior model. In addition, inequality constraints are imposed during parameter estimation. For illustration, the approach is applied in predicting cell biomass and secondary metabolite in a fed-batch penicillin fermentation. Our results show that prior knowledge enhances the generalization capabilities of a pure neural network model. The approach is shown to require less data for parameter estimation, produce more accurate and consistent predictions, and provide more reliable extrapolation.
    Additional Material: 8 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/aic.690400806
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  • 204
    Electronic Resource
    Electronic Resource
    Automated synthesis of distillation sequences using fuzzy logic and simulation (1994)
    Hoboken, NJ : Wiley-Blackwell
    AIChE Journal 40 (1994), S. 1341-1348 
    Details
    ISSN: 0001-1541
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: An automated distillation sequencing system (DSEQSYS) is presented, which consists of three components: a control program, a fuzzy heuristic synthesis program, and a process simulator. DSEQSYS, when applied to problems previously reported in the literature, overcomes some of the disadvantages of using heuristics or mathematical programming alone. DSEQSYS can address problems involving nonsharp separations, nonideal chemical behavior, and conflicting heuristics. A simple approach for converting the traditional separation heuristics into corresponding fuzzy heuristics is also demonstrated.
    Additional Material: 10 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/aic.690400807
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  • 205
    Electronic Resource
    Electronic Resource
    Computer-aided molecular design of solvents for separation processes (1994)
    Hoboken, NJ : Wiley-Blackwell
    AIChE Journal 40 (1994), S. 1349-1360 
    Details
    ISSN: 0001-1541
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: The search for potential solvents for liquid extraction and extractive distillation is carried out through a group contribution molecular design of solvents (MOLDES) approach. A set of submolecular groups (UNIFAC) is used for the synthesis of molecular structures with desired solvent properties. Submolecular group combination (linking) properties are characterized to ensure the chemical feasibility of the MOLDES generated molecular structures. The size of the combinatorial problem posed by the molecular synthesis procedure is reduced by group selection and by imposing physical and molecular constraints at different stages. Criteria are developed for solvent evaluation and the reliability of the VLE and the LLE UNIFAC parameter tables for solvent screening are compared with experimental data for the recovery of oxychemicals by liquid extraction from dilute aqueous solutions.
    Additional Material: 5 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/aic.690400808
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  • 206
    Electronic Resource
    Electronic Resource
    Rapid three-dimensional velocimetry by nuclear magnetic resonance imaging (1994)
    Hoboken, NJ : Wiley-Blackwell
    AIChE Journal 40 (1994), S. 1404-1407 
    Details
    ISSN: 0001-1541
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
    Additional Material: 3 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/aic.690400811
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  • 207
    Electronic Resource
    Electronic Resource
    Monitoring batch processes using multiway principal component analysis (1994)
    Hoboken, NJ : Wiley-Blackwell
    AIChE Journal 40 (1994), S. 1361-1375 
    Details
    ISSN: 0001-1541
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Multivariate statistical procedures for monitoring the progress of batch processes are developed. The only information needed to exploit the procedures is a historical database of past successful batches. Multiway principal component analysis is used to extract the information in the multivariate trajectory data by projecting them onto low-dimensional spaces defined by the latent variables or principal components. This leads to simple monitoring charts, consistent with the philosophy of statistical process control, which are capable of tracking the progress of new batch runs and detecting the occurrence of observable upsets. The approach is contrasted with other approaches which use theoretical or knowledge-based models, and its potential is illustrated using a detailed simulation study of a semibatch reactor for the production of styrene-butadiene latex.
    Additional Material: 12 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/aic.690400809
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  • 208
    Electronic Resource
    Electronic Resource
    Calculating critical transitions of fluid mixtures: Theory vs. experiment (1994)
    Hoboken, NJ : Wiley-Blackwell
    AIChE Journal 40 (1994), S. 1376-1403 
    Details
    ISSN: 0001-1541
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: The progress in predicting critical transitions in fluid mixtures is reviewed. The critical state provides a valuable insight into the general phase behavior of a fluid and is closely linked with the nature and strength of intermolecular interaction. Calculations of critical equilibria have been confined mainly to binary mixtures. The prediction of binary gas-liquid critical properties was initially limited to empirical correlations. These techniques have been superseded by rigorous calculations of the critical conditions using realistic models of the fluid or equations of state. All of the known types of critical phenomena exhibited by binary mixtures can be, at least, qualitatively calculated. If an optimal combining rule parameter is allowed, continuous gas-liquid properties can be calculated accurately for a wide variety of mixtures. Similarly, the pressure and composition dependence of upper critical solution phenomena can be accurately predicted. Progress has been achieved in predicting discontinuous critical transitions in polar and nonpolar binary mixtures. There is increasing interest in calculating the critical properties of ternary and multicomponent mixtures. Although the techniques applied to binary mixtures often can be directly extended to ternary mixture calculations, calculated critical properties of ternary mixtures indicate that their behavior cannot be considered as a simple extension of binary mixture phenomena. Consequently, ternary critical calculations are likely to provide a superior insight into the phase behavior of multicomponent fluids.
    Additional Material: 16 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/aic.690400810
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  • 209
    Electronic Resource
    Electronic Resource
    Inorganic materials by D. W. Bruce and D. O'hare, witey, new york, 1992, 543 pp. (1994)
    Hoboken, NJ : Wiley-Blackwell
    AIChE Journal 40 (1994), S. 382-383 
    Details
    ISSN: 0001-1541
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/aic.690400223
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  • 210
    Electronic Resource
    Electronic Resource
    Solubility of HFC-134a refrigerant in glycol-type compounds: Effects of glycol structure (1994)
    Hoboken, NJ : Wiley-Blackwell
    AIChE Journal 40 (1994), S. 726-737 
    Details
    ISSN: 0001-1541
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Environmental concerns have dictated the replacement of CFC-12 refrigerant with HFC-134a in automotive air-conditioning (A/C) systems. Since polyglycols are synthetic compounds compatible with HFC-134a and considered as lubricants for the A/C compressor, interations of HFC-134a with glycol-type compounds and thermodynamic properties of the solutions are important in designing an A/C system. In this work, the solubility of HFC-134a in four glycol-type compounds was measured at -5 to 80°C and 90 to 960 kPa. HFC-134a had the greatest solubility in tetraethylene glycol dimethyl ether. HFC-134a was less soluble in hexylene glycol and tetraethylene glycol and least soluble in triethylene glycol. Mixtures of HFC-134a with TRIG or TGDE showed phase separation. Solubility data were used to calculate the activity coefficient of HFC-134a in glycol solutions. An equation of the form, lnγr = (1 - xr)[A + Bxr], was found to correlate γr to the mole fraction of HFC-134a in the solution where A and B are constants which may depend on the temperature. Based on a model assuming a specific interaction between molecules and using the activity of HFC-134a, a higher degree of interaction is expected between HFC-134a and tetraethylene glycol dimethyl ether molecules than between the molecules of HFC-134a and other glycols. In general, glycols with free -OH groups may have less affinity for HFC-134a. Solubility is discussed in terms of its parameters and chemical structure of the glycols, as well as the effect of temperature on the solubility, the activity coefficient, and the thermodynamic properties of the HFC-134a/glycol solutions.
    Additional Material: 15 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/aic.690400415
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  • 211
    Electronic Resource
    Electronic Resource
    Modeling of supercritical extraction of organics from solid matrices (1994)
    Hoboken, NJ : Wiley-Blackwell
    AIChE Journal 40 (1994), S. 777-785 
    Details
    ISSN: 0001-1541
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: The desorption profiles of various organics from soil and activated carbon using dense liquid and supercritical carbon dioxide were modeled. The model accounts for effective diffusion of the organics in the solid pores, axial dispersion in the fluid phase, and external mass transfer to the fluid phase from the particle surface. This model, involving partial differential equations, is solved using the orthogonal collocation on finite elements. The model is able to predict the experimental data quite well without any adjustable parameters. The importance of each parameter depended on the system, although adsorption equilibrium and the effective pore diffusion of the organic were the most significant parameters in all the systems investigated.
    Additional Material: 13 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/aic.690400505
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  • 212
    Electronic Resource
    Electronic Resource
    Factors affecting coalescence frequency of droplets in a stirred liquid-liquid dispersion (1994)
    Hoboken, NJ : Wiley-Blackwell
    AIChE Journal 40 (1994), S. 767-776 
    Details
    ISSN: 0001-1541
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Liquid-liquid dispersions are commonly used for separations and reaction systems, because the added interfacial area due to dispersion aids in mass transfer and chemical reaction rates. Transient coalescence experiments have been performed for a wide range of dispersed-phase fractions and impeller speeds. A similarity transformation of the experimental drop-size distribution is possible for most of the experiments. The drop-size-dependent coalescence frequency is obtained from an inverse problem procedure previously developed. Over the range of drop sizes encountered in our experiments, the coalescence frequency increases with increases in the size of the coalescing drops, the dispersed-phase fraction, and the impeller speed. For a dispersephase system of neutrally buoyant droplets of benzene/carbon tetrachloride in water, the coalescence frequency is K(v, v′)= 3.72 (10-3)φ1.42N20.52(v1/2+v′1/2) as a function of dispersed-phase fraction, φ, impeller speed, N2, and volumes of the coalescing droplets, v and v′. The results are compared with previous models for the coalescence frequency. Models predicting an eventual decrease in coalescence rates with drop size are disqualified unless this decrease occurs beyond the sizes observed in our experiments.
    Additional Material: 11 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/aic.690400504
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  • 213
    Electronic Resource
    Electronic Resource
    u′v′ Reynolds stress in the viscous sublayer over a wide range of Re numbers (1994)
    Hoboken, NJ : Wiley-Blackwell
    AIChE Journal 40 (1994), S. 29-39 
    Details
    ISSN: 0001-1541
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: To test the ability of different turbulence models to predict the turbulent momentum transport in the viscous sublayer, measurements are performed with a laser Doppler velocimeter (LDV). The main objective of the experiments is to measure the u′v′ correlation in the near wall region. The results support the correlation: -u′v′+ = Aky+3. The results of 2-D computer simulations using four different low Reynolds number k-∊ turbulence models are compared with the experimental LDV data. The models tested are the original low Reynolds number k-∊ model of Jones and Launder (1972, 1973) and three later modifications by Chien (1980), Lam and Bremhorst (1981), and Nagano and Hishida (1987). The u′v′ correlation was found to be underestimated with all four models, but the Chien model was superior, with only a 40% underestimation in the viscous sublayer.
