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  • 1980-1984  (8)
  • 1
    ISSN: 1432-1181
    Source: Springer Online Journal Archives 1860-2000
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Description / Table of Contents: Zusammenfassung Der Einfluß der thermischen Einlauflänge, die polymere Zersetzung und die Lösungsmittelchemie wurden als wichtige Einflußgrößen bei der Bestimmung des Widerstandes und Wärmeüberganges bei turbulenter Rohrströmung von viskoelastischen Fluiden erkannt. Für Lösungen mit relativ hoher Konzentration wurden die minimalen asymptotischen Wärmeübergangszahlen in der thermischen Einlaufstrecke und der voll ausgebildeten Strömung experimentell ermittelt. Folgende Gleichungen beschreiben den Wärmeübergang: $$\begin{gathered} j_H = 0.13\left( {\frac{x}{d}} \right)^{ - 0.24} \operatorname{Re} _a^{ - 0.45} f\ddot ur das thermische Einlaufgebiet \hfill \\ x/d〈 450 \hfill \\ j_H = 0.03 \operatorname{Re} _a^{ - 0.45} f\ddot ur die ausgebildete Str\ddot omung \hfill \\ x/d〈 450 \hfill \\ \end{gathered} $$ Bei verdünnten Polymerlösungen ist der Wärmeübergang eine Funktion vonx/d, der Re-Zahl und der Polymerkonzentration. Die Reynolds-Analogie zwischen Impuls- und Wärmetransport, die in der Literatur häufig auf Newtonsche Fluide angewendet wird, ist nicht anwendbar bei widerstandsreduzierenden, viskoelastischen Fluiden.
    Notes: Abstract The effects of thermal entrance length, polymer degradation and solvent chemistry were found to be critically important in the determination of the drag and heat transfer behavior of viscoelastic fluids in turbulent pipe flow. The minimum heat transfer asymptotic values in the thermally developing and in the fully developed regions were experimentally determined for relatively high concentration solutions of heat transfer resulting in the following correlations: $$\begin{gathered} j_H = 0.13\left( {\frac{x}{d}} \right)^{ - 0.24} \operatorname{Re} _a^{ - 0.45} thermally developing region \hfill \\ x/d〈 450 \hfill \\ j_H = 0.03 \operatorname{Re} _a^{ - 0.45} thermally developed region \hfill \\ x/d〈 450 \hfill \\ \end{gathered} $$ For dilute polymer solutions the heat transfer is a function ofx/d, the Reynolds number and the polymer concentration. The Reynolds analogy between momentum and heat transfer which has been widely used in the literature for Newtonian fluids is found not to apply in the case of drag-reducing viscoelastic fluids.
    Type of Medium: Electronic Resource
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  • 2
    Electronic Resource
    Electronic Resource
    s.l. : American Chemical Society
    Industrial and engineering chemistry 20 (1981), S. 314-318 
    Source: ACS Legacy Archives
    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
    Type of Medium: Electronic Resource
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  • 3
    ISSN: 0006-3592
    Keywords: Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Glucoamylase and glucose oxidase have been immobilized on carbodiimide-treated activated carbon particles of various sizes. Loading data indicate nonuniform distribution of immobilized enzyme within the porous support particles. Catalysts with different enzyme loading and overall activities have been prepared by varying enzyme concentration in the immobilizing solution. Analysis of these results by a new method based entirely upon experimentally observable catalyst properties indicates that intrinsic catalytic activity is reduced by immobilization of both enzymes. Immobilized glucoamylase intrinsic activity decreases with increasing enzyme loading, and similar behavior is suggested by immobilized glucose oxidase data analysis. The overall activity data interpretation method should prove useful in other immobilized enzyme characterization research, especially in situations where the intraparticle distribution of immobilized enzyme is nonuniform and unknown.
    Additional Material: 3 Ill.
