FLOW PATTERNS AND AXIAL MIXING IN LIQUID/LIQUID SPRAY COLUMNS - 4. DETECTION OF A MULTIPLE CIRCULATION PATTERN GENERATED BY THE APPLICATION OF A POSITIVE TEMPERATURE GRADIENT.

Experiments in tall spray columns are reported, in which pressure and temperature were accurately measured as a function of the height of the column. By means of these profiles and the Barnea-Mizrahi relation between the slip velocity of particles and their volume fraction, the shear stress acting upon the wall of the column was calculated as a function of height. From these shear stress profiles and in view of the temperature profiles the favorable effect of the application of a higher temperature at the top than at the bottom is concluded; the overall circulation which occurs in an isothermally operated system is split up into smaller circulations. Circulations in neighboring zones are of opposite sense. It is supposed that the question whether and to what degree splitting up will take place is dependent, among other things, on the value of the slip velocity.