    Additional Material: 15 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/aic.690400106
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  • 214
    Electronic Resource
    Electronic Resource
    Breakthrough of lysozyme through an affinity membrane of cellulose-cibacron blue (1994)
    Hoboken, NJ : Wiley-Blackwell
    AIChE Journal 40 (1994), S. 40-49 
    Details
    ISSN: 0001-1541
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: The dynamic affinity adsorption oflysozyme through stacked flat-sheet cellulose membranes with immobilized cibacron blue 3GA was studied and compared to three affinity-membrane models: diffusion model to explore the importance of axial and radial diffusion; variation model to study the effects of pore-size distribution or thickness variation; and stack model to investigate the effects of stacking flat-sheet membranes. For the diffusion model, when Per 〉 0.1, radial diffusional resistance is significant, but when Pez 〈 25, axial dispersion must be considered. For the variation model, increasing pore-size distribution or nonuniform membrane thickness greatly broadens the breakthrough curve. The stack model shows that the stacking of membranes significantly sharpens the breakthrough curves by averaging out the flow dispersion due to pore-size distribution or thickness variation.
    Additional Material: 11 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/aic.690400107
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  • 215
    Electronic Resource
    Electronic Resource
    Strategies for equilibrium-stage separation calculations on parallel computers (1994)
    Hoboken, NJ : Wiley-Blackwell
    AIChE Journal 40 (1994), S. 65-72 
    Details
    ISSN: 0001-1541
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: When multicomponent, multistage separation problems are solved on parallel computers by successive linearization methods, the solution of a large sparse linear equation system becomes a computational bottleneck, since other parts of the calculation are more easily parallelized. When the standard problem formulation is used, this system has a block-tridiagonal form. It is shown how this structure can be used in parallelizing the sparse matrix computation. By reformulating the problem so that it has a bordered-block-bidiagonal superstructure, it can be made even more amenable to parallezation. These strategies permit the use of a two-level hierarchy of parallelism that provides substantial improvements in computational performance on parallel machines.
    Additional Material: 10 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/aic.690400109
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  • 216
    Electronic Resource
    Electronic Resource
    Rate enhancement and multiplicity in a partially wetted and filled pellet: Experimental study (1994)
    Hoboken, NJ : Wiley-Blackwell
    AIChE Journal 40 (1994), S. 97-111 
    Details
    ISSN: 0001-1541
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Phase transition during an exothermic multiphase reaction was studied experimentally using a single catalytic pellet reactor. Cyclohexene hydrogenation (to cyclohexane) and disproportionation (to benzene and cyclohexane) on Pd/Al2O3 comprised the test reaction system. The steady-state behavior of the pellet exposed on part of its surface by a flowing liquid rivulet containing the liquid reactant (cyclohexene) and the other part by a flowing gas containing the gaseous reactant (hydrogen) was examined. Measurements included the pellet weight (liquid holdup), degree of external wetting, center and surf ace temperature and overall reaction rates. Two regimes observed are: a low-rate regime for all hydrogen gas-phase concentrations in which the partially wetted pellet is filled mostly with liquid and nearly isothermal; a high-rate regime for hydrogen concentrations exceeding a critical value in which the pellet is filled only partially with liquid and the pellet temperature rise is considerable. Benzene formation was observed in this state. The difference in overall cyclohexane formation rates between the two states was as high as a factor of 20 for the same bulk conditions. Over the range where multiple states were observed, the steady state of the pellet depended on whether the pellet was pref tiled with the reactive gas mixture or with liquid cyclohexene. The range over which the high-rate state was sustained was the largest for the most active catalyst and declined as the catalyst slowly deactivated. Data features are interpreted using the theoretical foundations of the half-wetted catalytic slab model (Harold and Watson, 1993).
    Additional Material: 13 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/aic.690400112
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  • 217
    Electronic Resource
    Electronic Resource
    Determination of vapor pressure in vapor-induced puffing (1994)
    Hoboken, NJ : Wiley-Blackwell
    AIChE Journal 40 (1994), S. 160-165 
    Details
    ISSN: 0001-1541
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Water vapor pressure for cornstarch and popcorn grits at a temperature of between 100 and 180° C was determined by measuring vapor pressures generated at various moisture contents in a heated, closed system. At a higher temperature, fugacity of water increased with increasing temperature probably because of melting or partial melting of starch. The apparent heat of sorption for cornstarch changed significantly with moisture content and temperature. Noncondensible gases were produced by heating popcorn grits to temperatures above 150°C. It is not accurate to estimate vapor pressure based on the heat of sorption or extrapolation of currently used empirical isotherm equations to a temperature above 100°C. Vapor pressure inside popcorn at the instant of popping are. roughly 758 to 827 kPa (110 to 120psia).
    Additional Material: 8 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/aic.690400118
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  • 218
    Electronic Resource
    Electronic Resource
    Generalized quartic equation of state for pure nonpolar fluids (1994)
    Hoboken, NJ : Wiley-Blackwell
    AIChE Journal 40 (1994), S. 152-159 
    Details
    ISSN: 0001-1541
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: A generalized quartic equation of state has been developed for pure nonpolar fluids. The equation of state contains four parameters which depend on three properties of the fluid - critical temperature, critical volume, and acentric factor. A mathematical approximation based on previously reported hard-sphere molecular dynamics simulations has been used to model repulsive contributions to the pressure. Attractive forces were modeled using an empirical term. While the quartic equation yields four roots, one root is always negative and hence physically meaningless, and three roots behave like three roots of a cubic equation. Thus, the new equation of state has the advantages of a cubic, simplicity and unequivocal identification of the roots, while correctly modeling the attractive and repulsive contributions to the pressure. The new equation of state is more accurate than either the Peng-Robinson or a previously proposed quartic equation of state. Accuracy in the supercritical and compressed liquid regions is improved substantially.
    Additional Material: 14 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/aic.690400117
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  • 219
    Electronic Resource
    Electronic Resource
    Removal of VOCs from groundwater using membrane-assisted solvent extraction (1994)
    Hoboken, NJ : Wiley-Blackwell
    AIChE Journal 40 (1994), S. 166-177 
    Details
    ISSN: 0001-1541
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: A membrane-assisted solvent extraction (MASX) system coupled to a membrane-assisted distillation stripping (MADS) system for use in decontaminating ground-water is evaluated. Volatile organic compounds (VOCs) in the groundwater are extracted in the MASX unit using a sunflower oil solvent. In the MADS unit, VOCs are stripped from the sunflower oil, which is recycled to the MASX unit. Thermodynamic data for the sunflower oil-water-VOCs system were measured. The results were used along with published membrane mass-transfer data to design MASX and MADS modules.
    Additional Material: 8 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/aic.690400119
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  • 220
    Electronic Resource
    Electronic Resource
    Family plots for evaluating physical properties of organosilicon compounds (1994)
    Hoboken, NJ : Wiley-Blackwell
    AIChE Journal 40 (1994), S. 373-377 
    Details
    ISSN: 0001-1541
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
    Additional Material: 6 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/aic.690400217
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  • 221
    Electronic Resource
    Electronic Resource
    Prediction and correlation of accessible area of large multiparticle aggregates (1994)
    Hoboken, NJ : Wiley-Blackwell
    AIChE Journal 40 (1994), S. 1167-1182 
    Details
    ISSN: 0001-1541
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Aggregates (composed of large numbers of primary particles) are produced in many engineering environments. One convenient characterization is the fractal dimension, the exponent describing how the number of primary particles in each aggregate scales with radial distance from its center of mass. We describe a finite-analytic pseudo-continuum prediction of the normalized accessible surface area of an isothermal quasi-spherical fractal aggregate containing N (≫ 1) primary particles, on the surfaces of which a first-order chemical process occurs. Results are displayed for specific fractal dimensions (2.5, 2.18, and 1.8) frequently observed in aggregating systems. An effective Thiele modulus is used to develop an efficient and accurate scheme for predicting/correlating the effectiveness factor for an aggregate containing N primary particles in terms of aggregate fractal dimension, reaction probability, and Knudsen number. Our methods now allow calculations of the accessible surface area of populations of aggregates, provided pdf \documentclass{article}\pagestyle{empty}\begin{document}$ \rlap{--} \rlap{--} ($\end{document}N, Df, …\documentclass{article}\pagestyle{empty}\begin{document}$ \rlap{--})$\end{document} is known for the populations of interest.
    Additional Material: 12 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/aic.690400708
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  • 222
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    Vapor-liquid equilibrium of polymer solutions using a cubic equation of state (1994)
    Hoboken, NJ : Wiley-Blackwell
    AIChE Journal 40 (1994), S. 1203-1209 
    Details
    ISSN: 0001-1541
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: A recently proposed mixing rule has been combined with a cubic equation of state to correlate the vapor-liquid equilibria of various polymer + solvent and solvent + long chain hydrocarbon mixtures. We find that the two-parameter version of this model can correlate the solvent partial pressure in concentrated polymer solutions with high accuracy over a range of temperatures and pressures with temperature-independent parameters. For the solvent + long chain hydrocarbon systems, for which accurate vapor-phase concentrations are also important, the model is best used as a three-parameter correlation. Advantages of this approach are that it extends the application of cubic equations of state to polymer + solvent systems in a simple fashion and that generally only temperature-independent parameters are required which allow for accurate interpolation and extrapolation of available data.
    Additional Material: 7 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/aic.690400711
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    Heavy metal removal and recovery by contained liquid membrane permeator (1994)
    Hoboken, NJ : Wiley-Blackwell
    AIChE Journal 40 (1994), S. 1223-1237 
    Details
    ISSN: 0001-1541
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Heavy metals like Cu2+, Cr6+, and Hg2+ were removed successfully from wastewater and concentrated in a strip aqueous solution for recycle using the hollowfiber-contained liquid membrane (HFCLM) technique. Using cotransport, Cr6+ and Hg2+ present as anions in the feed solution were transferred individually through a liquid membrane containing tri-n-octylamine in xylene and concentrated in an alkaline solution on the strip side. The removal efficiency of each heavy metal was studied as a function of the aqueous feed flow rate in an HFCLM permeator. Copper present as cation Cu2+ was removed and concentrated by countertransport using LIX84 in n-heptane as the liquid membrane. The efficiency of copper removal was studied as a function of feed copper concentration, feed flow rate, strip flow rate, and area ratio between the feed fiber set and strip fiber set. The strip side flow rate did not affect the Cu2+ transfer rate. A theoretical model presented predicts the copper transport rate from the feed solution to the strip solution in an HFCLM permeator with a variable feed to strip-side membrane area. Both feed aqueous boundary layer and interfacial complexation reaction on the feed side dominate the observed Cu2+ removal process through LIX 84 in n-heptane for feed concentration levels used 90-500 mg/L. It was verified by providing two times larger liquid-liquid interfacial area in the feed aqueous side or in the strip aqueous side. The model can be used to design the membrane area required on the feed and strip fiber sides to remove essentially all of the copper from a given wastewater stream.
    Additional Material: 17 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/aic.690400713
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    Determining fluid saturations during multiphase flow experiments by NMR imaging techniques (1994)
    Hoboken, NJ : Wiley-Blackwell
    AIChE Journal 40 (1994), S. 1238-1245 
    Details
    ISSN: 0001-1541
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: The quantitative determination of porosity and saturation distributions in porous media using unclear magnetic resonance imaging techniques is addresed. A method based on multiple image acquisitions with extrapolation within a model of transverse relaxation was investigated for new experimental situations. The determination of saturation was validated with limestone and sandstone samples. Experimental evidence for dependencies of transverse relaxation and linewidth on saturation is discussed, as well as their impact on image resolution and quantitation. An automatic production measurement device for independent verification of average saturations during dynamic experiments is investigated.
