HOMOGENIZATION OF FLUIDS IN MIXING VESSEL S WITH LAMINAR-FLOW

Homogenization of fluids in mixing vessels with a rotating stirrer is investigated in a comprehensive study by means of theoretical-numerica l methods. The results show details of the unsteady mixing process tha t can not be obtained by any other means. For a theoretical treatment of the process of homogenization the stirrer was substituted by a stir rer model of simple geometry. As former investigations prove, this mod el creates a fluid motion similar to the real conditions. The concentr ation fields that occur after a second component has been given into t he vessel have been calculated. This component was introduced either o ver the free surface of the liquid or over the surface of the stirrer. Three different positions of the stirrer in the vessel were investiga ted, furthermore the values of the Reynolds-number and the Schmidt-num ber were varied in a wide range. With the help of these investigations it was possible to determine the time dependency of the maximal conce ntration and to calculate the mixing time The lowest values of the mix ing time can be obtained if the component is introduced over the surfa ce of the stirrer, situated in a middle position. The mixing time is a function of the convection-number Re12.Sc and of the Reynolds-number Re12 as well. For Re12.Sc-->infinity the mixing time reaches a final v alue, which depends only on the Reynolds-number.