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  • 1995-1999  (730)
  • 1890-1899
  • 1995  (730)
  • Chemical Engineering  (730)
  • 101
    Digitale Medien
    Digitale Medien
    Mathematical model on the sensing behavior of a biooxidation biosensor (1995)
    Hoboken, NJ : Wiley-Blackwell
    AIChE Journal 41 (1995), S. 1025-1036 
    Details
    ISSN: 0001-1541
    Schlagwort(e): Chemistry ; Chemical Engineering
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie , Werkstoffwissenschaften, Fertigungsverfahren, Fertigung
    Notizen: A phenomenological model developed describes the steady-state sensing characteristics of a biosensor based on biooxidation of organic solutes by dissolved oxygen. The model is experimentally verified using a recently developed dopamine sensor that enzymatically oxidizes dopamine by polyphenolase in apple tissues. It adequately describes its steady-state sensing characteristics, including the effects of mass of immobilized apple fines in the biofilm, temperature, and pH of the substrate solution. The parameters provide a basis for evaluating the suitability of different bioactive materials or the same bioactive material from different sources for biosensor fabrication. At zero thickness of the membranes and biofilm, the model describes the sensing characteristics of a dissolved oxygen probe in which the oxygen diffusivity through the Teflon membrane is 9.83 × 10-11 m2/s, comparable with a previously reported value. It can also describe the sensing behavior of any nonbiocatalyzed oxidation-related sensor in a two-substrate system simply by replacing the governing faradaic equations for the dissolved oxygen probe with those appropriate to the type of probe used.
    Zusätzliches Material: 8 Ill.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/aic.690410434
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  • 102
    Digitale Medien
    Digitale Medien
    Masthead (1995)
    Hoboken, NJ : Wiley-Blackwell
    AIChE Journal 41 (1995) 
    Details
    ISSN: 0001-1541
    Schlagwort(e): Chemistry ; Chemical Engineering
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie , Werkstoffwissenschaften, Fertigungsverfahren, Fertigung
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/aic.690410501
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  • 103
    Digitale Medien
    Digitale Medien
    Numerical simulation of flow in helical ducts (1995)
    Hoboken, NJ : Wiley-Blackwell
    AIChE Journal 41 (1995), S. 1071-1080 
    Details
    ISSN: 0001-1541
    Schlagwort(e): Chemistry ; Chemical Engineering
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie , Werkstoffwissenschaften, Fertigungsverfahren, Fertigung
    Notizen: Helical pipes and ducts are used widely in industry. There is a huge literature on flow in curved pipes and bends, but comparatively little has been published on flow in helical pipes. To simplify the problem, most theoretical work on flow in helical pipes has assumed zero pitch: a toroidal pipe following the work of Dean in 1927. Recent theoretical studies on helical pipes have used helical coordinate systems. These systems, however, are not appropriate when studying helical ducts. The following results are reported: a coordinate system appropriate for helical ducts; the detailed equations of continuity and motion in this coordinate system; the numerical method used to find the fully developed laminar flow of a Newtonian liquid in helical ducts; the simulations vs. published experimental data; and effects of the pitch ratio, curvature ratio and pressure gradient on secondary flow in a helical duct.
    Zusätzliches Material: 12 Ill.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/aic.690410504
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  • 104
    Digitale Medien
    Digitale Medien
    Rapid estimation of cylinder erosion rates in abrasive dust-laden streams (1995)
    Hoboken, NJ : Wiley-Blackwell
    AIChE Journal 41 (1995), S. 1081-1098 
    Details
    ISSN: 0001-1541
    Schlagwort(e): Chemistry ; Chemical Engineering
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie , Werkstoffwissenschaften, Fertigungsverfahren, Fertigung
    Notizen: Erosion yield data for particular combinations of target and projectile materials (via laboratory experiments carried out with a narrow-size distribution over the important range of impact velocities and incidence angles), together with recently developed rational correlations for inertial impaction of suspended particles on a cylinder in high Reynolds number crossflow are used to provide a tractable framework for predicting the erosion rates of, say, heat exchanger tubes immersed in particle-laden streams of combustion products.“Universal” results are cast in terms of the following accessible parameters: sensitivity of erosion yield to projectile incident velocity and angle, ratio of mean particle size to the threshold size required for impaction on the cylindrical target, spread of the mainstream particle size distribution (here log-normal), and the characteristic “slip” Reynolds number for the critical size abrasive particle in the mainstream. Applications of the results are illustrated, and several generalizations are discussed.
    Zusätzliches Material: 24 Ill.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/aic.690410505
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  • 105
    Digitale Medien
    Digitale Medien
    Unified excitation and performance diagnostic adaptive control framework (1995)
    Hoboken, NJ : Wiley-Blackwell
    AIChE Journal 41 (1995), S. 110-121 
    Details
    ISSN: 0001-1541
    Schlagwort(e): Chemistry ; Chemical Engineering
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie , Werkstoffwissenschaften, Fertigungsverfahren, Fertigung
    Notizen: Model-based controllers contain two elements that must be adjusted to maintain desired performance: parameters of the process model and a tuning parameter in the controller design equation. A unified framework is presented where vector quantizing networks are used in pattern-based methods for diagnosing process excitation and controller performance. Excitation diagnostics identify sufficiently excited dynamic process data for model updating. Performance diagnostics analyze set point response data and determine appropriate updates to the tuning parameter. Supervisory adaptation logic enables these two adaptive mechanisms to work together to maintain model accuracy and desired controller performance. The method is general to a number of model-based control algorithms and process model forms. Demonstrations employ a FOPDT model, as well as both the PI and DMC algorithms for set point tracking and disturbance rejection in a simulation and a bench-scale process.
    Zusätzliches Material: 12 Ill.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/aic.690410111
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  • 106
    Digitale Medien
    Digitale Medien
    Dynamic simulation and nonlinear-model-based product quality control of a crude tower (1995)
    Hoboken, NJ : Wiley-Blackwell
    AIChE Journal 41 (1995), S. 122-134 
    Details
    ISSN: 0001-1541
    Schlagwort(e): Chemistry ; Chemical Engineering
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie , Werkstoffwissenschaften, Fertigungsverfahren, Fertigung
    Notizen: The dynamic stagewise adiabatic flash algorithm is applied to the dynamic simulation of a crude column. This algorithm is based on the implicit integration of the model equations of each stage and the explicit combination of the stage models to form the column model. Stable, efficient integration for the crude column model is observed with simulation CPU requirements that are 20 times faster than real time using a 50 MHz 486 P.C. Specific dynamic of a crude column are identified such as one-way interaction and inverse action. The dynamic crude column model is used to study product quality control of a crude column using nonlinear-process-model-based control (PMBC) which was tested using two different steady-state controller models for setpoint tracking and disturbance rejection. Both nonlinear PMBC controllers show good control performance, but are limited by the inherent inverse action of the crude column. Control results for a set of single-loop PI controllers is also presented as a point of reference.
    Zusätzliches Material: 12 Ill.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/aic.690410112
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  • 107
    Digitale Medien
    Digitale Medien
    Impact of process design on the multiplicity behavior of a jacketed exothermic CSTR (1995)
    Hoboken, NJ : Wiley-Blackwell
    AIChE Journal 41 (1995), S. 135-147 
    Details
    ISSN: 0001-1541
    Schlagwort(e): Chemistry ; Chemical Engineering
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie , Werkstoffwissenschaften, Fertigungsverfahren, Fertigung
    Notizen: Research on exothermic reactor operation has been based mostly on the classic two-state continuous stirred tank reactor model, implicitly assuming that the cooling jacket temperature dynamics are negligible. In this case, the cooling jacket temperature is the manipulated input instead of the cooling jacket flow rate for feedback control of reactor temperature. Adding a cooling jacket energy balance results in much more complex behavior than a simple lag effect. A stabilizing inner-loop cascade controller is assumed in the two-state CSTR model, because the three-state model incorporating cooling jacket temperature dynamics may be open-loop unstable when the two-state model is open-loop stable. The influence of design parameters on the multiplicity behavior of a three-state model is considered. Elementary catastrophe theory is used to study the effect of process parameters such as the cooling jacket flow rate, heat-transfer coefficient, heat of reaction, and cooling jacket feed temperature on the steady-state multiplicity of the three-state model. This multiplicity analysis is particularly relevant for control because the primary bifurcation parameter is the cooling jacket flow rate, the manipulated input for feedback control in the three-state model. This multiplicity analysis guides improvements in process design and/or operation to eliminate difficult operating regions associated with steady-state multiplicities; the presence of multiple steady states results in safety and operation problems due to ignition/extinction phenomena. Reactor scale-up affects the presence of these infeasible reactor operating regions. Certain design parameter changes that remove multiplicities in the two-state model cannot remove multiplicities in the three-state model.
    Zusätzliches Material: 17 Ill.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/aic.690410113
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  • 108
    Digitale Medien
    Digitale Medien
    Silica gels made by bicontinuous microemulsion polymerization (1995)
    Hoboken, NJ : Wiley-Blackwell
    AIChE Journal 41 (1995), S. 159-165 
    Details
    ISSN: 0001-1541
    Schlagwort(e): Chemistry ; Chemical Engineering
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie , Werkstoffwissenschaften, Fertigungsverfahren, Fertigung
    Notizen: Microporous silica gels can be made by polymerizing partially hydrolyzed tetramethoxysilane sols present in the aqueous phase of bicontinuous microemulsions stabilized with didodecyldimethylammonium bromide. When vacuum-dried, the gels made in microemulsions have about twice the specific surface area of conventional vacuum-dried silica gels. They have 70% of the specific area of supercritically dried gels. Small-angle X-ray Scattering measurements in these gels show two characteristic sizes. One size, around 24Å, in the original microemulsion is retained during polymerization, but lost when the detergent is extracted. The second size grows with the square root of time during the polymerization, suggesting diffusion-controlled gelation.
    Zusätzliches Material: 9 Ill.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/aic.690410115
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  • 109
    Digitale Medien
    Digitale Medien
    Application of multiresponse estimation to a wetted wall column model (1995)
    Hoboken, NJ : Wiley-Blackwell
    AIChE Journal 41 (1995), S. 2327-2332 
    Details
    ISSN: 0001-1541
    Schlagwort(e): Chemistry ; Chemical Engineering
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie , Werkstoffwissenschaften, Fertigungsverfahren, Fertigung
    Zusätzliches Material: 5 Ill.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/aic.690411018
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  • 110
    Digitale Medien
    Digitale Medien
    Isotope study on diffusion in CaSO4 formed during sorbent-flue-gas reaction (1995)
    Hoboken, NJ : Wiley-Blackwell
    AIChE Journal 41 (1995), S. 2337-2340 
    Details
    ISSN: 0001-1541
    Schlagwort(e): Chemistry ; Chemical Engineering
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie , Werkstoffwissenschaften, Fertigungsverfahren, Fertigung
    Zusätzliches Material: 5 Ill.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/aic.690411020
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  • 111
    Digitale Medien
    Digitale Medien
    Applied fluid mechanics by T. C. Papanastasiou, Prentice-Hall, Englewood Cliffs, NJ, 1994, 520 pp. (1995)
    Hoboken, NJ : Wiley-Blackwell
    AIChE Journal 41 (1995), S. 2342-2342 
    Details
    ISSN: 0001-1541
    Schlagwort(e): Chemistry ; Chemical Engineering
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie , Werkstoffwissenschaften, Fertigungsverfahren, Fertigung
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/aic.690411022
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  • 112
    Digitale Medien
    Digitale Medien
    Masthead (1995)
    Hoboken, NJ : Wiley-Blackwell
    AIChE Journal 41 (1995) 
    Details
    ISSN: 0001-1541
    Schlagwort(e): Chemistry ; Chemical Engineering
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie , Werkstoffwissenschaften, Fertigungsverfahren, Fertigung
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/aic.690411101
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  • 113
    Digitale Medien
    Digitale Medien
    Rheology: Principles, measurements, and applications by C. Macosko, VCH Publishers, 1994, 550pp., $95.00 (1995)
    Hoboken, NJ : Wiley-Blackwell
    AIChE Journal 41 (1995), S. 2344-2344 
    Details
    ISSN: 0001-1541
    Schlagwort(e): Chemistry ; Chemical Engineering
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie , Werkstoffwissenschaften, Fertigungsverfahren, Fertigung
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/aic.690411025
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  • 114
    Digitale Medien
    Digitale Medien
    Necessary and sufficient conditions for reactive azeotropes in multireaction mixtures (1995)
    Hoboken, NJ : Wiley-Blackwell
    AIChE Journal 41 (1995), S. 2383-2392 
    Details
    ISSN: 0001-1541
    Schlagwort(e): Chemistry ; Chemical Engineering
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie , Werkstoffwissenschaften, Fertigungsverfahren, Fertigung
    Notizen: Necessary and sufficient conditions for azeotropy in reactive mixtures derived show that in the space of transformed compositions, they take the same functional form as the conditions for azeotropy in nonreactive mixtures. In general, reactive azeotropes do not correspond to points of equal mole fraction (or mass fraction) across the coexisting equilibrium phases. The relationship between stationary points in the equilibrium temperature or pressure surface and reactive azeotropes is also considered, as well as their relevance to the Gibbs-Konovalov theorems.
