ALBERT

All Library Books, journals and Electronic Records Telegrafenberg

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
  • 1
    Electronic Resource
    Electronic Resource
    Inhibition of PbO2 formation during lead electrowinning (1985)
    Springer
    Journal of applied electrochemistry 15 (1985), S. 937-945 
    Details
    ISSN: 1572-8838
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Electrical Engineering, Measurement and Control Technology
    Notes: Abstract The effect of the addition of arsenic compounds on the inhibition of PbO2 formation on the anode, thus promoting oxygen evolution in the electrowinning process of lead, has been investigated. Various possible anode reactions involving arsenic have been discussed. Preferential adsorption of arsenic compounds on the electrode surface seems to be the most probable reason for the inhibition of PbO2 formation.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00614370
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 2
    Electronic Resource
    Electronic Resource
    Laminar radial flow electrochemical reactors. I. Flow fields (1988)
    Springer
    Journal of applied electrochemistry 18 (1988), S. 768-780 
    Details
    ISSN: 1572-8838
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Electrical Engineering, Measurement and Control Technology
    Notes: Abstract The velocity fields of three laminar radial flow electrochemical reactors are modeled using numerical and semi-analytical techniques. The capillary gap cell configuration is modeled using Galerkin finite element (GFEM) analysis and the asymptotic form of its velocities presented. An approximate asymptotic expression for entry length is also derived and compared to predicted entry lengths from the GFEM. Qualitative agreement is achieved. Two areas of flow separation are observed, their location being a function of gap width, flow Reynolds number (Re) and inlet pipe diameter. The rotating electrolyzer (REL) flow field is also simulated with the GFEM model. The insensitivity of the REL radial velocity profiles as a function of flow rate is shown. The shape of the radial velocity profiles and the degree of separation of the radial velocity jets are shown to be determined by the Taylor number (being the ratio of half-gap width over the theoretical boundary layer thickness). The asymptotic entry length solution is shown to provide a better estimate for this cell than for the capillary gap cell. Unlike the previous cells the pump cell shows less asymptotic behavior and is therefore more difficult to simulate. The GFEM approach is usually too costly for this cell and therefore perturbation techniques are applied. The resulting semi-analytical solution adequately represents laminar pump cell velocity profiles over a broad range of parameter values and is very short and easy to implement. One high Taylor number simulation is performed using the GFEM and the previously reported decoupling of electrodic mass transfer is interpreted via velocity profiles.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01016906
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 3
    Electronic Resource
    Electronic Resource
    Laminar radial flow electrochemical reactors. III. Electroorganic sysnthesis (1989)
    Springer
    Journal of applied electrochemistry 19 (1989), S. 856-867 
    Details
    ISSN: 1572-8838
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Electrical Engineering, Measurement and Control Technology
    Notes: Abstract This paper investigates the performance and design of three laminar radial flow electrochemical cells (the capillary gap cell, stationary discs; the rotating electrolyzer, co-rotational discs; the pump cell, one disc rotating and the other stationary). Modeling of a competing electrosynthesis pathway is described — the methoxylation of furan. The model developed incorporates convective, diffusive and migrative influences with three homogeneous and two electrodic reactions. Two sizes of reactors are considered and the performance of the different reactor types analyzed as a function of size. The superiority of the rotational cells is illustrated for this reaction scheme compared to both the capillary gap cell (CG) and a parallel plate reactor (PPER). Scale-up criteria are scrutinized and two approaches to laminar radial flow reactor scale-up are investigated. The one suggested herein shows that Taylor number, residence time,IR drop and rotational Reynolds number must all be accounted for even with a fairly simple electrosynthesis pathway. A quantitative evaluation of this scale-up procedure is included.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01007933
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 4
    Electronic Resource
    Electronic Resource
    Laminar radial flow electrochemical reactors. II. Convective diffusion of inert tracer (1989)
    Springer
    Journal of applied electrochemistry 19 (1989), S. 845-855 
    Details
    ISSN: 1572-8838
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Electrical Engineering, Measurement and Control Technology
