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Item type:Publication, Access status: without files , Real time magnetic resonance imaging and numerical modelling of gas-solid hydrodynamics in vibrated bubbling fluidized bedsGas-solid fluidized beds are widely utilized in various process engineering applications for their enhanced heat and mass transfer rates. Vibration can improve the performance of fluidized beds by enhancing fluidization of cohesive particles, breaking agglomerates, improving mixing, and enhancing heat transfer in drying [1]. Studying hydrodynamics is challenging due to the chaotic nature of fluidized beds. The addition of vibration makes the dynamics even more complex, and our understanding of their hydrodynamics remains limited, especially in three-dimensional (3D) systems. Tomographic techniques, such as Magnetic Resonance Imaging (MRI) [2], have emerged as indispensable tools for the non-invasive and spatially resolved analysis of 3D beds. This work investigates the hydrodynamics of 3D beds, with and without vibration, using real-time MRI with a unique 3T vertical MRI scanner. The vertical orientation of the magnet enables the measurement of samples up to 400 mm in diameter and several meters in height. An electrodynamic shaker generates vertical sinusoidal acceleration, with vibrations transmitted to the bed via glass fiber-reinforced tubes. The MRI system is elevated from the ground and offers a unique radiofrequency shielding, making it possible to place the electrodynamic shaker in axis. Properties such as bubble size, rise velocity and the influence of particle properties are investigated. Furthermore, complex phenomena, such as dynamically structured bubbling [3], can be studied in 3D systems. Numerical simulations, such as CFD-DEM, which combines computational fluid dynamics and the discrete element method, offer valuable insights into hydrodynamics. In collaboration with the Institute of Solids Process Engineering and Particle Technology, MRI data is compared with CFD-DEM results to validate drag force models and coarse-graining approaches. The project is financially supported by the German Research Foundation (DFG) under project number 471615686. [1] Guo, Q. et al., Current Opinion in Chemical Engineering, 2023, 100977 [2] Penn, A. et al., Science Advances, 2017, 117-123 [3] Guo, Q. et al., PNAS, 2021, 35, e2108647118Publicationtype: Conference Presentation49 - Some of the metrics are blocked by yourconsent settings
Item type:Publication, Access status: without files , Magnetic resonance imaging of structured packings(2025-03-19)Structured packings as internals play a crucial role to improve the fluid dynamics and mass transfer within thermal separation processes, such as absorption and distillation. By increasing the interfacial area between the phases, they improve the mass transfer, which potentially lowers the energy demand of these energy-intensive operations. To evaluate and optimize the design of a structured packing, detailed information about the liquid distribution within and the pressure drop over the packing are of high importance. However, due to the opacity of columns, the use of optical methods is impractical, making traditional studies reliant on integral experiments, like pressure drop measurements and collector experiments. While these experiments provide valuable global insights into structured packing efficiency, they lack of spatially resolved data over the column height. Tomographic techniques, such as magnetic resonance imaging (MRI), can overcome this limitation by providing detailed, non-invasive spatial information about liquid distributions inside the packing. In this study, MRI measurements are used to investigate the liquid distribution in an MRI-compatible absorption column model with an inner diameter of 54 mm. We investigated two types of 3D-printed structured packings under varying liquid (water) and gas (air) loadings using a recently commissioned 3 T MRI-scanner located at the Hamburg University of Technology. The vertical orientation of the scanner allows for the measurement of setups up to 300 mm in diameter and up to several meters in height. For a 1000 mm tall packing bed, horizontal slices are taken in a central 110 mm section. The data are acquired with a spatial resolution of 0.5 x 0.5 x 1 mm3 and a temporal resolution of 1.3 seconds and provide detailed information about the liquid distribution within the packing. This study aims to demonstrate the advantages and limitations of using MRI for investigating processes in chemical engineering and assisting to validate and refine numerical simulations.Publicationtype: Conference Poster22 - Some of the metrics are blocked by yourconsent settings
