The influence of flow regime on electrostatic destabilisation of water-in-oil emulsions: A theoretical and experimental assessment.

In this study the growth of water droplets in a water-in-oil emulsion under an applied electric field is considered. The significance of the flow regime, laminar or turbulent, has been investigated theoretically and experimentally with respect to droplet coalescence and break-up mechanisms. It is shown that whilst turbulent flow may enhance the coalescence of small droplets, it can also lead to disintegration of larger ones. Experimental assessment of suspended droplet size, performed on emulsions flowing through a purpose-built compact electrocoalescer test duct, showed good agreement with theoretical predictions of maximum droplet size under turbulent flow and electrostatic stresses. It is suggested that in this case the droplet break-up was primarily due to turbulent stresses in subsequent pipe-work rather than the combined turbulent and electrostatic stresses in the duct itself.