ALBERT

All Library Books, journals and Electronic Records Telegrafenberg

Your email was sent successfully. Check your inbox.

An error occurred while sending the email. Please try again.

Proceed reservation?

Export
Filter
  • Chemical Engineering  (3,294)
  • Wiley-Blackwell  (3,294)
  • 1990-1994  (3,294)
  • 1
    Electronic Resource
    Electronic Resource
    Hoboken, NJ : Wiley-Blackwell
    AIChE Journal 40 (1994), S. 1-1 
    ISSN: 0001-1541
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 2
    Electronic Resource
    Electronic Resource
    Hoboken, NJ : Wiley-Blackwell
    AIChE Journal 40 (1994), S. 11-18 
    ISSN: 0001-1541
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: The dynamic evolution of the cluster-size distribution (CSD) in the precoalescence stages of nucleation and growth for sizes within and beyond the nucleation barrier layer (NBL) has been obtained. The existence of several universal kinetic laws of nucleation is predicted. In the precoalescence stages of nucleation, the CSD for sizes within and beyond the NBL obeys dynamic scaling relations. In a range of sizes beyond the NBL, the CSD exhibits a universal power law behavior, the exponent of which depends only on the interphase monomer transfer mechanism. Based on the results for the CSD, a general foundation is developed for nucleation kinetic measurements including the determination of the nucleation barrier and the inter-facial monomer transport rate by measuring the CSD. A preliminary comparison with an experimental study confirms the predicted dynamic scaling and the power law behavior of the CSD in the early stages of nucleation and growth.
    Additional Material: 4 Ill.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 3
    Electronic Resource
    Electronic Resource
    Hoboken, NJ : Wiley-Blackwell
    AIChE Journal 40 (1994), S. 50-64 
    ISSN: 0001-1541
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Monitoring and control of batch pulp digesters, which convert wood chips to pulp by Kraft process are discussed. The Kappa number, which represents the extent of delignification, is the key controlled variable, which cannot be measured on-line and must be estimated through secondary liquor measurements. Given a fixed batch time, the final Kappa number should be as close to the target Kappa number as possible, despite errors in the initial state estimates and input disturbances. To fulfill this objective, a state-observer-based model-predictive controller is designed using a detailed nonlinear dynamic model of the digester. The extended Kalman filter (EKF) using on-line measurements of various liquor characteristics is capable of recovering from significant errors in the initial state estimates. In addition, the EKF is shown to be robust to the errors in the covariance matrices and most model parameters, but quite sensitive to some model parameter errors. Coupled with the EKF, a finite-horizon model predictive controller (MFC) based on successive linearization of the nonlinear pulping model, is found to work efficiently for controlling the Kappa number and batch time.
    Additional Material: 9 Ill.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 4
    Electronic Resource
    Electronic Resource
    Hoboken, NJ : Wiley-Blackwell
    AIChE Journal 40 (1994), S. 88-96 
    ISSN: 0001-1541
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: A dynamic model for emulsion polymerization in a tubular reactor has been developed and compared with experimental data. The model uses an axial dispersion coefficient to fit experimentally measured residence time distributions and to represent axial mixing during reaction. Very general emulsion polymerization kinetics are assumed so that a wide range of monomers and operating conditions can be handled. Orthogonal collocation on finite elements was chosen as the numerical solution technique. Comparisons show good agreement between model and experiments for two different monomers.
    Additional Material: 9 Ill.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 5
    Electronic Resource
    Electronic Resource
    Hoboken, NJ : Wiley-Blackwell
    AIChE Journal 40 (1994), S. 120-130 
    ISSN: 0001-1541
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Spatiotemporal patterns existing in a one-dimensional fixed-bed reactor with oscillatory or excitable kinetics are analyzed to develop the methodology of motion identification and classification. The reactor model accounts for a local (solid-phase) oscillator and a global (gas-phase) convective interaction. The local oscillator incorporates a fast and diffusing surface temperature and a localized activity as its dynamic variables. Such kinetics admit a traveling pulse solution or homogeneous oscillations in a uniform medium. In a fixed-bed reactor, the local conditions in the bed (the phase plane character) vary along the system. The response of an excitable bed to local perturbations depends on its location (at inlet or outlet) and the nature of the initial steady state ( ignite or extinguished). The main spatiotemporal-sustained patterns in the bed are: almost homogeneous oscillations that appear as parallel bands in the time-space contour map; oscillatory fronts that emerge from the reactor exit, and aperiodic motion that appears as split-bands. Pattern selection is determined by the phase planes spanned by the reactor and the ratio of the two slowest time scales: front residence time and period of oscillations.
    Additional Material: 11 Ill.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 6
    Electronic Resource
    Electronic Resource
    Hoboken, NJ : Wiley-Blackwell
    AIChE Journal 40 (1994), S. 152-159 
    ISSN: 0001-1541
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: A generalized quartic equation of state has been developed for pure nonpolar fluids. The equation of state contains four parameters which depend on three properties of the fluid - critical temperature, critical volume, and acentric factor. A mathematical approximation based on previously reported hard-sphere molecular dynamics simulations has been used to model repulsive contributions to the pressure. Attractive forces were modeled using an empirical term. While the quartic equation yields four roots, one root is always negative and hence physically meaningless, and three roots behave like three roots of a cubic equation. Thus, the new equation of state has the advantages of a cubic, simplicity and unequivocal identification of the roots, while correctly modeling the attractive and repulsive contributions to the pressure. The new equation of state is more accurate than either the Peng-Robinson or a previously proposed quartic equation of state. Accuracy in the supercritical and compressed liquid regions is improved substantially.
    Additional Material: 14 Ill.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 7
    Electronic Resource
    Electronic Resource
    Hoboken, NJ : Wiley-Blackwell
    AIChE Journal 40 (1994), S. 187-192 
    ISSN: 0001-1541
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
    Additional Material: 5 Ill.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 8
    Electronic Resource
    Electronic Resource
    Hoboken, NJ : Wiley-Blackwell
    AIChE Journal 40 (1994), S. 178-181 
    ISSN: 0001-1541
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
    Additional Material: 4 Ill.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 9
    Electronic Resource
    Electronic Resource
    Hoboken, NJ : Wiley-Blackwell
    AIChE Journal 40 (1994), S. 536-542 
    ISSN: 0001-1541
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Increasing and constant temperature gravimetric methods were used to measure the thermal decomposition rates of Mg(OH)2 particles. An Arrhenius-type kinetic equation was proposed and tested. Temperature, exposure time on surface area of the calcined particles and other effects of variables were explored. A fractional-order sintering rate expression was developed on the basis of collected experimental data. An integrated model is also presented that considers the surface area generation by calcination and the simultaneous surface reduction caused by sintering of the nascent oxide. Obtained results enable specifying the operating conditions needed for the production of the high surface, reactive magnesium oxide.
    Additional Material: 5 Ill.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 10
    Electronic Resource
    Electronic Resource
    Hoboken, NJ : Wiley-Blackwell
    AIChE Journal 40 (1994), S. 570-575 
    ISSN: 0001-1541
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
    Additional Material: 6 Ill.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 11
    Electronic Resource
    Electronic Resource
    Hoboken, NJ : Wiley-Blackwell
    AIChE Journal 40 (1994), S. 207-214 
    ISSN: 0001-1541
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: The interactive effects of heat and mass transfer in evaporation of binary mixtures flowing as falling films on vertical surfaces was investigated. Evaporative heat-transfer coefficients were measured for aqueous mixtures of ethylene and propylene glycol, with boiling ranges up to 55°C. Tests were carried out at atmospheric pressure with heat fluxes ranging from 3,000 to 25,000 W/m2, and film Reynolds numbers ranging from 300 to 3,000. Results indicated that the heat-transfer coefficient for mixtures depends weakly on wall superheat and film Reynolds number, but strongly depends on mixture composition. Analysis of the results indicates that mass-transfer resistance in the liquid film causes significant elevation of the interface temperature, causing a reduction of the effective temperature driving force. A semiempirical model for correlation of the interactive heat-and mass-transfer phenomena is proposed.
    Additional Material: 10 Ill.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 12
    Electronic Resource
    Electronic Resource
    Hoboken, NJ : Wiley-Blackwell
    AIChE Journal 40 (1994), S. 627-646 
    ISSN: 0001-1541
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: The Åström-Hägglund autotuner is extended to multivariable systems. The proposed multivariable automatic tuning performs the identification-design procedure in a sequential manner. Its advantages are discussed, as well as the process characteristics resulted from sequential design. One important feature is that the sequential design often leads to underdamped process characteristics. Given these characteristics, potential problems in the Ziegler-Nichols tuning are discussed and a modification is made. The sequential identification and the modified Ziegler-Nichols controller design method form the basic structure for the multivariable autotuner. The properties of convergence, the implications of tuning sequence, and the indications of undesirable pairing for the autotuner are explored. Consequently, a multivariable autotuning procedure is proposed. Two nonlinear distillation examples and a 3 × 3 linear system are used to illustrate the effectiveness of the autotuner. Simulation results show that good performance can be obtained with minimal engineering effort and the autotuner works well for very difficult processes in a very simple way.
