The Tomographical Dual Wavelength Photometry—A New Tool to Distinguish Micro-and Macro-Mixing

  • Mathias Buchmann
  • Dieter Mewes
Part of the Heat and Mass Transfer book series (HMT)


The newly developed tomographical dual wavelength photometry enables the measurement of the local intensity of segregation at a multitude of points inside stirred vessels. This is done by injecting a mixture of an inert and a reacting dye into the vessel. The inert dye serves as a tracer for the macromixing, whereas the vanishing of the reacting dye shows the micromixing. The concentration fields of the two dyes are measured simultaneously by transluminating the vessel from three directions with superimposed laser beams of different wavelength. The light absorption by the dyes is measured with CCD-cameras and these projections of the dye construction are used for the tomographic reconstruction of the concentration fields. Low Reynolds number measurements were performed with a combination of two Rushton turbines and a combination of two Pitched Blade Impellers. The combination of the Pitched Blade Impellers yields a good axial transport but a slow micromixing. The injection in the middle between the combination of the two Rushton turbines yields a faster micromixing, but the macrotransport is limited to the region between the stirrers.


Concentration Field Tomographic Reconstruction Algebraic Reconstruction Technique Rushton Turbine Zero Shear Rate Viscosity 
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  1. [1]
    Bourne JR, Baldyga J (1983) Simplification of Micromixing Calculations. II. New Applications. The Chemical Engineering Journal 42:93–101Google Scholar
  2. [2]
    Danckwerts PV (1958) The effect of incomplete mixing on homogeneous reactions. Chem Eng Sci 8:93–102CrossRefGoogle Scholar
  3. [3]
    Haarde W (1989) Das Vermischen mit Hilfe von Flüssigkeitsstrahlen. Dissertation, University Hanover, GermanyCrossRefGoogle Scholar
  4. [4]
    Hiby JW (1979) Definition und Messung der Mischgüte in flüssigen Gemischen. Chem Ing Tech 51:704–709CrossRefGoogle Scholar
  5. [5]
    Käppel M (1976) Entwicklung und Anwendung einer Methode zur Messung des Mischungsverlaufs bei Flüssigkeiten. Dissertation, University Munich, GermanyGoogle Scholar
  6. [6]
    Mewes D, Herman C, Renz R (1994) Tomographic Measurements and Reconstruction Techniques. In: Mayinger F (ed) Optical Measurements. Springer, Berlin New YorkCrossRefGoogle Scholar
  7. [7]
    Ostendorf W, Mewes D (1988) Measurement of three-dimensional unsteady temperature profiles in mixing vessels by optical tomography. Chem Eng Tech 11:148–155CrossRefGoogle Scholar
  8. [8]
    Reinecke N, Buchmann M, Petritsch G, Mewes D (1996) Enchancement of resolution for reconstruction algorithms for limited views absorption spectroscopy. In: Institution of Mechanical Engineers (ed) Optical Methods and Data Progressing in Heat and Fluid Flow. Professional Engineering Publishing Limited, Suffolk, pp 383–391Google Scholar
  9. [9]
    Renz R (1992) Das diskontinuierliche Vermischen von Flüssigkeitsstrahlen in zylindrischen Behältern. Dissertation, University Hanover, GermanyGoogle Scholar
  10. [10]
    Villermaux J, Falk, Fournier MC (1994) Scale-up on Micromixing Effects in Stirred Tank Reactors by a Parallel Competing Reaction System, in 8th European Conference on Mixing”, Cambridge, UK, BHRA, 1994, pp. 251–258Google Scholar

Copyright information

© Springer-Verlag Berlin Heidelberg 1999

Authors and Affiliations

  • Mathias Buchmann
    • 1
  • Dieter Mewes
    • 1
  1. 1.Institut für VerfahrenstechnikUniversität HannoverHannoverGermany

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