Prof. Dr. Alexander Penn – Institute of Process Imaging

Director

Office: TUHH campus, building L, room 3010
Email:
Tel: +49 40 30601 3801

Curriculum Vitae

Born in 1987 in Bozen, Italy, Alexander Penn studied Technical Physics at Vienna University of Technology, Austria, including an Erasmus exchange semester at Universidad Autónoma de Madrid, and graduated in 2013. He then joined ETH Zurich, where he received his PhD in early 2018 for his work on real-time magnetic resonance imaging of granular and multiphase flows. From 2018 to 2020 he led a research group at ETH Zurich, advised Columbia University, New York, on magnetic resonance technology and held research stays at Columbia University and at Osaka University, Japan. In 2020 he was appointed to Hamburg University of Technology (TUHH) as a full professor and founding director of the Institute of Process Imaging. From 2020 to 2023 he served as local research coordinator for TUHH in the European Consortium of Innovative Universities (ECIU), and from 2021 to 2022 he coordinated the International master’s program Chemical and Bioprocess Engineering at TUHH. He was dean of the school of Process Engineering from 2023 to 2025 and has been deputy dean of the school of Process Engineering since 2025. He also coordinates the master’s program Chemie- und Bioingenieurwesen, which he initiated and developed during his term as dean.

Research area

The work of Alexander Penn and his group is dedicated to understanding the complex transport and reaction processes that occur within chemical and biotechnological reactors. To this end, the group develops magnetic resonance methods across scales: imaging that quantifies multiphase flow, transport, temperature and chemical reaction inside reactors at laboratory and pilot scale with high temporal and spatial resolution, and time-domain NMR and relaxometry that probe molecular interactions and mass transport in bio-based materials and biocatalysts. Machine learning methods for image reconstruction and phase segmentation are developed alongside the measurements. The resulting spatially resolved data provide a basis for validating reactor models and for scale-up. The research mission is to contribute to making industrial production in the chemical, biotechnological and pharmaceutical sectors, as well as our energy system, more sustainable, resource- and energy-efficient and carbon-neutral.

Publications

Google Scholar Profile

ORCID ID

Journal articles

2026

Integral experiments and magnetic resonance Imaging of lab-scale liquid distributors - Journal Article
Rennebaum, Hannah S. ; Dobschall, Alina ; Bindseil, Jenni ; Skiborowski, Mirko ; Penn, Alexander
Chemie Ingenieur Technik e70147: (2026)
Open Access | Publisher DOI
Core–shell particles with tailored magnetic susceptibility for signal-efficient magnetic resonance imaging of granular systems - Journal Article
Benders, Stefan ; Metzger, Jens ; Suter, Mathieu ; Dudle, Alice ; Nussbaum, Jenifer ; Gross, Simon P. ; Serial, M. Raquel ; Müller, Christoph ; Prüssmann, Klaas P. ; Penn, Alexander
Journal of Magnetic Resonance 389: 108092 (2026)
Open Access | Publisher DOI
The sinking dynamics of a solid intruder in concentrated cornstarch suspensions studied using ultra-fast magnetic resonance imaging - Journal Article
Kirov, Nikolay K. ; McLaren, Christopher P. ; Prüssmann, Klaas P. ; Müller, Christoph R. ; Penn, Alexander
Soft Matter 22 (21): 3806-3818 (2026)
Open Access | Publisher DOI
Comprehensive study of 3D liquid flow fields in additively manufactured structures for SMART reactors using large-scale vertical magnetic resonance imaging and computational fluid dynamics - Journal Article
Merbach, Timo Alexander ; Adrian, Muhammad ; Wigger, Christoph ; Iraqi Houssaini, Selma ; Bayer, Benedict ; Tsanda, Artyom ; Acikgöz, Serhan ; Weiland, Christian ; Kexel, Felix ; Herzog, Dirk ; Hoffmann, Marko ; Kelbassa, Ingomar ; Knopp, Tobias ; Penn, Alexander ; Schlüter, Michael
Chemical Engineering Journal 539: 176536 (2026)
Open Access | Publisher DOI
Three-dimensional CFD-DEM simulations of vibrated fluidized beds validated by real-time MRI: implications of slice-based versus full-domain analysis - Journal Article
Hildebrandt, Nick ; Özdemir, Melis ; Pietsch-Braune, Swantje ; Benders, Stefan ; Penn, Alexander ; Heinrich, Stefan
Powder Technology (477): 122468 (2026)
Open Access | Publisher DOI
The hydrodynamics of pseudo-2D and 3D bubbling fluidized beds: a magnetic resonance imaging study - Journal Article
Rennebaum, Hannah Sophie ; Brummerloh, Daniel Lukas ; Benders, Stefan ; Penn, Alexander
Chemical Engineering Science 322: 122977 (2026)
Open Access | Publisher DOI
MRI-validated CFD–DEM simulation and recurrence-based time extrapolation (rCFD) of a bubbling fluidized bed: Drag model selection and computational speed-up - Journal Article
Asif, Shaik ; Pietsch-Braune, Swantje ; Pirker, Stefan ; Özdemir, Melis ; Adrian, Muhammad ; Penn, Alexander ; Heinrich, Stefan
Chemical Engineering Research and Design 227: 879–893 (2026)
Open Access | Publisher DOI
NMR relaxometry probes solvent-polarity-dependent molecular interactions in stimuli-responsive lyogels - Journal Article
Adrian, Muhammad ; Eckert, Kathrin ; Serial, Maria Raquel ; Tsanda, Artyom ; Rennpferdt, Lukas ; Benders, Stefan ; Trieu, Hoc Khiem ; Knopp, Tobias ; Smirnova, Irina ; Penn, Alexander
Physical Chemistry Chemical Physics 28: 1645–1654 (2026)
Open Access | Publisher DOI
A novel method for quantifying enzyme immobilization in porous carriers using simple NMR relaxometry - Journal Article
Serial, Maria Raquel ; Schmidt, Luca ; Adrian, Muhammad ; Brauckmann, Grit ; Benders, Stefan ; Bueschler, Victoria ; Liese, Andreas ; Penn, Alexander
Biochemical Engineering Journal 225: 109909 (2026)
Open Access | Publisher DOI