    Additional Material: 10 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/aic.690400714
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    Masthead (1994)
    Hoboken, NJ : Wiley-Blackwell
    AIChE Journal 40 (1994) 
    Details
    ISSN: 0001-1541
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/aic.690400801
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  • 226
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    Microwave driven convection in a square cavity (1994)
    Hoboken, NJ : Wiley-Blackwell
    AIChE Journal 40 (1994), S. 1268-1272 
    Details
    ISSN: 0001-1541
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
    Additional Material: 7 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/aic.690400718
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  • 227
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    Stochastic dynamic approach to transport phenomena (1994)
    Hoboken, NJ : Wiley-Blackwell
    AIChE Journal 40 (1994), S. 1297-1311 
    Details
    ISSN: 0001-1541
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: A stochastic dynamic approach to the equations of change is introduced here, which first is applied to linear equations and is based on the formal analogy between certain forms of the equations of change and the Fokker-Planck equation. A stochastic differential equation associated with the Fokker-Planck equation can be derived from the latter and solved numerically, thus yielding the solution to the original equation of change. The proper treatment of boundary conditions is essential for the success of the method. We show that the method is able to handle the eight fundamental types of boundary conditions (Carslaw and Jaeger, 1959; Crank, 1975). In addition, the stochastic dynamic approach provides a deeper insight in the physical processes underlying transport phenomena than do traditional techniques.
    Additional Material: 10 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/aic.690400804
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  • 228
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    Model identification and control strategies for batch cooling crystallizers (1994)
    Hoboken, NJ : Wiley-Blackwell
    AIChE Journal 40 (1994), S. 1312-1327 
    Details
    ISSN: 0001-1541
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: The open-loop optimal control strategy to regulate the crystal-size distribution of batch cooling crystallizers handles input, output, and final-time constraints, and is applicable to crystallization with size-dependent growth rate, growth dispersion, and fines dissolution. The objective function can be formulated to consider solid-liquid separation in subsequent processing steps.A model-based control algorithm requires a model that accurately predicts system behavior. Uncertainty bounds on model parameter estimates are not reported in most crystallization model identification studies. This obscures the fact that resulting models are often based on experiments that do not provide sufficient information and are therefore unreliable. A method for assessing parameter uncertainty and its use in experimental design are presented. Measurements of solute concentration in the continuous phase and the transmittance of light through a slurry sample allow reliable parameter estimation. Uncertainty in the parameter estimates is decreased by data from experiments that achieve a wide range of supersaturation. The sensitivity of the control policy to parameter uncertainty, which connects the model identification and control problems, is assessed. The model identification and control strategies were experimentally verified on a bench-scale KNO3-H2O system. Compared to natural cooling, increases in the weight mean size of up to 48% were achieved through implementation of optimal cooling policies.
    Additional Material: 17 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/aic.690400805
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  • 229
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    New group contribution method for estimating properties of pure compounds (1994)
    Hoboken, NJ : Wiley-Blackwell
    AIChE Journal 40 (1994), S. 1697-1710 
    Details
    ISSN: 0001-1541
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: A new group contribution method for the estimation of properties of pure organic compounds is presented. Estimation is performed at two levels: the basic level uses contributions from first-order groups, while the next higher level uses a small set of second-order groups having the first-order groups as building blocks. Thus, the method provides both a first-order approximation (first-order group contributions) and a more accurate second-order prediction (first- and second-order group contributions). This article discusses methods for prediction of normal boiling point, normal melting point, critical pressure, critical temperature, critical volume, standard enthalpy of vaporization at 298 K, standard Gibbs energy, and standard enthalpy of formation at 298 K. The predictions are based exclusively on the molecular structure of the compound, and the method is able to distinguish among isomers. Compared to the currently-used methods, this technique demonstrates significant improvements in accuracy and applicability.
    Additional Material: 2 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/aic.690401011
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  • 230
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    Slotted orifice flowmeter (1994)
    Hoboken, NJ : Wiley-Blackwell
    AIChE Journal 40 (1994), S. 1757-1760 
    Details
    ISSN: 0001-1541
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
    Additional Material: 5 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/aic.690401015
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    Characterizing patterns in plant somatic embryo cultures: Its morphology and development (1994)
    Hoboken, NJ : Wiley-Blackwell
    AIChE Journal 40 (1994), S. 1728-1740 
    Details
    ISSN: 0001-1541
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: While being developed, plant somatic embryos change shape and increase size. An effective kinetic description of growth and development of somatic embryos is important for process scale-up and optimization. An essential component of such a kinetic description is the developmental characterization of the individual embryos present in culture. Embryo morphological data obtained by image processing techniques were transformed into sizeand size-independent morphological descriptors. Qualitative relations between the descriptors and geometric properties of the embryos were established to interpret the results. For training, a branch-and-bound search technique was used to search for optimal subsets of descriptors, as determined by member clustering and class separability properties evaluated from within-class and between-class scatter matrices. In the classification mode, individuals were identified using a voting nearest neighbor classifier. This nonparametric nearest-neighbor classifier was trained on optimal projections of the feature space established from developmental stage discrimination (branch-and-bound algorithm). Using a test population, normal and abnormal embryos and callus were assigned to six morphological classes. The image-analysis-based classification was in 80-90% agreement compared to the results obtained through visual classification by an experienced operator.
    Additional Material: 12 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/aic.690401013
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    Turbulent gas-particle flow in vertical risers (1994)
    Hoboken, NJ : Wiley-Blackwell
    AIChE Journal 40 (1994), S. 215-228 
    Details
    ISSN: 0001-1541
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Many experimental studies on the cross-sectional distribution of particles in vertical risers have revealed marked segregation of particles. These flows are inherently unsteady with large fluctuations in suspension density. In this article, we have analyzed the time-smoothed equations for the motion of dense suspensions to demonstrate the role of these fluctuations on the occurrence of segregation. It is shown that the particles will congregate in regions where the kinetic energy of fluctuations associated with the particles is small. In the context of transport of small particles such as FCC, a simplified model based on the mixture velocity can be constructed. A speculative K-∊ model based on this velocity is analyzed to illustrate the extent of segregation of particles afforded by unsteady fluctuations.
    Additional Material: 14 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/aic.690400204
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  • 233
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    Protein precipitation: Effects of mixing on protein solubility (1994)
    Hoboken, NJ : Wiley-Blackwell
    AIChE Journal 40 (1994), S. 349-360 
    Details
    ISSN: 0001-1541
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Mixing effects in protein precipitation processes are very poorly understood. They impact apparent protein solubility, protein structure in precipitates, particle size, morphology and recoverable activity. In this work, a model is proposed to describe the impact of mixing on protein solubility in precipitation processes. A series of semibatch-mode precipitation experiments were performed using bovine liver catalase and ammonium sulfate to test model predictions. The process variables studied include initial protein supersaturation, agitation rate, and rate of addition of salt solution to the initial protein solution. The mixing model parameters were estimated independently with the aid of a series-parallel dye reaction. The results showed good agreement between model and experiment. The initial protein supersaturation was the most important variable at the 1-L scale. The influence of mixing on recoverable activity was also examined. Scale-up guidelines are suggested based on model simulations and experimental results.
    Additional Material: 8 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/aic.690400213
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  • 234
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    Control of emulsion polymerization reactors (1994)
    Hoboken, NJ : Wiley-Blackwell
    AIChE Journal 40 (1994), S. 1993-2021 
    Details
    ISSN: 0001-1541
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: The interest in emulsion polymerization is strong because it offers the possibility of producing products with special properties not easily produced by other types of polymerization processes. Because the main reaction medium is water, not an organic solvent, its importance is steadily increasing with efforts to design environmentally benign processes. The control of emulsion polymerization is a challenging problem due to major limitations encountered in its modeling and on-line monitoring. Although emulsion polymerization has been studied and used for several decades, progress has been slow. Industrial practice relies heavily on experience while several controversial issues are still being studied. The literature related to this issue is vast and sometimes contradictory, and most deals with experimental investigation of specific emulsion polymerization systems to improve the process understanding and develop a process model. However, universally accepted conclusions are scarce. This article reviews the major issues related to control of emulsion polymerization. The latest contributions in process understanding, mathematical modeling, sensor technology, and process control techniques for emulsion polymerization are discussed. Emphasis is on contributions, which are important in resolving the control of emulsion polymerization processes.
    Additional Material: 3 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/aic.690401210
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  • 235
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    Oxidation of benzyl alcohol using hypochlorite ion via phase-transfer catalysis (1994)
    Hoboken, NJ : Wiley-Blackwell
    AIChE Journal 40 (1994), S. 2028-2033 
    Details
    ISSN: 0001-1541
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Heterogeneous oxidation of benzyl alcohol using hypochlorite ion with phase-transfer catalyst is carried out in an agitated vessel with a flat interface. Cetyltrimethylammonium bromide and toluene are chosen as the best catalyst and solvent, respectively. Observed reaction rates are proportional to the interfacial concentration of cetyltrimethylammonium hypochlorite in the organic phase, which is formed by ion exchange between bromide and hypochlorite ions. They are reasonably explained by the proposed theoretical model for the phase-transfer catalysis. The reaction rate constant evaluated by fitting the rate data to the model prediction is 22.7 m3 /kmol·s at 303 K, independent of the physical properties in the aqueous solutions. The maximum yield of benzaldehyde is about 90% and the selectivity is 100% for the conversion of hypochlorite ion less than 80%.
    Additional Material: 6 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/aic.690401212
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  • 236
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    Prediction of pH in complex aqueous mixtures using a group-contribution method (1994)
    Hoboken, NJ : Wiley-Blackwell
    AIChE Journal 40 (1994), S. 1210-1222 
    Details
    ISSN: 0001-1541
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Expressions that suitably describe the behavior of weak electrolytes in aqueous systems are developed. A new numerical procedure is presented to allow for partial dissociation phenomena and so consider the whole species in solution. It is based on mass balances, the electroneutrality assumption, and dissociation constants of electrolytes. Combining it with a modified UNIFAC electrolyte group-contribution model based on the solvation concept directly allows calculation of pH, activities, and concentrations of species. The validity and usefulness of the expressions are tested using data for the pH of buffer solutions and complex aqueous mixtures such as fermentation media and liquid foods: pH values accurate to within ±0.05 pH units were obtained.
    Additional Material: 3 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/aic.690400712
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  • 237
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    Automatic synthesis of batch plant procedures: Process-oriented approach (1994)
    Hoboken, NJ : Wiley-Blackwell
    AIChE Journal 40 (1994), S. 1650-1664 
    Details
    ISSN: 0001-1541
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: A strategy for the automatic synthesis of plant operating procedures, through the integration of artificial intelligence and mathematical modeling tools is discussed. This “predicative/numerical” modeling paradigm integrates qualitative and quantitative aspects of the problem in a same framework. It uses a “process-centered” qualitative modeling approach together with MILP optimization techniques to automatically generate operating strategies. The operation procedures network (OP-Net), formulated in terms of processes from a generic library, describes abstract (hardware-independent) processing paths leading to the desired operational goals. In this approach, the model assumptions, conservation expressions and data are described at the same level of abstraction, using the same formal representation. This permits the direct, automatic generation and modification of operation procedures in situations involving changes in basic assumptions and initial scenarios. Thus, flexibility, an essential feature of batch processing, is safeguarded.
