Modeling of Particle Formation via Emulsion Combustion Spray Method

In this paper, a theoretical model is developed to simulate the process of vaporization and burning of emulsion droplets and the evolution and the formation of micro- and nano- particles via the Emulsion Combustion Method (ECM). In ECM, a precursor solution is mixed and stirred with a fuel to form an emulsion of micro-solution droplets suspended in the oil phase. The emulsion liquid is sprayed into in emulsion droplets that are therefore composed of a fuel and tiny micro solution droplets. Spray droplets are ignited and burn to form final micro- or nanoparticles. In this paper, the principles of the method and the main governing equations of the developed model are discussed. Model equations are solved numerically and the results will be presented. The model predicts that depending on the operating and processing conditions, such as the initial size and concentration of the suspended micro solution droplets in emulsion droplets, the fuel fraction of the emulsion droplets, and the fuel combustion enthalpy, the final particles may be mono-dispersed nanoparticles, or larger agglomerate particles. Due to the similarity of the emulsion combustion method with spray pyrolysis and flame spray pyrolysis, most of the equations presented here are applicable to those methods, as well.