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Felix Faber, Sebastian Gruber, Petra Först, Evangelos Tsotsas, Nicole Vorhauer-Huget. . Available at https://doi.org/10.1016/j.cej.2026.172870

Freeze-drying (FD) is an important, but also expensive and slow conservation process for pharmaceuticals and foods. The interactions of coupled heat and mass transfer with the solid structure of the frozen product are complex and in most cases only addressed with macroscopic modeling approaches that heavily rely on averaged structural data. To enable a better physical understanding of primary FD, this work employs a non-isothermal pore network model (PNM) for primary FD together with empirical data obtained with 4D X-ray imaging. Drying of maltodextrin (5 % w/w solid content) is experimentally tracked with time- and space-resolved operando X-ray imaging. The porous structure of the very same sample is afterwards reconstructed for PNM simulations. As the size of the sample is much larger than the geometric peculiarities of the sublimation front, it is for the first time possible to study correlations between individual pore temperatures and pressures, pore-scale heat and mass transfer and evolution of the sublimation front inside the amorphous microstructure numerically, which is guided by results of the previous experimental 4D X-ray imaging of the FD process. Complementary to the experimental data, the time-dependent spatial temperature and pressure variations within the pore space are explored with the PNM approach. Given the sublimation front widening during the process, significant temperature and pressure differences within this region are demonstrated. Such information is generally not available from experimental measurements alone, and macroscopic mathematical models do not resolve the process sufficiently on the pore scale, which underscores the strengths of the PNM in this study.

We are very happy to announce that Mr. Haashir Altaf has defended sucessfully his doctoral work on the topic "Pore Network Modeling and Neutron Imaging-Based Analysis of Transport in Fibrous Porous Transport Layers for PEM Electrolyzers" . Haashir is the first Ph.D. candidate from our TPM research group who will obtain his doctorate.

We hope that Haashir enjoyed the traditionall ride on the horse to the Otto statue at Alter Markt quite well. We wish Haashir and his family all the best for their future.

Vom 26. - 28. November 2025 fand in diesem Jahr das Promovierendenseminar der DECHEMA/VDI Fachgruppe "Wärme- und Stoffübertragung" (WSUE) am Lehrstuhl für Thermische Verfahrenstechnik an der OVGU statt.

Neben kollegialen Austausch zwischen den Promovierenden, einem spannenden Vortrag zum Thema "Scientific Publishing in the AI age: are the “old” rules of good scientific practice still sufficient?", standen auch die fachlichen Themen im Vordergrund des Seminars, welche in kurzen Vorträgen präsentiert und anschließend diskutiert wurden.

Zum Abschluss wurde das Seminar mit einer spannenden Werksbesichtigung in der Industrie bei der Pergande Group in Weißandt-Gölzau abgerundet. Hier gab es tolle Einblicke in die industrielle Formulierung von Feststoffprodukten mit der Wirbelschichtgranulation.

A success story that will hopefully continue: 

Carter William Schmitt, an American and Purdue Universityundergraduate student, visited OVGU as part of his studies in the first half of 2025 (FVST Auslandsaufenthalt). In addition to successfully completing numerous courses in process and systems engineering, Carter actively participated in research at the Chair of Thermal Process Engineering as an intern and student assistant in the Transport in Porous Media research group.

He was able to present his successful experiments with mealworms in a lecture at the international online conference “The 4th International Electronic Conference on Processes.” Carter's preliminary investigations were continued in a cooperation project with the University of Chemical Technology and Metallurgy in Sofia (Bulgaria) in the second half of the year and, with a little luck, will be the starting point for a scientific research project between OVGU and the Technical University of Munich in the coming year.

We would like to thank Carter for his tremendous support of our experiments and their evaluation, as well as for his phenomenal presentation at the 4th International Electronic Conference on Processes! We wish him every success and all the best for his studies and hope to stay in touch with him in the future!

Our Ph.D. student Mr. Lucas Briest has received the first award for the best oral presentation at the AMPERE conference 2025, which took place from 15th to 18th September in Bari, Italy. The international conference with key focus on high power microwave applications takes place every two years. Lucas has presented our recent results in the field of microwave drying of bricks and tiles.

We wish Lucas much success with his excellent work for the future.

Felix Faber has received the Förderpreis 2025 from the VDI Bezirksverband Magdeburg for his Master thesis on "Development of a non-isothermal pore network model for primary freeze-drying of pore structures reconstructed from X-ray tomography image data". Further details can be found in his publication in Drying Technology: https://doi.org/10.1080/07373937.2024.2407062.

We congratulate him to this great achievement and wish him all the best!

(Fotos: VDI Magdeburger Bezirksverein, © Viktoria Kühne)