    Additional Material: 16 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/aic.690401007
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  • 238
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    Diffusion-convection-reaction in multicomponent mixtures (1994)
    Hoboken, NJ : Wiley-Blackwell
    AIChE Journal 40 (1994), S. 1665-1668 
    Details
    ISSN: 0001-1541
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: We analyze the mathematical structure of a multicomponent reactive mixture in a plug flow reactor with axial diffusion. Quasilinearity of the kinetic equation assuming “uniformity” does not carry over to the second-order equations when diffusion is considered and a perturbation expansion method needs to be developed. Perturbation around the limit of a CSTR is regular, which leads to nonhomogeneous second-order differential equations containing no unknown kinetic term, so that the procedure cascades down to the solution of the CSTR problem. Perturbation around the PFR problem is singular, but the inner (boundary layer) solution is easy. The outer solution leads to a series of integro-differential equations, which can be reduced to complete Volterra integral equations of the second kind; these are known to admit unique solutions. A formal approach to finding these solutions is discussed.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/aic.690401008
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  • 239
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    Analysis of steric hindrance effects on adsorption kinetics and equilibria (1994)
    Hoboken, NJ : Wiley-Blackwell
    AIChE Journal 40 (1994), S. 1685-1696 
    Details
    ISSN: 0001-1541
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Most existing adsorption models do not properly consider steric hindrance effects of preadsorbed solutes. As a consequence, the models often fail to represent the adsorption kinetics and equilibria accurately. In this work, we extend the random sequential adsorption concept for irreversible adsorption to analyze reversible adsorption on a continuous surface and a random site surface. Based on simulation results of these processes, general kinetic equations for one-component adsorption are developed. The equations are used to correlate chromatography frontal curves of lysozyme and isotherm data of ethane adsorption on activated carbon and ethylene adsorption on a molecular sieve. The significance of the equations, as compared with the Langmuir equation, lies not only in their ability to correlate the experimental data more accurately, but in the physical significance of the adsorption parameters such as the maximum adsorption capacity obtained from the correlation. Our study shows that steric hindrance effects alone result in nonlinear Scatchard and Hill plots with negative cooperativity.
    Additional Material: 14 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/aic.690401010
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    Equations of state and activity coefficient models for vapor-liquid equilibria of polymer solutions (1994)
    Hoboken, NJ : Wiley-Blackwell
    AIChE Journal 40 (1994), S. 1711-1727 
    Details
    ISSN: 0001-1541
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Four noncubic equations of state, (EOS) and five activity coefficient models are applied to binary polymer and solvent solutions. Solvent activities at intermediate concentrations and equilibrium pressures are predicted with the perturbed-soft-chain theory (PSCT), group-perturbed-soft-chain theory, (GPSCT), group-contribution-lattice fluid (GCLF) EOS, GC-Flory EOS, UNIFAC-FV, entropic-FV and GK-FV models, “new” UNIFAC, and modified Flory-Huggins model. Free-volume activity coefficient models (UNIFAC-FV, entropic-FV) are simpler and, when applied to polymer solutions, more accurate than the EOS. Activity coefficient models are restricted to low-pressure calculations and require accurate values of pure-component volumes. Mixture parameters for activity coefficient models and GC-Flory EOS have been previously evaluated from experimental vapor-liquid equilibrium data for mixtures with only low-molecular-weight compounds. The GC-Flory EOS, though more complicated than activity coefficient models, provides equally good or in some cases better predictions. The application of GC-Flory EOS developed as an activity coefficient model is restricted to low-pressure calculations. On the other hand, PSCT and GCLF developed as “true” EOS provide reliable equilibrium predictions using mixture parameters evaluated solely from pure-component properties together with standard mixing and combining rules. PSCT EOS performs generally better than GCLF EOS for polymer solutions considered in this study.
    Additional Material: 7 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/aic.690401012
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    Modeling the role of bacteria in leaching of low-grade ores (1994)
    Hoboken, NJ : Wiley-Blackwell
    AIChE Journal 40 (1994), S. 1741-1756 
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    ISSN: 0001-1541
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: A robustious structural model is developed to describe the role of bacteria in the leaching process of low-grade ores under conditions controlled by intraparticle diffusion. The main impetus behind developing this model is to provide an insight into such systems, together with a suitable framework for interpreting experimental data. The model is derived in detail with respect to reaction chemistry and the role of bacteria in catalyzing these reactions, specifically the synergism of chemistry, physics and biology in determining the overall behavior of the system. The model is used to simulate the atmospheric oxidation of iron disulfide contained in porous solids in the presence of Thiobacillus ferrooxidans (T. ferrooxidans). The experimental data are predicted well by the model, which demonstrates its applicability and supports the view that the rate of intraparticle diffusion is the controlling mechanism for this system.
    Additional Material: 6 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/aic.690401014
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    Collision integrals of discrete-sectional model in simulating powder production (1994)
    Hoboken, NJ : Wiley-Blackwell
    AIChE Journal 40 (1994), S. 1761-1764 
    Details
    ISSN: 0001-1541
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
    Additional Material: 2 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/aic.690401016
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    Fouling of tube surfaces: Modeling of removal kinetics (1994)
    Hoboken, NJ : Wiley-Blackwell
    AIChE Journal 40 (1994), S. 1804-1813 
    Details
    ISSN: 0001-1541
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Fouling of tube surfaces from flowing solutions or suspensions is examined. A new approach to the removal aspects of this process is presented linking removal to the morphological and mechanical characteristics of deposit microstructure. A simplified description of deposit microstructure is employed, involving a collection of geometrically similar roughness elements. A dynamic situation is envisioned whereby these elements grow due to deposition and suffer breakage under the action of hydrodynamic forces. A mathematical model for the macroscopic fouling behavior based on the techniques of population balances is obtained and numerically analyzed. The behavior found is in agreement with experimental evidence.
    Additional Material: 8 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/aic.690401105
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    Effect of kinetics on residue curve maps for reactive distillation (1994)
    Hoboken, NJ : Wiley-Blackwell
    AIChE Journal 40 (1994), S. 1814-1824 
    Details
    ISSN: 0001-1541
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: A class of models is derived for studying the effects of chemical kinetics on residue curve maps for reactive distillation. Activity-based rate and phase equilibrium expressions provide an accurate and thermodynamically consistent description of composition changes in nonideal, reacting vapor-liquid mixtures. For certain strategies of operation, which dictate the rate of product removal, the model equations are nonautonomous, leading to unusual dynamic behavior. However, for a certain special product removal policy, the effects of kinetics can be described by a single parameter, the Damköhler number, which measures the rate of reaction relative to product removal. For small values of the Damköhler number, the nonreactive simple distillation residue curve map is recovered and the singular points are the pure components and azeotropes in the nonreactive mixture. A bifurcation analysis shows the deformation and, in some cases, the disappearance of these singular points as the Damköhler number is increased until the equilibrium reactive residue curve map is recovered at large values. This bifurcation analysis reveals the limitations of the equilibrium analysis. A model problem for the reactive distillation of methyl tertbutyl ether from isobutene and methanol is solved.
    Additional Material: 15 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/aic.690401106
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    On-line terpolymer composition control in semicontinuous emulsion polymerization (1994)
    Hoboken, NJ : Wiley-Blackwell
    AIChE Journal 40 (1994), S. 1850-1864 
    Details
    ISSN: 0001-1541
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: A closed-loop strategy for terpolymer composition control in semicontinuous emulsion polymerization of high solids content systems is presented. This strategy is based on a nonlinear adaptive controller that calculates the flow rate of the more reactive monomers to be added into the reactor to produce a terpolymer of a given composition. The nonlinear adaptive controller is based on a simplified mathematical model of the process that includes the on-line estimation of an adjustable parameter. The addition of a conventional feedback proportional-integral (PI) controller to the prediction of the nonlinear controller was studied by simulation. It is shown that the contribution of the PI controller is negligible. The controller was checked by computer simulation and also experimentally verified during the semicontinuous emulsion terpolymerization of high solids content (55 wt. %) of vinyl acetate, methyl methacrylate and butyl acrylate.
    Additional Material: 11 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/aic.690401109
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  • 246
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    Correction (1994)
    Hoboken, NJ : Wiley-Blackwell
    AIChE Journal 40 (1994), S. 1900-1900 
    Details
    ISSN: 0001-1541
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/aic.690401113
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  • 247
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    Dynamic data rectification by recurrent neural networks vs. Traditional methods (1994)
    Hoboken, NJ : Wiley-Blackwell
    AIChE Journal 40 (1994), S. 1865-1875 
    Details
    ISSN: 0001-1541
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Recurrent neural networks are used to demonstrate the dynamic data rectification of process measurements containing Gaussin noise. The performance of these networks is compared to the traditional extended Kalman filtering approach and to published results for model-based nonlinear programming techniques for data reconciliation. The recurrent network architecture is shown to provide comparable, if not superior, results when compared to traditional methods. The networks used were trained using conventional nonlinear programming techniques in a batch fashion.
    Additional Material: 14 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/aic.690401110
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  • 248
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    Computation of phase and chemical equilibria in flue-gas/water systems (1994)
    Hoboken, NJ : Wiley-Blackwell
    AIChE Journal 40 (1994), S. 1892-1900 
    Details
    ISSN: 0001-1541
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: The phase and chemical equilibria of flue-gas/water systems containing sour gases such as HCl, HF, SO2, SO3, NOx and volatile heavy metal compounds such as Hg, HgCl2, and SeO2 are calculated from thermodynamic standard data using the Gibbs free energy minimization method. The Pitzer/Debye/Hückel equation is used for the activity coefficients of the ions in the aqueous solution. The inhibition of certain oxidation reactions is considered by a proper formulation of the atom matrix. The comparison of the calculated equilibrium values to experimental data from a coalfired power plant show that concentrations of most pollutants at the outlet of the absorbers are close to the equilibrium values of one single theoretical stage. The extension of the Gibbs free energy minimization to multistage countercurrent absorbers gives the concentration profiles of various components.
    Additional Material: 2 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/aic.690401112
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  • 249
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    Retention of proteins in cross-flow UF through asymmetric inorganic membranes (1994)
    Hoboken, NJ : Wiley-Blackwell
    AIChE Journal 40 (1994), S. 1901-1910 
    Details
    ISSN: 0001-1541
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: The flow and retention of 0.1% w/w aqueous solutions of pepsin, bovine serum albumin (BSA), lipase, γ-globulin, and invertase with molecular weights of 36,000, 67,000, 80,000, 150,000, and 270,000 dalton (g/mol) are studied when they are tangentially filtered through an inorganic microporous membrane with a nominal pore size of 0.02 × 10-6 m made by Anopore, with transmembrane pressure differences up to 100 kPa. The data were analyzed within the frame of the film layer theory for the concentration polarization phenomenon. This allows the mass-transfer coefficient to be obtained for the cell used as a function of the feed circulation speed and the molecular weight of the solute. Apparent and true retention curves obtained lead to a size exclusion radius smaller than the nominal one but very similar to that obtained from scanning electronic photographs.