    Zusätzliches Material: 5 Ill.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/aic.690411105
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  • 115
    Digitale Medien
    Digitale Medien
    Properties of pulsing flow in a trickle bed (1995)
    Hoboken, NJ : Wiley-Blackwell
    AIChE Journal 41 (1995), S. 2371-2382 
    Details
    ISSN: 0001-1541
    Schlagwort(e): Chemistry ; Chemical Engineering
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie , Werkstoffwissenschaften, Fertigungsverfahren, Fertigung
    Notizen: An experimental study of pulsing flow in trickle beds is presented, based on data from two measuring techniques. New evidence on pulse arrangement and propagation in the bed, and data on basic pulse characteristics (frequency, celerity, length, duration) as well as liquid holdup and pressure drop measurements are included. Some of these data, such as the length of the liquid-rich zone of pulses, are not currently available. Two flow regions exhibit different trends of pulse characteristics, “mild” and “wild” pulsing for relatively small and large liquid flow rates, respectively. New findings are compared with previously available data and correlations. An effort to develop new or modify existing generalized correlations is made for the aforementioned quantities.
    Zusätzliches Material: 15 Ill.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/aic.690411104
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  • 116
    Digitale Medien
    Digitale Medien
    Efficiency estimation of liquid-liquid Hydrocyclones using trajectory analysis (1995)
    Hoboken, NJ : Wiley-Blackwell
    AIChE Journal 41 (1995), S. 1395-1402 
    Details
    ISSN: 0001-1541
    Schlagwort(e): Chemistry ; Chemical Engineering
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie , Werkstoffwissenschaften, Fertigungsverfahren, Fertigung
    Notizen: As the use of hydrocyclones for liquid-liquid separation becomes increasingly common, the need for a satisfactory method to assess their efficiency increases. Curerntly available efficiency theories were developed for liquid-solid separations, based on the velocity distributions inside a hydrocyclone. These theories, however, appear less suitable for emulsions where the dispersed phase is slightly lighter than the continuous phase, such as oil/water emulsions. An efficiency computation based on the analysis of the trajectories of the droplets is presented. Trajectories are characterized through a differential equation combining models for the three bulk velocity distributions (axial, radial, and tangential) and the settling velocity defined by Stokes' law. From the critical trajectory and given operating conditions, a characteristic droplet diameter d100 can be deduced that corresponds to the smallest droplet with a 100% efficiency. Other efficiencies are obtained by changing the initial condition for the trajectory equation. The efficiency result of different hydrocyclone configurations are compared with experimental results, and residual emulsion distributions are estimated.
    Zusätzliches Material: 7 Ill.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/aic.690410606
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  • 117
    Digitale Medien
    Digitale Medien
    Gas separations in hollow-fiber adsorbers (1995)
    Hoboken, NJ : Wiley-Blackwell
    AIChE Journal 41 (1995), S. 1413-1425 
    Details
    ISSN: 0001-1541
    Schlagwort(e): Chemistry ; Chemical Engineering
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie , Werkstoffwissenschaften, Fertigungsverfahren, Fertigung
    Notizen: The adsorption of ethane from helium was measured in beds packed with 2.5 μm zeolite crystals and containing either a single hollow fiber or multiple fibers. THe single-fiber experiments indicate that the mass-transfer rate in bends containing zeolite 13X is limited by diffusion across the fiber wall and through macropores. FOr adsorption in single-fiber beds packed with zeolite 4A, mass transfer is limited by micropore diffusion within the particles. Breakthrough curves from beds containign 13X are adequately described with the linear driving force model, while curves from beds containing 4A are consistent with the Rosen model.Breakthrough curves from beds packed with zeolite 13X and containing multiple fibers can be predicted from the experiments with single-fiber beds when the fibers are evenly spaced. When fibers are unevenly spaced, the breakthrough curves are more disperse. Unevenly spaced fibers are the normal case. Even when fibers are evenly spaced, the productivity of hollow-fiber beds is expected to be no greater than that in conventional beds.
    Zusätzliches Material: 11 Ill.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/aic.690410608
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  • 118
    Digitale Medien
    Digitale Medien
    Simulation of hydrosol deposition in granular media (1995)
    Hoboken, NJ : Wiley-Blackwell
    AIChE Journal 41 (1995), S. 1426-1442 
    Details
    ISSN: 0001-1541
    Schlagwort(e): Chemistry ; Chemical Engineering
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie , Werkstoffwissenschaften, Fertigungsverfahren, Fertigung
    Notizen: An algorithm is developed for simulating particle deposition from liquid suspensions flowing through granular media, specifically the prediction of the extent of deposition and the change of media permeability on a local basis. The formulation is based on the premise that granular media may be considered as an assembly of collectors represented by a dual-configuration - either spherical or capillaric  -  to be applied for deposition and permeability reduction considerations. Comparisons with experiments indicate that the simulation algorithm can indeed be used as a predictive tool for estimating the transport and distribution of particulate matter in granular media.
    Zusätzliches Material: 22 Ill.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/aic.690410609
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  • 119
    Digitale Medien
    Digitale Medien
    Reducing data dimensionality through optimizing neural network inputs (1995)
    Hoboken, NJ : Wiley-Blackwell
    AIChE Journal 41 (1995), S. 1471-1480 
    Details
    ISSN: 0001-1541
    Schlagwort(e): Chemistry ; Chemical Engineering
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie , Werkstoffwissenschaften, Fertigungsverfahren, Fertigung
    Notizen: A neural network method for reducing data dimensionality based on the concept of input training, in which each input pattern is not fixed but adjusted along with internal network parameters to reproduce its corresponding output pattern, is presented. With input adjustment, a property configured network can be trained to reproduce a given data set with minimum distortion; the trained network inputs provide reduced data.A three-layer network with input training can perform all functions of a flue-layer autoassociative network, essentially capturing nonlinear correlations among data. In addition, simultaneous training of a network and its inputs is shown to be significantly more efficient in reducing data dimensionality than training an autoassociative network The concept of input training is closely related to principal component analysis (PCA) and the principal curve method, which is a nonlinear extension of PCA.
    Zusätzliches Material: 15 Ill.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/aic.690410612
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  • 120
    Digitale Medien
    Digitale Medien
    Experimental and theoretical investigation of the validity of asymptotic lumped kinetics (1995)
    Hoboken, NJ : Wiley-Blackwell
    AIChE Journal 41 (1995), S. 1513-1520 
    Details
    ISSN: 0001-1541
    Schlagwort(e): Chemistry ; Chemical Engineering
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie , Werkstoffwissenschaften, Fertigungsverfahren, Fertigung
    Notizen: Continuum approximation is often used to treat problems involving reaction mixtures of a vast number of species. Previous studies predicted that in many situations the lumped kinetics of a continuum of reactions, regardless of their kinetics, are of the power law form after a long time. In this article we present experimental support for such asymptotic power law kinetics. The system considered is catalytic deep desulfurization of a petroleum distillate. In addition, a theoretical analysis is made to establish the condition under which the continuum approximation is valid in the long-time limit. The condition turns out not to be very stringent for practical purposes.
    Zusätzliches Material: 4 Ill.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/aic.690410615
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  • 121
    Digitale Medien
    Digitale Medien
    Continuous kinetics for thermal degradation of polymer in solution (1995)
    Hoboken, NJ : Wiley-Blackwell
    AIChE Journal 41 (1995), S. 1521-1533 
    Details
    ISSN: 0001-1541
    Schlagwort(e): Chemistry ; Chemical Engineering
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie , Werkstoffwissenschaften, Fertigungsverfahren, Fertigung
    Notizen: Continuous kinetics of thermal degradation of poly (styrene-allyl alcohol) (PSA) in solution are explored theoretically and experimentally. Thermal degradation experiments for PSA of number-average molecular weight 1,640 in t-butanol solution were conducted in a steady-state flow reactor at 6.8 MPa and 403-473 K. The molecular-weight distributions (MWDs) of the original polymer and its reaction products were measured as a function of residence time by gel permeation chromatography The MWD of the initial PSA is described by a gamma distribution function. Experimental data indicated that the polymer cracks to specific, low-molecular-weight (MW) products and degrades by random chain scission. Results are interpreted by a mathematical model based on the continuous kinetics for specific and random degradation processes. Rate coefficients are determined separately from the dynamic data of the MW moments for the specific products and the MWDs for the reacting polymer. Activation energies obtained are 5.9 - 7.4 kcal/mol for specific degradation processes and 35 kcal/mol for the random degradation process. The detailed MWDs are related to conventional lumped (numberaverage molecular-weight) data.
    Zusätzliches Material: 12 Ill.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/aic.690410616
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  • 122
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    Digitale Medien
    Isothermal bistability due to remote control: A model for selective catalytic oxidation (1995)
    Hoboken, NJ : Wiley-Blackwell
    AIChE Journal 41 (1995), S. 1543-1549 
    Details
    ISSN: 0001-1541
    Schlagwort(e): Chemistry ; Chemical Engineering
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie , Werkstoffwissenschaften, Fertigungsverfahren, Fertigung
    Notizen: Special kinetic behaviors in isothermal reactions on heterogeneous catalysts composed of two components with different roles are studied with the focus on hi stabilities that could occur in stirred-tank flow reactors when control of catalytic sites on one component by mobile (spillover) species produced by the other operates. The comprehensive kinetic model involves: (1) generation of spillover species on the second phase, their transfer to the potentially catalytic phase, and their reaction with this acceptor to generate selective sites; (2) the kinetics of the catalytic reaction. We developed a model for selective catalytic oxidation, where catalyst sites change from nonselective to selective under the influence of the control by spillover oxygen. The model is based on the system of differential equations. By integration and iteration to the steady state for each value of the external control parameter under investigation, the oxygen and hydrocarbon reactant consumption, as well as the state of the catalyst, is calculated. These calculations predict bistable selectivity for certain ranges of concentration in the feed. Data on the boundaries of the hysteresis loops as a function of catalyst composition and oxygen partial pressure are discussed, as well as the variation of these hysteresis boundaries as a function of the internal parameters.
    Zusätzliches Material: 10 Ill.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/aic.690410618
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  • 123
    Digitale Medien
    Digitale Medien
    Thermodynamic modeling of concentrated aqueous electrolyte and nonelectrolyte solutions (1995)
    Hoboken, NJ : Wiley-Blackwell
    AIChE Journal 41 (1995), S. 1563-1571 
    Details
    ISSN: 0001-1541
    Schlagwort(e): Chemistry ; Chemical Engineering
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie , Werkstoffwissenschaften, Fertigungsverfahren, Fertigung
    Notizen: A new approach is presented for calculation of activity coefficients in aqueous electrolyte solutions. This approach requires only standard thermodynamic properties for the pure components and for the solutes at infinite dilution. No adjustable mixture parameters are necessary. This new procedure has been applied to calculate: (1) the solubility of salts and the activity of water in binary aqueous solutions; (2) the temperature dependence of the solubility of salts; (3) the azeotropic composition of a system containing a volatile electrolyte, (H2—HNO3); (4) the solubility of carbon dioxide in water at elevated pressures and at different temperatures.
    Zusätzliches Material: 3 Ill.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/aic.690410620
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  • 124
    Digitale Medien
    Digitale Medien
    Comparing various multicomponent adsorption equilibrium models (1995)
    Hoboken, NJ : Wiley-Blackwell
    AIChE Journal 41 (1995), S. 1585-1592 
    Details
    ISSN: 0001-1541
    Schlagwort(e): Chemistry ; Chemical Engineering
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie , Werkstoffwissenschaften, Fertigungsverfahren, Fertigung
    Zusätzliches Material: 8 Ill.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/aic.690410623
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  • 125
    Digitale Medien
    Digitale Medien
    Experimental study of the peridoic operation of a trickle -bed reactor (1995)
    Hoboken, NJ : Wiley-Blackwell
    AIChE Journal 41 (1995), S. 1593-1597 
    Details
    ISSN: 0001-1541
    Schlagwort(e): Chemistry ; Chemical Engineering
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie , Werkstoffwissenschaften, Fertigungsverfahren, Fertigung
    Zusätzliches Material: 6 Ill.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/aic.690410624
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  • 126
    Digitale Medien
    Digitale Medien
    Masthead (1995)
    Hoboken, NJ : Wiley-Blackwell
    AIChE Journal 41 (1995) 
    Details
    ISSN: 0001-1541
    Schlagwort(e): Chemistry ; Chemical Engineering
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie , Werkstoffwissenschaften, Fertigungsverfahren, Fertigung
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/aic.690410701
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  • 127
    Digitale Medien
    Digitale Medien
    Effect of solute-solute correlations on rapid reactions in supercritical fluids (1995)
    Hoboken, NJ : Wiley-Blackwell
    AIChE Journal 41 (1995), S. 346-356 
    Details
    ISSN: 0001-1541
    Schlagwort(e): Chemistry ; Chemical Engineering
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie , Werkstoffwissenschaften, Fertigungsverfahren, Fertigung
    Notizen: Brownian and molecular dynamics simulations are used to study rapid bimolecular reactions at near-infinite dilution in near-critical and supercritical fluids. We probe the dynamics of both nonreactive and reactive collisions and measure rate constants for reaction and collision. Collision rate constants are nearly independent of bulk solvent density, but affected by local solute-solute density enhancements at a given density: their magnitudes depend on the length scale for molecular encounters (cybotactic radius) in the reaction through the equilibrium solute-solute radial distribution function. In contrast, reaction rate constants asymptotically approach the gas-kinetic limit at low densities and the Smoluchowski liquid-like limit at high densities. They also display the same radial dependence as collision rate constants at lower densities and a direct dependence on the cybotactic radius at higher densities (as in the Smoluchowski theory). Their behavior is explained in terms of a transition from a collision-limited regime at low densities to a diffusion-limited regime at higher densities. The transition between these regimes depends on the cybotactic radius and the density of the system, the interplay of which causes shifts in the transition region which depend not only on the properties of the near-critical solvent: they differ for different reactions, even at the same solvent density. This explains some of the apparent inconsistencies among previous experimental and computational studies of reactions in supercritical fluid media.