    Additional Material: 24 Ill.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 13
    Electronic Resource
    Electronic Resource
    Hoboken, NJ : Wiley-Blackwell
    AIChE Journal 40 (1994), S. 312-320 
    ISSN: 0001-1541
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: A statistical thermodynamics model based on the original work of van der Waals and Platteeuw is presented for structure-H hydrates. The model is an extension of the hydrate prediction method generalized by Parrish and Prausnitz for structure-I and-II hydrates. Four structure-H-forming systems, methane+ adamantane, methane+ neohexane, methane+isopentane, and methane+methylcyclohexane, were considered. Optimized Kihara core parameters are presented for each of the large hydrocarbon guest molecules. The optimized reference chemical potential difference and reference enthalpy difference for structure-H hydrates are also presented. The results show good agreement with the experimentally determined phase-equilibria conditions. A sensitivity analysis is presented for the parameters in the model, and their relative order of influence on the accurate evaluation of the quilibrium pressure is determined.
    Additional Material: 10 Ill.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 14
    Electronic Resource
    Electronic Resource
    Hoboken, NJ : Wiley-Blackwell
    AIChE Journal 40 (1994), S. 381-381 
    ISSN: 0001-1541
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 15
    Electronic Resource
    Electronic Resource
    Hoboken, NJ : Wiley-Blackwell
    AIChE Journal 40 (1994), S. 381-382 
    ISSN: 0001-1541
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 16
    Electronic Resource
    Electronic Resource
    Hoboken, NJ : Wiley-Blackwell
    AIChE Journal 40 (1994), S. 385-394 
    ISSN: 0001-1541
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Two methods are presented for calculating the interfacial tension between two immiscible Newtonian fluids. The procedures require only two measurements of the approximate interface shape during the low-Reynold-number interfacial-tension-driven transient motion of (i) the relaxation of a modestly elongated drop back to a spherical shape or (ii) the growth of capillary wave instabilities along the surface of a thread. The interfacial tension can be estimated by comparing the time differences between the two experimental measurements with tabulated and numerically generated results for the approximate shape evolution. The numerical results are generated using boundary integral method for similar model free-boundary problems at low Reynolds numbers. The tabulated results are presented for drop to suspending fluid viscosity ratios 0.01 to 10.
    Additional Material: 9 Ill.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 17
    Electronic Resource
    Electronic Resource
    Hoboken, NJ : Wiley-Blackwell
    AIChE Journal 40 (1994), S. 424-432 
    ISSN: 0001-1541
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Mixing effects are evaluated for double jet semibatch and continuous stirred precipitators by a model which gives the variation of the primary nucleation flux from the mixing conditions. The predicted trends are compared with results of various authors, including those from a new study of calcium oxalate semibatch double-jet precipitation. Satisfactory qualitative agreement is found for the different chemical systems as a function of feed rate, stirring speed and feed locations for calcium oxalate precipitation. Two types of precipitation systems are demonstrated, depending on the ratio added/tank volume, the initial supersaturations and the intrinsic stiffness factor of a given precipitation. The difference between the two types depends on the increase or reduction of the primary nucleation flux by imperfect mixing with respect to the reference primary nucleation flux obtained with perfect mixing.
    Additional Material: 11 Ill.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 18
    Electronic Resource
    Electronic Resource
    Hoboken, NJ : Wiley-Blackwell
    AIChE Journal 40 (1994), S. 473-495 
    ISSN: 0001-1541
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: This work concerns the synthesis of discrete-time feedforward/feedback control systems for general nonlinear processes with stable zero dynamics. Depending on the process under consideration, the derived feedforward/feedback controllers can completely eliminate the effect of measurable disturbances and produce a prespecified linear response with respect to a reference input, or provide integral-square error optimal response to step changes in the disturbances and a prespecified linear response with respect to a reference input. In either case, the developed feedforward/feedback controllers allow for the asymptotic rejection of unmeasurable disturbances. These controllers are derived within the globally linearizing control frame-work, first under full state information and then in the absence of state measurements. The internal stability of the closed-loop system is addressed. The derived controllers are interpreted from a model-predictive point of view, and their connections with the feedforward internal model control and the model algorithmic control are established. The theoretical results are illustrated through a continuous stirred-tank reactor example.
    Additional Material: 9 Ill.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 19
    Electronic Resource
    Electronic Resource
    Hoboken, NJ : Wiley-Blackwell
    AIChE Journal 40 (1994), S. 521-535 
    ISSN: 0001-1541
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: The oxidative coupling of methane was carried out in the absence of catalyst in a continuous flow setup at total pressures up to 1,000 kPa, temperatures from 950 to 1,230 K, and inlet molar ratios of CH4/O2 down to 2.5. At constant temperature and residence time, the conversions of methane and oxygen increase drastically with increasing pressure. At oxygen conversions higher than 80%, product selectivities are comparable at different pressures. The space-time yield of the C2 products reaches a level comparable to that required for industrial operations from 400 kPa on. A radical-reaction network consisting of 38 elementary reactions allows to describe the experimental data. To describe adequately the effect of total pressure, the pressure fall-off behavior of the rate coefficients for the unimolecular reactions in the network has to be taken into account explicitly.General features of the reaction mechanism do not depend on the total pressure. Methyl and hydrogen peroxy radicals are the most abundant radicals. The total pressure increase results in a drastic increase of the concentrations of the chain carriers, particularly the hydrogen peroxy radical. Higher pressure favor the oxidative route from ethane to ethylene compared to the pyrolytic route. Increasing the total pressure leads to an increase of the primary and a decrease of the consecutive CO formation relative to the coupling. The balance between these nonselective routes determines the effect of the total pressure on the integral selectivity to C2 products at different conversions. The major contribution to the integral CO selectivity comes from the oxidation of methyl radicals.
    Additional Material: 8 Ill.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 20
    Electronic Resource
    Electronic Resource
    Hoboken, NJ : Wiley-Blackwell
    AIChE Journal 40 (1994) 
    ISSN: 0001-1541
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 21
    Electronic Resource
    Electronic Resource
    Hoboken, NJ : Wiley-Blackwell
    AIChE Journal 40 (1994), S. 606-612 
    ISSN: 0001-1541
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Influence of local voids on flow maldistribution in randomly packed fiber bundles is examined by Voronoi tessellation. A theoretical expression for the local void distribution caused by random placement of fibers is developed by using a randomcell model. Simulations and packing experiments have been conducted to assess the accuracy of the theoretical distribution of cell sizes. In the case of shell side, laminar flow parallel to the fibers, the theoretical distribution is used to estimate fRe (friction factor times Reynolds number) and volumetric flows, and to compare results with ordered arrays and experimental data from literature. The results are used to assess the contributions of local voidage variation to flow bypass. This has implications for the prediction of pressure drop and heat and mass transfer in hollow-fiber module applications where transport is dominated by flow on the shell side.
    Additional Material: 4 Ill.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 22
    Electronic Resource
    Electronic Resource
    Hoboken, NJ : Wiley-Blackwell
    AIChE Journal 40 (1994), S. 1055-1066 
    ISSN: 0001-1541
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: The conversion of radiant light energy into chemical affinity by microorganisms in photobioreactors is examined. The kinetics of entropy production in the system is theoretically established from entropy and energy balances for the material and photonic phases in the reactor. A negative chemical affinity term compensated for by a radiant energy term at a higher level of energy characterizes photosynthetic organisms. The local volumetric rate of radiant light energy absorbed, which appears in the dissipation function as an irreversible term, is calculated for monodimensional approximations providing analytical solutions and for general tridimensional equations requiring the solution of a new numerical algorithm. Solutions for the bluegreen alga Spirulina platensis cultivated in photoreactors with different geometries and light energy inputs are compared. Thermodynambic efficiency of the photosynthesis is calculated. The highest value of 15% found for low radiant energy absorption rates corresponds to a maximum quantum yield in the reactor.
    Additional Material: 7 Ill.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 23
    ISSN: 0001-1541
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 24
    Electronic Resource
    Electronic Resource
    Hoboken, NJ : Wiley-Blackwell
    AIChE Journal 40 (1994), S. 1089-1089 
    ISSN: 0001-1541
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 25
    Electronic Resource
    Electronic Resource
    Hoboken, NJ : Wiley-Blackwell
    AIChE Journal 40 (1994) 
    ISSN: 0001-1541
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 26
    Electronic Resource
    Electronic Resource
    Hoboken, NJ : Wiley-Blackwell
    AIChE Journal 40 (1994), S. 1105-1117 
    ISSN: 0001-1541
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Pressure drops, gas holdup, and mass-transfer coefficients were measured in two concentric-tube airlift reactors of 30 and 300 L (nominal volume). The aspect ratio and the ratio of riser to downcomer cross section were the same for both reactors, but the geometry of the gas separation section was different. The influence of the bottom and top clearances was studied using water and carboxymethyl cellulose solutions and covering a range of effective viscosity from 10-3 to 25 × 10-3 Pa·s. The pressure drop results expressed as a Euler number were satisfactorily correlated with Fr, Ga, and a bubble disengagement group M. Correlations are presented also for the gas holdup in the riser, downcomer, and gas separator. The last-mentioned coincides with the correlation for the total holdup in the reactor. The gas-liquid mass-transfer coefficients for all the liquids and geometric variables in both reactors were successfully correlated as Sherwood numbers.
