Analysis of dissolved-gas atomization: supercritical CO2 dissolved in water

Supercritical dissolved-gas atomization is an atomization process in which carbon dioxide at temperature and pressure above its critical point is used as the atomizing gas. The spray characteristics in terms of droplets size and distribution have been experimentally studied using a laser diffraction method based on a Malvern apparatus. The main parameter that influences the droplets size is the gas-to-liquid mass ratio (GLR); the injection pressure in the range of 7.4-13 MPa has a minor effect. Upon variation of the GLR from 0.5 to 3, the droplet mean diameter changes from about 8.0 to 2.0 μm; very narrow droplet size distributions are also produced. From the point of view of the atomization mechanism, the mean droplet diameter is mainly influenced by the sudden release of the gas dissolved in the liquid. The overall analysis of the experimental data confirms that dissolved-gas atomization allows for the formation of micrometric droplets that can produce precipitates with controlled sizes and distributions that are useful in several fine-particles production processes