    Zusätzliches Material: 17 Ill.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/aic.690410216
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  • 128
    Digitale Medien
    Digitale Medien
    Detailed kinetics of titanium nitride synthesis (1995)
    Hoboken, NJ : Wiley-Blackwell
    AIChE Journal 41 (1995), S. 377-388 
    Details
    ISSN: 0001-1541
    Schlagwort(e): Chemistry ; Chemical Engineering
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie , Werkstoffwissenschaften, Fertigungsverfahren, Fertigung
    Notizen: A thermogravimetric analyzer is used to study the synthesis of TiN from Ti powder over a wide range of temperature, conversion and heating rate, and for two Ti precursor powders with different morphologies. Conversions to TiN up to 99% are obtained with negligible oxygen contamination. Nonisothermal initial rate and isothermal data are used in a nonlinear least-squares minimization to determine the most appropriate rate law. The logarithmic rate law offers an excellent agreement between the experimental and calculated conversions to TiN and can predict afterburning, which is an important experimentally observed phenomenon. Due to the form of the logarithmic rate law, the observed activation energy is a function of effective particle size, extent of conversion, and temperature even when the intrinsic activation energy remains constant. This aspect explains discrepancies among activation energies obtained in previous studies. The frequently used sedimentation particle size is a poor measure of the powder reactivity. The BET surface area indicates the powder reactivity much better.
    Zusätzliches Material: 9 Ill.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/aic.690410219
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  • 129
    Digitale Medien
    Digitale Medien
    Simultaneous autocatalytic reaction and diffusion in a slab (1995)
    Hoboken, NJ : Wiley-Blackwell
    AIChE Journal 41 (1995), S. 1321-1323 
    Details
    ISSN: 0001-1541
    Schlagwort(e): Chemistry ; Chemical Engineering
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie , Werkstoffwissenschaften, Fertigungsverfahren, Fertigung
    Zusätzliches Material: 1 Ill.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/aic.690410527
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  • 130
    Digitale Medien
    Digitale Medien
    Turbulence suppression by polymer solutions in opposed jets flow (1995)
    Hoboken, NJ : Wiley-Blackwell
    AIChE Journal 41 (1995), S. 1333-1336 
    Details
    ISSN: 0001-1541
    Schlagwort(e): Chemistry ; Chemical Engineering
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie , Werkstoffwissenschaften, Fertigungsverfahren, Fertigung
    Zusätzliches Material: 5 Ill.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/aic.690410530
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  • 131
    Digitale Medien
    Digitale Medien
    Turbulence structure in bubble disengagement zone: Role of polymer addition (1995)
    Hoboken, NJ : Wiley-Blackwell
    AIChE Journal 41 (1995), S. 1329-1332 
    Details
    ISSN: 0001-1541
    Schlagwort(e): Chemistry ; Chemical Engineering
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie , Werkstoffwissenschaften, Fertigungsverfahren, Fertigung
    Zusätzliches Material: 5 Ill.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/aic.690410529
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  • 132
    Digitale Medien
    Digitale Medien
    Tortuosity of bubble rise path in a liquid-solid fluidized bed: Effect of particle shape (1995)
    Hoboken, NJ : Wiley-Blackwell
    AIChE Journal 41 (1995), S. 1368-1374 
    Details
    ISSN: 0001-1541
    Schlagwort(e): Chemistry ; Chemical Engineering
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie , Werkstoffwissenschaften, Fertigungsverfahren, Fertigung
    Notizen: Effects of particle properties on the rise of single bubbles in a liquid-solid fluidized bed ared studied by focusing on the particle-shape effect at various bed voidages near incipient fluidization of glass beads and sand particles. Experiments, covering the bubble-size range 6-37 mm and solids holdups as high as 0.94 times that in the packed state, are conducted in a 2-D column to directly observe the possible relationship between the rate and tortuous path of bubble rise. The shape effect, being significant when the close-range (surface-to-surface) interactions between particles are predominant, is appreciable for the relative solids holdups exceeding 0.9. Marked reduction in the bubble rise velocity is observed as the bubble size is decreased below 8 and 12 mm for the spherical glass and irregular sand particles, respectively. This anomalous reduction stems partly from the tortuousness in the rise path and partly from the “hesitation” in the net vertical movement. The former, in particular, is quantified in terms of the tortuosity of the 2-D rise path. The results support the peculiar trend in the rise velocity observed, especially for the sand particles.
    Zusätzliches Material: 9 Ill.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/aic.690410603
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  • 133
    Digitale Medien
    Digitale Medien
    PSA performance of densely packed adsorbent beds (1995)
    Hoboken, NJ : Wiley-Blackwell
    AIChE Journal 41 (1995), S. 1389-1394 
    Details
    ISSN: 0001-1541
    Schlagwort(e): Chemistry ; Chemical Engineering
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie , Werkstoffwissenschaften, Fertigungsverfahren, Fertigung
    Notizen: The separation of air by pressure swing adsorption is improved by filling the interparticle voids in kineticaly selective adsorbent beds with fine particles of the adsorbent or inert material. He ratio of the average diameter of the coarse adsorbent particles to the average diameter of the fine particles, the size of the fine particles themselves, and the percent of volume of the fine particles in the bed are all critical to optimum PA performance.
    Zusätzliches Material: 12 Ill.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/aic.690410605
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  • 134
    Digitale Medien
    Digitale Medien
    Modeling chemically active liquid membranes in tubular inorganic supports (1995)
    Hoboken, NJ : Wiley-Blackwell
    AIChE Journal 41 (1995), S. 1403-1412 
    Details
    ISSN: 0001-1541
    Schlagwort(e): Chemistry ; Chemical Engineering
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie , Werkstoffwissenschaften, Fertigungsverfahren, Fertigung
    Notizen: A numerical model is presented to evaluate the dynamic behavior of mas transfer in the shell-and-tube-type membrane modules for metal ion removal from aqueous streams. The analysis that considers the effects of axial-flow velocity on the radial pressure difference across the membrane wall permits the specifications of this operating parameter to avoid expression of impregnated carrier from the membranes adn to prevent membrane wall rupture. The model accounts for effects of boundary layer mass-transfer and kinetic rate resistances at the interfces on membrane flux. The performance of different size membrane modules was estimated for two operating modes of a shell-and-tube-type module: one for the flow of feed solution inside the membrane tube and strip solution flow in the annular region and the other for the flow of strip solution inside the membrane tube and feed solution flow in the annular region of the module. A case system evaluated is copper ion extraction from acidic solutions using 2-hydroxy-5-nonylacetophenone oxime impregnated in α-alumina/silica ceramic membranes. The performance of shell-and-tube-type membrane modules depends on the sizes and operating methods. In these calculations, the operation condition of no-pressure difference across the membrane was imposed on the design. This condition is achieved by adjusting the ratio of the flow velocities of the feed and strip solutions within the inside and annular regions of the modules.
    Zusätzliches Material: 9 Ill.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/aic.690410607
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  • 135
    Digitale Medien
    Digitale Medien
    Cake formation in 2-D cross-flow filtration (1995)
    Hoboken, NJ : Wiley-Blackwell
    AIChE Journal 41 (1995), S. 1443-1455 
    Details
    ISSN: 0001-1541
    Schlagwort(e): Chemistry ; Chemical Engineering
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie , Werkstoffwissenschaften, Fertigungsverfahren, Fertigung
    Notizen: The mechanism of cake formation is studied in 2-D cross-flow filtrations. By analyzing the forces exerted on a depositing particle, the value of the critical friction angle, βc, which leads the particle to be stuck on the contact position, is determined. Not only the probability of particle deposition but also the size distribution of deposited particles can be calculated from the theoretical value of βc. Numerical programs are constructed to simulate the packing structure and size distribution of particles in a formed cake and the path of cake compression. The local cake properties in the cake, such as local porosity and local specific filtration resistance, are also estimated by applying the design program and the data of filtration volume vs. time. The predicted values of average cake porosity and average specific filtration resistance agree very well with the experimental data.
    Zusätzliches Material: 21 Ill.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/aic.690410610
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  • 136
    Digitale Medien
    Digitale Medien
    Bypassing eutectics with extractive crystallization: Design alternatives and tradeoffs (1995)
    Hoboken, NJ : Wiley-Blackwell
    AIChE Journal 41 (1995), S. 1456-1470 
    Details
    ISSN: 0001-1541
    Schlagwort(e): Chemistry ; Chemical Engineering
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie , Werkstoffwissenschaften, Fertigungsverfahren, Fertigung
    Notizen: A systematic design method reported here uses extractive crystallization to separate a three-component mixture despite the presence of eutectics. Phase behavior can be classified into six basic types, and six flowsheet structures can handle systems with any of these solid-liquid-phase behaviors. Design equations are formulated for these flowsheet structures, and design variables and constraints are identified. In addition, design issues, such as the choice of solvent, the effect of design variables on recycle flows, and the magnitude of the costs, are discussed.
    Zusätzliches Material: 18 Ill.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/aic.690410611
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  • 137
    Digitale Medien
    Digitale Medien
    Flow through curved rectangular channels of large aspect ratio (1995)
    Hoboken, NJ : Wiley-Blackwell
    AIChE Journal 41 (1995), S. 1061-1070 
    Details
    ISSN: 0001-1541
    Schlagwort(e): Chemistry ; Chemical Engineering
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie , Werkstoffwissenschaften, Fertigungsverfahren, Fertigung
    Notizen: Numerical solutions were obtained for the field of velocity in angular forced flow through the annulus between two concentric cylinders of large and infinite aspect ratio with a gap-to-inner radius ratio of 0.05 using a finite-element representation and the FIDAP code. For an infinite aspect ratio, velocity vectors reveal a purely angular motion below a critical Dean number of 37.31 and a secondary motion in the form of pairs of counterrotating vortices above that value. The wavelength of these vortices and the friction factor are correlated in terms of the Dean number. For large but finite aspect ratios a weak secondary motion around the periphery is found to occur below the critical Dean number, while for greater values the vortex at each end of the channel is greatly extended. The computed patterns of flow are in good agreement with prior experimental visualizations as well as with those carried out as part of this investigation. The computed characteristics are also in good agreement with prior theoretical results for limiting cases. The adaptation of the results for flow through an Archimedean spiral is described.
    Zusätzliches Material: 11 Ill.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/aic.690410503
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  • 138
    Digitale Medien
    Digitale Medien
    Two-phase flow in the vicinity of an elongated bubble in a fluidized bed (1995)
    Hoboken, NJ : Wiley-Blackwell
    AIChE Journal 41 (1995), S. 1113-1121 
    Details
    ISSN: 0001-1541
    Schlagwort(e): Chemistry ; Chemical Engineering
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie , Werkstoffwissenschaften, Fertigungsverfahren, Fertigung
    Notizen: Fluid and solid dynamics inside and outside a stable elongated gas bubble in operating conditions corresponding to those of the channeling regime in a fluidized bed are described. It considers the prolate ellipsoid of revolution as a model of the bubble. The results of the analytical model show a significant increase of the fluid velocity inside the bubble with the growth of its relative height. The maximum values of the fluid velocities exist along the vertical axis of the bubble. For the limiting case of a spherical bubble, the fluid and gas performance, such as the existence of a surface of penetration outside the bubble boundaries and circulation zone inside the bubble, are in good agreement with the existing theory.
    Zusätzliches Material: 9 Ill.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/aic.690410507
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  • 139
    Digitale Medien
    Digitale Medien
    Modeling of heat generation in ammonia-treated solid rocket propellant (1995)
    Hoboken, NJ : Wiley-Blackwell
    AIChE Journal 41 (1995), S. 1572-1580 
    Details
    ISSN: 0001-1541
    Schlagwort(e): Chemistry ; Chemical Engineering
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie , Werkstoffwissenschaften, Fertigungsverfahren, Fertigung
    Notizen: One approach to demilitarize solid rocket propellants is treatment with ammonia. Ammonia extracts the oxidizers ammonium perchlorate and HMX, yielding a solid residue that is more suitable for incineration and less sensitive to impact and other modes of accidental initiation. Ammonia treatment of nitroglycerin-containing propellants is complicated by an exothermic reaction between ammonia an nitroglycerin. If not removed, the heat generated by this reaction can cause propellant ignition. To help design safe treatment processes, a model for the ammonia-propellant reaction was developed, which integrates transient energy and species conservation equations to simulate ammonia diffusion, heat generation, and heat flow in a propellant and in the solid residue resulting from ammonia treatment. It was calibrated using residue thickness and thermocouple data for one propellant. The calibrated model was used to predict conditions leading to ignition of thin propellant strips. The results agree well with experimental observations.