    Additional Material: 13 Ill.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 27
    Electronic Resource
    Electronic Resource
    Hoboken, NJ : Wiley-Blackwell
    AIChE Journal 40 (1994), S. 911-911 
    ISSN: 0001-1541
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 28
    Electronic Resource
    Electronic Resource
    Hoboken, NJ : Wiley-Blackwell
    AIChE Journal 40 (1994) 
    ISSN: 0001-1541
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 29
    Electronic Resource
    Electronic Resource
    Hoboken, NJ : Wiley-Blackwell
    AIChE Journal 40 (1994), S. 935-943 
    ISSN: 0001-1541
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Equilibrium and kinetic data for adsorption of trace CF2Cl2 (Freon-12) from various carrier gases on BPL activated carbon are reported. Coadsorption of the bulk carrier gas can severely reduce the equilibrium adsorption capacity and adsorptive mass-transfer coefficient of strongly adsorbed CF2Cl2. The difference in size between CF2Cl2 and the bulk carrier gas molecules plays a major role in establishing the binary or multicomponent equilibrium adsorption properties. The multisite (single and multicomponent) Langmuir model, which accounts for differences in adsorbate sizes, provides a reasonable framework for describing the size effects. The adsorptive mass transfer of CF2Cl2 under the experimental conditions investigated is dominated by surface diffusion into the pores of the activated carbon. The surface diffusivity is a strong function of the extent of coverage and strength of adsorption of the bulk components.
    Additional Material: 8 Ill.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 30
    Electronic Resource
    Electronic Resource
    Hoboken, NJ : Wiley-Blackwell
    AIChE Journal 40 (1994), S. 980-990 
    ISSN: 0001-1541
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: This experimental work concerns the multivariable nonlinear control of a pilotsize continuous polymerization reactor with generically singular characteristic matrix. The control problem is to control conversion and temperature in a continuous stirred tank reactor by manipulating two coordinated flow rates (reactor residence time) and two coordinated heat inputs. A nonlinear controller is synthesized within the framework of the globally linearizing control (GLC) method and is implemented on a microcomputer. Conversion is inferred from on-line measurements of density and temperature. A key feature of the control problem is that its characteristic matrix is generically singular. Singularity of the characteristic matrix is handled by using a dynamic input/output linearizing state feedback rather than a static feedback. A reduced-order observer is used to calculate the monomer, initiator, and solvent concentration estimates, which are needed for the calculation of controller action. In the presence of active state and input constraints, the reactor-startup and setpointtracking performance of the controller is evaluated through experimental runs.
    Additional Material: 14 Ill.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 31
    ISSN: 0001-1541
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: The mechanism of alginate droplet formation and experimental parameters for producing very small polymer microbeads (less than 100 μm dia.) using an electrostatic droplet generator studied showed that the microbead size was a function of needle diameter, charge arrangement (electrode geometry and spacing) and strength of electric field. Perfectly spherical and uniform polymer beads, 170 μm dia., for example, were obtained at a potential difference of 6 kV with a 26-gauge needle and an electrode distance of 2.5 cm. Increasing the electric field, and thus the surface charge in the vicinity of the needle, by increasing the applied potential, resulted in needle oscillation, giving a bimodal bead size distribution with a large fraction (30-40%) of microbeads with a mean diameter of 50 μm. The process of alginate droplet formation under the influence of electrostatic forces assessed with an image analysis/video system revealed distinct stages. After a voltage was applied, the liquid meniscus at the needle tip was distorted from a spherical shape into an inverted cone-like shape. Consequently, alginate solution flowed into this cone at an increasing rate causing formation of a neck-like filament. When this filament broke away, producing small droplets, the meniscus relaxed back to a spherical shape until flow of the polymer caused the process to start again. A large-scale multineedle device with a processing capacity of 0.7 L/h was also designed and produced uniform 400 ± 150 μm microbeads.
    Additional Material: 5 Ill.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 32
    Electronic Resource
    Electronic Resource
    Hoboken, NJ : Wiley-Blackwell
    AIChE Journal 40 (1994), S. 1067-1081 
    ISSN: 0001-1541
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Protein denaturation, common in hydrophobic adsorption systems, causes misinterpretation of adsorption mechanisms, interferes with analysis in analytical chromatography, and complicates the design of large-scale adsorption processes. A detailed adsorption model isolates the effects due to denaturation from those due to mass transfer and intrinsic adsorption kinetics. The model is verified using protein gradient elution data. Simulations establish that typical symptoms of denaturation in frontal and elution chromatogrrams include sensitivity to changes in feed composition, column length, particle size, and operating conditions (feed size, flow rate, and column history). When a denatured species adsorbs irreversibly, the elution chromatogram shows decreasing peak area with increasing incubation time and apparent adsorption hysteresis over repeated cycles. In gradient elution, the peak elution order, resolution, and relative peak height depend highly on modulator properties and operating conditions. Interfering species limit solid-phase induced denaturation by competing for binding sites. Strategies for detecting and minimizing denaturation are proposed.
    Additional Material: 12 Ill.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 33
    Electronic Resource
    Electronic Resource
    Hoboken, NJ : Wiley-Blackwell
    AIChE Journal 40 (1994), S. 1087-1087 
    ISSN: 0001-1541
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 34
    Electronic Resource
    Electronic Resource
    Hoboken, NJ : Wiley-Blackwell
    AIChE Journal 40 (1994), S. 1312-1327 
    ISSN: 0001-1541
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: The open-loop optimal control strategy to regulate the crystal-size distribution of batch cooling crystallizers handles input, output, and final-time constraints, and is applicable to crystallization with size-dependent growth rate, growth dispersion, and fines dissolution. The objective function can be formulated to consider solid-liquid separation in subsequent processing steps.A model-based control algorithm requires a model that accurately predicts system behavior. Uncertainty bounds on model parameter estimates are not reported in most crystallization model identification studies. This obscures the fact that resulting models are often based on experiments that do not provide sufficient information and are therefore unreliable. A method for assessing parameter uncertainty and its use in experimental design are presented. Measurements of solute concentration in the continuous phase and the transmittance of light through a slurry sample allow reliable parameter estimation. Uncertainty in the parameter estimates is decreased by data from experiments that achieve a wide range of supersaturation. The sensitivity of the control policy to parameter uncertainty, which connects the model identification and control problems, is assessed. The model identification and control strategies were experimentally verified on a bench-scale KNO3-H2O system. Compared to natural cooling, increases in the weight mean size of up to 48% were achieved through implementation of optimal cooling policies.
    Additional Material: 17 Ill.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 35
    Electronic Resource
    Electronic Resource
    Hoboken, NJ : Wiley-Blackwell
    AIChE Journal 40 (1994), S. 1287-1296 
    ISSN: 0001-1541
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: A mean free path gas kinetic theory is used to model the conductive heat transport of a gas within a void volume enclosed in a Fourier solid. A variational upper bound principle is derived for a void of arbitrary shape and applied to obtain a rigorous upper bound equation for the void gas conductivity in a spherical void. The variational void gas conductivity equation is exact in both the large and small Knudsen number (Kn) limits and provides a means to determine the accuracy of the reciprocal additivity interpolation formula as applied to thermal conductivity rather than diffusive mass transfer (maximum error 6% at Kn = 0.5 and α = 1). Temperature jump will occur even at atmospheric pressures and higher for sufficiently small thermal accommodation coefficients (α 〈 0.1). Experimental void gas heat conductivities vs. pressure data for H2, He, Ne, N2, CO2, and F12 in a polyurethane foam are compared with theoretical mean free path void gas conductivity vs. inverse Knudsen number curves drawn for various α. Estimates of the thermal accommodation coefficients for the gas- polyurethane surface exhibit a maximum with increasing molecular mass of the gas molecules, which qualitatively agrees with the predictions of Baule's classical theory. Results also point to a rather sharp shift of the S curve to higher pressures with decreasing thermal accommodation.
    Additional Material: 4 Ill.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 36
    Electronic Resource
    Electronic Resource
    Hoboken, NJ : Wiley-Blackwell
    AIChE Journal 40 (1994) 
    ISSN: 0001-1541
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 37
    Electronic Resource
    Electronic Resource
    Hoboken, NJ : Wiley-Blackwell
    AIChE Journal 40 (1994), S. 1223-1237 
    ISSN: 0001-1541
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Heavy metals like Cu2+, Cr6+, and Hg2+ were removed successfully from wastewater and concentrated in a strip aqueous solution for recycle using the hollowfiber-contained liquid membrane (HFCLM) technique. Using cotransport, Cr6+ and Hg2+ present as anions in the feed solution were transferred individually through a liquid membrane containing tri-n-octylamine in xylene and concentrated in an alkaline solution on the strip side. The removal efficiency of each heavy metal was studied as a function of the aqueous feed flow rate in an HFCLM permeator. Copper present as cation Cu2+ was removed and concentrated by countertransport using LIX84 in n-heptane as the liquid membrane. The efficiency of copper removal was studied as a function of feed copper concentration, feed flow rate, strip flow rate, and area ratio between the feed fiber set and strip fiber set. The strip side flow rate did not affect the Cu2+ transfer rate. A theoretical model presented predicts the copper transport rate from the feed solution to the strip solution in an HFCLM permeator with a variable feed to strip-side membrane area. Both feed aqueous boundary layer and interfacial complexation reaction on the feed side dominate the observed Cu2+ removal process through LIX 84 in n-heptane for feed concentration levels used 90-500 mg/L. It was verified by providing two times larger liquid-liquid interfacial area in the feed aqueous side or in the strip aqueous side. The model can be used to design the membrane area required on the feed and strip fiber sides to remove essentially all of the copper from a given wastewater stream.