2025

Enhancing swelling kinetics of pNIPAM lyogels: the role of crosslinking, copolymerization, and solvent - Journal Article
Eckert, Kathrin ; Bonsen, Christin Jelisa ; Hajnal, Anja ; Gmeiner, Johannes ; Hasse, Jonah ; Adrian, Muhammad ; Karsten, Julian ; Kißling, Patrick ; Penn, Alexander ; Fiedler, Bodo ; Luinstra, Gerrit A. ; Smirnova, Irina
Fluid Phase Equilibria 597: 114462 (2025)
Open Access | Publisher DOI
Vertical tubes in bubbling fluidized beds: A magnetic resonance imaging study of particle and bubble behavior - Journal Article
Rennebaum, Hannah Sophie ; Müller, Christoph ; Penn, Alexander
Powder Technology 457: 120870 (2025)
Open Access | Publisher DOI
Magnetic resonance imaging in granular flows: An overview of recent advances - Review Article
Clarke, Daniel ; Hogendoorn, Willian ; Penn, Alexander ; Serial, Maria Raquel
Particuology 101: 18-32 (2025)
Open Access | Publisher DOI

2024

Magnetic resonance velocimetry of particle hydrodynamics in a three-dimensional draft tube spout-fluid bed - Journal Article
Metzger, Jens P. ; Chen, Boyuan ; Penn, Alexander ; Guenthner, Christian ; Prüssmann, Klaas P. ; Müller, Christoph R.
Chemical Engineering Journal 485: 149678 (2024)
Open Access | Publisher DOI
The effect of baffles on the hydrodynamics of a gas-solid fluidized bed studied using real-time magnetic resonance imaging - Journal Article
Rennebaum, Hannah Sophie ; Brummerloh, Daniel Lukas ; Benders, Stefan ; Penn, Alexander
Powder Technology 432: 119114 (2024)
Open Access | Publisher DOI

2023

Computer simulation of magnetic resonance imaging of the flow of fluidized particles - Journal Article
Bordbar, Alireza ; Benders, Stefan ; Zia, Wasif ; Penn, Alexander ; Boyce, Christopher M.
Industrial and Engineering Chemistry Research 62 (29): 11677–11688 (2023-07-12)
Publisher DOI
Temperature distribution in a gas-solid fixed bed probed by rapid magnetic resonance imaging - Journal Article
Serial, Maria Raquel ; Benders, Stefan ; Rotzetter, Perrine ; Brummerloh, Daniel Lukas ; Metzger, Jens Patrick ; Gross, Simon P. ; Nussbaum, Jennifer ; Müller, Christoph ; Prüssmann, Klaas P. ; Penn, Alexander
Chemical Engineering Science 269: 118457 (2023-04-05)
Publisher DOI