    Zusätzliches Material: 7 Ill.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/aic.690410621
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  • 140
    Digitale Medien
    Digitale Medien
    Masthead (1995)
    Hoboken, NJ : Wiley-Blackwell
    AIChE Journal 41 (1995) 
    Details
    ISSN: 0001-1541
    Schlagwort(e): Chemistry ; Chemical Engineering
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie , Werkstoffwissenschaften, Fertigungsverfahren, Fertigung
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/aic.690410901
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  • 141
    Digitale Medien
    Digitale Medien
    Correction (1995)
    Hoboken, NJ : Wiley-Blackwell
    AIChE Journal 41 (1995), S. 1851-1851 
    Details
    ISSN: 0001-1541
    Schlagwort(e): Chemistry ; Chemical Engineering
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie , Werkstoffwissenschaften, Fertigungsverfahren, Fertigung
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/aic.690410816
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  • 142
    Digitale Medien
    Digitale Medien
    Multiphase ozonolysis of organics in wastewater by a novel membrane reactor (1995)
    Hoboken, NJ : Wiley-Blackwell
    AIChE Journal 41 (1995), S. 1998-2012 
    Details
    ISSN: 0001-1541
    Schlagwort(e): Chemistry ; Chemical Engineering
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie , Werkstoffwissenschaften, Fertigungsverfahren, Fertigung
    Notizen: Conventional ozonation of recalcitrant organic compounds in wastewater suffers from low transfer rate of ozone into water. The low transfer rate can be enhanced by adding an inert fluorocarbon (FC) liquid immiscible with water but having a much higher solubility for ozone. A novel membrane reactor was studied for the destruction of organic pollutants by using PC liquid simultaneously as a reaction medium and a liquid membrane. The membrane reactor consisted of two sets of microporous and/or non-porous hollow-fiber membranes well-mixed in a cylindrical shell filled with the inert FC liquid. Wastewater was allowed to flow through the lumen of one set of microporous fibers; O3-containing gas flowed through the bore of the other set. Oxidative degradation products get partitioned back into the two mobile phases. Degradation of such pollutants as phenol, acrylonitrile, nitrobenzene, trichloroethylene, and toluene in such a reactor is presented. The kinetics of degradation of each pollutant in the two-phase (aqueous- FC) system were studied using batch and semibatch experiments. Simulation results based on a first-order model to predict the behavior of pollutant degradation in such a membrane reactor are compared with experimental data.
    Zusätzliches Material: 19 Ill.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/aic.690410815
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  • 143
    Digitale Medien
    Digitale Medien
    Wave model for longitudinal dispersion: Analysis and applications (1995)
    Hoboken, NJ : Wiley-Blackwell
    AIChE Journal 41 (1995), S. 2029-2039 
    Details
    ISSN: 0001-1541
    Schlagwort(e): Chemistry ; Chemical Engineering
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie , Werkstoffwissenschaften, Fertigungsverfahren, Fertigung
    Notizen: An analysis and applications of the wave model for longitudinal dispersion are pre-sented. Asymptotic forms of the wave model are considered and analytical solutions of typical linear stationary and nonstationary problems of chemical reactor engineering interest are obtained and compared to those for the Fickian dispersion model. The wave model leads to efficient analytical solutions for linear problems, which in principle differ from the solutions of the Fickian dispersion model; only for slowly varying concentration fields do the soluctions of both models approach each other. Spatial and time moments of the concentration distribution are obtained for pulse-dispersion problems; the first three spatial moments of the mean, variance, and skewness have exact, large-time asymptotic forms in the case of Taylor dispersion. Old experiments that could not be explained with the standard dispersion model are reconsidered and explained: the change with time of the variance of a concentration pulse when the flow direction is reversed and the difference in values of the apparent axial dispersion coefficient and the backmixing coefficient in a rotating disk contactor. The experimental determination of model parameters is discussed.
    Zusätzliches Material: 3 Ill.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/aic.690410903
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  • 144
    Digitale Medien
    Digitale Medien
    Origin of disturbances in cocurrent gas-liquid packed bed flows (1995)
    Hoboken, NJ : Wiley-Blackwell
    AIChE Journal 41 (1995), S. 1653-1666 
    Details
    ISSN: 0001-1541
    Schlagwort(e): Chemistry ; Chemical Engineering
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie , Werkstoffwissenschaften, Fertigungsverfahren, Fertigung
    Notizen: Visual, video, pressure, and conductance techniques were used to study time-varying disturbances in cocurrent flow in packed beds with vertical and horizontal columns. It is found that the trickle-pulse transition, as defined in previous studies, corresponds to conditions where traveling disturbances finaly become measurable, not the conditions at which infinitesimal disturbances begin to grow. Observations demonstrate that even if the liquid and gas are uniformly distributed initially, segregated, vertical flowing regions with higher or lower than average liquid holdup form after a short distance. Horizontal packed bed experiments, designed to study how regions of differing liquid holdup interact, indicate that the first type of disturbance is infiltration of gas into the liquid region. A simple model suggests that infiltration occurs if the pressure drop exceeds a value necessary to push gas through liquid-filled pores. Once infiltration is significant enough to form a third “bubbly” phase, traveling wave instabilities form and grow into pulses if sufficient column length is available. A three-layer Kelving-Helmholtz stability model is used to interpret the growth of disturbances in horizontal flows. Video obeservations of small-scale events in the bed failed to detect significant correlations between different regions. Thus it should be possible to describe flow behaviour in these systems with volum-averaged equations, as long as the presence of segregated regions is considered. Column diameter or thickness significantly affects the frequency of disturbances.
    Zusätzliches Material: 16 Ill.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/aic.690410706
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  • 145
    Digitale Medien
    Digitale Medien
    Pressure filtration of flocculated suspensions (1995)
    Hoboken, NJ : Wiley-Blackwell
    AIChE Journal 41 (1995), S. 1687-1700 
    Details
    ISSN: 0001-1541
    Schlagwort(e): Chemistry ; Chemical Engineering
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie , Werkstoffwissenschaften, Fertigungsverfahren, Fertigung
    Notizen: From the development of a compressional rheology of a flocculated suspension, a number of separation processes have been modeled. With respect to the two-stage pressure filtration process of compact formation and then consolidation, the rheological formulation appears at first examination to eb significantly at variance with the conventional engineering approach. The present model may be reconciled to the early engineering model. Moreover, the filtration parameters extracted from experiments can be related to the more fundamental rheological parameters, r(φ), the hindered settling factor, which is a function of solids volume fraction φ  -  it takes into account hydrodynamic interactions between local particles, which increase the drag forces. Useful estimates of the compact bed formation resistance and the formation time are provided as a function of applied pressure. The initial time dependence of the consolidation ratio on the elapsed consolidation time is not found to be a square root behaviour as suggested by the conventional modeling.
    Zusätzliches Material: 13 Ill.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/aic.690410709
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  • 146
    Digitale Medien
    Digitale Medien
    Detection of gross erros in data reconciliation by principal component analysis (1995)
    Hoboken, NJ : Wiley-Blackwell
    AIChE Journal 41 (1995), S. 1712-1722 
    Details
    ISSN: 0001-1541
    Schlagwort(e): Chemistry ; Chemical Engineering
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie , Werkstoffwissenschaften, Fertigungsverfahren, Fertigung
    Notizen: Statistical testing provides a tool for engineers and operators to judge the valididty of process measurements and data reconciliation. Univeriate, maximum power and chisquare tests have been widely used for this purpose. Their performance, however, has not always been satisfactory. A new class of test statistics for detection and identification of gross errors is presented based on principal component analysis and is compared to the other statistics. It is shown that the new test is capable of detecting gross erros of smallmaginitudes and has substantial power to correctly identify the variables in error, when the other tests fail.
    Zusätzliches Material: 14 Ill.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/aic.690410711
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  • 147
    Digitale Medien
    Digitale Medien
    New concept of gas purification by electron attachment (1995)
    Hoboken, NJ : Wiley-Blackwell
    AIChE Journal 41 (1995), S. 1701-1711 
    Details
    ISSN: 0001-1541
    Schlagwort(e): Chemistry ; Chemical Engineering
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie , Werkstoffwissenschaften, Fertigungsverfahren, Fertigung
    Notizen: A new concept of gas purification by electron attachment is proposed. Low-energy electrons generated in a corona-discharge reactor are captured by electronegative impurities, producing negative ions. The ions drift to the anode in the electric field and are removed at the anode of the reactor. Two types of reactors were used to remove the negative ions: a deposition-type reactor, which deposits negative ions at the anode surface; a sweep-out-type reactor, which sweeps out enriched electronegative impurities through the porous anode. Removals of dilute sulfur compounds, oxygen and iodine from nitrogen were conducted to verify the concept of gas purification. Simulation models were used to estimate removal efficiencies of these compounds, by taking into account electron attachment, and experiemental constants of the models were determined. The removal efficiency correlated by the models agreed well with the experiemental one.
    Zusätzliches Material: 16 Ill.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/aic.690410710
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  • 148
    Digitale Medien
    Digitale Medien
    Reactions at supercritical conditions: Applications and fundamentals (1995)
    Hoboken, NJ : Wiley-Blackwell
    AIChE Journal 41 (1995), S. 1723-1778 
    Details
    ISSN: 0001-1541
    Schlagwort(e): Chemistry ; Chemical Engineering
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie , Werkstoffwissenschaften, Fertigungsverfahren, Fertigung
    Notizen: Supercritical fluids posses properties that make them attractive as media for chemical reactions. Conducting chemical reactions at supercritical conditions affords opportunities to manipulate the reaction environment (solvent properties) by manipulating pressure, to enhance the solubilities of reactants and products, to eliminate interphase transport limitations on reaction rates, and to integrate reaction and separation unit operations. Supercritical conditions may be advantageous for reactions involved in fuels processing, biomass conversion, biocatalysis, homogeneous and heterogeneous catalysis, environmental control, polymerization, materials synthesis, and chemical synthesis. Moreover, supercritical fluids can be used profitably in fundamental chemical investigations of intermolecular interactions and their influence on chemical processes. Work on chemical reactions in and with supercritical fluids is reviewed. We discuss both fundamental studies and applications of reactions at supercritical conditions, with focus on work published after 1985.
    Zusätzliches Material: 43 Ill.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/aic.690410712
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  • 149
    Digitale Medien
    Digitale Medien
    Binary kinetics in the Y-Ba-Cu system: 1. Mixed powders (1995)
    Hoboken, NJ : Wiley-Blackwell
    AIChE Journal 41 (1995), S. 1779-1789 
    Details
    ISSN: 0001-1541
    Schlagwort(e): Chemistry ; Chemical Engineering
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie , Werkstoffwissenschaften, Fertigungsverfahren, Fertigung
    Notizen: The kinetics of the reactions between mixed powders BaCO3 and CuO, as well as BaCO3 and Y2O3, have been studied using DXRD techniques as a function of particle size, temperature, and CO2 pressure. Except for intial nucleation phenomena, the reaction ration rates are governed by shrinking core bahavior for BaCO3 particle sizes between 6 and 33 μm. During the initial stages of the reactions, the surface reaction kinetics are gare governing, whereas the diffusion of CuO, Y2O3, and CO2 are limiting factors at later stages in the reactions. Quantitative conversion dat were used to determine the values of the activation energies and the pertinent diffucivities in these systems.
    Zusätzliches Material: 11 Ill.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/aic.690410713
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  • 150
    Digitale Medien
    Digitale Medien
    Eddy diffusivity of solid particles in a turbulent liquid flow in a horizontal pipe (1995)
    Hoboken, NJ : Wiley-Blackwell
    AIChE Journal 41 (1995), S. 1815-1820 
    Details
    ISSN: 0001-1541
    Schlagwort(e): Chemistry ; Chemical Engineering
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie , Werkstoffwissenschaften, Fertigungsverfahren, Fertigung
    Zusätzliches Material: 3 Tab.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/aic.690410716
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  • 151
    Digitale Medien
    Digitale Medien
    Stagnant film model for effect of diffusional layer thickness on heat transfer and exerted friction (1995)
    Hoboken, NJ : Wiley-Blackwell
    AIChE Journal 41 (1995), S. 1821-1825 
    Details
    ISSN: 0001-1541
    Schlagwort(e): Chemistry ; Chemical Engineering
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie , Werkstoffwissenschaften, Fertigungsverfahren, Fertigung
    Zusätzliches Material: 2 Ill.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/aic.690410717
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  • 152
    Digitale Medien
    Digitale Medien
    Binary kinetics in the Y-Ba-Cu system: 2. Nanosized particles (1995)
    Hoboken, NJ : Wiley-Blackwell
    AIChE Journal 41 (1995), S. 1790-1797 
    Details
    ISSN: 0001-1541
    Schlagwort(e): Chemistry ; Chemical Engineering
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie , Werkstoffwissenschaften, Fertigungsverfahren, Fertigung
    Notizen: The kinetics of binaty mixtures of Y2O3 - BaCO3-CuO (Ba-Cu) and Y2O3 -CuO(Y-Cu) prepared by citrate sot-gel techniques were studied in both air and helium. Particle sizes resulting from the sol - gel preparation were between 5 and 100 nm, and the prevailing kinetics differed significantly from those observed in the companion study of micron-sized particles. That is, nucleation-growth kinetics of the Avrami-Erofe'eu type adequately model the kinetics over the entire conversion range as opposed to the diffusion mechanisms that describe the kinetics in larger sized particles. An alternate nucleation-growth model, which neglects overlapping volumes during reaction (Austin - Rickett model), was also adequate in the Ba-Cu system where particle size/spacing was larger, but was only applicable in other reaction systems at lower conversions. Activation energies obtained from the Avrami- Erofe'ev were consistently lower than those from the Austin - Rickett model, because the former model contains two parameters that are temperature-sensitive.