    Additional Material: 17 Ill.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 38
    Electronic Resource
    Electronic Resource
    Hoboken, NJ : Wiley-Blackwell
    AIChE Journal 40 (1994), S. 1262-1267 
    ISSN: 0001-1541
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Magnetic resonance imaging is used to make nondestructive experimental measurements of fluid flow velocity and rock porosity inside a brine-filled Casper sand-stone sample during brine injection. Two-dimensional images of these values are obtained in arbitrary cross sections, with pixel sizes on the order of 1 mm2. The data are then statistically analyzed to find the variation of the average interstitial velocity as a function of porosity, as well as frequency distributions for both the velocity and porosity. The results show that as local porosity increases, the local flow velocity increases, according to the empirical relationship, V = 0.0669 φ + 0.0055. Thus, higher porosity regions of the core are better contacted by the displacement fluid. Results also imply bypassing of fluid around the perimeter of the core, indicating the need for a coreholder capable of sustaining higher overburden pressures on the order of 225 psi (1.55 MPa).
    Additional Material: 8 Ill.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 39
    Electronic Resource
    Electronic Resource
    Hoboken, NJ : Wiley-Blackwell
    AIChE Journal 40 (1994), S. 1549-1557 
    ISSN: 0001-1541
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: A “capillary condensation” in liquid phase was analyzed theoretically and experimentally, in which a solute in solvent could be separated out as a liquid into small pores by capillary effect. The “liquid-phase capillary condensation” is defined as capillary phase separation. The separated phase is counted as “adsorbed” amount on porous materials. The relation between the concentration and a critical radius of the phase separation was derived. A new method to estimate liquid-phase adsorption isotherms of adsorbates with limited solubility from pore-size distribution of solids is based on this concept. The amount absorbed consists of the separated phase and adsorption on surface expressed with a single parameter. While the surface adsorption alone could not explain measured isotherms, this model showed good agreements between experimental and estimated isotherms for adsorption of four kinds of aromatic compounds from aqueous solution onto three categories of porous solids to demonstrate the significance of the capillary phase separation. The applicability of the method to solid solutes is also discussed.
    Additional Material: 10 Ill.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 40
    Electronic Resource
    Electronic Resource
    Hoboken, NJ : Wiley-Blackwell
    AIChE Journal 40 (1994) 
    ISSN: 0001-1541
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 41
    Electronic Resource
    Electronic Resource
    Hoboken, NJ : Wiley-Blackwell
    AIChE Journal 40 (1994), S. 1601-1610 
    ISSN: 0001-1541
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: The effect of imposed large-amplitude oscillations on turbulent drag is studied. The system consists of water flow through a straight 5.08-cm pipe. The velocity gradient at the wall is measured with flush-mounted electrochemical mass-transfer probes. Newly developed numerical algorithms are used to analyze the probe performance in the presence of unsteady flows. Sinusoidal oscillations are at large enough frequencies, ω+ = 0.0138-0.0506, that a pseudo-steady-state approximation cannot be made. The ratio of the time-averaged velocity gradient at the wall, with and without oscillations, S̄, varies between 1.00 and 1.03, provided flow reversal does not occur. However, two experiments in which reversed flows existed at the wall for an appreciable period of time show drag reductions of 7 and 13%.Imposed nonsinusoidal oscillations are also studied for a period of favorable pressure gradient, about twice longer than that of unfavorable, and two sudden changes in the pressure gradient. Experiments at Re = 9,700 with T0 of 2.00, 2.45, and 3.46 s, and at Re = 19,200 with T0 = 3.46 give values of S̄ = 1.04-1.08. At Re = 19,200 and T0 = 2.00, 1.50, 1.00 s, drag reductions are 10-15%. This phenomenon could be associated with the speed with which a flow adjusts to sudden changes in the pressure gradient.
    Additional Material: 17 Ill.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 42
    Electronic Resource
    Electronic Resource
    Hoboken, NJ : Wiley-Blackwell
    AIChE Journal 40 (1994), S. 1639-1649 
    ISSN: 0001-1541
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Elliptical basis function (EBF) networks are introduced as a new nonparametric method of estimating probability density functions for process data. Unlike Parzen window density estimators that use identical hyperspherical basis functions, the EBF method uses elliptical basis functions adapted to the local character of the data. This technique overcomes the spikiness problem associated with Parzen windows, where in high dimension, they can fail to produce smooth probability density estimates. The EBF estimator produces valid density functions that converage to the underlying distribution of the data in the limit of an infinite number of training examples. A technique based on statistical cross validation is introduced for evaluating different density estimators. The criterion is a measure of how well the density estimator estimates the density of data not used in the training. The EBF density estimation method and the evaluation technique are demonstrated using several examples of fault diagnosis.
    Additional Material: 6 Ill.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 43
    Electronic Resource
    Electronic Resource
    Hoboken, NJ : Wiley-Blackwell
    AIChE Journal 40 (1994), S. 1459-1465 
    ISSN: 0001-1541
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Experimental studies were performed to assess the effect of salt addition on the extraction of 1-butanol, ethanol and acetone from dilute aqueous solutions using cyclopentanol, n-valeraldehyde, tert-amyl alcohol, and Adol 85NF as extractants. The liquid-liquid partitioning was examined for a few strong electrolytes in a broad range of concentrations. Results demonstrate that the distribution coefficient and selectivity in systems with reduced water activity resulting from salt addition were markedly increased. These observations can be qualitatively explained on the basis of the hydration theory. It was also determined that strong electrolytes added to the aqueous feed reduced extractant solubility in the aqueous phase, thus contributing to lower solvent losses. The results showed that the extraction efficiency was not significantly affected by increasing salt content beyond a level that reduces the water activity to a value of 0.92.
    Additional Material: 8 Ill.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 44
    Electronic Resource
    Electronic Resource
    Hoboken, NJ : Wiley-Blackwell
    AIChE Journal 40 (1994), S. 1669-1684 
    ISSN: 0001-1541
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: In heterogenous olefin polymerization with Ziegler catalysts, the influence of monomer mass transport in the growing granule on polymer properties has been extensively modeled, but it has not been possible to clearly establish the importance of diffusion experimentally since the multisited nature of most Ziegler catalysts can produce similar effects. In this study, ethylene-propylene copolymers were made with single-sited metallocene catalysts by slurry polymerization in liquid monomers. These copolymers had a relatively narrow molecular weight distribution with a composition distribution (CD) broader than expected for a single-site catalyst. Data analysis indicates that mass-transfer limitations in the polymer particles are the most likely explanation for the observed results. For amorphous copolymers, a diffusion/reaction model could predict CD breadth in good agreement with experimental data, but for semicrystalline polymers the model was inaccurate. We postulate that model inadequacies are due to radial gradients in monomer diffusivity during polymerization which the model does not account for.
    Additional Material: 23 Ill.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 45
    Electronic Resource
    Electronic Resource
    Hoboken, NJ : Wiley-Blackwell
    AIChE Journal 40 (1994), S. 1524-1534 
    ISSN: 0001-1541
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Isobutene is the only product of the uncatalyzed and acid-catalyzed dehydration of tert-butanol in compressed liquid water at 250°C. The uncatalyzed dehydration reaction is fast: equilibrium is established after about 30 s. Only one of many chemically-motivated kinetic models is able to fit all the experimental data. This model presumes a heterolytic dehydration mechanism that involves protonated alcohol, carbocation, di-tert-butyl ether, and protonated ether as intermediates. The model permits tert-butanol to dissociate as both an Arrhenius acid and a Bronsted acid while catalyzing its dehydration to isobutene. The pKa of tert-butanol at 250°C is predicted to be about 9, whereas its value at normal temperature and pressure is 18. This 109 increase in the Ka value of tert-butanol hints of the promising new world of reaction chemistry in near- and supercritical water.
    Additional Material: 9 Ill.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 46
    Electronic Resource
    Electronic Resource
    Hoboken, NJ : Wiley-Blackwell
    AIChE Journal 40 (1994), S. 1574-1579 
    ISSN: 0001-1541
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: A relatively simple continuous dilution method with on-line spectrophotometric measurement has been used to determine the phase transition boundaries of aqueous two-phase polymer systems. The observed range of compositions over which the phase transition occurs is dominated by the polydispersity of the polymers, but also is a function of the dilution path followed. The binodal curve obtained by the continuous dilution method agrees well with the results obtained by the traditional method of phase equilibration, separation and analysis of liquid chromatography, which is slower and requires more expensive equipment.
    Additional Material: 8 Ill.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 47
    Electronic Resource
    Electronic Resource
    Hoboken, NJ : Wiley-Blackwell
    AIChE Journal 40 (1994), S. 1558-1573 
    ISSN: 0001-1541
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: A general molecular-based formalism developed rigorously establishes microscopic bases of the supercritical solubility enhancement in terms of well-defined molecular correlation function integrals by unambiguously splitting the mixture's properties into short-(finite) and long-range (diverging) contributions. Consequently, the short-range nature of the solute's and solvent's residual chemical potentials is proved and the change of the solvent's local environment around an infinitely dilute solute and its finite contribution to solute mechanical partial molar properties are interpreted in terms of the short-range solute-solvent and solvent-solvent direct correlation function integrals. The solute-induced effect on the system's microstructure and thermodynamics approaches zero as the mixture approaches ideality or the solute becomes an ideal gas particle. At the solvent's critical conditions, the solute-induced effect on the solute's partial molar properties shows no compressibility-driven singularity, though along the critical isotherm it can exhibit a finite extremum or a change of curvature near critical density, depending on the type and strength of solute-solvent interactions. The utility of the proposed solvation formalism is illustrated using statistical mechanical integral equation calculations for three simple models of infinitely dilute near-critical mixtures: pyrene-CO2, diterbutyl nitroxide-ethane, and Ne-Xe.
