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  • 1
    Electronic Resource
    Electronic Resource
    Hoboken, NJ : Wiley-Blackwell
    AIChE Journal 2 (1956), S. 489-497 
    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 on point and integral average conversion of chemical reaction, coupled with radial diffusion and radial distribution of reaction times in viscous-flow tubular reactors, is reported. Solutions are given for first-order reaction over an extensive range of dimensionless rate and time variables. An expression is given for a criterion of the conditions when the contribution of diffusion is so small that it may safely be disregarded as a variable. Another criterion also is given for the situation when diffusivity is so large, in comparison with other system constants, that the simple plug flow solution may be used without incurring more than a specified error.The hydrolysis of acetic anhydride was studied in 1/4- and 1/2-in.-diam. reactors in 10- and 15-ft. lengths. Reynolds numbers were between 40 and 400 and temperatures between 25° and 35 °C. It was found that the derived equations form a proper description of experiments in the smaller tube. Deviations from theory in the larger tube are explained in terms of free convection arising from nonisothermal conditions and from concentration gradients in the tube. Grashof criteria for initiation of convection in the system are discussed.
    Additional Material: 11 Ill.
    Type of Medium: Electronic Resource
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  • 2
    Electronic Resource
    Electronic Resource
    Hoboken, NJ : Wiley-Blackwell
    AIChE Journal 5 (1959), S. 486-496 
    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 paper concerns a study of radiation as a contributing mechanism in the transfer of heat between discrete solid particles. A theory for transfer in such systems is generalized to include planar-, spherical-, and cylindrical-bed geometries; because of the particulate nature of the system the generalization is given in terms of finite-difference equations. Transfer experiments were performed in a quiescent cylindrical bed with an axial heat source and a cylinderical containing-wall sink. Heat fluxes and radial-temperature profiles were measured. As the experiments were arranged, only modest temprature gradients were established between source and sink, but the ambient sink temperature was taken in steps from 100° to 1,000°C. For a bed of 3.8-mm.-diameter alumina spheres the ratio of heat transferred by radiation to that transferred by conduction was estimated to increase with average bed temperature from the order of 0.1 at 100°C., to 1.2 at 1,000°C. The effects of temperature on bed reflectivity and transmissivity and on apparent boundary-temperature discontinuities are discussed.
    Additional Material: 10 Ill.
    Type of Medium: Electronic Resource
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  • 3
    Electronic Resource
    Electronic Resource
    Hoboken, NJ : Wiley-Blackwell
    AIChE Journal 6 (1960), S. 682-685 
    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 electrical conductivity probe capable of measuring liquid phase concentration fluctuations occurring at frequencies up to 8 kc. is described. The design permits concentration measurements in volume elements of the order of 3 × 10-5 cc. The probe was applied successfully to the measurement of turbulent concentration fluctuations.
    Additional Material: 7 Ill.
    Type of Medium: Electronic Resource
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  • 4
    Electronic Resource
    Electronic Resource
    Hoboken, NJ : Wiley-Blackwell
    AIChE Journal 9 (1963), S. 12-19 
    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 stirred vessel is maintained in a quasisteady state by continuously introducing water and a conductive tracer solution and continuously removing the resulting mixture by overflow. Detailed properties of the system are elucidated by measuring tracer concentration changes with a conductivity probe in a volume element of the order of 0.3 cu. mm. By the use of suitable electronic equipment the following statistical concentration parameters are measured in experiments with three diameters of flat-bladed turbines and with a tenfold range of rotational speed: temporal mean, total root-mean-square fluctuation, spectral distribution of fluctuations, and Eulerian micro time scale. Results are interpreted in terms of behavior of time-average and fluctuation measures in three regions, the generation region within the impeller volume, the decay region which starts in the horizontal fluid sheet issuing from the impeller, and the recirculation flow region in the vessel.Generation of concentration fluctuations within the confines of the impeller is described in terms of a model involving gross mixing, without significant decay, in the wake of each flat blade. Distributions of mean and fluctuating concentrations are suggested to provide a measure of uniformity in the vessel as a whole. The former, in particular, was remarkably constant throughout the vessel.
    Additional Material: 16 Ill.
    Type of Medium: Electronic Resource
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  • 5
    Electronic Resource
    Electronic Resource
    Hoboken, NJ : Wiley-Blackwell
    AIChE Journal 24 (1978), S. 912-920 
    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 paper deals with a particular type of limit cycle in chemical reaction systems, the so-called relaxation oscillation. This phenomenon can be caused by thermal or kinetically induced instabilities in a loop reactor or a CSTR, but can also occur in a catalytic fixed-bed reactor for an endothermic reaction with self-inhibiting or self-accelerating steps.