    Zusätzliches Material: 9 Ill.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/aic.690410714
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  • 153
    Digitale Medien
    Digitale Medien
    Growth of naphthalene crystals from supercritical CO2 solution (1995)
    Hoboken, NJ : Wiley-Blackwell
    AIChE Journal 41 (1995), S. 2227-2236 
    Details
    ISSN: 0001-1541
    Schlagwort(e): Chemistry ; Chemical Engineering
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie , Werkstoffwissenschaften, Fertigungsverfahren, Fertigung
    Notizen: The growth phenomena, mechanism, and kinetics of naphthalene crystal from supercritical CO2 solution were studies by using a single-crystal technique. Distinct growth features were observed, including the development of individuals from the seeds and the sprouting of plates from the individuals. The surface integration proceeded by two-dimensional nucleation mechanism at face corners and by subsequent spreading of the nuclei. The measured growth rates as functions of supersaturation and solubility were consistent with the derived growth-rate equations, based on the corner nucleation mechanism. In comparison with crystal growth from conventional media, the growth of naphthalene crystals from supercritical CO2 solution is similar to liquid-solution growth as far as growth mechanism and kinetics are concerned.
    Zusätzliches Material: 9 Ill.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/aic.690411006
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  • 154
    Digitale Medien
    Digitale Medien
    Redundant sensor network design for linear processes (1995)
    Hoboken, NJ : Wiley-Blackwell
    AIChE Journal 41 (1995), S. 2237-2249 
    Details
    ISSN: 0001-1541
    Schlagwort(e): Chemistry ; Chemical Engineering
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie , Werkstoffwissenschaften, Fertigungsverfahren, Fertigung
    Notizen: Measurements of process variables have a considerable impact on the control, optimization, safety, and reliability of chemical processes. In a 1993 article, Ali and Narasimhan developed a systematic graph-theoretic procedure for optimally locating a minimum number of sensors in linear steady-state processes. The sensor network was designed to maximize the probability of estimating variables when sensors are likely to fail. This article extends that procedure for the optimal design of a redundant sensor network for linear processes. The algorithm proposed also accounts for specifications of measurable and important variables. The efficiency and robustness of the proposed algorithm are demonstrated on realistically large processes.
    Zusätzliches Material: 6 Ill.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/aic.690411007
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  • 155
    Digitale Medien
    Digitale Medien
    Wetting of fiber mats for composites manufacturing: I. Visualization experiments (1995)
    Hoboken, NJ : Wiley-Blackwell
    AIChE Journal 41 (1995), S. 2261-2273 
    Details
    ISSN: 0001-1541
    Schlagwort(e): Chemistry ; Chemical Engineering
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie , Werkstoffwissenschaften, Fertigungsverfahren, Fertigung
    Notizen: Wetting of glass fibers was visualized using an oil with the same refractive index. With both a video-enhanced microscope and a high-magnification video camera we followed the flow front and qualitatively measured the entrapped air bubbles by image analysis. Due to different permeabilities between the fiber mats and bundles, air bubbles are entrapped. Two major kinds of air bubbles are observed: small cylindrical micro voids between fiber filaments (inside fiber bundles) and spherical macro voids outside fiber bundles. These air bubbles can be described by three major mechanisms initial liquid bypassing/air trapping, later capillary invasion of disordered fiber bundles, and air bubble mobilization. Both random and unidirectional fiber mats were used in this study. Vacuum as well as different fluid viscosities and surface tensions were also investigated, which led us to guidelines of optimum processing parameters of fiber wetting for resin transfer molding and structural reaction injection molding. They are low viscosity, vacuum, high mold temperature, and high pressure.
    Zusätzliches Material: 17 Ill.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/aic.690411009
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  • 156
    Digitale Medien
    Digitale Medien
    Modeling of polymer erosion in three dimensions: Rotationally symmetric devices (1995)
    Hoboken, NJ : Wiley-Blackwell
    AIChE Journal 41 (1995), S. 2292-2299 
    Details
    ISSN: 0001-1541
    Schlagwort(e): Chemistry ; Chemical Engineering
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie , Werkstoffwissenschaften, Fertigungsverfahren, Fertigung
    Notizen: A three-dimensional erosion model was developed to simulate the erosion of polymer cylinders. Erosion is regarded as a random event. After contact with the erosion medium small polymer parts are randomly assigned lifetimes from a first-order Erlang distribution using a Monte Carlo sampling technique. The model takes into account the partially crystalline nature of polymers as well as the geometry of the devices. It allows investigation of the effect of slow or nonerodible coatings. It was found that by partially coating cylinders, erosion periods of polyanhydride polymers can be expanded substantially. This is very important for using polyanhydrides as drug carriers where the polymer erosion period controls drug release.
    Zusätzliches Material: 9 Ill.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/aic.690411012
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  • 157
    Digitale Medien
    Digitale Medien
    First-order corrections to infinite dilution fugacity coefficients using computer simulation (1995)
    Hoboken, NJ : Wiley-Blackwell
    AIChE Journal 41 (1995), S. 2300-2305 
    Details
    ISSN: 0001-1541
    Schlagwort(e): Chemistry ; Chemical Engineering
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie , Werkstoffwissenschaften, Fertigungsverfahren, Fertigung
    Notizen: The relative merits of various approaches using computer simulation methods for estimating first-order correction terms to Henry's law in dilute supercritical mixtures are investigated. Three thermodynamic formulations are provided for the calculation of these properties. One method, termed the fluctuation integral approach, requires the explicit calculation of solute-solvent pair correlation functions at the infinite dilution limit, which is a difficult task for simulations given the conflicting demands of both small numbers of solute species (for approximating the infinite dilution limit) as well as the need for large numbers of solute species to improve simulation statistics. A second approach, called the pressure gradient method, does not require the explicit, determination of these solute-solute functions and, as a result, is not as sensitive to the choice of system size and other difficulties associated with establishing an adequate ensemble size and/or number of solute species to be used in the simulations. The third approach uses the exact formulation for the property of interest using Kirkwood-Buff theory. This approach, however, requires all the solute pair correlation functions to be established, making it the most sensitive to issues concerning number of solute species used in the simulations, and so on. An examples is given showing simulation results for these approaches, illustrating their respective strengths and drawbacks.
    Zusätzliches Material: 6 Ill.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/aic.690411013
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  • 158
    Digitale Medien
    Digitale Medien
    Nonlinear controller for batch crystallization: Development and experimental demonstration (1995)
    Hoboken, NJ : Wiley-Blackwell
    AIChE Journal 41 (1995), S. 2318-2321 
    Details
    ISSN: 0001-1541
    Schlagwort(e): Chemistry ; Chemical Engineering
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie , Werkstoffwissenschaften, Fertigungsverfahren, Fertigung
    Zusätzliches Material: 3 Ill.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/aic.690411016
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  • 159
    Digitale Medien
    Digitale Medien
    Effect of shell-side flows on hollow-fiber membrane device performance (1995)
    Hoboken, NJ : Wiley-Blackwell
    AIChE Journal 41 (1995), S. 2322-2326 
    Details
    ISSN: 0001-1541
    Schlagwort(e): Chemistry ; Chemical Engineering
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie , Werkstoffwissenschaften, Fertigungsverfahren, Fertigung
    Zusätzliches Material: 5 Ill.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/aic.690411017
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  • 160
    Digitale Medien
    Digitale Medien
    Neural model-predictive control of distributed parameter crystal growth process (1995)
    Hoboken, NJ : Wiley-Blackwell
    AIChE Journal 41 (1995), S. 2333-2336 
    Details
    ISSN: 0001-1541
    Schlagwort(e): Chemistry ; Chemical Engineering
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie , Werkstoffwissenschaften, Fertigungsverfahren, Fertigung
    Zusätzliches Material: 7 Ill.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/aic.690411019
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  • 161
    Digitale Medien
    Digitale Medien
    Letter to the editor (1995)
    Hoboken, NJ : Wiley-Blackwell
    AIChE Journal 41 (1995), S. 2341-2342 
    Details
    ISSN: 0001-1541
    Schlagwort(e): Chemistry ; Chemical Engineering
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie , Werkstoffwissenschaften, Fertigungsverfahren, Fertigung
    Zusätzliches Material: 1 Ill.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/aic.690411021
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  • 162
    Digitale Medien
    Digitale Medien
    Numerical methods for problems with moving fronts By Bruce A. Finlayson, Ravenna Park Publishing, Seattle, WA, 1992, 605 pp., $60.00 (1995)
    Hoboken, NJ : Wiley-Blackwell
    AIChE Journal 41 (1995), S. 2342-2343 
    Details
    ISSN: 0001-1541
    Schlagwort(e): Chemistry ; Chemical Engineering
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie , Werkstoffwissenschaften, Fertigungsverfahren, Fertigung
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/aic.690411023
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  • 163
    Digitale Medien
    Digitale Medien
    Membrane handbook edited by W. S. Winston Ho, and Kamalesh K. Sirkar, Van Nostrand Reinhold, New York, 1992, 954 pp. $131.95 (1995)
    Hoboken, NJ : Wiley-Blackwell
    AIChE Journal 41 (1995), S. 2343-2344 
    Details
    ISSN: 0001-1541
    Schlagwort(e): Chemistry ; Chemical Engineering
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie , Werkstoffwissenschaften, Fertigungsverfahren, Fertigung
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/aic.690411024
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  • 164
    Digitale Medien
    Digitale Medien
    A mathematical model for a dissolving polymer (1995)
    Hoboken, NJ : Wiley-Blackwell
    AIChE Journal 41 (1995), S. 2345-2355 
    Details
    ISSN: 0001-1541
    Schlagwort(e): Chemistry ; Chemical Engineering
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie , Werkstoffwissenschaften, Fertigungsverfahren, Fertigung
    Notizen: In certain polymer-penetrant systems, nonlinear viscoelastic effects dominate those of Fickian diffusion. This behavior is often embodied in a memory integral incorporating nonlocal time effects into the dynamics; this integral can be derived from an augmented chemical potential. The mathematical framework presented is a moving boundary-value problem. The boundary separates the polymer into two distinct states: glassy and rubbery, where different physical processes dominate. The moving boundary condition that results is not solvable by similarity solutions, but can be solved by perturbation and integral equation techniques. Asymptotic solutions are obtained where sharp fronts move with constant speed. The resultant profiles are quite similar to experimental results in a dissolving polymer. It is then demonstrated that such a model has a limit on the allowable front speed and a self-regulating mass uptake.
    Zusätzliches Material: 6 Ill.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/aic.690411102
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  • 165
    Digitale Medien
    Digitale Medien
    Direct numerical simulation of chemical selectivity in homogenous turbulence (1995)
    Hoboken, NJ : Wiley-Blackwell
    AIChE Journal 41 (1995), S. 2356-2370 
    Details
    ISSN: 0001-1541
    Schlagwort(e): Chemistry ; Chemical Engineering
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie , Werkstoffwissenschaften, Fertigungsverfahren, Fertigung
    Notizen: Direct numerical simulations were used to study chemical selectivity in a series-parallel reaction scheme in a decaying, homogenous turbulent flow, where A, B, R, and S represent chemical species with R the principal product and S the secondary product. These simulations involve solution of the unsteady Navier-Stokes and mass conservation equations by a pseudo-spectral method in a 643 wavenumber domain. Reactants A and B were initially spatially segregated, corresponding to a nonpremixed system. The effect of turbulence Reynolds number and other physical parameters on selectivity was determined. Turbulence increases the formation of primary product R over byproduct S compared to the case of no fluid motion, as expected. It was also found that any mechanism promoting homogenization of reactants favors the formation of R, Whereas any mechanism sustaining segregation favors the formation of S.
    Zusätzliches Material: 19 Ill.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/aic.690411103
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  • 166
    Digitale Medien
    Digitale Medien
    Adsorption kinetics for the case of setp and S-shape isotherms (1995)
    Hoboken, NJ : Wiley-Blackwell
    AIChE Journal 41 (1995), S. 2393-2398 
    Details
    ISSN: 0001-1541
    Schlagwort(e): Chemistry ; Chemical Engineering
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie , Werkstoffwissenschaften, Fertigungsverfahren, Fertigung
    Notizen: The Kinetics of diffusion in a spherical pellet saturated by a sorbate in the presence of an inert component are considered for the case of a step isotherm. A new convective flux inside the pores due to sorption effect has been taken into consideration, and an analytical expression for sorption kinetics is obtained. The convective flux may result in considerable increase in the sorption rate. It is also found that the formula obtained also gives a satisfactory description of sorption kinetics for the case of an S-shaped isotherm.
    Zusätzliches Material: 5 Ill.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/aic.690411106
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  • 167
    Digitale Medien
    Digitale Medien
    Simulation of diffusion in zeolitic structures (1995)
    Hoboken, NJ : Wiley-Blackwell
    AIChE Journal 41 (1995), S. 2399-2414 
    Details
    ISSN: 0001-1541
    Schlagwort(e): Chemistry ; Chemical Engineering
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie , Werkstoffwissenschaften, Fertigungsverfahren, Fertigung
    Notizen: Using Maxwell-Stefan equations, experimental and computational results of binary diffusion in pore- and cage-type zeolitic structures are described. In the generalized Maxwell-Stefan (GMS) formulation, the Fick diffusivity is written as the product of two separate contributions, the GMS or corrected diffusivity and the thermodynamic factor. The concentration dependence of the GMS diffusivity for one- and two-component diffusion in zeolitic structures is investigated. From the Maxwell - Stefan equations, different models for the Fick diffusion coefficient matrix for the description of binary mass transport in molecular sieve materials are derived. Various models used predict binary diffusion in zeolitic structures. First, theoretical predictions of binary apparent diffusivities as a function of the occupancy are compared to results from Monte Carlo simulations. Second, theoretical results of binary uptake profiles are compared to experimental results for the system ethylbenzene/benzene/ZSM-5. For different zeolitic structures, that is, pore- and cage-type structures, results of the Monte Carlo simulations agree well with the theoretical predictions. In cage-type structures, the effect of counterexchange between sorbed molecules is demonstrated. Experimental results of transient uptake profiles of a mixture of benzene and ethylbenzene in ZSM-5 follow predictions of the theoretical single-file diffusion model.