2022

A review on fast tomographic imaging techniques and their potential application in industrial process control - Journal Article
Hampel, Uwe ; Babout, Laurent ; Banasiak, Robert ; Schleicher, Eckhard ; Soleimani, Manuchehr ; Wondrak, Thomas ; Vauhkonen, Marko ; Lähivaara, Timo ; Tan, Chao ; Hoyle, Brian ; Penn, Alexander
Sensors 22 (6): 2309 (2022)
Open Access | Publisher DOI

2021

CFD-DEM study of bubble properties in a cylindrical fluidized bed of Geldart Group D particles and comparison with prior MRI data - Journal Article
Xi, Kenan ; Kovar, Thomas M. ; Fullmer, William D. ; Penn, Alexander ; Musser, Jordan ; Boyce, Christopher M.
Powder Technology 389: 75-84 (2021-09)
Publisher DOI
Mechanism of anomalous sinking of an intruder in a granular packing close to incipient fluidization - Journal Article
Tsuji, Takuya ; Penn, Alexander ; Hattori, Taisuke ; Prüssmann, Klaas P. ; Müller, Christoph ; Oshitani, Jun ; Washino, Kimiaki ; Tanaka, Toshitsugu
Physical Review Fluids 6 (6): 064305 (2021-06)
Publisher DOI

2020

Link between packing morphology and the distribution of contact forces and stresses in packings of highly nonconvex particles - Journal Article
Conzelmann, Nicholas ; Penn, Alexander ; Partl, Manfred N. ; Clemens, F. J. ; Poulikakos, Lily ; Müller, Christoph Rüdiger
Physical Review E 6 (102): 062902 (2020-12-21)
Publisher DOI
Asynchronous bubble pinch-off pattern arising in fluidized beds due to jet interaction : a magnetic resonance imaging and computational modeling study - Journal Article
Penn, Alexander ; Padash, Azin ; Lehnert, M. ; Prüssmann, Klaas P. ; Müller, Christoph ; Boyce, Christopher M.
Physical Review Fluids 9 (5): 094303 (2020-09-25)
Open Access | Publisher DOI
Regimes of jetting and bubbling in a fluidized bed studied using real-time magnetic resonance imaging - Journal Article
Penn, Alexander ; Boyce, Christopher M. ; Pruessmann, Klaas Paul ; Müller, Christoph Rüdiger
Chemical Engineering Journal (383): 123185 (2020-03-01)
Publisher DOI
Magnetic resonance thermometry of gas‐solid systems - Journal Article
Rotzetter, Perrine ; Pruessmann, Klaas Paul ; Müller, Christoph Rüdiger ; Penn, Alexander
Chemie Ingenieur Technik 9 (92): 1180-1180 (2020)
Publisher DOI

2019

Wake volume of injected bubbles in fluidized beds: A magnetic resonance imaging velocimetry study - Journal Article
Boyce, Christopher M. ; Penn, Alexander ; Lehnert, M. ; Pruessmann, Klaas Paul ; Müller, Christoph Rüdiger
Powder Technology (357): 428-435 (2019-12-01)
Publisher DOI
Characteristics of a single jet injected into an incipiently fluidized bed: A magnetic resonance imaging study - Journal Article
Boyce, Christopher M. ; Penn, Alexander ; Lehnert, M. ; Pruessmann, Klaas Paul ; Müller, Christoph Rüdiger
Advanced Powder Technology 12 (30): 3146-3152 (2019-12)
Publisher DOI
Magnetic resonance imaging of interaction and coalescence of two bubbles injected consecutively into an incipiently fluidized bed - Journal Article
Boyce, Christopher M. ; Penn, Alexander ; Lehnert, M. ; Pruessmann, Klaas Paul ; Müller, Christoph Rüdiger
Chemical Engineering Science (208): 115152 (2019-11-23)
Publisher DOI
Magnetic resonance imaging of single bubbles injected into incipiently fluidized beds - Journal Article
Boyce, Christopher M. ; Penn, Alexander ; Lehnert, M. ; Pruessmann, Klaas Paul ; Müller, Christoph Rüdiger
Chemical Engineering Science (200): 147-166 (2019-06-08)
Publisher DOI
Gravitational instabilities in binary granular materials - Journal Article
McLaren, Christopher ; Kovar, Thomas M. ; Penn, Alexander ; Müller, Christoph Rüdiger ; Boyce, Christopher M.
Proceedings of the National Academy of Sciences of the United States of America 19 (116): 9263-9268 (2019-05-07)
Publisher DOI
Real-time magnetic resonance imaging of fluidized beds with internals - Journal Article
Penn, Alexander ; Boyce, Christopher M. ; Conzelmann, Nicholas ; Bezinge, Gaëtan ; Pruessmann, Klaas Paul ; Müller, Christoph Rüdiger
Chemical Engineering Science (198): 117-123 (2019-04-28)
Publisher DOI
Anomalous collapse of interacting bubbles in a fluidized bed : a magnetic resonance imaging study - Journal Article
Boyce, Christopher M. ; Penn, Alexander ; Padash, Azin ; Lehnert, M. ; Prüssmann, Klaas P. ; Müller, Christoph
Physical Review Fluids 3 (4): 034303 (2019-03-18)
Open Access | Publisher DOI
Effect of liquid bridging on bubbles injected into a fluidized bed: A magnetic resonance imaging study - Journal Article
Boyce, Christopher M. ; Penn, Alexander ; Lehnert, M. ; Pruessmann, Klaas Paul ; Müller, Christoph Rüdiger
Powder Technology (343): 813-820 (2019-02-01)
Publisher DOI

