Developing a framework to model the primary drying step of a continuous freeze-drying process based on infrared...

Area of Science:

• Pharmaceutical Engineering
• Process Control
• Heat Transfer

Background:

• Conventional batch freeze-drying faces limitations in efficiency and product uniformity.
• Continuous freeze-drying offers potential improvements through vial spinning and non-contact energy transfer.
• Automated control necessitates fundamental mechanistic modeling of process steps.

Purpose of the Study:

• To develop a modeling and control framework for the continuous primary drying step using infrared (IR) radiation.
• To evaluate the influence of material transmission properties on IR radiation transfer.
• To support the model-based design of a continuous freeze-drying prototype.

Main Methods:

• Mechanistic modeling combining physical laws with Monte Carlo simulations for energy transfer.
• Experimental verification of computed energy transfer.
• Evaluation of IR radiation profiles through various materials.

Main Results:

• The study successfully modeled IR energy transfer to spin-frozen vials.
• Material transmission properties significantly affect the IR radiation profile.
• The modeling framework aids in selecting appropriate IR window materials for the prototype.

Conclusions:

• The presented modeling framework is suitable for the model-based design of continuous freeze-drying prototypes.
• This approach enables assessment of engineering parameters, mechanical tolerances, and material options.
• The findings facilitate the optimization of continuous freeze-drying processes for enhanced efficiency and product quality.