Advanced Freeze-Drying Modeling: Validation of a Sorption-Sublimation Model

Modeling freeze-drying is crucial due to the complex interplay of heat and mass transfer, which significantly impacts product quality and process efficiency. Traditional experimental approaches can be time-consuming and resource-intensive, making rigorous modeling an essential tool for optimization. Sorption-sublimation models incorporate the dynamic nature of the drying steps by accurately describing heat and mass transfer, enabling precise calculation of product temperature and residual moisture. Here, the moving boundary is mapped to the boundary of a fixed domain by the introduction of two new coordinates. Simulation results are validated by the approach from Sixt et al. The model shows good agreement with experimental data, with deviations reduced to as low as 3.9%. This represents a significant improvement over previous models, such as the pseudostationary approach, which exhibits deviations up to 42.2% for edge vials at the end of primary drying. For residual moisture, the experiment and simulation show similar error margins of 7% and the simulation deviates by only 8% from the experimental value. The model's accuracy and precision offer valuable insights for optimizing process parameters, ultimately enhancing product quality and reducing development costs. The successful validation against experimental data shows the model's potential as a robust tool for predicting process behavior in vial lyophilization, paving the way for its application in both research and industrial settings.