2018

Magnetic resonance imaging of gas–solid fluidization with liquid bridging - Journal Article
Boyce, Christopher M. ; Penn, Alexander ; Pruessmann, Klaas Paul ; Müller, Christoph Rüdiger
AIChE Journal 8 (64): 2958-2971 (2018-08)
Publisher DOI
Real-Time magnetic resonance imaging of bubble behavior and particle velocity in fluidized beds - Journal Article
Penn, Alexander ; Boyce, Christopher M. ; Kovar, Thomas M. ; Tsuji, Takuya ; Pruessmann, Klaas Paul ; Müller, Christoph Rüdiger
Industrial and Engineering Chemistry Research 29 (57): 9674-9682 (2018-07-25)
Publisher DOI
A high-performance gradient insert for rapid and short-T₂ imaging at full duty cycle - Journal Article
Weiger, Markus ; Overweg, Johan ; Rösler, Manuela Barbara ; Froidevaux, Romain ; Hennel, Franciszek ; Wilm, Bertram Jakob ; Penn, Alexander ; Sturzenegger, Urs ; Schuth, Wout ; Mathlener, Menno ; Borgo, Martino ; Börnert, Peter ; Leussler, Christoph ; Luechinger, Roger ; Dietrich, Benjamin Emanuel ; Reber, Jonas ; Brunner, David Otto ; Schmid, Thomas M. ; Vionnet, Laetitia ; Pruessmann, Klaas Paul
Magnetic Resonance in Medicine 6 (79): 3256-3266 (2018-06)
Publisher DOI
Im Takt des Kernspins: Blitzschnelle Bilder aus den Inneren granularer Medien - Journal Article
Penn, Alexander ; Pruessmann, Klaas Paul ; Müller, Christoph Rüdiger
GIT Labor-Fachzeitschrift 62 (9): (2018)

2017

Real-time probing of granular dynamics with magnetic resonance - Journal Article
Penn, Alexander ; Tsuji, Takuya ; Brunner, David Otto ; Boyce, Christopher M. ; Pruessmann, Klaas Paul ; Müller, Christoph Rüdiger
Science Advances 9 (3): e1701879 (2017-09)
Open Access | Publisher DOI

2014

Correlating surface cation composition and thin film microstructure with the electrochemical performance of lanthanum strontium cobaltite (LSC) electrodes - Journal Article
Rupp, Ghislain M. ; Limbeck, Andreas ; Kubicek, Markus ; Penn, Alexander ; Stöger-Pollach, Michael ; Friedbacher, Gernot ; Fleig, Jürgen
Journal of Materials Chemistry A 2 (19): 7099-7108 (2014-05-21)
Open Access | Publisher DOI
Electrochemical properties of La₀.₆Sr₀.₄CoO 3 - δ thin films investigated by complementary impedance spectroscopy and isotope exchange depth profiling - Journal Article
Kubicek, Markus ; Huber, Tobias M. ; Welzl, Andreas ; Penn, Alexander ; Rupp, Ghislain M. ; Bernardi, Johannes ; Stöger-Pollach, Michael ; Hutter, Herbert ; Fleig, Jürgen
Solid State Ionics (256): 38-44 (2014-03-01)
Open Access | Publisher DOI

2013

Cation diffusion in La₀.₆Sr₀.₄CoO 3 - δ below 800 °C and its relevance for Sr segregation - Journal Article
Kubicek, Markus ; Rupp, Ghislain M. ; Huber, Stefanie ; Penn, Alexander ; Opitz, Alexander K. ; Bernardi, Johannes ; Stöger-Pollach, Michael ; Hutter, Herbert ; Fleig, Jürgen
Physical Chemistry Chemical Physics 16 (6): 2715-2726 (2014-02-14)
Open Access | Publisher DOI

Conference contributions