Modeling of a valve-type low-pressure homogenizer for oil-in-water emulsions

Abstract

The geometric configuration of a valve-type homogenizer can have a significant influence on the performance of the emulsification process. Three new variants of low-pressure valve-type homogenizers which differ from one another by how the valve nose profiles and the upstream fluid chamber geometries are constructed were used to study fluid flow characteristics. All the three variants were conceived such that hydrodynamic cavitation can be induced as the oil-in-water emulsion passes through the valve. The computational fluid dynamic (CFD) simulations showed that by changing the valve nose shape from smooth profile to serrated nose profile, a substantially higher strain rate in the gap can be achieved, leading to higher stress on the droplet thus increasing the emulsification efficiency. The CFD simulations have also demonstrated that, incorporating a stagnation bluff in the upstream chamber results in a violence collapse of cavitating bubbles. This in turn promotes turbulence inertial and viscous effects which are essential parameters for enhancing emulsification efficiency. Droplet size analysis of oil-in-water emulsions from the physical experiments found that the serrated nose valve profile and the bluff in the chamber resulted in a mean droplet size of about 95 nm.