    Zusätzliches Material: 7 Ill.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/aic.690411107
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  • 168
    Digitale Medien
    Digitale Medien
    Optimal liner regualtion with hard constraints (1995)
    Hoboken, NJ : Wiley-Blackwell
    AIChE Journal 41 (1995), S. 2439-2450 
    Details
    ISSN: 0001-1541
    Schlagwort(e): Chemistry ; Chemical Engineering
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie , Werkstoffwissenschaften, Fertigungsverfahren, Fertigung
    Notizen: An l∞ approach to the design of linear multivariable controllers for descrete-time systems with hard time-domain constraints is presented. The notion of polar of the set of the exogenous inputs is used to parameterize the set of closed-loop transfer functions that meet regulation constraints. The constraints may include magintude and rate bounds on all relevant process variables, including the control inputs. Solutions for optimal l∞ design are found by solving a linear program for the impulse-response coefficients of the controllers, or for the coefficients of an ARMA controller model. Using these formulation, s and analytical frame work is provided for delineating the tradeoffs that govern design of linear control systems.
    Zusätzliches Material: 9 Ill.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/aic.690411110
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  • 169
    Digitale Medien
    Digitale Medien
    Axial dispersion of solid particles in a continuous rotary kiln (1995)
    Hoboken, NJ : Wiley-Blackwell
    AIChE Journal 41 (1995), S. 2465-2475 
    Details
    ISSN: 0001-1541
    Schlagwort(e): Chemistry ; Chemical Engineering
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie , Werkstoffwissenschaften, Fertigungsverfahren, Fertigung
    Notizen: Six algorithms following single particle trajectories are used to predict the axial dispersion in rolling or slumping flow in a continuous rotary kiln. Models incorporating different physical phenomena show that axial dispersion is affected by the Froude number, L/D ratio, solid fill level, and rolling or slumping layer thickness. The main cause of axial dispersion is segregation of the nonuniform particle size, density and shape. In a rolling bed with uniform particles the rolling layer thickness and the time of roll have to be accounted for in the prediction of the dispersion. The Peclet numbers computed for sold particles with uniform physical properties are of the order of 104. The sold segregated motion may lead to Peclet numbers of the order of 10 - 103, a much larger dispersion. The main obstacle for a-priori prediction of the axial dispersion is lack of a reliable relation between the segregated roll or slump distance and the variation in particles properties, as well as the change in segregation as the flow properties of kparticles are changed during calcination.
    Zusätzliches Material: 12 Ill.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/aic.690411112
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  • 170
    Digitale Medien
    Digitale Medien
    Foamed gel barriers in porous media: Breakdown and permeability evolution (1995)
    Hoboken, NJ : Wiley-Blackwell
    AIChE Journal 41 (1995), S. 2487-2498 
    Details
    ISSN: 0001-1541
    Schlagwort(e): Chemistry ; Chemical Engineering
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie , Werkstoffwissenschaften, Fertigungsverfahren, Fertigung
    Notizen: Foamed del has begun to play an important role in permeability modification applications because of the reduced chemical requirements. Foamed gels create impermeable barriers in porous media; however, once a critical pressure differential is exceeded, the permeability increases with increasing pressure. A two-dimensional network model was developed to estimate foamed gel barrier performance in terms of the maximum pressure a barrier can withstand and the evolution of the foamed gel barrier's permeability. The formation of conductive pathways and the accopanying permeability increase were estimated from a model of the pressure-induced deformation and repture of individual lenses. The evolution of conductive pathways changed from invasion percolation (high elastic modulus, rigid gel) to a lens rupture chain reaction initiated by teh rupture of a single lens (low elstic modulus gel) as the elastic modulus of the gel was decreased. The apparent fractal dimension of the first conductive channel ranged from 1.89 to 1.06 for high and low wlastic modulus gels, respectively. This dependency of breakthrough and breakdown is unique and produces a large range of breakdown behavior for any degree of microscopic heterogeneity.
    Zusätzliches Material: 17 Ill.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/aic.690411114
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  • 171
    Digitale Medien
    Digitale Medien
    Masthead (1995)
    Hoboken, NJ : Wiley-Blackwell
    AIChE Journal 41 (1995) 
    Details
    ISSN: 0001-1541
    Schlagwort(e): Chemistry ; Chemical Engineering
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie , Werkstoffwissenschaften, Fertigungsverfahren, Fertigung
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/aic.690411201
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  • 172
    Digitale Medien
    Digitale Medien
    Mixing, reaction, and precipitation: Interaction by exchange with mean micromixing models (1995)
    Hoboken, NJ : Wiley-Blackwell
    AIChE Journal 41 (1995), S. 2537-2548 
    Details
    ISSN: 0001-1541
    Schlagwort(e): Chemistry ; Chemical Engineering
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie , Werkstoffwissenschaften, Fertigungsverfahren, Fertigung
    Notizen: An analysis of interaction by exchange with the mean micromixing model is extended to a process involving elementary chemical reaction between two species and subsequent crystallization of product in a continuous mixed suspension mixed product removal etystallizer. Two specific feed conditions are considered: premixed and anpremixed feeds are considered. The sensitivity of these two cases to several parameterv like the Damköhler number, micromixing parameter, fractional flow rate, and dimensionless inlet concentration of excess reactant is explored. Both reaction and crystallizaLion performance characteristics are significantly influenced by the fred conditions. Results for the case of premixed feeds tend to suggest that the model description may be better suited to a nearly segregated configuration.
    Zusätzliches Material: 7 Ill.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/aic.690411204
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  • 173
    Digitale Medien
    Digitale Medien
    Synthesis of separation system flowsheels (1995)
    Hoboken, NJ : Wiley-Blackwell
    AIChE Journal 41 (1995), S. 2522-2536 
    Details
    ISSN: 0001-1541
    Schlagwort(e): Chemistry ; Chemical Engineering
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie , Werkstoffwissenschaften, Fertigungsverfahren, Fertigung
    Notizen: A hierarchical decision procedure for the synthesis of separation system flowsheets for vapor-organic liquid- aqueous liquid- solid mixtures is proposed. An expanded set of synthesis rules that can be used to obtain a first design is discussed, but the final goal of the procedure is to generate a complete list of separation alternatives (by changing the decisions) that when coupled with short-cut screening techniques, can be used to identify the best few process flowsheets. The procedure is based on a decomposition of the separation system synthesis problem by phase splitting into a vapor recovery system, a solid recovery system, and liquid separation systems. A general superstructure presented for these subsystems includes all of the common unit operations for petrochemical processes. The procedure focuses on the development of a complete flowsheet for the separation system: which separation system recycle loops (in contrast to reactor system recycle loops) are required, as well as interactions among separation subsystems and those between the separation system and remainder of the process. An example presented illustrates the procedure, and the opportunities for pollution prevention at the source are noted.
    Zusätzliches Material: 10 Ill.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/aic.690411203
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  • 174
    Digitale Medien
    Digitale Medien
    Solution of equations describing fluid-soil reactions in packed columns (1995)
    Hoboken, NJ : Wiley-Blackwell
    AIChE Journal 41 (1995), S. 2549-2555 
    Details
    ISSN: 0001-1541
    Schlagwort(e): Chemistry ; Chemical Engineering
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie , Werkstoffwissenschaften, Fertigungsverfahren, Fertigung
    Notizen: A semianalytical technique is presented frr solving the equations describing an isothermal, irreversible reaction of a trace component in a packed bed of a solid reactant or adsorbent The reaction-rate expression is assumed to have an arbitrary dependence on the solid reactant concentration, but a first-order dependence on the trace gas component. The technique relies on an integral transformation that reduces the set of partial differential equations to a set of two coupled ordinary differential equations in the spatial variables. Solving these two equations is simpler than solving the original equations by finite differences or finite elements, especially in the presence of steep concentration gradients. Two examples presented illustrate the technique: a progressive conversion model with reaction occurring at dispersed sites within the adsorbent pellet and a reaction proceeding in the shrinking core mode.
    Zusätzliches Material: 7 Ill.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/aic.690411205
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  • 175
    Digitale Medien
    Digitale Medien
    Separation devices for gas mixing (1995)
    Hoboken, NJ : Wiley-Blackwell
    AIChE Journal 41 (1995), S. 2585-2602 
    Details
    ISSN: 0001-1541
    Schlagwort(e): Chemistry ; Chemical Engineering
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie , Werkstoffwissenschaften, Fertigungsverfahren, Fertigung
    Notizen: When two fluid streams with different compositions mix, a significant amount of exergy is lost Utilizing the mixing exergy of gaseous streams of different compositions can reduce equipment cost and energy consumption as well as generate electric power. Suitable modification of known separation processes such as distillation, membranes, adsorption, and absorption to convert them into efficient mixing processes is discussed in detail Mixing may also be combined with a separation process such that the same device is used for both purposes which results in the use of the mixing exergy. This combined separation/mixing process is a single and relatively simple device with efficiencies not typically attainable in the generally used two-step method of separation followed by mixing. For such applications, some is∼ teresting results are presented for the processes using membrane, adsorption and absoqrion devices.
    Zusätzliches Material: 15 Ill.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/aic.690411208
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  • 176
    Digitale Medien
    Digitale Medien
    Robust output regulation for nonlinear chemical processes with unmeasurable disturbances (1995)
    Hoboken, NJ : Wiley-Blackwell
    AIChE Journal 41 (1995), S. 2565-2584 
    Details
    ISSN: 0001-1541
    Schlagwort(e): Chemistry ; Chemical Engineering
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie , Werkstoffwissenschaften, Fertigungsverfahren, Fertigung
    Notizen: It becomes a problem when the input-output feedback linearization of nonlinear processes presents unmeasurable disturbances that appear linear in the model and are not in the span of control input space. The prcsented hybrid nonlinear controller, which consists of a nonlinear static state fredback with a series of a adjustable parameters and an internal model, can achieve disturbance attenuation and offset-free performance. The major advantage of the proposed control system design is to reject disturbance without producing a vigorous control action. A simple estimation method of computing a single parameter that replaces a series of adjustable parameters of the controller is developed. The proposed estimation strategy of computing a single parameter is based on the Lyapunov stability theory. These control schemes are illustrated by an example of a chemical reactor to obtain satisfactory control.
    Zusätzliches Material: 12 Ill.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/aic.690411207
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  • 177
    Digitale Medien
    Digitale Medien
    Modeling and dynamic simulation of a bleach plant (1995)
    Hoboken, NJ : Wiley-Blackwell
    AIChE Journal 41 (1995), S. 2603-2613 
    Details
    ISSN: 0001-1541
    Schlagwort(e): Chemistry ; Chemical Engineering
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie , Werkstoffwissenschaften, Fertigungsverfahren, Fertigung
    Notizen: A dynamic model of five-stage (C+D)EDED bleach plant was developed using SIMNON a dynamic simulation language developed at Lund Institute of Technology, as a platform. The model is composed of individual modules that represent each bleaching stage. Each module includes chemical addition and mixing, diffusion and reaction in a retention towel, and washing. These unit operations are coupled with chemical kinetics for each bleaching stage using appropriate models. A relationship between the (C+D)E Kappa number and the input absorption coefficient to the D1 stage was used to link the delignification and brightening partial sequences of the bleach plant. The model, verified using steady-state data, was used to model the dynamic response of the plant to step changes in production rate, (C+D) chemical addition, and incoming Kappa number, as well as the open-loop response of the plant to a simulated variation in incoming Kappa number. The modular structure of the program allows a variety of bleach plants to be assessed once flow parameters and chemical kinetics are known. The dynamic model can also be used to develop and compare control strategies before being implemented at the mill.
    Zusätzliches Material: 7 Ill.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/aic.690411209
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  • 178
    Digitale Medien
    Digitale Medien
    Bubble dissolution viscous liquids in simple shear flow (1995)
    Hoboken, NJ : Wiley-Blackwell
    AIChE Journal 41 (1995), S. 2637-2641 
    Details
    ISSN: 0001-1541
    Schlagwort(e): Chemistry ; Chemical Engineering
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie , Werkstoffwissenschaften, Fertigungsverfahren, Fertigung
    Notizen: The dissolution of a gas bubble in a viscous Newtonian liquid in simple shear and creeping flow was studied experimentally A simple theoretical model for bubble growth or dissolution at high Peclet numbers is also presented. The main result of the model shows that for high capillary numbers (slender bubbles) the dissolution or growth rate is proportional to the shear rate to the 3/8 power The experimental work was carried out in a Couette apparatus. Air and carbon dioxide bubbles were injected into polymer liquids (low-molecular-weight polyisobutylenes) and photographed under shear. No “tip-streaming” was observed, and experimental results compared favorably with predictions of the simple model, based on a mechanism that combines diffusion and convection.
    Zusätzliches Material: 6 Ill.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/aic.690411213
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  • 179
    Digitale Medien
    Digitale Medien
    Visualization and simulation of bubble growth in pore networks (1995)
    Hoboken, NJ : Wiley-Blackwell
    AIChE Journal 41 (1995), S. 214-222 
    Details
    ISSN: 0001-1541
    Schlagwort(e): Chemistry ; Chemical Engineering
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie , Werkstoffwissenschaften, Fertigungsverfahren, Fertigung
    Notizen: Nucleation and growth of bubbles in porous media are important problems encountered in processes such as pressure depletion and boiling. Experiments and numerical simulations are studied in micromodel geometries to understand their basic aspects. Experiments of bubble growth by pressure depletion are carried out in 2-D etched-glass micromodels and in Hele-Shaw cells. Nucleation of bubbles and subsequent growth of gas clusters are visualized. Contrary to the bulk or Hele-Shaw cells, gas clusters in the micromodel have irregular and ramified shapes and share many of the features of an external invasion process (such as percolation during drainage). A pore network numerical model developed simulates the growth of multiple gas clusters under various conditions. It is based on the solution of the convection-diffusion equation and accounts for capillary and viscous forces, which play an important role in determining growth patterns. Numerical simulation agrees well with the experimental results.
