Comparison of Knudsen diffusion and the dusty gas approach for the modeling of the freeze-drying process of bulk food products

Freeze-drying is generally used to achieve high quality products and preserve thermal sensitive components; however, it is also considered as a high energy and costly process. Modeling of the process can help to optimize the process to reduce these drawbacks. In this work, a mathematical model is presented to predict the heat and mass transfer behavior for freeze-drying of porous frozen food particles during freeze-drying to optimize the process. For the mass transfer, a comparison between Knudsen diffusion and the more complex dusty-gas approach is performed. Simulation results of a single particle are validated by experiments of single-layer drying to extend the usage of this model from a single particle to a particle bed. For the moisture transfer, adaption parameters are introduced and evaluated. A comparison shows a good agreement of the model with experimental results. The results furthermore suggest a strong correlation of the drying kinetics with pore size and particle porosity. An increase in the pore diameter strongly improves the overall mass transfer rates and hence is a suitable parameter for an effective increase of the drying rates in freeze-drying.

Subjects

freeze-drying

drying of frozen particles

modeling

dusty gas model

improvement of mass transfer

internal porous structure

DDC Class

600: Technik

620: Ingenieurwissenschaften

670: Industrielle Fertigung

More Funding Information

This research received no external funding.

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publishedVersion

Lizenz

https://creativecommons.org/licenses/by/4.0/

Name

processes-10-00548-v2.pdf

Size

2.72 MB

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Adobe PDF

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Comparison of Knudsen diffusion and the dusty gas approach for the modeling of the freeze-drying process of bulk food products