    Additional Material: 18 Ill.
    Type of Medium: Electronic Resource
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  • 6
    Electronic Resource
    Electronic Resource
    Hoboken, NJ : Wiley-Blackwell
    AIChE Journal 3 (1957), S. 83-91 
    ISSN: 0001-1541
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Measurements are reported on axial mixing of binary gas mixtures at room temperature and atmospheric pressure in a random bed of spherical particles. By means of the Fick's Law equation for diffusion an axial Peclet number, dp U/Ez (where dp is particle diameter, U is interstitial velocity, and Ez is axial eddy diffusivity), was computed in terms of the ratio of the amplitudes of a sinusoidal concentration wave at the inlet and outlet of the bed. An experimental method was devised to eliminate end effects in the system. For the gas systems H2—N2 and C2H4—N2 and for Reynolds numbers between 100 and 400 the mean of twenty-one determinations of axial Peclet number was 1.88 ± 0.15. This value is in excellent agreement with a value of 2.0 predicted theoretically on the assumption that the bed acts as a series of n perfect mixers, where n is the number of particles traversed between inlet and outlet.Axial diffusivity for turbulent flow of gases among particles is about sixfold larger than radial diffusivity, previously determined. It is suggested that axial diffusivity may not, perhaps, be neglected in contacting devices, such as adsorbers and catalytic reactors.
    Additional Material: 10 Ill.
    Type of Medium: Electronic Resource
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  • 7
    Electronic Resource
    Electronic Resource
    Hoboken, NJ : Wiley-Blackwell
    AIChE Journal 4 (1958), S. 423-429 
    ISSN: 0001-1541
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Solutions of linearized Navier-Stokes equations have been developed for the motion of arbitrary two-dimensional waves occurring at any interface between the emulsion phase of a fluidized bed and the particle-free, fluid phase. In all cases for which the bed particles are denser than the fluidizing fluid the solutions showed that the lower interface of a bed always is unstable and the upper, stable. The quality of fluidization is suggested to be related at least in part to the rate of growth of surface waves, this rate depending upon physical properties of the system and length of the disturbing wave.
    Additional Material: 8 Ill.
    Type of Medium: Electronic Resource
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  • 8
    Electronic Resource
    Electronic Resource
    Hoboken, NJ : Wiley-Blackwell
    AIChE Journal 2 (1956), S. 372-380 
    ISSN: 0001-1541
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Measuring the spreading of a tracer dye from a point source yields information on diffusion in glass-sphere beds fluidized in water. Particulately fluidized beds, which are here formed, are well described by the statistical turbulence equations of Taylor. Mixing parameters - eddy diffusivity, scale, and intensity of turbulence - are established. Transition of these variables is traced from fixed beds through fluidized beds in different degrees of bed expansion.Mixing characteristics of these “ideal” types of fluidization may provide a frame of reference for consideration of more complex systems.
    Additional Material: 18 Ill.
    Type of Medium: Electronic Resource
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  • 9
    Electronic Resource
    Electronic Resource
    New York, NY : Wiley-Blackwell
    Plant/Operations Progress 10 (1991), S. 189-193 
    ISSN: 0278-4513
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Inappropriate combinations of moisture, alloy and mercury can accelerate corrosion and form explosive compounds. Are there ways of preventing these potential hazards?
    Additional Material: 6 Ill.
    Type of Medium: Electronic Resource
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  • 10
    Electronic Resource
    Electronic Resource
    Brookfield, Conn. : Wiley-Blackwell
    Polymer Composites 13 (1992), S. 197-206 
    ISSN: 0272-8397
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Notes: As part of an engineering analysis and experimental methodology to characterize prepreg tack, a compression-to-tension test was optimized to enhance reproducibility and generate intrinsic property data. With the resulting stress-strain compression and tension data, a theoretical model was developed to describe tack as a bulk viscoelastic property of a prepreg laminate stack. Using the viscoelastic analysis, four intrinsic material parameters to characterize prepreg tack could be defined. These were 1) relaxed modulus, 2) unrelaxed modulus, 3) relaxation time, and 4) initial void content of the prepreg stack. Relaxed and unrelaxed moduli of the prepreg stack were independent of temperature, while the relaxation time was highly dependent on temperature and matrix viscosity. In addition, the relaxation time was found to be influenced by resin/fiber content and prepreg surface characteristics, which also influenced the void content of the prepreg stack. Using these measured parameters, good agreement was observed between theory and experimental data for both the stress-strain curve of the tack test and the simplified compression tack index (CTI*), defined as the ratio of output energy of the prepreg stack during tensile unloading to input energy during compressive loading.
    Additional Material: 11 Ill.
    Type of Medium: Electronic Resource
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