Modeling of Aerosol Spray Characteristics for Synthesis of Mixed-Oxide Nanocomposite Sensor Film

A model is developed of aerosol synthesis of mixed metal oxide nanocomposite film for sensor applications. The synthesis technique involves atomization of a solution of mixed salts in water, spraying of solution droplets, droplet deposition on a heated substrate, evaporation and chemical reaction to produce the mixed oxides, and film growth. The precise control of oxide nanoparticle size distribution and inter-particle spacing in the film is crucial to achieving high sensitivity. These in turn largely depend on the droplet characteristics prior to impingement on the substrate. This paper focuses on development of a model to describe the atomization and spray processes before the film growth. Specifically, a mathematical model is developed utilizing Computational Fluid Dynamics solution of the equations governing the transport of atomized droplets from the nozzle to predict droplet characteristics in flight. The predictions include spatial distribution of droplet size and concentration, and the effect on these characteristics of swirling inlet flow at the spray nozzle.