    Additional Material: 22 Ill.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 48
    Electronic Resource
    Electronic Resource
    Hoboken, NJ : Wiley-Blackwell
    AIChE Journal 40 (1994), S. 1594-1598 
    ISSN: 0001-1541
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
    Additional Material: 5 Ill.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 49
    Electronic Resource
    Electronic Resource
    Hoboken, NJ : Wiley-Blackwell
    AIChE Journal 40 (1994), S. 1925-1926 
    ISSN: 0001-1541
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 50
    ISSN: 0001-1541
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 51
    Electronic Resource
    Electronic Resource
    Hoboken, NJ : Wiley-Blackwell
    AIChE Journal 40 (1994), S. 1927-1927 
    ISSN: 0001-1541
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 52
    Electronic Resource
    Electronic Resource
    Hoboken, NJ : Wiley-Blackwell
    AIChE Journal 40 (1994), S. 1940-1949 
    ISSN: 0001-1541
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Studies on the dynamics of phase inversion available offer limited information due to the difficulty of following the transient mean and drop-size distribution. A new technique developed provides such data. A stereo microscope with a very shallow depth of field attached to a video camera gives sharp images of droplets in intensely-agitated, immiscible liquid dispersions by using a Strobotach pulsing at the camera framing rate. Droplets from 40 μm upward at concentrations up to 70% by volume dispersed phase can be measured accurately. Droplets of continuous organic phase in aqueous drops can be seen. The pictures can be analyzed semiautomatically using a computer and in-house software to give, using a variety of discretizations, cumulative and frequency distributions to any base and any mean size. Means and distributions are a function of time for phase inversions generated in three ways. The technique gives a powerful tool for understanding fast, complex dispersion processes.
    Additional Material: 9 Ill.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 53
    Electronic Resource
    Electronic Resource
    Hoboken, NJ : Wiley-Blackwell
    AIChE Journal 40 (1994), S. 1983-1992 
    ISSN: 0001-1541
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: A novel device for gas-liquid contact operations is proposed to feed a liquid onto wires (or threads) hanging down in a gas stream is proposed. The liquid disintegrates into beads strung on each wire at regular intervals; if the wire is moderately wettable, a thin film forms to sheathe the wire, thereby interconnecting the beads. Since the beads fall down slowly, which possibly renews the film flowing down even more slowly a sufficient gas-liquid contact time is available even in a contactor with considerably limited height. An approximate calculation method is developed for predicting the variation in the temperature effectiveness for the liquid (the fractional approach of the liquid exit temperature to the gas inlet temperature) with the falling distance, assuming an applicability of strings-of-beads contactors to thermal energy recovery from hot gas streams.
    Additional Material: 8 Ill.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 54
    Electronic Resource
    Electronic Resource
    Hoboken, NJ : Wiley-Blackwell
    AIChE Journal 40 (1994), S. 2055-2059 
    ISSN: 0001-1541
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
    Additional Material: 2 Ill.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 55
    Electronic Resource
    Electronic Resource
    Hoboken, NJ : Wiley-Blackwell
    AIChE Journal 40 (1994), S. 2060-2064 
    ISSN: 0001-1541
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
    Additional Material: 5 Ill.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 56
    Electronic Resource
    Electronic Resource
    Hoboken, NJ : Wiley-Blackwell
    AIChE Journal 40 (1994), S. 2034-2044 
    ISSN: 0001-1541
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: The parallel transport of a protein by surface and pore diffusion within a highly porous ion exchanger is studied by measuring equilibria and uptake curves for adsorption of bovine serum albumin (BSA) on two different strongly basic chitosan ion exchangers (hard gels): Ch-2503 and Ch-2507 at pH 6.9 and 298 K. Experimental equilibrium isotherms are correlated by the Langmuir equation. Intraparticle effective diffusivities of BSA (Deff) are determined from the homogeneous Fickian diffusion model, increasing with the bulk phase concentration increase of BSA (C0). It suggests the existence of parallel diffusion. The surface diffusivity DS for the parallel diffusion model is determined from the Deff, and DS = 0.47 × 10-13 m2 · s-1 (Ch-2507) and 2.4 × 10-13 m2 · s-1 (Ch-2503) were obtained. Pore diffusivities based on the pore diffusion control (D′P) are obtained by matching the shrinking core model with the experimental uptake curves. D′P decreases with increasing C0. Since D′P in Ch-2507 is constant when C0 ≥ 1 kg·m-3, the constant value 2.7 × 10-11 m2 · s-1 is taken as the accurate pore diffusivity (DP). As D′P in Ch-2503 does not approach a constant value, DP = 1.0 × 10-11 m2 · s-1 is determined by matching the parallel diffusion model with the uptake data, and the model calculated using experimental values of DS and DP agrees reasonably well with the uptake data for Ch-2507 and Ch-2503. This theoretical approach may be applied not only for intraparticle diffusion of proteins but any adsorbates in porous materials.
    Additional Material: 10 Ill.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 57
    Electronic Resource
    Electronic Resource
    Hoboken, NJ : Wiley-Blackwell
    AIChE Journal 40 (1994), S. 888-898 
    ISSN: 0001-1541
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: The design of efficient continuous sterilization equipment for flowing solid-liquid food mixtures requires that temperature and velocity distributions within the fluid are known. In electrical (ohmic) heating, electric current is passed through a two-sterilize it. This allows rapid sterilization of solid-liquid mixtures which minimizes quality loss. A computational process model simulates the effect of realistic physical property changes. The effect of variations in physical properties can have a significant effect on the temperature of the product and thus on its sterility. Realistic designs will have to cope with temperature differences between phases. Experimental data for velocities in a food flow have been incorporated into an enthalpy balance model for heat transfer in solid-liquid mixtures. The effect of inlet temperature on the length of hold tube required to give the necessary process sterility calculated shows the variation in output conditions that might results in real systems.
    Additional Material: 9 Ill.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 58
    Electronic Resource
    Electronic Resource
    Hoboken, NJ : Wiley-Blackwell
    AIChE Journal 40 (1994), S. 957-965 
    ISSN: 0001-1541
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: A study of flash equations associated with multicomponent systems that can form three phases at a given temperature and pressure indicated that different equations are needed at different boundaries of the solution space. This problem dictates that one- and two-phase trial solutions be obtained first on the boundaries prior to a search in the three-phase interior region. Two new formulations of the flash equations have been developed to avoid this problem. Solutions at boundaries as well as those in the three-phase region can now be obtained with a single search procedure. The new formulations are made using functions that are monotonic in the selected coordinates. These properties facilitate the use of nested, single-variable search methods. Interpolating with second-order functions, when applicable, nested search methods are often faster than two-dimensional simultaneous search methods. Tests of these formulations have demonstrated the advantages of these characteristics.
    Additional Material: 18 Ill.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 59
    Electronic Resource
    Electronic Resource
    Hoboken, NJ : Wiley-Blackwell
    AIChE Journal 40 (1994), S. 966-979 
    ISSN: 0001-1541
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: The dynamic behavior of processing systems exhibits both continuous and significant discrete aspects. Process simulation is therefore a combined discrete/continuous simulation problem. In addition, there is a critical need for a declarative process modeling environment to encompass the entire range of processing system operation, from purely continuous to batch. These issues are addressed by this article.A new formal mathematical description of the combined discrete/continuous simulation problem is introduced to enhance the understanding of the fundamental discrete changes required to model processing systems. The modeling task is decomposed into two distinct activities: modeling fundamental physical behavior, and modeling the external actions imposed on this physical system. Both require significant discrete components. Important contributions include a powerful representation for discontinuities in physical behavior, and the first detailed consideration of how complex sequences of control actions may be modeled in a general manner.
    Additional Material: 12 Ill.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 60
    Electronic Resource
    Electronic Resource
    Hoboken, NJ : Wiley-Blackwell
    AIChE Journal 40 (1994), S. 1005-1017 
    ISSN: 0001-1541
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Ignition and extinction characteristics of homogeneous combustion of methane in air near inert surfaces are studied by numerical bifurcation theory for premixed methane/air gases impinging on planar surfaces with detailed chemistry involving 46 reversible reactions and 16 species. One-parameter bifuraction diagrams as functions of surface temperature and two-parameter bifurcation diagrams as functions of equivalence ratio and strain rate are constructed for both isothermal and adiabatic walls. Lean and rich composition limits for ignition and extinction, and energy production are determined from two parameter bifurcation diagrams. For a strain rate of 500 s-1, CH4/air mixtures exhibit hysteresis from ∼ 0.5% up to ∼ 12.5% and from ∼ 5.5% up to ∼ 13.5% near isothermal surfaces and adiabatic walls, respectively. Ignition temperature rises with composition from 1,700 to 1,950 K, without a maximum around the stoichiometric ratio. Under some conditions multiple ignitions and extinctions can occur with up to five multiple solutions, and wall quenching, kinetic limitations, and transport can strongly affect flame stability. Flames near the stoichiometric ratio cannot be extinguished by room temperature surfaces for sufficiently low strain rates. The role of intermediates in enhancing or retarding ignition and extinction is studied, and implications of the effect of catalytic surfaces on homogeneous ignition and extinction are discussed. Removal of H atoms and CH3 radicals by wall adsorption can increase extinction and ignition temperature of 6% CH4 in air by up to 300 K for a strain rate of 500 s-1.
    Additional Material: 9 Ill.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 61
    Electronic Resource
    Electronic Resource
    Hoboken, NJ : Wiley-Blackwell
    AIChE Journal 40 (1994), S. 73-87 
    ISSN: 0001-1541
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Experimental results using a pulsed tubular reactor are presented. The use of a pulsation source eliminates the reactor fouling and plugging issue that has occurred in previous investigations. Startup data and steady-state profiles are presented. Comparisons in monomer conversion and particle-size distribution for batch, CSTR and tubular reactor are made. The influence of pulsation on the particle-size dis-tribution is discussed. It is shown that high-conversion latex with a narrow particle size distribution can be produced continuously in the pulsed tubular reactor.