    Additional Material: 14 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/aic.690401114
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  • 250
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    Film deposition by plasma techniques. By Mitsuharu Konuma, Springer-Verlag, 1992, 221 pp. (1994)
    Hoboken, NJ : Wiley-Blackwell
    AIChE Journal 40 (1994), S. 1924-1924 
    Details
    ISSN: 0001-1541
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/aic.690401117
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  • 251
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    Granular matter: An interdisciplinary approach. Edited By A. Mehta, Springer-Verlag, New York, 306 pp., 1994 (1994)
    Hoboken, NJ : Wiley-Blackwell
    AIChE Journal 40 (1994), S. 1925-1925 
    Details
    ISSN: 0001-1541
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/aic.690401119
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  • 252
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    Polymeric gas separation membranes. By R. E. Kesting and A. K. Fritzsche, Wiley Interscience Publishers, New York, 1993, XI + 416 pp. (1994)
    Hoboken, NJ : Wiley-Blackwell
    AIChE Journal 40 (1994), S. 1925-1926 
    Details
    ISSN: 0001-1541
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/aic.690401120
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  • 253
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    Reduced kinetic mechanisms for applications in combustion systems. Edited by N. Peters and B. Rogg, Spring-Verlag, New York, Lecture Notes in Physics, Monograph 15, 1993, 360 pp. (1994)
    Hoboken, NJ : Wiley-Blackwell
    AIChE Journal 40 (1994), S. 1926-1927 
    Details
    ISSN: 0001-1541
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/aic.690401122
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  • 254
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    The design of drugs to macromolecular targets. Edited by C. R. Beddell (1994)
    Hoboken, NJ : Wiley-Blackwell
    AIChE Journal 40 (1994), S. 1927-1927 
    Details
    ISSN: 0001-1541
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/aic.690401123
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  • 255
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    Core-annular flow of liquid membrane emulsion (1994)
    Hoboken, NJ : Wiley-Blackwell
    AIChE Journal 40 (1994), S. 1961-1968 
    Details
    ISSN: 0001-1541
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: A modeling and experimental study of the core-annular flow (CAF) was carried out with a viscous liquid membrane emulsion as the core and an aqueous solution as the annulus. A hydrodynamic model has been developed for stable CAF with a centered, nondeformable core surrounded by a turbulent aqueous annulus with or without a drag reducer. This model has been verified with data from flow tests with viscous emulsions in a horizontal flow loop of 3/4-in. (19-mm) tubing and a fullscale, down-hole well tubing of 2-7/8 in. (73 mm). By the use of this model along with the data, the effects of annular size on total and core flow rates and pressure drop are investigated for annuli with and without a drag reducer.
    Additional Material: 10 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/aic.690401205
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  • 256
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    Video technique for measuring dynamics of liquid-liquid dispersion during phase inversion (1994)
    Hoboken, NJ : Wiley-Blackwell
    AIChE Journal 40 (1994), S. 1940-1949 
    Details
    ISSN: 0001-1541
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Studies on the dynamics of phase inversion available offer limited information due to the difficulty of following the transient mean and drop-size distribution. A new technique developed provides such data. A stereo microscope with a very shallow depth of field attached to a video camera gives sharp images of droplets in intensely-agitated, immiscible liquid dispersions by using a Strobotach pulsing at the camera framing rate. Droplets from 40 μm upward at concentrations up to 70% by volume dispersed phase can be measured accurately. Droplets of continuous organic phase in aqueous drops can be seen. The pictures can be analyzed semiautomatically using a computer and in-house software to give, using a variety of discretizations, cumulative and frequency distributions to any base and any mean size. Means and distributions are a function of time for phase inversions generated in three ways. The technique gives a powerful tool for understanding fast, complex dispersion processes.
    Additional Material: 9 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/aic.690401203
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  • 257
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    Minimum entrainer flows for extractive distillation: A bifurcation theoretic approach (1994)
    Hoboken, NJ : Wiley-Blackwell
    AIChE Journal 40 (1994), S. 243-268 
    Details
    ISSN: 0001-1541
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: In addition to a minimum reflux, every extractive distillation exhibits a maximum reflux, above which the desired separation is impossible, and a minimum entrainer flow rate, below which the separation is also impossible. Both of these quantities correspond to bifurcations of the finite difference equations describing the middle section of the column and, given a VLE model, can be easily calculated knowing only information about the column feed and the desired product compositions, that is, prior to any column design calculations.Both maximum reflux and minimum entrainer flows have important implications for the design and operation of extractive distillations. By limiting the range of feasible operating reflux ratios, the maximum reflux affects the flexibility, operability and controllability of the column. Ranking a set of feasible extractive entrainers according to their minimum entrainer flows provides a simple effective method for identifying the most promising candidates. Near optimal design values of the entrainer flow can then be estimated using the heuristic presented.
    Additional Material: 28 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/aic.690400206
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  • 258
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    A thermodynamic model for structure-H hydrates (1994)
    Hoboken, NJ : Wiley-Blackwell
    AIChE Journal 40 (1994), S. 312-320 
    Details
    ISSN: 0001-1541
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: A statistical thermodynamics model based on the original work of van der Waals and Platteeuw is presented for structure-H hydrates. The model is an extension of the hydrate prediction method generalized by Parrish and Prausnitz for structure-I and-II hydrates. Four structure-H-forming systems, methane+ adamantane, methane+ neohexane, methane+isopentane, and methane+methylcyclohexane, were considered. Optimized Kihara core parameters are presented for each of the large hydrocarbon guest molecules. The optimized reference chemical potential difference and reference enthalpy difference for structure-H hydrates are also presented. The results show good agreement with the experimentally determined phase-equilibria conditions. A sensitivity analysis is presented for the parameters in the model, and their relative order of influence on the accurate evaluation of the quilibrium pressure is determined.
    Additional Material: 10 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/aic.690400210
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  • 259
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    Random motility of swimming bacteria: Single cells compared to cell populations (1994)
    Hoboken, NJ : Wiley-Blackwell
    AIChE Journal 40 (1994), S. 334-348 
    Details
    ISSN: 0001-1541
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: The motility of a population of swimming bacteria can be characterized by a random motility coefficient, μ, the operational equivalent of a diffusion coefficient at the macroscopic level and in the absence of interacting chemical gradients. At the microscopic level, random motility is related to the single-cell parameters: speed, tumbling probability, and index of directional persistence (related to the angle a cell's path assumes following a change in direction). Various mathematical models have been proposed for relating the macroscopic random motility coefficient to these microscopic single-cell parameters. In separate experiments, we have measured motility at both the cell-population and single-cell levels for Escherichia coli. The agreement of these results shows that the macroscopic transport behavior of a population of motile bacteria can be predicted from straightforward microscopic observations on single cells.
    Additional Material: 12 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/aic.690400212
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  • 260
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    Kinetics of H2S absorption into aqueous ferric solutions of edta and hedta (1994)
    Hoboken, NJ : Wiley-Blackwell
    AIChE Journal 40 (1994), S. 433-444 
    Details
    ISSN: 0001-1541
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Kinetics of the reaction of hydrogen sulfide with ferric chelates of ethylenediaminetetraacetic acid (EDTA) at 22°C and with ferric chelates of hydroxyethyle-thylenediaminetriacetic acid (HEDTA) from 21°C to 60°C were studied in a stirred cell reactor under industrial conditions. Concentration of the ferric chelates ranged from 40 to 150 mol/m3 and the pH was varied from 4 to 10. Only the hydroxy forms of the ferric chelates appear to react with hydrogen sulfide. Under the conditions applied, the reaction appeared to be first-order in hydrogen sulfide and first-order in hydroxy ferric chelate. At 22°C the rate constant for the EDTA complex is 14-21 m3/mol·s. Uncertainty in this constant is due to the characteristics of the EDTA complex at pH values above 7. For the HEDTA complex, the activation energy of the reaction of hydrogen sulfide with the monohydroxy ferric chelate is (26.4 ± 0.6) kJ/mol with k11m = 1.8 m3/mol·s at 25°C. The rate constant for the reaction with the dihydroxy ferric chelate is (300 ± 150) m3/mol·s in the temperature range investigated.
    Additional Material: 12 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/aic.690400307
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  • 261
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    Synthesis of reactive mass-exchange networks with general nonlinear equilibrium functions (1994)
    Hoboken, NJ : Wiley-Blackwell
    AIChE Journal 40 (1994), S. 463-472 
    Details
    ISSN: 0001-1541
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: The problem of synthesizing reactive mass-exchange networks (REAMENs) is addressed for which the equilibrium relations governing the transfer of a certain species from rich streams to reactive mass-separating agents are nonlinear (convex and/or nonconvex). Previously developed synthesis procedures for REAMENs are not applicable to such cases, since they were developed for cases of linear and/or convex equilibria. Two peculiar phenomena are associated with REAMENs with general nonlinear equilibria: the location of a mass-exchangers may straddle the pinch point even for networks featuring the minimum cost of mass-separating agents. To account for such intriguing characteristics, a systematic procedure is developed to synthesize cost-effective REAMENs with general nonlinear equilibria. In addition, a robust solution procedure is devised to guarantee the identification of the global solution of the developed optimization programs. Applicability and usefulness of the proposed synthesis procedure are demonstrated via a case study on the desulfurization of gaseous wastes from a coal-to-methanol plant.
    Additional Material: 12 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/aic.690400309
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  • 262
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    A knowledge-based framework for automating HAZOP analysis (1994)
    Hoboken, NJ : Wiley-Blackwell
    AIChE Journal 40 (1994), S. 496-505 
    Details
    ISSN: 0001-1541
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Hazard and operability (HAZOP) analysis is the study of systematically identifying every conceivable abnormal process deviation, its abnormal causes and adverse hazardous consequences in a chemical plant. HAZOP analysis is a difficult, time-consuming, and labor-intensive activity. A automated HAZOP system can reduce the time and effort involved in a HAZOP review, make the review more thorough and detailed, and minimize or eliminate human errors. Towards that goal, a knowledge-based system, called HAZOPExpert, has been proposed in this article. In this approach, HAZOP knowledge is divided into process-specific and processindependent components in a model-based manner. The framework allows for these two components to interact during the analysis to address the process-specific aspects of HAZOP analysis while maintaining the generality of the system. Process-general knowledge is represented as HAZOP models that are developed in a process-independent manner and are applicable to a wide variety of process flowsheets. The important features of HAZOPExpert and its performance on an industrial case study are described.