    Notes: Abstract Mixing is investigated in three laminar radial flow cells (capillary gap cell (stationary discs), pump cell (one disc spinning) and the rotating electrolyser (co-rotating discs)) using numerical and semianalytical methods for inert tracer transport. Results are compared to existing data. Mixing in the three cells is modelled using finite element techniques applied to convection-dominated inert tracer transport. For the capillary gap cell modes of tracer tagging and detection are commented on with respect to which type provides the correct representation of the residence time distribution. The extent of cross-gap communication, from anode to cathode, is quantified and compared to that observed in the other radial cell designs. Two semi-analytical solutions (convection only, Taylor diffusion) are derived for inert tracer transport in this configuration and are compared to the detailed numerical results. Convection only is relevant fort d/t c ratios of greater than 100 and the Taylor diffusion model applies fort d/t c ratios of about 0.10 and only beyond a critical radius defined herein. Pump cell (PC) mixing is modelled using finite element techniques for the tracer, the velocity field being provided by a semi-analytical solution. Mixing is quantified in this cell and cross-gap communication evaluated. The large axial velocities provide for significant cross-gap mixing. The rotating electrolyser is modelled and the efficiency of separation of catholyte/anolyte streams is observed to be determined by Taylor number (Taylor number (α) — ratio of half-gap width divided by theoretical boundary layer thickness). The superiority of separation in this cell is quantified by definition of the zeroth wall moment and comparison with the other two radial cells. For the example modelled, cross-gap communication was less than half that of the other cells.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01007932
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 5
    Electronic Resource
    Electronic Resource
    Performance of catalytically activated anodes in the electrowinning of metals (1997)
    Springer
    Journal of applied electrochemistry 27 (1997), S. 579-583 
    Details
    ISSN: 1572-8838
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Electrical Engineering, Measurement and Control Technology
    Notes: Abstract The performance of titanium anodes coated with oxides of Ir–Co or Ir–Ta has been compared using long term polarization techniques under simulated electrowinning conditions. Possible reasons for anode failure are explained from SEM and XRD. Potentiodynamic studies in 2m H2SO4 indicate that approximately 450mV reduction in anode potential can be achieved with Ti/(Ir–Co) as against lead. This anode is also suitable in chloride contaminated sulfate electrolyte. The anode potential measurements in different electrowinning electrolytes indicate that a potential saving up to 370– 420mV can be achieved. It is interesting to note that mixed electrolyte containing sulfate and chloride behaves similarly to pure chloride electrolyte with respect to anode potential.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1018454830073
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 6
    Electronic Resource
    Electronic Resource
    Effect of pretreatment on the anodic behaviour of lead alloys for use in electrowinning operations. I (1980)
    Springer
    Journal of applied electrochemistry 10 (1980), S. 623-626 
    Details
    ISSN: 1572-8838
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Electrical Engineering, Measurement and Control Technology
    Notes: Abstract Lead alloys are widely used as anodes in electrowinning operations, for the recovery of metals such as zinc, copper and chromium. When lead alloys are used as such it takes a long time for the build up of a compact, adherent and protective lead dioxide film. During the initial period prior to the build up of the compact layer of lead dioxide, the rate of anodic dissolution is very high, leading to a decrease in the purity of the cathode deposit. In order to minimize the duration of the conditioning of the anode, it is customary to build up a compact lead dioxide layer by pretreating the anodes in suitable electrolytes. An attempt is made to evaluate the performance of the pretreated electrodes by potentiodynamic methods.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00615485
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 7
    Electronic Resource
    Electronic Resource
    An investigation of blood lead content and atmospheric lead levels in Bangkok (1977)
    Springer
    Water, air & soil pollution 7 (1977), S. 79-93 
    Details
    ISSN: 1573-2932
    Source: Springer Online Journal Archives 1860-2000
    Topics: Energy, Environment Protection, Nuclear Power Engineering
    Notes: Abstract Experiments were conducted during a 5 mo period (September 1975 to January 1976) to determine the Pb concentrations in Bangkok streets and blood Pb levels of Bangkok's population. A total of 185 air samples and 222 blood samples was collected and analyzed. Street Pb levels are in the range of 6.16 to 22.48 μg m−3 and blood Pb levels are in the range of 1 to 34 μg (100 g)−1 of whole blood, with an average value of 12.3 μg (100 g)P−1. The effects of various parameters on air and blood Pb levels are discussed in this paper. Air Pb levels are found to be closely related to traffic volume and proximity to the roads. Blood Pb levels are found to increase progressively with age, reaching a saturation value at about 40 yr of age. The average time spent daily on roads by the people and the distance of their residence/workplace from the main road are found to be major parameters, affecting the blood Pb levels. There is no evidence to show that blood and air Pb levels are directly related, at the present ambient exposure levels.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00283801