    Additional Material: 26 Ill.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 62
    Electronic Resource
    Electronic Resource
    Hoboken, NJ : Wiley-Blackwell
    AIChE Journal 40 (1994), S. 19-28 
    ISSN: 0001-1541
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: A theoretical model for the process of bubble and drop formation in flowing liquids, applicable for both terrestrial and microgravity environments, has been developed by using a force balance. The contact angle variation at the nozzle due to the bubble motion and the added mass coefficient of the bubble moving through a pipe have been theoretically analyzed, considering bubble motions during its expansion and detachment stages. Predictions of bubble size of the model show satisfactory agreement with available experimental results in the case of normal gravity. The effects of the nondimensional variables on bubble and drop size are evaluated in microgravity conditions. In microgravity, the bubble is detached from the nozzle only by the liquid flow drag, and in the region of low liquid velocity the bubble size becomes much larger than that in normal gravity.
    Additional Material: 9 Ill.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 63
    Electronic Resource
    Electronic Resource
    Hoboken, NJ : Wiley-Blackwell
    AIChE Journal 40 (1994), S. 40-49 
    ISSN: 0001-1541
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: The dynamic affinity adsorption oflysozyme through stacked flat-sheet cellulose membranes with immobilized cibacron blue 3GA was studied and compared to three affinity-membrane models: diffusion model to explore the importance of axial and radial diffusion; variation model to study the effects of pore-size distribution or thickness variation; and stack model to investigate the effects of stacking flat-sheet membranes. For the diffusion model, when Per 〉 0.1, radial diffusional resistance is significant, but when Pez 〈 25, axial dispersion must be considered. For the variation model, increasing pore-size distribution or nonuniform membrane thickness greatly broadens the breakthrough curve. The stack model shows that the stacking of membranes significantly sharpens the breakthrough curves by averaging out the flow dispersion due to pore-size distribution or thickness variation.
    Additional Material: 11 Ill.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 64
    Electronic Resource
    Electronic Resource
    Hoboken, NJ : Wiley-Blackwell
    AIChE Journal 40 (1994), S. 65-72 
    ISSN: 0001-1541
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: When multicomponent, multistage separation problems are solved on parallel computers by successive linearization methods, the solution of a large sparse linear equation system becomes a computational bottleneck, since other parts of the calculation are more easily parallelized. When the standard problem formulation is used, this system has a block-tridiagonal form. It is shown how this structure can be used in parallelizing the sparse matrix computation. By reformulating the problem so that it has a bordered-block-bidiagonal superstructure, it can be made even more amenable to parallezation. These strategies permit the use of a two-level hierarchy of parallelism that provides substantial improvements in computational performance on parallel machines.
    Additional Material: 10 Ill.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 65
    Electronic Resource
    Electronic Resource
    Hoboken, NJ : Wiley-Blackwell
    AIChE Journal 40 (1994), S. 361-364 
    ISSN: 0001-1541
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Various phenolic compounds in aqueous buffer solutions were contacted batchwise with powdered activated carbon. Relatively slow, but continual, decreases in the solution phenolic concentrations were measured over a period of several weeks. The decreases were due to oxidative coupling reactions of the phenolics which occurred on the carbon surface subsequent to adsorption. The effects of time, pH, dissolved oxygen, and the molecular nature of the phenolic were determined.
    Additional Material: 5 Ill.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 66
    Electronic Resource
    Electronic Resource
    Hoboken, NJ : Wiley-Blackwell
    AIChE Journal 40 (1994), S. 378-379 
    ISSN: 0001-1541
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
    Additional Material: 1 Ill.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 67
    Electronic Resource
    Electronic Resource
    Hoboken, NJ : Wiley-Blackwell
    AIChE Journal 40 (1994), S. 463-472 
    ISSN: 0001-1541
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: The problem of synthesizing reactive mass-exchange networks (REAMENs) is addressed for which the equilibrium relations governing the transfer of a certain species from rich streams to reactive mass-separating agents are nonlinear (convex and/or nonconvex). Previously developed synthesis procedures for REAMENs are not applicable to such cases, since they were developed for cases of linear and/or convex equilibria. Two peculiar phenomena are associated with REAMENs with general nonlinear equilibria: the location of a mass-exchangers may straddle the pinch point even for networks featuring the minimum cost of mass-separating agents. To account for such intriguing characteristics, a systematic procedure is developed to synthesize cost-effective REAMENs with general nonlinear equilibria. In addition, a robust solution procedure is devised to guarantee the identification of the global solution of the developed optimization programs. Applicability and usefulness of the proposed synthesis procedure are demonstrated via a case study on the desulfurization of gaseous wastes from a coal-to-methanol plant.
    Additional Material: 12 Ill.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 68
    Electronic Resource
    Electronic Resource
    Hoboken, NJ : Wiley-Blackwell
    AIChE Journal 40 (1994), S. 166-177 
    ISSN: 0001-1541
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: A membrane-assisted solvent extraction (MASX) system coupled to a membrane-assisted distillation stripping (MADS) system for use in decontaminating ground-water is evaluated. Volatile organic compounds (VOCs) in the groundwater are extracted in the MASX unit using a sunflower oil solvent. In the MADS unit, VOCs are stripped from the sunflower oil, which is recycled to the MASX unit. Thermodynamic data for the sunflower oil-water-VOCs system were measured. The results were used along with published membrane mass-transfer data to design MASX and MADS modules.
    Additional Material: 8 Ill.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 69
    Electronic Resource
    Electronic Resource
    Hoboken, NJ : Wiley-Blackwell
    AIChE Journal 40 (1994) 
    ISSN: 0001-1541
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 70
    Electronic Resource
    Electronic Resource
    Hoboken, NJ : Wiley-Blackwell
    AIChE Journal 40 (1994), S. 192-192 
    ISSN: 0001-1541
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 71
    Electronic Resource
    Electronic Resource
    Hoboken, NJ : Wiley-Blackwell
    AIChE Journal 40 (1994), S. 594-605 
    ISSN: 0001-1541
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Optimum experimental conditions and column design parameters are calculated for most economical separation of binary mixtures by preparative liquid chromatography. The solvent consumption and capital costs are regarded as the two major cost contributions. Calculations were performed by using the numerical solution of the equilibrium-dispersive model of chromatography and a nonlinear simplex algorithm. Solvent consumption depends only on the column efficiency, the retention factor, and the loading factor. The production rate depends on the particle size, the column length, the mobile-phase flow velocity, the retention and the loading factors, and can be optimized with or without recovery yield constraints. A hybrid objective function was constructed to find the tradeoffs between the production rate and the solvent consumption.
    Additional Material: 10 Ill.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 72
    Electronic Resource
    Electronic Resource
    Hoboken, NJ : Wiley-Blackwell
    AIChE Journal 40 (1994), S. 321-333 
    ISSN: 0001-1541
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: A mathematical model has been developed to predict the coupled hydrodynamics and high-molecular-weight protein transport in mammalian-cell hollow-fiber bioreactors (HFBRs). The analysis applies to reactors with isotropic ultrafiltration membranes under startup conditions when the extracapillary space (ECS) is essentially unobstructed by cells. The model confirms the experimental finding that secondary ECS flows, engendered by the primary flow in the fiber lumens, can cause significant downstream polarization of ECS proteins at typical mammalian-cell HFBR operating conditions. It also reveals that the osmotic activity of the proteins, by curtailing transmembrane fluid fluxes, can influence strongly the outcome of the polarization process. In fact, at order-of-magnitude higher protein concentrations and/or lower recycle flow rates, the secondary flow velocities can be reduced by as much as six orders-of-magnitude throughout the ECS, thereby virtually eliminating the polarization problem. This result has important implications for improved reactor startup procedures.
    Additional Material: 10 Ill.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 73
    Electronic Resource
    Electronic Resource
    Hoboken, NJ : Wiley-Blackwell
    AIChE Journal 40 (1994), S. 692-703 
    ISSN: 0001-1541
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: The adhesion of biological cells to substrates is often mediated by binding between cellular receptors and substrate-bound ligand. In this work, we used a centrifugation assay to measure the adhesion of rat basophilic leukemia (RBL) cells coated with immunoglobulin E (IgE) to substrates coated with the ligand dinitrophenol (DNP). Increasing force, decreasing DNP substrate density, and decreasing cell surface IgE density all led to decreasing adhesion. Experiments performed at low IgE cell surface densities, in which few tethers from between cell and substrate suggest individual tethers have a binding strength of 2 to 4 microdyne, in agreement with previous measurements of the force to uproot receptors from the plasma membrane. We use this system to show how subpopulations expressing different numbers of cell surface receptors may be separated by exploiting their differential adhesiveness to substrates.