    Additional Material: 7 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/aic.690400311
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    Thermal dehydration of magnesium hydroxide and sintering of nascent magnesium oxide (1994)
    Hoboken, NJ : Wiley-Blackwell
    AIChE Journal 40 (1994), S. 536-542 
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    ISSN: 0001-1541
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Increasing and constant temperature gravimetric methods were used to measure the thermal decomposition rates of Mg(OH)2 particles. An Arrhenius-type kinetic equation was proposed and tested. Temperature, exposure time on surface area of the calcined particles and other effects of variables were explored. A fractional-order sintering rate expression was developed on the basis of collected experimental data. An integrated model is also presented that considers the surface area generation by calcination and the simultaneous surface reduction caused by sintering of the nascent oxide. Obtained results enable specifying the operating conditions needed for the production of the high surface, reactive magnesium oxide.
    Additional Material: 5 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/aic.690400314
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  • 264
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    Hindered settling function with no empirical parameters for polydisperse suspensions (1994)
    Hoboken, NJ : Wiley-Blackwell
    AIChE Journal 40 (1994), S. 570-575 
    Details
    ISSN: 0001-1541
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
    Additional Material: 6 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/aic.690400317
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  • 265
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    Reduction of ion-exchange equilibria data using an error in variables approach (1994)
    Hoboken, NJ : Wiley-Blackwell
    AIChE Journal 40 (1994), S. 556-569 
    Details
    ISSN: 0001-1541
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: An error in variables method (EVM) was used to reduce binary ion-exchange equilibria data. Ion-exchange equilibria data were collected via batch equilibrium experiments. Three binary ion-exchange systems were studied: the Na+1-Cd+2, Na+1-Cu+2, and Cu+2-Cd+2 systems with a strong acid synthetic ion-exchange resin. The Wilson model and a three-suffix, two-parameter Margules equation were used to model the dependency of the resin phase activity coefficients with resin-phase composition. The EVM was used to determine the best-fit estimates of the Wilson and Margules equation binary resin-phase activity coefficient parameters. Statistical analysis of the data fits indicates that although both equations were able to adequately model the resin phase nonidealities, the Wilson model provided the superior data fits based on the minimized objective functions.
    Additional Material: 9 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/aic.690400316
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  • 266
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    Nonlinear inferential control of pulp digesters (1994)
    Hoboken, NJ : Wiley-Blackwell
    AIChE Journal 40 (1994), S. 50-64 
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    ISSN: 0001-1541
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Monitoring and control of batch pulp digesters, which convert wood chips to pulp by Kraft process are discussed. The Kappa number, which represents the extent of delignification, is the key controlled variable, which cannot be measured on-line and must be estimated through secondary liquor measurements. Given a fixed batch time, the final Kappa number should be as close to the target Kappa number as possible, despite errors in the initial state estimates and input disturbances. To fulfill this objective, a state-observer-based model-predictive controller is designed using a detailed nonlinear dynamic model of the digester. The extended Kalman filter (EKF) using on-line measurements of various liquor characteristics is capable of recovering from significant errors in the initial state estimates. In addition, the EKF is shown to be robust to the errors in the covariance matrices and most model parameters, but quite sensitive to some model parameter errors. Coupled with the EKF, a finite-horizon model predictive controller (MFC) based on successive linearization of the nonlinear pulping model, is found to work efficiently for controlling the Kappa number and batch time.
    Additional Material: 9 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/aic.690400108
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  • 267
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    Tubular reactors for emulsion polymerization: I. Experimental investigation (1994)
    Hoboken, NJ : Wiley-Blackwell
    AIChE Journal 40 (1994), S. 73-87 
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    ISSN: 0001-1541
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Experimental results using a pulsed tubular reactor are presented. The use of a pulsation source eliminates the reactor fouling and plugging issue that has occurred in previous investigations. Startup data and steady-state profiles are presented. Comparisons in monomer conversion and particle-size distribution for batch, CSTR and tubular reactor are made. The influence of pulsation on the particle-size dis-tribution is discussed. It is shown that high-conversion latex with a narrow particle size distribution can be produced continuously in the pulsed tubular reactor.
    Additional Material: 26 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/aic.690400110
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    Tubular reactors for emulsion polymerization: II. Model comparisons with experiments (1994)
    Hoboken, NJ : Wiley-Blackwell
    AIChE Journal 40 (1994), S. 88-96 
    Details
    ISSN: 0001-1541
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: A dynamic model for emulsion polymerization in a tubular reactor has been developed and compared with experimental data. The model uses an axial dispersion coefficient to fit experimentally measured residence time distributions and to represent axial mixing during reaction. Very general emulsion polymerization kinetics are assumed so that a wide range of monomers and operating conditions can be handled. Orthogonal collocation on finite elements was chosen as the numerical solution technique. Comparisons show good agreement between model and experiments for two different monomers.
    Additional Material: 9 Ill.
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    URL: http://dx.doi.org/10.1002/aic.690400111
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    Influence of increased gas density on hydrodynamics of bubble-column reactors (1994)
    Hoboken, NJ : Wiley-Blackwell
    AIChE Journal 40 (1994), S. 112-119 
    Details
    ISSN: 0001-1541
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: A mechanistic background to the understanding of the hydrodynamics of high-pressure bubble column reactors in both the homogeneous and heterogeneous flow regimes is discussed. An important parameter determining the stability of homogeneous bubbly flow in a bubble column is shown to be the Richardson-Zaki exponent in the bubble swarm velocity relationship Vswarm = v∞(1-∊)n-1. Experimental data for the bubble swarm velocity were obtained in 0.05- and 0.1-m-dia. bubble columns with various gases (helium, air, argon, sulfur hexafluoride) using water as the liquid phase. Bubble swarm velocity data show that with increasing gas density the Richardson-Zaki exponent value decreases; physically this means that increasing gas density reduces interaction between neighboring bubbles and, consequently, reduces chance of propagation of instabilities. This rationalizes the experimental observation that the influence of increased gas density ρG is to delay the transition from homogeneous bubbly flow to churn-turbulent flow: increasing ρG increases the regime transition velocity. A stability analysis rationalizes the observations. The hydrodynamics of bubble columns in the churn-turbulent regime is considered to be analogous to that of a bubbling gas-solid fluidized bed, and the two-phase theory of gas-solid fluid beds is extended to describing bubble columns by identifying the “dilute” phase as the fast-rising large bubbles and the “dense” phase as the liquid phase with entrained small bubbles. A simple coalescence rationalizes experimental large-bubble holdup data.
    Additional Material: 11 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/aic.690400113
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    Modeling the spontaneous ignition of coal stockpiles (1994)
    Hoboken, NJ : Wiley-Blackwell
    AIChE Journal 40 (1994), S. 991-1004 
    Details
    ISSN: 0001-1541
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: The spontaneous ignition of coal stockpiles is a serious economic and safety problem. This phenomenon is analyzed using the approach of modern reaction engineering, which is made challenging by the nonlinear interactions of chemical reaction, heat transfer, and buoyancy-driven flows within and around the stockpile. A model developed represents reaction and transport within a realistically-shaped stockpile and transport and flow in the surrounding air. A new methodology based on the Galerkin finite-element method (Salinger, 1993b) allows for efficient solution of flows in both porous and open domains. Bifurcation analysis is used to track steady-state model solutions of relevant parameters, such as the Damköhler number (dimensionless reaction rate), Rayleigh number (dimensionless driving force for buoyant flow), and dimensionless permeability of the stockpile. The solutions provide an understanding of the roles of various transport mechanisms on the ignition behavior and nonlinear coupling between these mechanisms. Results clearly demonstrate the need for incorporating realistic descriptions of flow and transport in the surrounding air into the model.
    Additional Material: 9 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/aic.690400610
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    Explicit calculation of multicomponent equilibria for ideal adsorbed solutions (1994)
    Hoboken, NJ : Wiley-Blackwell
    AIChE Journal 40 (1994), S. 182-186 
    Details
    ISSN: 0001-1541
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
    Additional Material: 2 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/aic.690400121
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    Controlling the morphology of CVD films (1994)
    Hoboken, NJ : Wiley-Blackwell
    AIChE Journal 40 (1994), S. 1032-1045 
    Details
    ISSN: 0001-1541
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: The morphology of the gas-solid interface during typical chemical vapor deposition (CVD) processes is investigated. The dynamic behavior of the interface depends on many factors, including local curvature of the film, reactant diffusion, adsorption equilibrium, surface kinetics, and mobility of adatoms. These factors depend on material properties of the system and reactor conditions, such as the deposition temperature and pressure. A 2-D model proposed describes the evolution of the interface in Cartesian coordinates under the influence of stabilizing and destabilizing effects. A linear stability analysis is used to predict under which conditions a planar interface becomes unstable. Stability criteria of a simplified 1-D analysis is not necessarily valid if the real system has more than one dimension. The substrate temperature and reactor pressure are important factors affecting the stability of film growth and thus the morphology of CVD films. An increase in temperature stabilizes planar film growth if the deposition is diffusion-limited, but destabilizes it if the process is reaction-controlled. The reactor pressure has a destabilizing effect on planar film growth during a typical CVD process.
    Additional Material: 10 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/aic.690400614
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    Kinetics and mechanism of isobutene formation from T-butanol in hot liquid water (1994)
    Hoboken, NJ : Wiley-Blackwell
    AIChE Journal 40 (1994), S. 1524-1534 
    Details
    ISSN: 0001-1541
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Isobutene is the only product of the uncatalyzed and acid-catalyzed dehydration of tert-butanol in compressed liquid water at 250°C. The uncatalyzed dehydration reaction is fast: equilibrium is established after about 30 s. Only one of many chemically-motivated kinetic models is able to fit all the experimental data. This model presumes a heterolytic dehydration mechanism that involves protonated alcohol, carbocation, di-tert-butyl ether, and protonated ether as intermediates. The model permits tert-butanol to dissociate as both an Arrhenius acid and a Bronsted acid while catalyzing its dehydration to isobutene. The pKa of tert-butanol at 250°C is predicted to be about 9, whereas its value at normal temperature and pressure is 18. This 109 increase in the Ka value of tert-butanol hints of the promising new world of reaction chemistry in near- and supercritical water.
    Additional Material: 9 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/aic.690400911
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    Multicomponent separation using a column-switching chromatographic method (1994)
    Hoboken, NJ : Wiley-Blackwell
    AIChE Journal 40 (1994), S. 1843-1849 
    Details
    ISSN: 0001-1541
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: A cyclic chromatographic process based on the method of column switching was used to separate a three-component carbohydrate mixture. It permits continuous introduction of the feed and is designed to produce higher product concentration compared to a normal elution cyclic process. A fixed-bed model incorporating axial dispersion and a linear driving force for mass transfer was successfully used to estimate optimum operating conditions (switch times and fluid-flow rates). Its experimental setup can be easily constructed by modifying the apparatus of a simulated countercurrent process since both systems comprise segmented columns equipped with on-off valves for fluid-flow control. This allows one to conduct either multicomponent separation based on elution operation or binary separation based on countercurrent operation using essentially the same set of experimental apparatus with minor modification.
