Library

X
feed icon rss

Your email was sent successfully. Check your inbox.

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

Proceed reservation?

Export
  • 11
    Electronic Resource
    Electronic Resource
    Multiple roll systems: Steady-state operation (1995)
    Hoboken, NJ : Wiley-Blackwell
    AIChE Journal 41 (1995), S. 1045-1060 
    Details
    ISSN: 0001-1541
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Roll coaters for applying liquid coating to continuous strip or web are, with some two-roll exceptions, systems of three or more rolls in which liquid passes through two or more gaps or nips between rolls. Yet most of the literature on roll coating is devoted to some of the 11 distinct flows in individual gaps or nips. This article analyzes how the final coated layer thickness in several types of forward roll transfer and reverse roll coating systems depends, at steady state, on the number of rolls, their speeds, the gaps between roll pairs, and the doctoring of recycle films from the rolls. The inputs to the analysis are elementary mass balances at the gaps, and simple gap performance equations that approximate well the available experimental and theoretical findings about flow rates and film-splits at individual gaps. The results are fundamentals-based means of understanding, comparing, predicting, and ultimately designing performance of multiple roll systems.
    Additional Material: 20 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/aic.690410502
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 12
    Electronic Resource
    Electronic Resource
    Predicting drying in coatings that react and gel: Drying regime maps (1996)
    Hoboken, NJ : Wiley-Blackwell
    AIChE Journal 42 (1996), S. 55-67 
    Details
    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 competition between drying and reactions in a liquid coating containing precursors to a random network polymer can give rise to a variety of drying phenomena. Solidification, or gelation, of the polymer may occur before, after, or during the removal of solvents from the coating. Rates of drying and reaction are probed by solving the equations of mass transfer by diffusion along with chemical reaction in one dimension. Solutions to this system of equations are obtained by Galerkin's method with finite-element basis functions and entail large-scale computation. Skinning, or solidification at the surface of the coating while the bulk is still liquid, occurs in thick coatings when the diffusional resistance to drying is significant, that is, at high mass-transfer coefficients. Homogeneous solidification occurs in thin coatings at low mass-transfer coefficients. Drying regime maps represent these solidification phenomena as regions in parameter space.
    Additional Material: 14 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/aic.690420107
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 13
    Electronic Resource
    Electronic Resource
    On phase equilibrium at the gas-liquid interface during absorption (1958)
    Hoboken, NJ : Wiley-Blackwell
    AIChE Journal 4 (1958), S. 439-444 
    Details
    ISSN: 0001-1541
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: That phase equilibrium exists at the gas-liquid interface during gas absorption is usually assumed in the analysis and design of absorption equipment, but the validity of this assumption has been in doubt since Higbie's pioneering gas-absorption studies. Accurate measurements are reported herein of the absorption rates at 25°C. of carbon dioxide into short water jets in which the liquid was in laminar flow. The jets issued from circular nozzles of about 1.5-mm. diam., flowed intact downward through an atmosphere of carbon dioxide at average velocities of from 75 to 550 cm./sec. over distances of 1 to 15 cm., and were collected in a receiver slightly larger in diameter than the nozzles. The measured absorption rates are in excellent agreement with predictions based on unsteady state diffusion theory, when one assumes interfacial equilibrium. It is concluded from these results and those of other investigators that equilibrium prevails at a freshly formed, relatively clean, carbon dioxide-water interface and that the same statement probably applies to the absorption of other slightly soluble gases in water.Evidence is discussed which indicates that an accumulation of minute quantitities of surface-active materials may seriously reduce the rate of gas absorption, either by affecting the hydrodynamic characteristics of the system or perhaps by offering resistance to the transfer of solute molecules across the interface.
    Additional Material: 8 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/aic.690040412
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 14
    Electronic Resource
    Electronic Resource
    Fluid dynamics and diffusion calculations for laminar liquid jets (1959)