    Zusätzliches Material: 10 Ill.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/aic.690410203
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  • 180
    Digitale Medien
    Digitale Medien
    Direct-contact steam condensation with simultaneous noncondensable gas absorption (1995)
    Hoboken, NJ : Wiley-Blackwell
    AIChE Journal 41 (1995), S. 241-250 
    Details
    ISSN: 0001-1541
    Schlagwort(e): Chemistry ; Chemical Engineering
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie , Werkstoffwissenschaften, Fertigungsverfahren, Fertigung
    Notizen: Experimental results are reported on simulataneous heat transfer and gas dissolution during the direct-contact condensation of steam on water in the presence of CO2. A column filled with structured packing is used as condenser with the water in counterflow with the steam/CO2 mixture. The region along the column where the bulk of condensation takes place is controllable by suitable choice of the steam/water ratio. Measured local heat-transfer coefficients change by roughly an order of magnitude from the bottom to the top of the column. The extent of CO2 dissolution in the water/condensate under most conditions is unexpectedly high and depends strongly on the exit liquid temperature. A driving force based on the interfacial CO2 concentration, not the overall concentration difference used in conventional absorption operations, is suggested as more appropriate to describe the phenomenon. The data are complemented with preliminary results from a computational model based on the integration along the column of local heat- and mass-transfer rates.
    Zusätzliches Material: 11 Ill.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/aic.690410206
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  • 181
    Digitale Medien
    Digitale Medien
    Flow regimes of the three-phase circulating fluidized bed (1995)
    Hoboken, NJ : Wiley-Blackwell
    AIChE Journal 41 (1995), S. 267-271 
    Details
    ISSN: 0001-1541
    Schlagwort(e): Chemistry ; Chemical Engineering
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie , Werkstoffwissenschaften, Fertigungsverfahren, Fertigung
    Notizen: Gas-solids circulating fluidized beds have been successfully used in catalytic cracking of heavy oil, coal combustion, and some metallurgical and physical processes (Grace, 1990). Gas-liquid-solids fluidized beds are operated mainly in conventional fluidization regimes without solids circulation or in the transport regime with low solids holdups (less than 5%) (Fan, 1989). A circulating/fast fluidization regime, however, has not been studied. A three-phase circulating fluidized bed has several potential applications in biochemical and chemical processes. Three-phase fluidized-bed bioreactors generally use light and small particles (Berk et al., 1984). Circulating operation can promote solids mixing and increase product throughput per unit bed cross section, while high shear stress can promote biofilm renewal (Pirozzi et al., 1990). In three-phase hydrotreating reactors, solids catalysts lose their activity due to the deposit of metal and coke on the surface. Circulating operation not only regenerates deactivated catalyst continuously using accompanying downcomers but also transfers heat to and from the reactor. This article discusses the flow regimes of the three-phase circulating fluidized bed.
    Zusätzliches Material: 8 Ill.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/aic.690410209
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  • 182
    Digitale Medien
    Digitale Medien
    Continous-mixture kinetics of coke formation from olefinic oligomers (1995)
    Hoboken, NJ : Wiley-Blackwell
    AIChE Journal 41 (1995), S. 317-323 
    Details
    ISSN: 0001-1541
    Schlagwort(e): Chemistry ; Chemical Engineering
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie , Werkstoffwissenschaften, Fertigungsverfahren, Fertigung
    Notizen: A model for interpreting the molecular-weight distributions is presented for the olefinic oligomers and aromatic coke compounds that are experimentally observed in a catalyzed hexene isomerization process (the primary reaction). Reaction rate expressions for the secondary generation of hexene dimers, trimers and tetramers by irreversible reaction are represented in mass balances for a stirred-tank reactor. Dehydrogenation of the oligomers to form coke aromatics and their subsequent adsorption and desorption are included. A molecular-weight moment method allows solution of the model and computation of time dependence of molecular-weight distributions for all components. The model is consistent with observations of decreased catalyst deactivation rates when coke desorption rates approach coke production rates. Catalyst activity maintenance, which can occur under supercritical conditions, is also predicted by the model.
    Zusätzliches Material: 8 Ill.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/aic.690410213
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  • 183
    Digitale Medien
    Digitale Medien
    Liquid holdup in rotating packed beds: Examination of the film flow assumption (1995)
    Hoboken, NJ : Wiley-Blackwell
    AIChE Journal 41 (1995), S. 301-316 
    Details
    ISSN: 0001-1541
    Schlagwort(e): Chemistry ; Chemical Engineering
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie , Werkstoffwissenschaften, Fertigungsverfahren, Fertigung
    Notizen: Possibilities of predicting liquid holdup in rotating packed beds are examined using the film flow theory. A hydrodynamic model based on film flow on the particle scale accommodates both laminar and turbulent films in the entry and developed regime. Conductance measurement was used for experimental determination of liquid holdup and estimation of the degree of anisotropy of liquid distribution. Experimental results represent the first data for liquid holdup in the rotating packed bed as a function of operating conditions and liquid properties. They indicate an anisotropic liquid distribution dependent on the operating variables. While the film model can be fitted to the experimental data, such a fit lacks a theoretical basis and the classical theory of film flow on the particle scale cannot explain the liquid flow in rotating packed beds. An empirical expression correlates well the holdup data with the operating parameters.
    Zusätzliches Material: 11 Ill.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/aic.690410212
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  • 184
    Digitale Medien
    Digitale Medien
    Monolith froth reactor: Development of a novel three-phase catalytic system (1995)
    Hoboken, NJ : Wiley-Blackwell
    AIChE Journal 41 (1995), S. 337-345 
    Details
    ISSN: 0001-1541
    Schlagwort(e): Chemistry ; Chemical Engineering
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie , Werkstoffwissenschaften, Fertigungsverfahren, Fertigung
    Notizen: The monolith froth reactor, involving two-phase flow and a monolith catalyst, is developed. The flow within monolith channels, consisting of trains of gas bubbles and liquid slugs, is produced by forming a two-phase froth in a chamber immediately below the bottom of the monolith. The froth then flows upward into the monolith channels through pressure forces, which differs from previous methods since it may be carried out for a commercial-scale reactor. Because the liquid film which develops between the gas phase and the surface of the catalyst is extremely thin, two-phase flow within a monolith can provide reaction rates which are near their intrinsic values. Catalytic oxidation of aqueous phenol over copper oxide supported on γ-Al2O3 is used as a model reaction for investigating reactor performance. Generation of a froth is confirmed by visual inspection; the average bubble size is approximately that predicted by a force balance. The effect of externally controllable process variables (liquid and gas flow rates, temperature, and pressure) on the rate of phenol oxidation was investigated. Reaction rate increases with temperature or pressure increase and decreases with gas flow rate increase, achieving a maximum with respect to liquid flow rate. The activation energy calculated from the apparent reaction rate measured in the monolith froth reactor is similar to that of intrinsic value, suggesting minimal mass-transfer limitations.
    Zusätzliches Material: 8 Ill.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/aic.690410215
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  • 185
    Digitale Medien
    Digitale Medien
    Model for colloidal fouling of membranes (1995)
    Hoboken, NJ : Wiley-Blackwell
    AIChE Journal 41 (1995), S. 368-376 
    Details
    ISSN: 0001-1541
    Schlagwort(e): Chemistry ; Chemical Engineering
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie , Werkstoffwissenschaften, Fertigungsverfahren, Fertigung
    Notizen: A proposed theoretical model describes colloids deposition on a membrane surface accounting for surface interactions. A mass-transfer equation links the deposition rate to hydrodynamic conditions (permeation and tangential flow through a boundary layer thickness, δ) and to physicochemical properties of the suspension (diffusion, D, and potential barrier between particles, VB). This equation predicts the existence of a critical flux, Jcrit, for ultrafiltration, reverse osmosis, or microfiltration of large-size colloids as: \documentclass{article}\pagestyle{empty}\begin{document}$$ J_{crit} = \frac{D}{\delta}ln \left({\frac{{V_B}}{\delta}} \right) $$\end{document} Some of the trends observed when processing protein solutions are explained by this model. Previous experimental data for various colloids or our data with a clay suspension in the presence of electrolytes are also compared to predictions of our model. It explains the “flux anomaly” for particle sizes between 10 nm and 1 μm.
    Zusätzliches Material: 10 Ill.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/aic.690410218
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  • 186
    Digitale Medien
    Digitale Medien
    Henry's law and synergism in dilute near-critical solutions: Theory and simulation (1995)
    Hoboken, NJ : Wiley-Blackwell
    AIChE Journal 41 (1995), S. 389-401 
    Details
    ISSN: 0001-1541
    Schlagwort(e): Chemistry ; Chemical Engineering
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie , Werkstoffwissenschaften, Fertigungsverfahren, Fertigung
    Notizen: An asymptotic analysis based on Taylor series expansions is used for first-order correction terms to the Henry's law approximation to describe solvation phenomena in multiple solute-multiple solvent systems. The magnitude of these correction terms in solvent systems very near their critical points is of particular concern, as shown in model fluid calculations with the aid of integral equation theory. The results clearly demonstrate that close proximity to the critical point in pure and mixed solvent systems causes the Henry's law approximation to show large errors in predicting solubilities, especially near the critical azeotrope of a mixed solvent system. Theoretical results also show that cross solubility enhancements in a two solutesupercritical solvent system cause cooperative synergism (both solute solubilities are increased relative to the corresponding single solute situations) or reverse synergism (both depressed relative to the single solute situation). It appears to be consistent with the available data. In computer simulations, the solute's infinitely dilute reference state is often used as a basis for describing solute thermodynamic behavior. These simulations are best achieved in the canonical ensemble because of the weak composition dependence of free energies in terms of characteristic variables of this ensemble.
    Zusätzliches Material: 9 Ill.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/aic.690410220
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  • 187
    Digitale Medien
    Digitale Medien
    The effect of gravity degradation on low-speed centrifuge capillary pressure data (1995)
    Hoboken, NJ : Wiley-Blackwell
    AIChE Journal 41 (1995), S. 469-480 
    Details
    ISSN: 0001-1541
    Schlagwort(e): Chemistry ; Chemical Engineering
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie , Werkstoffwissenschaften, Fertigungsverfahren, Fertigung
    Notizen: The gravity degradation effect has been identified as a significant physical problem in using centrifuge techniques for determining capillary pressure curves. In 1992, the authors characterized the effect by an angle; however, such an evaluation is simplistic. Here, a new model is constructed to characterize the effect quantitatively. The results with simulated data sets show that there exists a pronounced effect of gravitation on the horizontal centrifugal field in low-speed experiments (≤ 500 rpm on a standard Beckman centrifuge). Gravity affects the production history for some samples, which leads to inaccurate interpretations of capillary pressure information near the threshold pressure.
    Zusätzliches Material: 11 Ill.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/aic.690410305
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  • 188
    Digitale Medien
    Digitale Medien
    Molecular dynamics simulation of diffusion in pillared clays (1995)
    Hoboken, NJ : Wiley-Blackwell
    AIChE Journal 41 (1995), S. 456-468 
    Details
    ISSN: 0001-1541
    Schlagwort(e): Chemistry ; Chemical Engineering
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie , Werkstoffwissenschaften, Fertigungsverfahren, Fertigung
    Notizen: The thermodynamics and transport properties of Lennard-Jones particles in pillared catalytic clays are studied by molecular dynamics simulation. The clays are represented by parallel sheets separated by a given distance and connected by pillars of a given size. Two different spatial distributions of the pillars are studied to determine their effect on the properties of the system. Calculations did not indicate a strong dependence of the diffusivity on the spatial distribution of the pillars, except at low porosities. The solvation force increases monotonically with decreasing porosity of the clays and increasing density of the molecules. The percolation threshold ϕc of the system is estimated from the diffusivity measurements in the limit of infinitely low sorbate densities. Near ϕc the diffusivity D vanishes according to the power law, D ˜ (ϕ - ϕc)n, where ϕ is the porosity of the system, and n is a universal constant. The simulations yield n ⋍ 1.7. Since 2- percolation systems require n ⋍ 1.3 and 3-D systems n ⋍ 2.0, pillared clays behave as a system with an effective dimensionality between 2 and 3.
    Zusätzliches Material: 24 Ill.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/aic.690410304
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  • 189
    Digitale Medien
    Digitale Medien
    New look at wave analogy for prediction of bubble terminal velocities (1995)
    Hoboken, NJ : Wiley-Blackwell
    AIChE Journal 41 (1995), S. 481-487 
    Details
    ISSN: 0001-1541
    Schlagwort(e): Chemistry ; Chemical Engineering
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie , Werkstoffwissenschaften, Fertigungsverfahren, Fertigung
    Notizen: The analogy between waves on the surface of an infinite fluid and bubbles rising in low-viscosity fluids of infinite extent, originally proposed by Mendelson for 3-D bubbles, has been used to predict the terminal velocity of plane bubbles. In terms of its terminal velocity, a plane bubble rising in a rectangular duct of small aspect (spacing-to-width) ratio behaves as if it were a 3-D bubble rising in an infinite medium as long as the end walls (the walls in the widthwise direction) are sufficiently far apart. As the end walls are moved toward each other, a wall effect is found to exist. A general expression for the terminal velocity of a bubble of any size rising in a rectangular duct including this wall effect is also developed based on the wave analogy and shown to compare well with existing data.
