Unveiling the Power of Computational Fluid Dynamics Simulations in Spray Drying Applications

Computational fluid dynamics simulations (CFD) have revolutionized the field of spray drying, enabling researchers to gain a deeper understanding of the complex transport and droplet drying kinetics within laboratory-scale spray dryers. In this article, we will delve into the world of CFD-based modeling and its application in predicting drying parameters and powder aerosolization metrics.

The study highlights the significance of maximum instantaneous droplet drying rates (κ max), which were found to be two orders of magnitude higher than time-averaged drying rates. This finding underscores the chaotic nature of the drying environment, characterized by high variability in time-averaged droplet drying rates (κ avg) with coefficients of variation ranging from 60-70%. The CFD-based drying parameters, including κ avg, κ max, and precipitation window, were averaged across all droplets in each spray dryer case.

The CFD model accounted for the complex interactions between phases, including two-way heat and mass transfer coupling and turbulent flow generated by acoustic streaming from the mesh nebulizer. This level of detail is crucial for accurately predicting drying rates and aerosolization metrics.

The study's findings were achieved through the development of a CFD model that captured spray dryer conditions from a previous experimental study on excipient-enhanced growth powders with L-leucine as a dispersion enhancer. The methodology employed can be applied to other engineering and science disciplines, making it a valuable resource for researchers.

The purpose of this study was to develop a new computational fluid dynamics (CFD)-based model of the complex transport and droplet drying kinetics within a laboratory-scale spray dryer, relating CFD-predicted drying parameters to powder aerosolization metrics from a reference dry powder inhaler (DPI). The ultimate goal is to establish a common terminology and methodology for verification and validation in computational fluid dynamics simulations.

In conclusion, this study demonstrates the power of computational fluid dynamics simulations in predicting drying rates and aerosolization metrics. As researchers continue to push the boundaries of CFD-based modeling, it is essential to establish clear guidelines for verification and validation. The findings presented here provide a solid foundation for further research in this area, ultimately leading to improved understanding and control of spray drying processes.

'Computational fluid dynamics simulations'