    Hoboken, NJ : Wiley-Blackwell
    AIChE Journal 5 (1959), S. 397-402 
    Details
    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 connection with a study of the mechanism of gas absorption the problem arose of predicting absorption rates into laminar liquid jets. A solution to the problem is presented in this paper, which provides an example of the application of fluid dynamics to the analysis of mass transfer in a complex flow system.The water jets considered here issued from circular nozzles of about 1.5-mm diameter, flowed intact downward through an atmosphere of solute gas at average velocities of from 75 to 550 cm./sec. over distances of 1 to 15 cm., and were collected in a receiver slightly larger in diameter than the nozzles. Equations describing the liquid flow near the jet surface are deduced from measurements of jet diameter and analogy to related flow situations. When one uses these equations, absorption rates are predicted from unsteady state diffusion theory with the assumption of interfacial equilibrium. The predicted rates for carbon dioxide at 25°C are in close agreement with experimental determinations over the observed range of contact time of the liquid with gas, namely 0.003 to 0.04 sec.
    Additional Material: 6 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/aic.690050328
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 15
    Electronic Resource
    Electronic Resource
    Absorption into an accelerating film (1958)
    Hoboken, NJ : Wiley-Blackwell
    AIChE Journal 4 (1958), S. 382 
    Details
    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
    URL: http://dx.doi.org/10.1002/aic.690040330
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 16
    Electronic Resource
    Electronic Resource
    Interfacial turbulence: Hydrodynamic instability and the marangoni effect (1959)
    Hoboken, NJ : Wiley-Blackwell
    AIChE Journal 5 (1959), S. 514-523 
    Details
    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 origin of interfacial turbulence, spontaneous agitation of the interface between two unequilibrated liquids, has been explained in terms of classical flow, diffusion, and surface processes. The essence of the explanation is the long-known though much neglected Marangoni effect, wherein movement in an interface is caused by longitudinal variations of interfacial tension. It is proposed that interfacial turbulence is a manifestation of hydrodynamic instability, which is touched off by ever present, small, random fluctuations about the interface.A simplified mathematical model has been analyzed in order to detail the mechanism of the “interfacial engine” which supplies the mechanical energy of interfacial turbulence. In its present form the analysis incorporates several drastic simplifications, though ways of removing some of these have been suggested. The groundwork has been laid for the more elaborate analyses that are needed for a decisive test of the theory.The analysis shows how some systems may be stable with solute transfer in one direction yet unstable with transfer in the opposite direction, a striking result. It also suggests that interfacial turbulence is usually promoted by (1) solute transfer out of the phase of higher viscosity, (2) solute transfer out of the phase in which its diffusivity is lower, (3) large differences in kinematic viscosity and solute diffusivity between the two phases, (4) steep concentration gradients near the interface, (5) interfacial tension highly sensitive to solute concentration, (6) low viscosities and diffusivities in both phases, (7) absence of surface-active agents, and (8) interfaces of large extent.That some of these effects have been observed in the laboratory lends credence to the theory.
    Additional Material: 8 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/aic.690050421
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 17
    Electronic Resource
    Electronic Resource
    Modeling and design of an industrial dryer with convective and radiant heating (1995)
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Applied Polymer Science 58 (1995), S. 1279-1290 
    Details
    ISSN: 0021-8995
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: Industrial equipment for drying polymeric coatings normally consists of a series of zones, each with a controlled temperature and airflow. Drying of a polymer-solvent solution is strongly affected by the variation of diffusivity, solvent vapor pressure, and solvent activity with temperature and composition. The equations of mass transfer by diffusion and of heat transfer by conduction and radiation describe changes in composition and temperature within the shrinking coating. This system of equations is solved by Galerkin's method with finite element basis functions. The boundary conditions on dryer airflow and temperature change at the entrance to each zone. In a few test cases, the predictions show how evaporative cooling can slow drying in early zones where the coating temperature drops below the dryer temperature, whereas in later zones the coating temperature rapidly approaches the dryer temperature. Infrared heating can be used to reduce the extent of evaporative cooling. In the test cases and experiments, “blistering” occurs in later zones where high oven temperature causes the solvent partial pressure to rise; dryer parameters can be chosen to maintain solvent partial pressure just below ambient pressure in order to avoid “blistering” with least sacrifice of process speed. © 1995 John Wiley & Sons, Inc.