    Additional Material: 6 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/aic.690401108
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    Robust design of countercurrent adsorption separation processes: 2. Multicomponent systems (1994)
    Hoboken, NJ : Wiley-Blackwell
    AIChE Journal 40 (1994), S. 1825-1842 
    Details
    ISSN: 0001-1541
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: The adsorption separation of a multicomponent mixture in a four-section countercurrent separation unit is analyzed. A procedure for the optimal and robust design of the unit is developed in the frame of equilibrium theory, where adsorption equilibria are described through the constant selectivity stoichiometric model, while mass-transfer resistances and axial dispersion are neglected.A set of conditions obtained defines a region in the operating parameters space where the unit achieves complete separation. In the case of binary separations, with a desorbent having any adsorptivity with respect to the components to be separated, the boundaries of this region are obtained explicitly. In the general multicomponent case, a numerical procedure is needed. An approximate shortcut method devised allows to obtain explicit and reliable relationships for estimating the boundaries of the exact region.The results provide a very convenient tool not only to analyze the role of the desorbent in determining the separation performance, but to find both optimal and robust operating conditions. Comparison between model predictions and experimental data assesses the reliability and accuracy of the theoretical findings.
    Additional Material: 12 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/aic.690401107
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    Colloidal gel filtration: Experiment and theory (1994)
    Hoboken, NJ : Wiley-Blackwell
    AIChE Journal 40 (1994), S. 1876-1891 
    Details
    ISSN: 0001-1541
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: The filtration of colloidal gels, consisting of octadecyl-coated silica spheres in hexadecane, is examined experimentally using CAT scanning. A number of interparticle strengths are explored, with significant differences in qualitative behavior relative to the filtration of stable dispersions. For stiff gels, the transmission of stresses from the cell wall to the dispersion results in a fracturing phenomenon during consolidation on a length scale substantially larger than the particle size. For more pliant gels, the radial propagation of stress is more local to the wall region and gravitational effects play a prominent role. The existing theory of network consolidation is compared against our experimental results for pliant gels, independent of the form of the constitutive functions for the sedimentation velocity and yield stress. Though our measurements seem consistent with the theory at early times, deviations at later moments question whether a compressive yield stress is actually present.
    Additional Material: 19 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/aic.690401111
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    Electrostatic spraying of nonconductive fluids into conductive fluids (1994)
    Hoboken, NJ : Wiley-Blackwell
    AIChE Journal 40 (1994), S. 1920-1923 
    Details
    ISSN: 0001-1541
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
    Additional Material: 4 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/aic.690401116
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    Reducing NOx in diesel exhausts by SCR technique: Experiments and simulations (1994)
    Hoboken, NJ : Wiley-Blackwell
    AIChE Journal 40 (1994), S. 1911-1919 
    Details
    ISSN: 0001-1541
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Results of experiments are compared to simulations of the performance of V2O5/γ-alumina SCR catalyst used to remove nitrogen oxides from diesel exhausts. The kinetic model is based on Eley-Rideal kinetics. Temperature programmed desorption (TPD) of the ammonia is used to evaluate adsorption/desorption parameters. Stationary experiments on a 3.6-dm3 engine with a 4.8-dm3 honeycomb catalyst is used to evaluate kinetic rate parameters for the reduction of NO with NH3. The desorption activation energy, Ea,des, is best fitted as a function of surface coverage yielding Ea,des = 240* (I -0.44* θNH30.36) kJ/mol. A dynamic test (FTP) with a 12-dm3 engine and24.8-dm3 honeycomb catalyst is done with astoichiometric injection of ammonia. The NOx conversion is 52%, but during the freeway traffic the conversion reached 72%. The prediction of NOx conversion is good, but there are some deviations for temperature and ammonia slip.
    Additional Material: 8 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/aic.690401115
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    Influence of dynamic interfacial properties on droplet breakup in simple shear flow (1994)
    Hoboken, NJ : Wiley-Blackwell
    AIChE Journal 40 (1994), S. 1929-1939 
    Details
    ISSN: 0001-1541
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: The breakup of droplets in an inhomogeneous flow is the key to emulsification. Frequently, the local flow experienced by the drops is a (quasi-) simple shear flow. The breakup of droplets in a steady, simple shear flow in the absence of emulsifiers has been studied extensively. In the presence of emulsifiers, the droplet interface may acquire viscoelastic properties, which are important in the prevention of coalescence, but their influence on droplet breakup has not been established solidly. This article reports on a phenomenological approach, which links the droplet breakup dynamics to the interfacial viscoelasticity, identifying the latter with the elasticity modulus of a deforming planar interface. Over a viscosity ratio range of three decades, the results have been found to agree with the model, which uses only independently known quantities derived from equilibrium interfacial tension properties.
    Additional Material: 12 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/aic.690401202
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    Experimental study and parameterization of gas absorption by water drops (1994)
    Hoboken, NJ : Wiley-Blackwell
    AIChE Journal 40 (1994), S. 1950-1960 
    Details
    ISSN: 0001-1541
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Liquid-phase mass-transfer coefficients are determined for the absorption of sulfur dioxide by water drops larger than 1.1 mm in dia. A local model based on the large eddy interfacial model proposed by Fortescue and Pearson (1967) is obtained by the characteristic interfacial scaling. In particular, the agitation process of the liquid phase in the interfacial region is characterized by the interfacial liquid friction velocity. Experiments of sulfur dioxide absorption and desorption from large individually free-falling water drops are also carried out in a 5-m rain shaft under various environmental conditions. These experimental results agree well with those from the local model characterizing the interfacial process in water drops greater than 1.1 mm in dia.
    Additional Material: 9 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/aic.690401204
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    Erratum (1994)
    Hoboken, NJ : Wiley-Blackwell
    AIChE Journal 40 (1994), S. 1982-1982 
    Details
    ISSN: 0001-1541
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/aic.690401208
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    Heat-transfer characteristics in viscous gas-liquid and gas-liquid-solid systems (1994)
    Hoboken, NJ : Wiley-Blackwell
    AIChE Journal 40 (1994), S. 745-755 
    Details
    ISSN: 0001-1541
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Local heat-transfer measurements are performed using a special heat-transfer probe in gas-liquid and gas-liquid-solid systems with viscous Newtonian liquids as the continuous phase. Effects of viscosity on bubble-liquid and bubble-liquid-solid interactions affecting local heat transfer are studied through heat-transfer experiments with simultaneous flow visualization in a simplified system involving single bubbles or a chain of gas bubbles moving in viscous liquids and liquid-solid systems. Effects of viscosity on bubble wake and local heat transfer are examined with reference to heat transfer in freely-bubbling beds (bubble columns and three-phase fluidized beds). The kinematic viscosity of the fluid greatly influences the nature of flow in the wake which affects local heat transfer in the bed. The local heat transfer decreases with the viscosity due to the rapid decay in the circulation strength of the bubble wake caused by increased viscous dissipation of vorticity. Local heat transfer due to cyclic/periodic injection of bubbles is significantly enhanced due to increased bubble-wake interactions which rapidly accelerate bubbles and increase average bubble rise velocity. Heat transfer in simplified liquid and liquid-solid systems with single- and chain-bubble injections characterizes the local heat-transfer performance of freely-bubbling beds (bubble columns and three-phase fluidized beds). A mechanistic model developed accounts for the heat-transfer behavior in bubble columns and three-phase fluidized beds with viscous liquids.
    Additional Material: 10 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/aic.690400502
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    Estimation of crystallization kinetics from batch cooling experiments (1994)
    Hoboken, NJ : Wiley-Blackwell
    AIChE Journal 40 (1994), S. 799-812 
    Details
    ISSN: 0001-1541
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: A direct optimization method to estimate nucleation and crystal growth rate parameters from seeded batch cooling crystallization experiments is evaluated. The experimental information applied comprises the concentration of the solution and the temperature as functions of time and the final product size distribution. Parameters in kinetic equations are determined by nonlinear optimization of a dynamic model of the experiment, by which intermediate approximations of experimental data are avoided. The optimization objective function includes both solution concentration data and product size distribution data. Kinetics are estimated for succinic acid crystallizing in aqueous solutions. Results from several different cooling crystallizations are simultaneously supplied into one single optimization to determine seven parameters.
    Additional Material: 14 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/aic.690400507
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    Optimization of distillation units using collocation models (1994)
    Hoboken, NJ : Wiley-Blackwell
    AIChE Journal 40 (1994), S. 813-825 
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    ISSN: 0001-1541
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Reduced-order models are developed based on orthogonal collocation on finite elements for the steady-state optimization of multicomponent distillation units. The formulation divides the column sections into subdomains (finite elements) to track irregularities in the column profiles accurately and requies that plates with discontinuities in the flows introduced by feedstreams or sidestreams should be treated as discrete equilibrium stages. Application of the model formulation to a number of examples show that reduced-order models converge to the same optimal solution as the full-order, tray-by-tray model. Optimization results show that computational time can be reduced significantly using the more compact model formulation, and it is possible to converge to the optimal solution from a larger region for the initial set of variable values.
    Additional Material: 8 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/aic.690400508
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    Diagnosis of multiple simultaneous fault via hierarchical artificial neural networks (1994)
    Hoboken, NJ : Wiley-Blackwell
    AIChE Journal 40 (1994), S. 839-848 
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    ISSN: 0001-1541
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: We discuss a new type of macroarchitecture of neural networks called a HANN and how to train it for fault diagnosis given appropriate data patterns. The HANN divides a large number of patterns into many smaller subsets so the classification can be carried out more efficiently via an artificial neural network. One of its advantages is that multiple faults can be detected in new data even if the network is trained with data representing single faults. The use of a HANN is illustrated in fault diagnosis of a chemical reactor.
    Additional Material: 3 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/aic.690400510
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    Food sterilization by electrical heating: Sensitivity to process parameters (1994)
    Hoboken, NJ : Wiley-Blackwell
    AIChE Journal 40 (1994), S. 888-898 
    Details
    ISSN: 0001-1541
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: The design of efficient continuous sterilization equipment for flowing solid-liquid food mixtures requires that temperature and velocity distributions within the fluid are known. In electrical (ohmic) heating, electric current is passed through a two-sterilize it. This allows rapid sterilization of solid-liquid mixtures which minimizes quality loss. A computational process model simulates the effect of realistic physical property changes. The effect of variations in physical properties can have a significant effect on the temperature of the product and thus on its sterility. Realistic designs will have to cope with temperature differences between phases. Experimental data for velocities in a food flow have been incorporated into an enthalpy balance model for heat transfer in solid-liquid mixtures. The effect of inlet temperature on the length of hold tube required to give the necessary process sterility calculated shows the variation in output conditions that might results in real systems.
