Electrohydrodynamic Atomisation of Aqueous Liquids

The high surface tension and high conductivity makes water unsuitable for EHD atomisation. The high electric field required to atomise water destabilises the atomisation process. A novel low voltage EHD spray nozzle was developed that can atomise water and weak saline solutions in the stable cone jet mode in ambient air. A CFD model was developed to describe and simulate the liquid cone formation and atomisation. The approach was to simultaneously solve the coupled EHD and electrostatic equations. The predicted velocity fields and operating windows were consistent with published results. The predicted droplet size compared well with experimental results. The simulation results also agree well with the experimental results for water atomisation with respect to the liquid cone shape and droplet size. A novel EHD spray drying set-up based on the low voltage nozzle was developed. The low voltage nozzle makes discharging unnecessary and allows for controlling and collecting of the particles using electric fields. The size distribution of the generated particles is very narrow. Both porous and completely spherical particles can be produced.