    Additional Material: 7 Ill.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 74
    Electronic Resource
    Electronic Resource
    Hoboken, NJ : Wiley-Blackwell
    AIChE Journal 40 (1994), S. 704-715 
    ISSN: 0001-1541
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Chemotaxis describes the ability of motile bacteria to bias their motion in the direction of increasing gradients of chemicals, usually energy sources, known as attractants. In experimental studies of the migration of chemotactic bacteria, 1-D phenomenological cell balance equations (Rivero et al., 1989) have been used to quantitatively analyze experimental observations (Ford et al., 1991; Ford and Lauffenburger, 1991). While attractive for their simplicity and the ease of solution, they are limited in the strict mathematical sense to the situation in which individual bacteria are confined to motion in one dimension and respond to attractant gradients in one dimension only. Recently, Ford and Cummings (1992) reduced the general 3-D cell balance equation of Alt (1980) to obtain an equation describing the migration of a bacterial population in response to a 1-D attractant gradient. Solutions of this equation for single gradients of attractants are compared to those of 1-D balance equations, results from cellular dynamics simulations (Frymier et al., 1993), and experimental data from our laboratory for E. coli responding to α-methylaspartate. We also investigate two aspects of the experimentally derived expression for the tumbling probability: the effect of different models for the down-gradient swimming behavior of the bacteria and the validity of ignoring the temporal derivative of the attractant concentration.
    Additional Material: 10 Ill.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 75
    Electronic Resource
    Electronic Resource
    Hoboken, NJ : Wiley-Blackwell
    AIChE Journal 40 (1994), S. 382-383 
    ISSN: 0001-1541
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 76
    Electronic Resource
    Electronic Resource
    Hoboken, NJ : Wiley-Blackwell
    AIChE Journal 40 (1994), S. 395-406 
    ISSN: 0001-1541
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: A substantial effort has been made by numerous investigators to describe droplet breakage and coalescence in turbulent dispersions. An attempt is made here to improve these models based on existing frameworks and recent advances described in the literature. Two-step mechanisms are considered for both the breakage and coalescence models. The drop breakage function is structured as the product of the drop-eddy collision frequency and breakage efficiency which reflect the energetics of turbulent liquid-liquid dispersions. The coalescence function retains the former structure of the product of drop-drop collision frequency and coalescence efficiency. The coalescence efficiency model has been modified to account for the effects of film drainage for drops with partially mobile interfaces. These models overcome several inconsistencies observed in previous efforts and are applicable for dense dispersions (about φ[0.10-0.30]). For the daughter drops produced by breakage, a probability density is proposed based on the energy requirements for the formation of daughter drops.
    Additional Material: 7 Ill.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 77
    Electronic Resource
    Electronic Resource
    Hoboken, NJ : Wiley-Blackwell
    AIChE Journal 40 (1994), S. 613-620 
    ISSN: 0001-1541
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: An advanced process is developed for the separation of H2S from natural gas through an electrochemical membrane. H2S is removed from natural gas by reduction to the sulfide ion and H2 at the cathode. The sulfide ion migrates to the anode through a molten salt electrolyte suspended in an inert ceramic matrix. Once at the anode it is oxidized to elemental sulfur and swept away for condensation in an inert gas stream. The natural gas is enriched with H2. Order-of-magnitude reductions in H2S concentration have been repeatedly recorded on a single pass through the cell. This process allows removal of H2S, while producing H2 and elemental sulfur directly. No absorbents are used, and there is no need for subsequent treatment of a concetrated H2S stream as with conventional gas sweetening technology. This makes the process economically attractive, since it is much less equipment-intensive than conventional technology.
    Additional Material: 9 Ill.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 78
    Electronic Resource
    Electronic Resource
    Hoboken, NJ : Wiley-Blackwell
    AIChE Journal 40 (1994), S. 716-725 
    ISSN: 0001-1541
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Two methods for generating smoothing splines are compared and applied to data from a fed-batch fermentation process. One method chose both the degree of the spline and its parameters by minimizing the generalized cross validation (GCV) function using a genetic algorithm (GA). The other method adjusted the smoothing spline to a specified chi-square goodness-of-fit, requiring prior knowledge of the measurement variability. The GCV/GA method led to excellent results with all the fermentation data records. The goodness-of-fit method gave a family of spline fits; splines with a low percentage fit extracted trends from the data, while for general use a 50% fit appeared satisfactory. The goodness-of-fit method executed more quickly than the GCV/GA method, but the GCV/GA method was more generally applicable as it chose both the degree of the spline and the amount of smoothing automatically.
    Additional Material: 8 Ill.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 79
    Electronic Resource
    Electronic Resource
    Hoboken, NJ : Wiley-Blackwell
    AIChE Journal 40 (1994), S. 1032-1045 
    ISSN: 0001-1541
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: The morphology of the gas-solid interface during typical chemical vapor deposition (CVD) processes is investigated. The dynamic behavior of the interface depends on many factors, including local curvature of the film, reactant diffusion, adsorption equilibrium, surface kinetics, and mobility of adatoms. These factors depend on material properties of the system and reactor conditions, such as the deposition temperature and pressure. A 2-D model proposed describes the evolution of the interface in Cartesian coordinates under the influence of stabilizing and destabilizing effects. A linear stability analysis is used to predict under which conditions a planar interface becomes unstable. Stability criteria of a simplified 1-D analysis is not necessarily valid if the real system has more than one dimension. The substrate temperature and reactor pressure are important factors affecting the stability of film growth and thus the morphology of CVD films. An increase in temperature stabilizes planar film growth if the deposition is diffusion-limited, but destabilizes it if the process is reaction-controlled. The reactor pressure has a destabilizing effect on planar film growth during a typical CVD process.
    Additional Material: 10 Ill.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 80
    Electronic Resource
    Electronic Resource
    Hoboken, NJ : Wiley-Blackwell
    AIChE Journal 40 (1994), S. 1085-1085 
    ISSN: 0001-1541
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 81
    Electronic Resource
    Electronic Resource
    Hoboken, NJ : Wiley-Blackwell
    AIChE Journal 40 (1994), S. 1087-1088 
    ISSN: 0001-1541
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 82
    Electronic Resource
    Electronic Resource
    Hoboken, NJ : Wiley-Blackwell
    AIChE Journal 40 (1994), S. 1117-1117 
    ISSN: 0001-1541
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
    Additional Material: 2 Ill.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 83
    Electronic Resource
    Electronic Resource
    Hoboken, NJ : Wiley-Blackwell
    AIChE Journal 40 (1994), S. 1210-1222 
    ISSN: 0001-1541
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Expressions that suitably describe the behavior of weak electrolytes in aqueous systems are developed. A new numerical procedure is presented to allow for partial dissociation phenomena and so consider the whole species in solution. It is based on mass balances, the electroneutrality assumption, and dissociation constants of electrolytes. Combining it with a modified UNIFAC electrolyte group-contribution model based on the solvation concept directly allows calculation of pH, activities, and concentrations of species. The validity and usefulness of the expressions are tested using data for the pH of buffer solutions and complex aqueous mixtures such as fermentation media and liquid foods: pH values accurate to within ±0.05 pH units were obtained.
    Additional Material: 3 Ill.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 84
    Electronic Resource
    Electronic Resource
    Hoboken, NJ : Wiley-Blackwell
    AIChE Journal 40 (1994), S. 1246-1253 
    ISSN: 0001-1541
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Devonian shales and other unconventional resources can be highly fractured and may have significant amounts of gas stored by adsorption. Conventional experiments are not well suited for characterizing the properties important for describing gas storage and transport in these media. Here, X-ray computed tomography scanning is used to determine gas storage in dynamic gas flow experiments on Devonian shale samples. Several important properties are obtained from these experiments, including fracture widths, adsorption isotherms, and matrix porosities and permeabilities.
    Additional Material: 8 Ill.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 85
    Electronic Resource
    Electronic Resource
    Hoboken, NJ : Wiley-Blackwell
    AIChE Journal 40 (1994), S. 1268-1272 
    ISSN: 0001-1541
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
    Additional Material: 7 Ill.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 86
    Electronic Resource
    Electronic Resource
    Hoboken, NJ : Wiley-Blackwell
    AIChE Journal 40 (1994) 
    ISSN: 0001-1541
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 87
    Electronic Resource
    Electronic Resource
    Hoboken, NJ : Wiley-Blackwell
    AIChE Journal 40 (1994), S. 1449-1458 
    ISSN: 0001-1541
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Gel/micelle materials, comprising hydrogels containing block copolymer micelles, have the potential to be very useful in a variety of extraction and controlled release applications. It is demonstrated that block copolymer surfactants can be immobilized in calcium alginate gels and that the resulting composite material preferentially solubilizes the model hydrophobic solute naphthalene. Five different polyethylene oxide-polyropylene oxide-polyethylene oxide triblock copolymer surfactants are considered, and the qualitatively different properties exhibited are interpreted in light of the properties of these surfactants in solution. Alginate gel concentrations of 22.5 and 52.5 g/L and surfactant concentrations ranging from 20.4 to 136 g/L are considered. The data indicate that micelles can be permanently immobilized for purposes of extraction or controlled release and that the extent of solute uptake or release can be altered by varying gel and surfactant concentration and the type of surfactant employed.
    Additional Material: 10 Ill.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 88
    Electronic Resource
    Electronic Resource
    Hoboken, NJ : Wiley-Blackwell
    AIChE Journal 40 (1994), S. 1412-1417 
    ISSN: 0001-1541
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
    Additional Material: 6 Ill.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 89
    Electronic Resource
    Electronic Resource
    Hoboken, NJ : Wiley-Blackwell
    AIChE Journal 40 (1994), S. 1426-1430 
    ISSN: 0001-1541
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
    Additional Material: 5 Ill.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 90
    Electronic Resource
    Electronic Resource
    Hoboken, NJ : Wiley-Blackwell
    AIChE Journal 40 (1994), S. 1515-1523 
    ISSN: 0001-1541
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Four different coals were instantaneously introduced into a laboratory-scale pyrolysis chamber at various temperatures, and their develatilization profiles were analyzed with respect to kinetics. The experimental setup consisted of a gas chromatograph (GC) with a pyrolysis unit, an empty column, and a detector. Detector signals were digitalized and stored for further handling. Normally, 1,024 values were sampled at 250 Hz. For deconvolving the true instantaneous devolatilization from the observed detector response, the residence time distribution was compensated for.An empirical model approach is developed to correlate the total devolatilization rates when instantaneously introducing a particle in a constant temperature environment. The model is also extended to pyrolysis application.
