(440c) Electrocoalescence of an Aqueous Drop at Water-Oil Interface

The performance of a water-in-oil emulsion electrocoalescence is proportional to the rate of coalescence between both drop-drop and drop-interface system. Beyond a critical electric field, undesirable phenomena such as non-coalescence in case of drop-drop interaction and partial-coalescence or non-coalescence in case of drop-interface interaction can reduce the separation efficiency. In this work, we discuss the effect of electro-capillary number (Ca), the viscosity of the oil medium, the frequency of electric field and conductivity of aqueous medium on coalescence, partial-coalescence and non-coalescence in this system. Our major results are, (i) The critical capillary number for partial-coalescence is independent of the viscosity of the oil medium. However, for non-coalescence, it decreases with viscosity. (ii) The difference between the critical capillary number for partial-coalescence and non-coalescence decreases with increase in Ohnesorge number (Oh). (iii) The size of partial-coalescence increases with an increase in Ca. (iv) The critical capillary number decreases with increasing conductivity of the aqueous medium. (v) The critical capillary number for partial-coalescence increases with frequency. These findings can help in the improvement of the design and performance of electrocoalescer used in oil refineries.