Multicomponent Droplet Drying Modeling Based on Conservation and Population Balance Equations

Area of Science:

• Chemical Engineering
• Materials Science
• Physical Chemistry

Background:

• Droplet drying is crucial for producing powders with specific properties.
• Understanding the complex physical and chemical changes during drying is essential for process control.
• Existing models often simplify the intricate phenomena occurring within multicomponent droplets.

Purpose of the Study:

• To develop and validate a computational model for predicting drying kinetics and phase behavior of multicomponent droplets.
• To investigate the influence of droplet size and internal transport phenomena on particle formation.
• To correlate model predictions with experimental data from spray-dried particles.

Main Methods:

• Coupling conservation equations with population balance equations (PBE) for multicomponent droplet modeling.
• Validating the model using data from single salt-water droplet drying.
• Extending the model to complex systems containing solvents, active ingredients, and excipients.
• Comparing model predictions with Focused-Ion Beam Scanning Electron Microscopy (FIB-SEM) imaging of spray-dried particles.

Main Results:

• Model accurately predicts trends for single salt-water droplet drying.
• FIB-SEM results align with model predictions for multicomponent systems.
• Intermittent shell formation is influenced by competing transport phenomena (solute diffusion, solvent efflux, intra-drop flow).
• Larger droplets exhibit more pronounced internal effects, impacting final particle structure and heterogeneity.
• Particle phase behavior and physical characteristics are functions of the initial atomized droplet size.

Conclusions:

• The developed model provides insights into the complex drying behavior of multicomponent droplets.
• Droplet size is a critical parameter influencing shell formation dynamics and particle morphology.
• Understanding these mechanisms can lead to optimized spray drying processes and improved product quality control.
• The study highlights the importance of considering internal fluid dynamics and transport phenomena in drying models.