    Type of Medium: Electronic Resource
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  • 4
    ISSN: 0001-1541
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: One of the major difficulties with mathematical models of staged separation systems is the large dimensionality of the process model. This paper is concerned with simple (reduced-order) steady-state and dynamic models for processes such as distillation, absorption and extraction. The model reduction procedure is based on approximating the composition and flow profiles in the column using polynomials rather than as discrete functions of the stages. The number of equations required to describe the system is thus drastically reduced. The method is developed using a simple absorber system. In the second part of this paper, the application of the method to nonlinear multicomponent separation systems is demonstrated.
    Additional Material: 6 Ill.
    Type of Medium: Electronic Resource
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  • 5
    ISSN: 0006-3592
    Keywords: Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Proteins have been immobilized in porous support particles held in a fixed-bed reactor through which protein solution is continuously circulated. Changing the recirculation flow rate alters the observed immobilization kinetics and the maximum enzyme loading which can be achieved for glucose oxidase and glucoamylase on carbodiimide-treated activated carbon and for glucoamylase immobilized on CNBr-Sepharose 4B. Direct microscopic examination of FITC-labelled protein in sectioned Sepharose particles and indirect activity-loading studies with activated carbon-enzyme conjugates all indicate that immobilized enzyme is increasingly localized near the outer surface of the support particles at larger recirculation flow rates. Restricted diffusion of enzymes may be implicated in this phenomenon. These contacting effects may be significant considerations in the scaleup of processes for protein impregnation in porous supports, since apparent activity and stability of the final preparation depend on internal protein distribution.
    Additional Material: 6 Ill.
    Type of Medium: Electronic Resource
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  • 6
    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 Part I, a novel method for reducing the order of models for countercurrent staged separation systems was presented. In this paper, the method is applied to the modeling and simulation of nonlinear multicomponent distillation systems. Some additional properties of the model reduction procedure are derived. The accuracy of the approximation is established by comparison of the steady-state profiles and transient responses to that of rigorous dynamic models. The results indicate that the proposed technique is an effective way of reducing the number of equations needed to model stagewise multicomponent separation systems.
    Additional Material: 10 Ill.
    Type of Medium: Electronic Resource
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  • 7
    ISSN: 1573-6776
    Source: Springer Online Journal Archives 1860-2000
    Topics: Process Engineering, Biotechnology, Nutrition Technology
    Notes: Summary The production of biogas with 52% methane from anaerobic fermentation of the alcohol stillage derived from sugarcane molasses has been studied using a two-stage digestor. Gas productivity of 0.4 m3/KgCOD day with four days of hydraulic retention time was much better than the reported holding times between 10 to 15 days with a single digestor.
    Type of Medium: Electronic Resource
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  • 8
    Electronic Resource
    Electronic Resource
    New York, NY [u.a.] : Wiley-Blackwell
    Biotechnology and Bioengineering 25 (1983), S. 2631-2640 
    ISSN: 0006-3592
    Keywords: Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Cracked corn was irradiated with gamma rays at 0-100 Mrad and the effects of the irradiation on sugar yield, susceptibility to enzymatic hydrolysis of starch, yeast growth, and alcohol production were studied. Gamma irradiation at 50 Mrad or greater produced a considerable amount of reducing sugar but little glucose. At lower dosages, gamma irradiation significantly increased the susceptibility of corn starch to enzymatic hydrolysis, but dosages of 50 Mrad or greater decomposed the starch molecules as indicated by the reduction in iodine uptake. About 12.5% reducing sugar was produced by amylase treatment of uncooked, irradiated corn. This amount exceeded the level of sugar produced from cooked (gelatinized) corn by the same enzyme treatment. The yeast numbers in submerged cultivation were lower on a corn substrate that was irradiated at 50 Mrad or greater compared to that on an unirradiated control. About the same level of alcohol was produced on uncooked, irradiated (105-106 rad) corn as from cooked (121°C for 30 min) corn. Therefore, the conventional cooking process for gelatinization of starch prior to its saccharification can be eliminated by irradiation. Irradiation also eliminated the necessity of sterilization of the medium and reduced the viscosity of high levels of substrate in the fermentation broth.
    Additional Material: 2 Ill.
    Type of Medium: Electronic Resource
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