    Additional Material: 9 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/aic.690400515
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    Masthead (1994)
    Hoboken, NJ : Wiley-Blackwell
    AIChE Journal 40 (1994) 
    Details
    ISSN: 0001-1541
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/aic.690400601
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    Hysteresis-dependent adsorption-desorption cycles: Generalization for isothermal conditions (1994)
    Hoboken, NJ : Wiley-Blackwell
    AIChE Journal 40 (1994), S. 913-924 
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    ISSN: 0001-1541
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Hysteresis-dependent adsorption-desorption equilibrium cycles are measured for the systems water vapor-silica gel at 25°C. Various and distinct types of equilibrium cycles are observed, depending on the relative positions of the limiting partial pressures with respect to the closure points of the main hysteresis loop as well as the history of the cycle. Hysteresis-dependent cycles are classified accordingly. The simple theoretical model based on the network pore blocking theory for predicting primary and secondary adsorption and desorption isotherms (Rajniak and Yang, 1993) is extended for predicting isotherms of higher orders and equilibrium cycles of all types. Only primary adsorption and desorption isotherms are needed for the predictions. Furthermore, there exists an infinite number of equilibrium cycles between any two partial pressures within the main hysteresis loop; the exact path of the cycle depends on the history before the cycle is initiated - it is memory-dependent.
    Additional Material: 12 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/aic.690400602
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    New lattice model for adsorption of small molecules in zeolite micropores (1994)
    Hoboken, NJ : Wiley-Blackwell
    AIChE Journal 40 (1994), S. 925-934 
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    ISSN: 0001-1541
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: A new adsorption model is developed for small molecules in zeolites whose form is based on features revealed by molecular simulation. Adsorption is assumed to occur onto a 3-D polyhedral lattice, and both the energy and entropy of the lattice sites are accounted for using a statistical mechanics approach. Energetic interactions are described by an Ising model with both 2- and multibody nearest-neighbor in-teractions. Entropic interactions are included by an adsorption site volume term which accounts for the loss of traslational freedom associated with lattice crowding.The model is applied to a system of small molecules (xenon, methane) adsorbed in idealized zeolite NaA, where adsorption has been shown by computer simulation to occur on finite, cuboctahedral lattices (Van Tassel et al., 1992). The model quantitavely predicts the simulated isotherm over the entire pressure range. Comparison is made with a Langmuir model and a van der Waals gas model which, although valid at low pressures, fail at high pressures due to overestimation of translational entropy and inaccurate portrayal of sorbate-sorbate interaction energy.
    Additional Material: 16 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/aic.690400603
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    Simulation and optimization of NOx absorption system in nitric acid manufacture (1994)
    Hoboken, NJ : Wiley-Blackwell
    AIChE Journal 40 (1994), S. 944-956 
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    ISSN: 0001-1541
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: A mathematical model has been developed for the prediction of the optimum design of packed and plate columns for the manufacture of nitric acid. The effects of inlet NOx composition, extent of oxidation and extent of absorption in each stage, temperature, and pressure have been included in the model. The optimization of the preoxidizer and the condenser has also been discussed.
    Additional Material: 17 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/aic.690400605
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    Optimizing experimental conditions for minimum production cost in preparative chromatography (1994)
    Hoboken, NJ : Wiley-Blackwell
    AIChE Journal 40 (1994), S. 594-605 
    Details
    ISSN: 0001-1541
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Optimum experimental conditions and column design parameters are calculated for most economical separation of binary mixtures by preparative liquid chromatography. The solvent consumption and capital costs are regarded as the two major cost contributions. Calculations were performed by using the numerical solution of the equilibrium-dispersive model of chromatography and a nonlinear simplex algorithm. Solvent consumption depends only on the column efficiency, the retention factor, and the loading factor. The production rate depends on the particle size, the column length, the mobile-phase flow velocity, the retention and the loading factors, and can be optimized with or without recovery yield constraints. A hybrid objective function was constructed to find the tradeoffs between the production rate and the solvent consumption.
    Additional Material: 10 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/aic.690400404
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  • 292
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    Nonlinear control of a polymerization CSTR with singular characteristic matrix (1994)
    Hoboken, NJ : Wiley-Blackwell
    AIChE Journal 40 (1994), S. 980-990 
    Details
    ISSN: 0001-1541
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: This experimental work concerns the multivariable nonlinear control of a pilotsize continuous polymerization reactor with generically singular characteristic matrix. The control problem is to control conversion and temperature in a continuous stirred tank reactor by manipulating two coordinated flow rates (reactor residence time) and two coordinated heat inputs. A nonlinear controller is synthesized within the framework of the globally linearizing control (GLC) method and is implemented on a microcomputer. Conversion is inferred from on-line measurements of density and temperature. A key feature of the control problem is that its characteristic matrix is generically singular. Singularity of the characteristic matrix is handled by using a dynamic input/output linearizing state feedback rather than a static feedback. A reduced-order observer is used to calculate the monomer, initiator, and solvent concentration estimates, which are needed for the calculation of controller action. In the presence of active state and input constraints, the reactor-startup and setpointtracking performance of the controller is evaluated through experimental runs.
    Additional Material: 14 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/aic.690400609
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  • 293
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    Electronic Resource
    Ignition and extinction of flames near surfaces: Combustion of CH4 in air (1994)
    Hoboken, NJ : Wiley-Blackwell
    AIChE Journal 40 (1994), S. 1005-1017 
    Details
    ISSN: 0001-1541
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Ignition and extinction characteristics of homogeneous combustion of methane in air near inert surfaces are studied by numerical bifurcation theory for premixed methane/air gases impinging on planar surfaces with detailed chemistry involving 46 reversible reactions and 16 species. One-parameter bifuraction diagrams as functions of surface temperature and two-parameter bifurcation diagrams as functions of equivalence ratio and strain rate are constructed for both isothermal and adiabatic walls. Lean and rich composition limits for ignition and extinction, and energy production are determined from two parameter bifurcation diagrams. For a strain rate of 500 s-1, CH4/air mixtures exhibit hysteresis from ∼ 0.5% up to ∼ 12.5% and from ∼ 5.5% up to ∼ 13.5% near isothermal surfaces and adiabatic walls, respectively. Ignition temperature rises with composition from 1,700 to 1,950 K, without a maximum around the stoichiometric ratio. Under some conditions multiple ignitions and extinctions can occur with up to five multiple solutions, and wall quenching, kinetic limitations, and transport can strongly affect flame stability. Flames near the stoichiometric ratio cannot be extinguished by room temperature surfaces for sufficiently low strain rates. The role of intermediates in enhancing or retarding ignition and extinction is studied, and implications of the effect of catalytic surfaces on homogeneous ignition and extinction are discussed. Removal of H atoms and CH3 radicals by wall adsorption can increase extinction and ignition temperature of 6% CH4 in air by up to 300 K for a strain rate of 500 s-1.
    Additional Material: 9 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/aic.690400611
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  • 294
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    Electrostatic droplet generation: Mechanism of polymer droplet formation (1994)
    Hoboken, NJ : Wiley-Blackwell
    AIChE Journal 40 (1994), S. 1026-1031 
    Details
    ISSN: 0001-1541
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: The mechanism of alginate droplet formation and experimental parameters for producing very small polymer microbeads (less than 100 μm dia.) using an electrostatic droplet generator studied showed that the microbead size was a function of needle diameter, charge arrangement (electrode geometry and spacing) and strength of electric field. Perfectly spherical and uniform polymer beads, 170 μm dia., for example, were obtained at a potential difference of 6 kV with a 26-gauge needle and an electrode distance of 2.5 cm. Increasing the electric field, and thus the surface charge in the vicinity of the needle, by increasing the applied potential, resulted in needle oscillation, giving a bimodal bead size distribution with a large fraction (30-40%) of microbeads with a mean diameter of 50 μm. The process of alginate droplet formation under the influence of electrostatic forces assessed with an image analysis/video system revealed distinct stages. After a voltage was applied, the liquid meniscus at the needle tip was distorted from a spherical shape into an inverted cone-like shape. Consequently, alginate solution flowed into this cone at an increasing rate causing formation of a neck-like filament. When this filament broke away, producing small droplets, the meniscus relaxed back to a spherical shape until flow of the polymer caused the process to start again. A large-scale multineedle device with a processing capacity of 0.7 L/h was also designed and produced uniform 400 ± 150 μm microbeads.
    Additional Material: 5 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/aic.690400613
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  • 295
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    Electronic Resource
    Percolation modeling of foam generation in Porous media (1994)
    Hoboken, NJ : Wiley-Blackwell
    AIChE Journal 40 (1994), S. 1082-1084 
    Details
    ISSN: 0001-1541
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
    Additional Material: 2 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/aic.690400618
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  • 296
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    Electronic Resource
    Conversion of radiant light energy in photobioreactors (1994)
    Hoboken, NJ : Wiley-Blackwell
    AIChE Journal 40 (1994), S. 1055-1066 
    Details
    ISSN: 0001-1541
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: The conversion of radiant light energy into chemical affinity by microorganisms in photobioreactors is examined. The kinetics of entropy production in the system is theoretically established from entropy and energy balances for the material and photonic phases in the reactor. A negative chemical affinity term compensated for by a radiant energy term at a higher level of energy characterizes photosynthetic organisms. The local volumetric rate of radiant light energy absorbed, which appears in the dissipation function as an irreversible term, is calculated for monodimensional approximations providing analytical solutions and for general tridimensional equations requiring the solution of a new numerical algorithm. Solutions for the bluegreen alga Spirulina platensis cultivated in photoreactors with different geometries and light energy inputs are compared. Thermodynambic efficiency of the photosynthesis is calculated. The highest value of 15% found for low radiant energy absorption rates corresponds to a maximum quantum yield in the reactor.
    Additional Material: 7 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/aic.690400616
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  • 297
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    Electronic Resource
    Bubbles, drops, and particles in non-newtonian fluids. By R. P. Chhabra, CRC Press, 1993, $169.95 (1994)
    Hoboken, NJ : Wiley-Blackwell
    AIChE Journal 40 (1994), S. 1085-1085 
    Details
    ISSN: 0001-1541
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/aic.690400619
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  • 298
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    Electronic Resource
    The microkinetics of heterogeneous catalysis. By J. A. Dumesic, D. F. Rudd, L. M. Aparicio, J. E. Rekoske, and A. A. Treviño, ACS Professional Reference Book, American Chemical Society, Washington, DC, 1993, 315 pp. (1994)
    Hoboken, NJ : Wiley-Blackwell
    AIChE Journal 40 (1994), S. 1085-1087 
    Details
    ISSN: 0001-1541
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/aic.690400620
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  • 299
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    Electronic Resource
    Physics of polymer surfaces and interfaces. Edited by Isaac C. Sanchez, Butterworth-Heinemann, 1992, 336 pp. (1994)
    Hoboken, NJ : Wiley-Blackwell
    AIChE Journal 40 (1994), S. 1088-1089 
    Details
    ISSN: 0001-1541
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/aic.690400623
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  • 300
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    Electronic Resource
    Receptors: Models for binding, trafficking and signaling. By Douglas A. Lauffenburger and Jennifer J. Linderman, Oxford University Press, 1993, $70.00 (1994)
    Hoboken, NJ : Wiley-Blackwell
    AIChE Journal 40 (1994), S. 1089-1089 
    Details
    ISSN: 0001-1541
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/aic.690400624
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