    Additional Material: 11 Ill.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 91
    Electronic Resource
    Electronic Resource
    Hoboken, NJ : Wiley-Blackwell
    AIChE Journal 40 (1994), S. 1466-1478 
    ISSN: 0001-1541
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: As recently recognized, distillation columns, operating with reflux and boilup as independent inputs, may have multiple steady-state solutions, even in the ideal binary case. Two fundamentally different sources may cause the multiplicity, and in both cases some operating points are found to be unstable. This article provides evidence for the instability and discusses the effect of operating conditions on stability. Increasing the internal flow rates increases the probability of instability; when flows other than reflux and boilup are used as independent inputs, an operating point may become unstable if the level control is not sufficiently tight. In this case, a limit cycle, usually stable, appears as the steady state goes unstable.
    Additional Material: 10 Ill.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 92
    Electronic Resource
    Electronic Resource
    Hoboken, NJ : Wiley-Blackwell
    AIChE Journal 40 (1994), S. 1328-1340 
    ISSN: 0001-1541
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: We present a method for synthesizing chemical process models that combines prior knowledge and artificial neural networks. The inclusion of prior knowledge is investigated as a means of improving the neural network predictions when trained on sparse and noisy process data. Prior knowledge enters the hybrid model as a simple process model and first principle equations. The simple model controls the extrapolation of the hybrid in the regions of input space that lack training data. The first principle equations, such as mass and component balances, enforce equality constraints. The neural network compensates for inaccuracy in the prior model. In addition, inequality constraints are imposed during parameter estimation. For illustration, the approach is applied in predicting cell biomass and secondary metabolite in a fed-batch penicillin fermentation. Our results show that prior knowledge enhances the generalization capabilities of a pure neural network model. The approach is shown to require less data for parameter estimation, produce more accurate and consistent predictions, and provide more reliable extrapolation.
    Additional Material: 8 Ill.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 93
    Electronic Resource
    Electronic Resource
    Hoboken, NJ : Wiley-Blackwell
    AIChE Journal 40 (1994), S. 1535-1548 
    ISSN: 0001-1541
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: A new counterflow jet reactor has been designed to study the purely homogeneous kinetics of endothermic reactions. The reactor consists of two vertical, coaxial, counterflowing, laminar jets and radial-flow exit region. It can be used to generate a reaction zone near the stagnation point and away from walls, thus eliminating the possibility of surface reactions. One jet is heated and contains only a suitable carrier gas such as hydrogen and nitrogen, while the other is unheated and contains the compound(s) under study diluted in the same carrier gas. A 2-D model of the process has been used to simulate the thermal decomposition of tertiary-butyl-arsine, a precursor for metal-organic chemical vapor deposition of GaAs films. Performance diagrams based on Reynolds and Demköhler numbers were constructed to identify optimal operating conditions and to demonstrate the feasibility of the technique. This reactor appears to be an attractive choice for studies of the purely homogeneous kinetics of endothermic reactions at pressures close to atmospheric.
    Additional Material: 10 Ill.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 94
    Electronic Resource
    Electronic Resource
    Hoboken, NJ : Wiley-Blackwell
    AIChE Journal 40 (1994), S. 1580-1593 
    ISSN: 0001-1541
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: General procedures are outlined for the simulation and propagation of random and systematic errors in thermophysical property experiments. Density second virial coefficients B(T) from sonic velocity and Joule-Thomson (J-T) experiments are examined for error propagation where the connecting thermodynamic identity is a differential equation with missing boundary conditions. A recent controversy is addressed concerning B(T) at subcritical temperatures for pure hydrocarbon gases from direct density measurements vs. new sonic velocity data. Sonic velocity results are more likely correct with adsorption errors causing the problem in the density measurements.Two new model consistency tests are developed for checking assumed temperature models in the reduction of sonic velocity and J-T data to B(T). Excellent values of B(T) are then obtained from either type of data when the original experiments are free of errors. Random errors propagate systematically when the connecting equation is a differential equation. Sonic data must be of high precision (± 10 ppm) to generate B(T) to ±1 cm3/mol due to complications in data reduction arising from the temperature model/random error interaction. Except perhaps for adsorption errors, systematic errors in the sonic velocities are unimportant to B(T). J-T data provide propagation factors near unity with errors in B(T) higher at higher temperature, unlike sonic velocities.
    Additional Material: 13 Ill.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 95
    Electronic Resource
    Electronic Resource
    Hoboken, NJ : Wiley-Blackwell
    AIChE Journal 40 (1994), S. 1611-1617 
    ISSN: 0001-1541
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: A capillary jet of liquid impinges on a planar surface that is normally oriented to the axis of the jet. The surface is initially covered with a thin uniform film of a viscous liquid. The impact and radial spreading of the liquid from the jet cause the underlying viscous film to be removed from the surface. An approximate analysis predicts the thinning rate of the film in the stagnation region of the jet. It uses the shear stress and pressure distribution of the classical Homann flow as boundary conditions for an analytical solution of the Reynolds lubrication equations in this underlying viscous film. A more exact analysis modifies the Homann flow to account for the mobility of the liquid film beneath the spreading jet and sheds light on the limitations of the analytical lubrication analysis. Data presented are in excellent agreement with the theory, subject only to the choice of a value for the hydrodynamic constant that appears in the Homann analysis.
    Additional Material: 7 Ill.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 96
    Electronic Resource
    Electronic Resource
    Hoboken, NJ : Wiley-Blackwell
    AIChE Journal 40 (1994), S. 1665-1668 
    ISSN: 0001-1541
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: We analyze the mathematical structure of a multicomponent reactive mixture in a plug flow reactor with axial diffusion. Quasilinearity of the kinetic equation assuming “uniformity” does not carry over to the second-order equations when diffusion is considered and a perturbation expansion method needs to be developed. Perturbation around the limit of a CSTR is regular, which leads to nonhomogeneous second-order differential equations containing no unknown kinetic term, so that the procedure cascades down to the solution of the CSTR problem. Perturbation around the PFR problem is singular, but the inner (boundary layer) solution is easy. The outer solution leads to a series of integro-differential equations, which can be reduced to complete Volterra integral equations of the second kind; these are known to admit unique solutions. A formal approach to finding these solutions is discussed.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 97
    Electronic Resource
    Electronic Resource
    Hoboken, NJ : Wiley-Blackwell
    AIChE Journal 40 (1994), S. 1697-1710 
    ISSN: 0001-1541
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: A new group contribution method for the estimation of properties of pure organic compounds is presented. Estimation is performed at two levels: the basic level uses contributions from first-order groups, while the next higher level uses a small set of second-order groups having the first-order groups as building blocks. Thus, the method provides both a first-order approximation (first-order group contributions) and a more accurate second-order prediction (first- and second-order group contributions). This article discusses methods for prediction of normal boiling point, normal melting point, critical pressure, critical temperature, critical volume, standard enthalpy of vaporization at 298 K, standard Gibbs energy, and standard enthalpy of formation at 298 K. The predictions are based exclusively on the molecular structure of the compound, and the method is able to distinguish among isomers. Compared to the currently-used methods, this technique demonstrates significant improvements in accuracy and applicability.
    Additional Material: 2 Ill.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 98
    Electronic Resource
    Electronic Resource
    Hoboken, NJ : Wiley-Blackwell
    AIChE Journal 40 (1994), S. 1741-1756 
    ISSN: 0001-1541
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: A robustious structural model is developed to describe the role of bacteria in the leaching process of low-grade ores under conditions controlled by intraparticle diffusion. The main impetus behind developing this model is to provide an insight into such systems, together with a suitable framework for interpreting experimental data. The model is derived in detail with respect to reaction chemistry and the role of bacteria in catalyzing these reactions, specifically the synergism of chemistry, physics and biology in determining the overall behavior of the system. The model is used to simulate the atmospheric oxidation of iron disulfide contained in porous solids in the presence of Thiobacillus ferrooxidans (T. ferrooxidans). The experimental data are predicted well by the model, which demonstrates its applicability and supports the view that the rate of intraparticle diffusion is the controlling mechanism for this system.
    Additional Material: 6 Ill.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 99
    Electronic Resource
    Electronic Resource
    Hoboken, NJ : Wiley-Blackwell
    AIChE Journal 40 (1994) 
    ISSN: 0001-1541
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 100
    Electronic Resource
    Electronic Resource
    Hoboken, NJ : Wiley-Blackwell
    AIChE Journal 40 (1994), S. 1794-1803 
    ISSN: 0001-1541
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Time-dependent viscous flows driven by capillarity act to minimize the surface area of a fluid bounded in a plane geometry with initial gradients in surface curvature. These free-surface flows are solved by a finite-element model applied to describe the viscous sintering of two-dimensional ceramic particles. The numerical model is validated by comparison to the analytical solution obtained by Hopper (1990) for the coalescence of two infinite cylinders of equal cross section and is applied to several other geometries pertinent to the study of particle sintering for which analytical results are not available. Details of the flow fields and morphological evolution lend insight to the physical behavior of these systems and provide a basis for the more complete understanding of viscous sintering phenomena.
    Additional Material: 8 Ill.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
Close ⊗
This website uses cookies and the analysis tool Matomo. More information can be found here...