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 8
    Electronic Resource
    Electronic Resource
    On a theorem of suryanarayana (1982)
    Springer
    Periodica mathematica Hungarica 13 (1982), S. 335-340 
    Details
    ISSN: 1588-2829
    Keywords: Primary 10H15 ; Secondary 10A05, 10H15 ; Multiplicative functions ; square-free divisors
    Source: Springer Online Journal Archives 1860-2000
    Topics: Mathematics
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01849246
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 9
    Electronic Resource
    Electronic Resource
    Heat transfer in the stagnation point flow of a micropolar fluid (1980)
    Springer
    Acta mechanica 36 (1980), S. 247-261 
    Details
    ISSN: 1619-6937
    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 Es werden ähnliche Lösungen der Gleichungen, die die thermische Randschicht eines mikropolaren Fluids längs einer ebenen Wand beschreiben, für die Staupunktsströmung bei parabolischer Änderung der Wandtemperatur gefunden. Zwei Typen von Randbedingungen werden für die Mikrorotation verwendet: (a) Der relative Spin der Teilchen am Rand ist verknüpft mit dem schiefsymmetrischen Anteil der Spannungen am Rand über einen Parameter, der ein Maß für die Konzentration der Mikroelemente darstellt. (b) Die Momentenspannung an der Berandung ist mit dem relativen Spin der Teilchen am Rand mit einem Reibungsfaktor verknüpft, der den Drehslip des Fluids längs der Berandung beschreibt. Die Geschwindigkeits-, Mikrorotations- und Temperaturfelder werden graphisch für verschiedene Werte des Parameters für die Randbedingungen dargestellt. Der Wandreibungskoeffizient, der Koeffizient der Wandmomentenspannung, Verschiebung und Impulsflußdicke und die Wärmeübergangsrate werden tabelliert. Ein Vergleich mit den entsprechenden Ergebnissen der Newtonschen Flüssigkeit wird angestellt.
    Notes: Summary Similar solutions of the equations describing the thermal boundary layer of a micropolar fluid on a plane wall are found to exist for the stagnation point flow when the wall temperature variation is parabolic. The two types of boundary conditions used for microrotation are: (a) the relative spin of the particles on the boundary is related to the skew symmetric part of the stress on the boundary by a parameter which is a measure of the concentration of microelements, and (b) the couple stress on the boundary is related to the relative spin of the particles on the boundary by a friction factor which accounts for the rotational slip of the fluid along the boundary. The velocity, microrotation and temperature fields have been presented graphically for various values of the boundary condition parameters. The skin friction coefficient, wall couple stress coefficient, displacement and momentum thicknesses and rate of heat transfer have been tabulated. A comparison with the corresponding results for a Newtonian fluid has been made.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01214635
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 10
    Electronic Resource
    Electronic Resource
    Thermal boundary layer of a micropolar fluid jet impinging normally on a flat plate (1979)
    Springer
    Acta mechanica 33 (1979), S. 281-294 
    Details
    ISSN: 1619-6937
    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 Wärmeübergang in der Grenzschicht einer ebenen Platte, zufolge des Auftreffens eines inkompressiblen, mikropolaren Flüssigkeitsstrahles wird untersucht. Die thermischen Grenzschichtgleichungen werden aus den Grundgleichungen für die stationäre zweidimensionale Strömung einer inkompressiblen, mikropolaren Flüssigkeit in kartesischen Koordinaten erhalten. Die Lösung der Energiegleichung innerhalb der Grenzschicht wird als Polynom in Termen des Abstandes zum Staupunkt angegeben. Die Temperatur der Platte, sowie die Temperatur außerhalb der Grenzschicht werden als konstant vorausgesetzt. Die Temperaturverteilung und der dimensionslose Wärmeübergangskoeffizient sind graphisch für verschiedene Werte der Materialparameter, zufolge der mikropolaren Eigenschaften der Flüssigkeit, dargestellt. Diese Ergebnisse wurden mit den entsprechenden Ergebnissen für Newtonsche Flüssigkeiten verglichen.
    Notes: Summary The heat transfer is studied in the boundary layer formed on a flat plate by the impingement of an incompressible micropolar fluid jet. The thermal boundary layer equations are obtained after writing the governing equations for the steady two-dimensional flow of an incompressible micropolar fluid in cartesian co-ordinate system. The solution for the energy equation inside the boundary layer is obtained as a polynomial in terms of the distance from the stagnation point. The temperature of the plate and the temperature outside the boundary layer are assumed to be constant. The temperature distribution and the dimensionless heat transfer coefficient are presented graphically for various values of the material parameters which arise due to the micropolar property of the fluid. These results have been compared with the corresponding results for a Newtonian fluid.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01202109
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
Close ⊗
This website uses cookies and the analysis tool Matomo. More information can be found here...