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  • Chemical Engineering  (54)
  • 1980-1984
  • 1970-1974  (54)
  • 1950-1954
  • 1971  (54)
  • 11
    Electronic Resource
    Electronic Resource
    Hoboken, NJ : Wiley-Blackwell
    AIChE Journal 17 (1971), S. 326-335 
    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 method has been developed for applying classical minimization techniques to forms of algebraic performance indices for use in optimal adaptive control systems. Essentially, the derivative of a general objective function is constrained to be equal to the integrand of a desired integral performance index. This generates a set of linear algebraic equations, the solution of which results in an algebraic objective function which is explicit in the system parameters. Derivatives of this function can be taken with respect to the controllable parameters, set equal to zero, and solved for the settings which minimize the performance index over time. Alternatively, the function itself may be searched for its minimum on the controllable parameters.The method has been applied to a stirred tank chemical reactor with an exothermic first-order reaction in which heat removal was accomplished by cooling coils. The cooling water flow rate was controlled by a proportional-plus-integral controller and by a three-mode controller. The adaptive control system adjusted the controller settings periodically. The plant, which was third-order, was controlled to a second-order dynamic reference model. The responses to both initial offsets (start-up problem) and disturbances in system parameters were investigated. In all cases, the adaptive control system performance was markedly superior to that for the unadapted, ordinary feedback control system.
    Additional Material: 10 Ill.
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  • 12
    Electronic Resource
    Electronic Resource
    Hoboken, NJ : Wiley-Blackwell
    AIChE Journal 17 (1971), S. 402-409 
    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 drag coefficients of spheres in a cubic packing of equal spheres have been determined at Reynolds numbers of 27,000, 10,000, 5,000 and 2,500, where NRe is based on superficial air velocity and a sphere diameter of 7 cm. Two cubic arrangements were used: in the regular arrangement, the mean flow was parallel to one of the principal axes, while in the skewed arrangement, the mean flow made equal angles with the three principal axes of the packing.The pressure drag coefficient of the central sphere has been measured for each of the 12 banks in the regular arrangement, and the effect of bed length has been determined for lengths varying between 1 and 12 banks. The pressure drag coefficient for the central sphere and the overall pressure drop in the skewed arrangement were found to be lower than for the regular arrangement at the same Reynolds number. From the distribution of local pressure measurements, the separation and reattachment points on the central sphere in each bank were determined, indicating that the boundary-layer behavior on a sphere in a packing is similar to that over a single sphere, when allowing for the effects of turbulence and of pressure gradient.
    Additional Material: 4 Ill.
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  • 13
    Electronic Resource
    Electronic Resource
    Hoboken, NJ : Wiley-Blackwell
    AIChE Journal 17 (1971), S. 470-475 
    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 method is presented for the determination of adsorption equilibria for pure components and mixtures both at high and low pressures. Isotherms for carbon dioxide, methane, ethane, propane, i-butane, n-butane, i-pentane, and n-pentane on activated carbon (Columbia grade NXC 8/10) and on silica gel (Mobil Sorbead H) at 75°, 125°, 200°, and 300°F. are given for pressures ranging from below atmospheric to 1,000 lb./sq. in. Also, adsorption equilibria data are presented for several multicomponent mixtures of the light hydrocarbon gases.The data collected were correlated with good accuracy by use of the two-layer kinetic model developed previously by Gonzalez.
    Additional Material: 5 Ill.
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  • 14
    Electronic Resource
    Electronic Resource
    Hoboken, NJ : Wiley-Blackwell
    AIChE Journal 17 (1971), S. 519-528 
    ISSN: 0001-1541
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Mean velocity and turbulence measurements in the void spaces of a cubic packing of equal spheres have been made at Reynolds numbers of 27,000, 10,000, 5,000 and 2,500, where NRe is based on superficial air velocity and a sphere diameter of 7 cm. Two cubic arrangements were used: in the regular arrangement, the mean flow was parallel to one of the principal axes, while in the skewed arrangement, the mean flow made equal angles with the three principal axes of the packing.Transverse mean velocity and turbulence intensity profiles across the center line of a central pore have been measured behind every bank and behind the bed for the regular arrangement of ten banks of spheres. The power spectrum and probability distribution of the fluctuating velocity have also been determined.