    Zusätzliches Material: 7 Ill.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/aic.690410306
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  • 190
    Digitale Medien
    Digitale Medien
    Phase transition extraction using solvent mixtures with critical point of miscibility (1995)
    Hoboken, NJ : Wiley-Blackwell
    AIChE Journal 41 (1995), S. 488-500 
    Details
    ISSN: 0001-1541
    Schlagwort(e): Chemistry ; Chemical Engineering
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie , Werkstoffwissenschaften, Fertigungsverfahren, Fertigung
    Notizen: A novel separation process, phase transition extraction, proposed in this article uses solvents that have a critical point of miscibility with the feed liquid to be extracted. Alternate heating and cooling across the coexistence curve leads alternatively to a homogeneous phase or two separate phases. The formation of a homogeneous phase in the mixing stage eliminates the need for intense agitation. Coalescence on cooling in the settling stage is rapid in the presence of impurities that in conventional extraction lead to emulsions. A fermentation broth is extracted without a centrifuge with improved recovery of the antibiotic extracted. The process may have a significant advantage for cases in which extraction is difficult either due to formation of stable emulsions and dispersions or shear sensitivity.
    Zusätzliches Material: 14 Ill.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/aic.690410307
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  • 191
    Digitale Medien
    Digitale Medien
    Agglomeration during precipitation: I. Tracer crystals for Al(OH)3 precipitation (1995)
    Hoboken, NJ : Wiley-Blackwell
    AIChE Journal 41 (1995), S. 518-524 
    Details
    ISSN: 0001-1541
    Schlagwort(e): Chemistry ; Chemical Engineering
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie , Werkstoffwissenschaften, Fertigungsverfahren, Fertigung
    Notizen: Tracer crystals are developed to study the agglomeration, growth and residence time behavior of gibbsite crystals, an industrially important polymorph of Al(OH)3, in continuous and batch precipitation. Satisfactory tracer crystals contain detectable amounts of Zn and have the crystal structure of gibbsite. The tracer crystals behave in the same manner during precipitation as the nontracer Al(OH)3 crystals. The application of the tracer crystals for investigating, both batch and continuous, seeded Al(OH)3 precipitation is demonstrated. The tracer experiments provide information on the growth and agglomeration kinetics of different size fractions. The tracers are a useful tool for the quantitative investigation of solid-phase residence time distributions within a crystallizer.
    Zusätzliches Material: 6 Ill.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/aic.690410310
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  • 192
    Digitale Medien
    Digitale Medien
    Cross-flow microfiltration with high-frequency reverse filtration (1995)
    Hoboken, NJ : Wiley-Blackwell
    AIChE Journal 41 (1995), S. 501-508 
    Details
    ISSN: 0001-1541
    Schlagwort(e): Chemistry ; Chemical Engineering
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie , Werkstoffwissenschaften, Fertigungsverfahren, Fertigung
    Notizen: A primary method of reducing membrane fouling during cross-flow microfiltration is periodic reverse filtration. This in situ method of cleaning the membrane forces clear fluid in the reverse direction through the membrane and readjusts the particle or solute accumulation on the retentate side of the membrane. This work focuses on the design of a high-frequency, reverse-filtration strategy to maximize the flux for washed yeast suspensions through 0.2- μm cellulose acetate flat sheet membranes. Several experiments were conducted with reverse-filtration times ranging from 0.5-4 s and forward-filtration times ranging from 1-40 s. For every back-filtration time, there exists an optimum forward-filtration time that gives the maximum global average flux. The optimum average flux increases with decreasing back filtration times and feed concentrations, but shows little dependence on cross-flow velocity and reverse filtration transmembrane pressure. The optimum flux with rapid backflushing is 20 to 30 times higher than the long-term flux in the absence of backflushing. A theory presented assumes that cake formation during forward filtration follows dead-end filtration theory and the cake is instantly removed during reverse filtration. The measured average flux per cycle follows the trends predicted by the theory, but the measured values exceed the predictions, presumably due to brief delays in cake removal and cake formation at the start of reverse and forward filtration, respectively, during each cycle.
    Zusätzliches Material: 9 Ill.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/aic.690410308
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  • 193
    Digitale Medien
    Digitale Medien
    Process analysis in the complex domain (1995)
    Hoboken, NJ : Wiley-Blackwell
    AIChE Journal 41 (1995), S. 585-590 
    Details
    ISSN: 0001-1541
    Schlagwort(e): Chemistry ; Chemical Engineering
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie , Werkstoffwissenschaften, Fertigungsverfahren, Fertigung
    Notizen: Analytical support for recent numerical work in process simulation in the complex domain is discussed. In particular, the observation that nondegenerate singular points are saddle points of the two-norm on the complex domain is proved rigorously and its numerical implications are discussed. The isothermal isobaric flash problem admits only real-valued two-phase solutions, provided that the feed conditions are real. Both single- and multivariable chemical process examples illustrate the theoretical results.
    Zusätzliches Material: 4 Ill.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/aic.690410316
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  • 194
    Digitale Medien
    Digitale Medien
    Adjustable discretized population balance for growth and aggregation (1995)
    Hoboken, NJ : Wiley-Blackwell
    AIChE Journal 41 (1995), S. 591-603 
    Details
    ISSN: 0001-1541
    Schlagwort(e): Chemistry ; Chemical Engineering
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie , Werkstoffwissenschaften, Fertigungsverfahren, Fertigung
    Notizen: The discretized population balance (DPB) of Hounslow et al. (1988) is extended to allow the use of an adjustable discretization of the size domain of the form νi+/ν1=2 1/q (where q ≥ 1 and is an integer). All the advantages of Hounslow et al.'s original work are retained: the zeroth and third moments of the particle-size distribution are correctly predicted, and the DPB is simple to solve with no integration within each size interval. The predicted and analytical particle size distributions are in excellent agreement for the cases of nucleation and growth and aggregation alone in batch and in continuous vessels. High-order moments and self-preserving particle-size distributions are accurately predicted when q ≥ 4.
    Zusätzliches Material: 13 Ill.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/aic.690410317
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  • 195
    Digitale Medien
    Digitale Medien
    Glucose hydrolysis and oxidation in supercritical water (1995)
    Hoboken, NJ : Wiley-Blackwell
    AIChE Journal 41 (1995), S. 637-648 
    Details
    ISSN: 0001-1541
    Schlagwort(e): Chemistry ; Chemical Engineering
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie , Werkstoffwissenschaften, Fertigungsverfahren, Fertigung
    Notizen: Glucose hydrolysis and oxidation occurred rapidly in supercritical water at 246 bar and at 425 to 600°C. A diverse set of products, present in the liquid-phase reactor effluent and also subject to hydrolysis, was formed. At 600°C and a 6-s reactor residence time, glucose is completely gasified, even in the absence of oxygen. In the presence of oxygen, destruction of liquid-phase products is enhanced, with none found above 550°C at a 6-s reactor residence time. Major products formed wee acetic acid, acetonylacetone, propenoic acid, and acetaldehyde in the liquid phase, and carbon monoxide, carbon dioxide, methane, ethane, ethylene, and hydrogen in the gas phase. Methane and hydrogen were present among the products at temperatures up to 600°C for reactor residence times of 6 s.
    Zusätzliches Material: 7 Ill.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/aic.690410320
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  • 196
    Digitale Medien
    Digitale Medien
    Feedback control of nonlinear differential-algebraic-equation systems (1995)
    Hoboken, NJ : Wiley-Blackwell
    AIChE Journal 41 (1995), S. 619-636 
    Details
    ISSN: 0001-1541
    Schlagwort(e): Chemistry ; Chemical Engineering
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie , Werkstoffwissenschaften, Fertigungsverfahren, Fertigung
    Notizen: The output feedback control problem is addressed for a class of nonlinear multivariable high-index differential-algebraic-equation systems in semiexplicit form. Initially, an algorithmic procedure is developed and used to derive an equivalent state-space relization of the constrained system. An output feedback synthesis problem is then formulated on the basis of the derived state-space realization and solved through the combination of state feedback and appropriate state observers. The developed methodology is applied to a two-phase reactor, and its performance and robustness characteristics are evaluated through simulations.
    Zusätzliches Material: 10 Ill.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/aic.690410319
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  • 197
    Digitale Medien
    Digitale Medien
    Modeling membrane filtration of protein and cell suspensions in a vortex flow filtration system (1995)
    Hoboken, NJ : Wiley-Blackwell
    AIChE Journal 41 (1995), S. 764-772 
    Details
    ISSN: 0001-1541
    Schlagwort(e): Chemistry ; Chemical Engineering
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie , Werkstoffwissenschaften, Fertigungsverfahren, Fertigung
    Notizen: Vortex flow filtration experiments with bovine serum albumin (BSA) solutions and Arthrobacter simplex cell suspensions in a rotary membrane device are modeled in the pressure-dependent flux and mass-transfer-controlled regions. An expression for the concentration-dependent diffusion coefficients accounting for hydrodynamic and long-range potential interactions between rigid spherical macromolecules is used for BSA. A shear-induced diffusion coefficient, strongly concentration-dependent on the cell concentration, is assumed to describe the diffusion behavior of the cell suspensions. The adjusted model parameters for albumin solutions in the pressure-dependent region of flux predict the permeation flux behavior for A. Simplex cell suspensions. When the mass-transfer correlation is calculated using cell diffusion coefficients, based on a volumetric cell fraction that is around half of the average value of the calculated membrane surface fractions, the fluxes are estimated within less than 10.5% relative error. In the mass-transfer-controlled region of flux, the volume fractions of cells at the membrane surface are between 0.16 and 0.35, depending on bulk concentration and hydrodynamic conditions.
    Zusätzliches Material: 6 Ill.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/aic.690410403
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  • 198
    Digitale Medien
    Digitale Medien
    Oscillatory, creep and steady flow behavior of Xanthan-thickened oil-in-water emulsions (1995)
    Hoboken, NJ : Wiley-Blackwell
    AIChE Journal 41 (1995), S. 783-794 
    Details
    ISSN: 0001-1541
    Schlagwort(e): Chemistry ; Chemical Engineering
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie , Werkstoffwissenschaften, Fertigungsverfahren, Fertigung
    Notizen: The rheological behavior of xanthan gum-thickened oil-in-water emulsions is studied with a cone-and-plate system using a constant-stress rheometer. Xanthan gum solutions and xanthan-thickened oil-in-water emulsions are strongly shear-thinning and viscoelastic in nature. The effects of polymer and oil concentrations on the rheological behavior of emulsions are investigated. The relative viscosity for the thickened emulsions, at any given oil concentration, increases with an increase in the shear rate, whereas the unthickened emulsions show the opposite trend. The theoretical models give reasonable predictions for the relative viscosity, storage modulus, and loss modulus of xan-than-thickened emulsions. The ratio of storage to loss moduli increases considerably with the increase in polymer and oil concentrations. The creep/recovery experiments confirm that the xanthan-thickened emulsions are highly viscoelastic in nature and that the degree of elasticity increase with the increase in polymer and oil concentrations.
    Zusätzliches Material: 16 Ill.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/aic.690410405
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  • 199
    Digitale Medien
    Digitale Medien
    Analysis of diffusion in polymers using evanescent field spectroscopy (1995)
    Hoboken, NJ : Wiley-Blackwell
    AIChE Journal 41 (1995), S. 795-804 
    Details
    ISSN: 0001-1541
    Schlagwort(e): Chemistry ; Chemical Engineering
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie , Werkstoffwissenschaften, Fertigungsverfahren, Fertigung
    Notizen: A rigorous analysis confirmed by experimental results is presented for attenuated total reflectance, Fourier-transform infrared (FTIR-ATR) spectroscopy applied to the study of small molecule diffusion in polymers. FTIR-ATR Fickian diffusion models are derived for a constant surface concentration and for an adjacent mass-transfer boundary layer. An FTIR-ATR Case II transport model demonstrates the ability to discriminate between transport modes. New experimental results for the acetone-polypropylene, methanol-polystyrene and methanol-poly(methyl methacrylate) systems are consistent with gravimetric sorption and nuclear magnetic resonance measurements. An important result is the detection of multiple hydroxyl peaks for methanol during diffusion, indicating different hydrogen bonding states and the calculation of separate diffusion coefficients for each state in polystyrene.
    Zusätzliches Material: 11 Ill.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/aic.690410406
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  • 200
    Digitale Medien
    Digitale Medien
    Experimental measurement of diffusion in aqueous polyvinylpyrrolidone solutions (1995)
    Hoboken, NJ : Wiley-Blackwell
    AIChE Journal 41 (1995), S. 812-818 
    Details
    ISSN: 0001-1541
    Schlagwort(e): Chemistry ; Chemical Engineering
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie , Werkstoffwissenschaften, Fertigungsverfahren, Fertigung
    Notizen: Diffusivities of aqueous dilute and semidilute polyvinylpyrrolidone solutions Mw = 50,500 and Mw = 867,000 were measured at 25°C. The measurements were performed by Taylor's hydrodynamic stability method and the dynamic light scattering (DLS) method. Taylor's method was compared to DLS and evaluated as an experimental technique to determine the molecular diffusivity in polymer solutions. The agreement between the two methods was very good with Taylor's method proving to be a reliable, simple, and inexpensive technique that provided diffusivity data with a maximum error of 5%.
    Zusätzliches Material: 4 Ill.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/aic.690410408
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