    Additional Material: 7 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/app.1995.070580809
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 18
    Electronic Resource
    Electronic Resource
    MULTIPLE STATES OF A VISCOUS FREE SURFACE FLOW: TRANSITION FROM PRE-METERED TO A METERING INFLOW (1997)
    Chichester : Wiley-Blackwell
    International Journal for Numerical Methods in Fluids 24 (1997), S. 813-831 
    Details
    ISSN: 0271-2091
    Keywords: pre-metered ; metered ; free boundary condition ; free surface flow ; viscous ; Engineering ; Numerical Methods and Modeling
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Notes: In a forward-roll coating gap or nip, steady laminar flow of liquid between counter-rotating cylinders or rolls is used to split the flow into a coated layer on one roll and a rejected layer on the other. Both layers have free surfaces in contact with air. Liquid may be carried into the gap as a layer on one or both rolls. If the arriving layer is not too thick, all of the liquid flows through the gap, a situation called pre-metered. If the arriving layer is too thick, part of the liquid is rejected and runs back down the lower roll. The flow rate through the gap is said to be metered and is not known a priori.The transition from a pre-metered regime to the metered situation was examined by solving the Navier-Stokes system for steady, two-dimensional flow in a domain bounded by free surfaces, two rigid roll surfaces and chosen inflow and outflow surfaces. The free boundary condition, as described by Papanastasiou et al. (Int. j. numer methods fluids, 14, 587 (1992)), was explored and proved to accommodate both the pre-metered and metered regimes. A run-back flow state across the synthetic inlet plane was obtained, provided a condition on the thickness of the arriving layer was replaced by a kinematic condition at a certain stage.The coupled equation system was solved by Galerkin's method with finite element basis functions. The resulting non-linear algebraic system was solved by Newton's method with initialization by pseduo-arc-length continuation and automatic parameter step adjustment.Results show the existence of multiple solutions which can lead to hysteresis. Flow regime maps were constructed to portray the operating parameter range in which a coating bead can exist and the ranges in which a coating gap operates in either the pre-metered or the metering regime. © 1997 by John Wiley & Sons, Ltd. Int. j. numer. methods fluids 24: 813-831, 1997.
    Additional Material: 18 Ill.
    Type of Medium: Electronic Resource
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
  • 19
    Electronic Resource
    Electronic Resource
    On the inlet stress condition and admissibility of solution of fiber-spinning (1996)
    Hoboken, NJ : Wiley-Blackwell
    Advances in Polymer Technology 15 (1996), S. 237-244 
    Details
    ISSN: 0730-6679
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Notes: To model fiber spinning and film casting, a boundary condition on the stress at a chosen synthetic inlet is necessary. However, the exact value of the stress for viscoelastic liquids at the synthetic inlet is a priori unknown. In this article, we present the application of the “free boundary condition” to the inlet stress, which avoids the necessity of specifying an a priori unknown value of stress at the synthetic inlet. To apply the free boundary condition, the process must be cast and studied as a two-point boundary value problem by finite elements. To verify the admissibility and accuracy of the free boundary condition, the same process is cast and studied as an initial value problem, directly solvable by a DGEAR subroutine. The initial value problem is cast in a matrix form that allows analytic investigation of admissible solutions: With the upper convected Maxwell model, the fiber can only slim monotonically with the downstream distance, whereas with the Giesekus model there may be cases of initially increasing and subsequently decreasing diameter, i.e., extrudate-swelling. © 1996 John Wiley & Sons, Inc.
    Additional Material: 5 Ill.
    Type of Medium: Electronic Resource
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
Close ⊗
This website uses cookies and the analysis tool Matomo. More information can be found here...