    Additional Material: 7 Ill.
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  • 15
    Electronic Resource
    Electronic Resource
    Hoboken, NJ : Wiley-Blackwell
    AIChE Journal 17 (1971), S. 536-541 
    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 processes of absorption and desorption with reversible reaction are compared theoretically for reactions of the type A ⇌ nB. With the same concentration difference between bulk and interface, it is found that in general, the rate of desorption is lower than that of absorption. Under certain conditions the difference may be as much as 35%.The analysis is based on the penetration theory. The numerical solution introduces a new transformation of the time and distance variables (based on the error function) which reduces the computing time required. An analytical examination of the penetration theory equations provides an explanation of the results of the numerical solution.
    Additional Material: 6 Ill.
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  • 16
    Electronic Resource
    Electronic Resource
    Hoboken, NJ : Wiley-Blackwell
    AIChE Journal 17 (1971), S. 677-682 
    ISSN: 0001-1541
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Principles are developed for the computer-aided generation of initial process flowsheets. The invention of a process concept is analogous to the proof of a multihypothesis/multiconclusion theorem, a mental activity which has been simulated on the computer. Techniques of artificial intelligence are combined with the concept of equivalence class matching and information flow logic to develop a working, computerized process synthesizer. This is part of a continuing project on the development of principles of process invention.
    Additional Material: 6 Ill.
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  • 17
    Electronic Resource
    Electronic Resource
    Hoboken, NJ : Wiley-Blackwell
    AIChE Journal 17 (1971), S. 664-669 
    ISSN: 0001-1541
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Mass transfer with chemical reactions in fully developed turbulent pipe flows has been studied theoretically. The pipe walls are assumed to remain at a constant prescribed concentration. The effect of arbitrary reaction orders and of Reynolds and Schmidt numbers upon the transfer coefficients was investigated. Radial and longitudinal concentration profiles were obtained to show the effect of reaction orders and dimensionless rate constants. Effects of concentration levels on these phenomena were also studied and proven significant. The ratio of the transfer coefficients with chemical reactions to those without chemical reactions increases as a function of the downstream aspect ratio.
    Additional Material: 9 Ill.
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  • 18
    Electronic Resource
    Electronic Resource
    Hoboken, NJ : Wiley-Blackwell
    AIChE Journal 17 (1971), S. 704-712 
    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 equations for the conservation of momentum and mass were solved numerically for the region downstream from the exit of an axial jet into a confined annular stream of the same fluid. An implicit, alternating direction method was used. Numerical results were obtained for radius ratios of 0.281, 0.470, and 0.563 over a range of jet-to-annular velocities from 0.85 to 2.77. The values for the limiting case of the entrance region in pipe flow are in good agreement with the values of Christiansen and Lemmon and Ventras, Duda, and Bargeron. Solution of the equations for the conservation of chemical components produced results for component transfer in agreement with the experimental compositions obtained by Wood for jet mixing. Representative calculations were carried out for a chemical reaction. The results indicate the efficiency of the mixing process for this type of reactor.Experiments were carried out with water and dye to define the conditions under which the assumption of steady, laminar jet mixing is valid. The experiments also indicated the conditions and location of turbulent breakup of the jet.
    Additional Material: 12 Ill.
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  • 19
    Electronic Resource
    Electronic Resource
    Hoboken, NJ : Wiley-Blackwell
    AIChE Journal 17 (1971), S. 729-731 
    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 extends the use of hot-wire and hot-film anemometry to the measurement of velocities in gas mixtures. It is demonstrated that the velocity data in binary gas mixtures can be satisfactorily predicted by calibration tests in pure systems alone or at any two convenient composition conditions. Furthermore, the actual transport properties of a fluid mixture may be inferred from direct calibrations of hot-wire, or hot-film anemometers in the mixture with known compositions.
    Additional Material: 5 Ill.
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  • 20
    Electronic Resource
    Electronic Resource
    Hoboken, NJ : Wiley-Blackwell
    AIChE Journal 17 (1971), S. 1160-1165 
    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: 11 Ill.
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