DROPLET BREAKAGE IN STIRRED DISPERSIONS - BREAKAGE FUNCTIONS FROM EXPERIMENTAL DROP-SIZE DISTRIBUTIONS

Transient breakage drop-size distributions have been experimentally me asured using an image analysis technique. The transient distributions show self-similar behavior. The breakage rate and daughter-drop distri bution functions have been determined using an inverse-problem approac h which takes advantage of this self-similarity. The inverse-problem r esults show that the breakage rate is not a power law function of the drop size. The breakage rate is found to increase sharply with the dro p size and the stirrer speed while decreasing sharply with increase in the interfacial tension. It is also found to decrease with increase i n the dispersed phase viscosity, though the dependence on the viscosit y is weaker than on the other variables. The daughter drop distributio n was found to be relatively insensitive to the stirrer speed and inte rfacial tension, but was found to depend on the dispersed phase viscos ity. As the drop viscosity increases, the breakage becomes more erosiv e in nature, leading to a broader size distribution of daughter drops. Generalized correlations for the breakage rate and daughter-drop dist ribution which account for the effect of physical properties and exper imental conditions are presented. These relations will be very useful in predicting the drop-size distributions in stirred dispersions. Mode ls for the breakage functions are compared with those determined in th is study and the model predictions of the transient-size distributions are compared with the experimental data.