Influence of experimental setup on observed values of mixing time in gas-stirred liquids

Mixing time of metallurgical reactors is gaining increasing importance. At first sight one single mixing time should be expected, being characteristic with regard to a given reactor and to given stirring conditions. The aim of the present paper is to call attention to the influence of the location of tracer injection and of the experimental method on the observed value of the mixing time. Two mixing times have been defined, namely “local mixing time” and “global mixing time”. The results have been compared with those of the literature. Partly, there is good agreement with some published correlations.     

The properties of CuInSe2-MnSe crystals

The composition and the impurity back-ground levels of (CuInSe₂)_1-x (MnSe)_2x alloy crystals are characterized by ion microprobe analyses. Room temperature photoreflectance (PR) and photoconductivity (PC) measurements in the temperature range 10 K ⪯ T ⪯ 300 K reveal changes in the point defect chemistry and a shift of the band gap with increasingx towards higher energies. Also, a deep luminescence feature at 0.89 eV is observed in Mn doped crystals, in addition to the contributions at 0.90 and 0.94 eV that appear in both doped and nominally undoped CuInSe₂. X-ray diffraction studies show that the chalcopyrite structure is retained to at leastx = 0.25.     

Flow fields in electromagnetic stirring of rectangular strands with linear inductors: Part II. computation of flow fields in billets, blooms, and slabs of steel

The model presented in Part I of this series of papers is used to compute flow velocities in the longitudinal stirring of steel blooms and billets, and in the horizontal stirring of steel slabs. In longitudinal stirring of blooms and billets the reverse flow is on the side of the strand opposite to the inductor. The effects of penetration depth of the electromagnetic force, of the force itself, of the length of the stirrer, and of the width of the liquid core were determined. In horizontal stirring of slabs the reverse flow takes place outside of the stirrer region, forming the so-called butterfly stirring pattern. The characteristics of this flow field depend to a considerable extent on the width of the stirrer. The effects of stirrer width, of thickness of the liquid core, of force and of width of the slab were elucidated. The maximum velocities in both types of stirring are represented as simple formulae. Formerly with Institut für Allgemeine Metallurgie, Technische Universit?t Clausthal