Liquids' atomization with two different nozzles: Modeling of the effects of some processing and formulation conditions by dimensional analysis

Liquid atomization is a largely widespread unit operation. The disintegration of a liquid into droplets depends on the nature of the nozzle, on the process parameters as well as physicochemical characteristics of the fluid. The aim of this work is to study the contribution of the process (liquid outlet speed and air pressure) and physicochemical (viscosity and surface tension) factors on the size distribution of droplets generated by single- and two-fluid flat spray nozzles. The obtained droplet median diameters which range between 77 and 594 μm for the single-fluid nozzle and between 11 and 599 μm for the two-fluid nozzle, are discussed in relation with operating conditions of atomization process. Dimensional analysis was performed as a modeling approach. Despite energy input for the droplet formation is known to be influenced by different origins according to single and two-fluid nozzles, it is shown that a unique correlation, with specific values of parameters for each nozzle type, gathers all the parameters affecting droplet size. In the range of process and formulation parameters tested, this correlation is validated and gives satisfactory agreement for the single- and two-fluid nozzles.

Predicted versus experimental dimensionless droplet diameters for the single- (gray triangles) and the two-fluid (black triangles) nozzles. The droplet size measurement was carried out with a laser beam placed at a fixed distance L = 14 cm from the extremity of the nozzle. Validation points of the model are shown in white circles.Figure optionsDownload as PowerPoint slideHighlights
► Droplets are obtained with single- and two-fluid nozzles.
► The influence of process and physicochemical factors on the droplet size is studied.
► When using two-fluid nozzles, droplet size is mainly affected by the air pressure.
► A mathematical modeling is conducted based on a dimensional analysis.
► A unique model is proposed with a set of coefficients for each studied nozzle type.