Numerical analysis of particle radial distribution during spray pyrolysis of dual-solute precursor

This study investigates the droplet-to-particle formation process in spray pyrolysis, focusing on interactions between low-solubility precursor A (KNO3) and high-solubility precursor B (NaNO3). A numerical model simulates evaporation, multi-component transport, and precipitation in droplets, and is validated with experimental data. The numerical results reveal that the preferential precipitation of KNO3 near the surface hinders NaNO3, lowering its surface molar concentration. The radial distribution of NaNO3 varies with parameters, exhibiting monotonic or non-monotonic trends. The presence of a small amount of low-solubility KNO3 decreases NaNO3 near the surface, while a higher KNO3 proportion forms a shell layer, increasing NaNO3 from the center to the surface. The results also show that environmental factors influence particle size and component structure. Adjusting the precipitation rate of KNO3, along with reduced temperature and droplet size, leads to smaller particles, enhancing NaNO3 accumulation inside and decreasing surface concentration. This work deepens un-derstanding of pyrolysis droplet evolution, supporting customizable particle design for improved droplet-based technologies.