Item type:Publication, Access status: without files , The TUHH process imaging system(2025-03-19); ; ; ; Chemical engineering is a crucial field in the production of many essential goods, with its processes undergoing major changes in the transition to a less fossil-dependent product chain. Yet, understanding these processes is often based on modeling and measurements with integral or local invasive sensors. Tomographic techniques such as magnetic resonance imaging (MRI) can overcome these limitations and provide essential information. However, MRI systems are typically not constructed with the needs of (bio)chemical reactors in mind. Most vertical MRI systems feature probe diameters of below 8 cm and maximum sample heights of below 1 meter. On the other end, clinical MRI systems are usually built horizontally and feature bore sizes of bigger than 30 cm and maximum sample lengths of a few meters. In these system, processes based on gravity have to conform to the bore size and are therefore limited. The TUHH system combines the advantages of both systems. It is a vertical bore magnet with a 40 cm bore diameter. Sitting on legs at 4 m height, samples of up to 3 meters can be measured. This is especially relevant for reactors based on gravity such as fluidized beds or bubble columns. The magnet itself is a cryogen-free magnet with a field strength of 3 T. The system is freshly commissioned in 2024 and is planned to be used in various projects. In particular, the work of Alexander Penn in ultrafast imaging will be continued and extended in scope[1,2]. A main focus here are fluidized beds and liquid-gas reactors, which can be investigated with temporal resolutions below 30 ms. Furthermore, techniques such as thermometry and chemically resolved imaging will be employed to reveal the processes inside important reactor systems. This work has been funded by the Deutsche Forschungsgemeinschaft: instrumentation proposal 422037415, research proposals 471615686 and 544956881 and the collaborative research center ”SMART Reactors” (503850735).Publicationtype: Conference Poster46 - Some of the metrics are blocked by yourconsent settings
Item type:Publication, Access status: without files , Advancing multiphase flow imaging with high-density receiver arrays: MRI velocity measurements in structured packing with Schwarz-Diamond-TPSf designEffective mixing is fundamental to optimizing process performance in the chemical and biochemical industries. The mixing efficiency is predominantly governed by the fluid flow within these systems [1]. Understanding such mixing processes significantly benefits from precise velocity measurements and high-resolution imaging techniques. Nonetheless, obtaining detailed three-dimensional insights into their mixing states continues to present a substantial challenge. Magnetic Resonance Imaging (MRI) is one of the most versatile among the various tomographic techniques suitable for process engineering applications. It leverages the nuclear magnetic resonance (NMR) phenomenon [2,3] to measure flow, diffusion, chemical composition, and temperature with high spatial and temporal resolution. Recent advancements have expanded its use in process engineering [4,5], enabling investigations into phase distributions, microreactor flows, and packed bed dynamics. To improve the signal-to-noise ratio (SNR) and temporal resolution of MRI systems, multiple receiver coils can be placed around the object to acquire the signal in parallel. Since MRI has been primarily applied in medical domain, the existing coil arrays are developed for human anatomies. In this work, we build custom coil arrays tailored to chemical reactors and investigate the impact of receiver coil density on MRI-based velocity measurements using the world’s largest vertical 3 Tesla MRI scanner. We compare 5-channel and 15-channel receive arrays to evaluate their performance in capturing flow behavior within structured packings with Schwarz-Diamond-Triply Periodic Surface (TPSf) designs, relevant to chemical engineering. Initial velocity measurements in water phantoms reveal that the 15-channel array significantly improves spatial resolution and SNR over the 5-channel configuration. These enhancements enable detailed mapping of velocity fields, finer resolution of flow dynamics, and improved visualization of mixing and bubble interactions within complex geometries. References [1] Weiland, C., Steuwe, E., Fitschen, J., Hoffmann, M., Schlüter, M., Padberg-Gehle, K., & von Kameke, A. Computational study of three-dimensional Lagrangian transport and mixing in a stirred tank reactor. Chemical engineering journal advances. 2023, 14. Jg., S. 100448 https://doi.org/10.1016/j.ceja.2023.100448 [2] Rabi, I. I.; Zacharias, J. R.; Millman, S.; Kusch, P. A New Method of Measuring Nuclear Magnetic Moment. Phys. Rev. 1938, 53 (4), 318–318. https://doi.org/10.1103/PhysRev.53.318. [3] Bloch, F. Nuclear Induction. Phys. Rev. 1946, 70 (7–8), 460–474. https://doi.org/10.1103/PhysRev.70.460. [4] Benders, S.; Blümich, B. Applications of Magnetic Resonance Imaging in Chemical Engineering. Phys. Sci. Rev. 2019, 4 (10). https://doi.org/10.1515/psr-2018-0177. [5] Gladden, L. F.; Sederman, A. J. Recent Advances in Flow MRI. J. Magn. Reson. 2013, 229, 2–11. https://doi.org/10.1016/j.jmr.2012.11.022.Publicationtype: Conference Poster44