8 results
Filters
Settings
Now showing1 - 8 of 8
- Some of the metrics are blocked by yourconsent settings
Item type:Publication, Access status: with files , Integral experiments and magnetic resonance Imaging of lab-scale liquid distributors(Wiley, 2026-07-15); ; ; ; Liquid maldistribution in packed beds can significantly reduce process efficiency and is strongly influenced by the liquid distributor design. In this work, four lab-scale liquid distributors based on gravity- and pressure-driven operating principles were investigated at two liquid loads. Their performance was evaluated using flow maps and the maldistribution factor, revealing substantial differences between designs. The distributor providing the most homogeneous distribution was further analyzed regarding flow stability, gas load, and packing interaction. Compared to a single-point liquid distribution, the proposed distributor reduced maldistribution and wall flow. Magnetic resonance imaging measurements showed a progressive deterioration of the flow homogeneity along the packing height.Publicationtype: Journal Article36 22 - Some of the metrics are blocked by yourconsent settings
Item type:Publication, Access status: without files , Large scale MRI for imaging of processes(2025-08-21); ; ; Introduction: Process engineering plays a pivotal role in the production of many essential goods. Therefore, increasing the understanding of the underlying processes is crucial. Conventionally, this has been achieved through integral measurements and modelling. The use of tomographic techniques, especially Magnetic Resonance Imaging (MRI), can provide spatially resolved maps of many relevant parameters. While there has been significant work on process engineering problems recently, most of the work focuses on small lab-scale systems. Yet, many processes are large-scale and rely on gravity and the limitations posed by small-bore vertical or large-bore horizontal MRI magnets can significantly constrain research efforts in these areas. System: To address these challenges, Hamburg University of Technology has introduced a vertical MRI system. This cryogen-free system boasts a field strength of 3 Tesla, a usable bore diameter of 40 cm, and is specifically designed to accommodate samples up to 3 meters in height. It can be equipped with tailor-made receive arrays, enabling the use of advanced acceleration techniques such as parallel imaging. Results and Discussion: This unique system enables the examination of significant process engineering systems, such as fluidized beds, trickle beds and stirred tank reactors in relevant scales. External devices such as motors and shakers can be placed in line with the experiment. Measurements of fluidized beds (with up to 30 cm diameter) and stirred-tank reactors reveal the possibility to observe process-relevant parameters such as flow and bubble sizes in these systems. Conclusion: The TUHH MRI system allows for the exploration of process engineering systems on a larger scale than previously possible. Initial experiments across various systems demonstrate the potential to deliver valuable measurement parameters that can enhance process efficiency and effectiveness.Publicationtype: Conference Presentation162 - Some of the metrics are blocked by yourconsent settings
Item type:Publication, Access status: without files , Magnetic Resonance Imaging of Structured Packings: Overcoming Spatial, Signal, and Geometric ChallengesStructured packings are widely employed in trickle beds to improve the mass transfer between the liquid and gas phases in absorption and distillation processes. While integral experiments, such as pressure drop measurements and collector experiments, offer overall insights, they lack spatial and temporal detail on liquid distribution. Magnetic Resonance Imaging (MRI) overcomes this by providing resolved flow visualization, though its application is challenged by low liquid content, the need for high temporal resolution, and difficulty achieving spatial resolution on the order of hundreds of micrometers with large-bore scanners. These issues are mitigated through optimized imaging sequences, doped aqueous solutions, and tailored radiofrequency coils, enabling MRI to deliver detailed insights into liquid behavior and packing efficiency. All experiments were conducted with a 3 Tesla vertical large-bore MRI system with the ability to measure samples with a height of several meters. The trickle bed included a one meter structured packing bed with a diameter of 54 mm. 3D-printed corrugated sheet packings (480 m²/m³) were studied under varying gas and liquid loadings. To shorten T₁ relaxation time to 50 ms and match the magnetic susceptibility of the gas phase, which is air, the aqueous solution was doped with 16.27 mM dysprosium(III) nitrate and 1 mM gadolinium(III) chloride. The liquid distribution was measured using a gradient echo imaging sequence. Two coil designs were compared, the system-integrated Transmit - Receive bird cage body coil and a tailored single-channel surface coil. The coils were compared with regard to signal-to-noise ratio (SNR) and spatiotemporal resolution. Unlike the body coil, which suffers from low spatial resolution and long acquisition times, the single-channel coil enables significantly higher spatiotemporal resolution (Fig. 1). The shortened T1 relaxation times allow faster signal recovery, enabling higher temporal resolution. Using a single-channel coil, doped aqueous solution, and gradient echo sequence enables MRI with spatial resolution up to 0.25 × 0.25 × 0.3 mm³. Combining data from partially and fully filled packings (Fig. 1) enables differentiation of liquid, gas, and structured packing, allowing the determination of the gas-liquid interfacial area, which is critical for the separation efficiency. MRI-derived maldistribution factors were validated against collector experiments at the column bottom, demonstrating good agreement. This study shows the use of MRI for temporally and spatially resolved measurements of liquid distribution in structured packings within trickle beds. A tailored surface coil, doped aqueous solutions, and optimized imaging enabled high-resolution imaging. MRI allows to distinguish between gas, liquid, and packing phases, enabling the determination of the gas–liquid interfacial area. The comparison with collector experiments showed good agreement, with MRI offering enhanced insight along the column height and improved radial resolution.Publicationtype: Conference Presentation82 - 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 Poster23 - 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 Poster49 - Some of the metrics are blocked by yourconsent settings
Item type:Publication, Access status: without files , Novel insights into the liquid distribution in structured packings(2025-02-04); ; ; ; Structured packings as internals in thermal separation processes, such as absorption and distillation, are of imminent importance for fluid dynamics and mass transfer. By increasing the interfacial area between the different phases mass transfer is improved, potentially reducing the energy demands of these energy-intensive processes. One important aspect to ensure the optimal performance of structured packings in gas liquid separation processes is achieving a homogeneous liquid distribution. Maldistribution can significantly decrease the overall separation efficiency of the column. Therefore, liquid collector and distributors are implemented inside packed columns, and the appropriate distributor design is essential for improved contacting of the phases. Within this contribution, magnetic resonance imaging (MRI) measurements and integral experiments are used to evaluate and compare the impact of four distributor designs in respect to the homogeneity of the water and air distribution within a column with an inner diameter of 54 mm. MRI-compatible distributor designs driven by gravity or capillary forces are designed and produced by additive manufacturing. In the integral experiments, a 3D-printed collector with thirteen compartments was attached to the bottom of the column to measure the radial and transversal liquid distribution. In addition to the distributor design, the number of 3D-printed corrugated sheet packings (480 m2/m3) and the liquid and gas loadings are varied as further influencing factors. For the distributor design with the lowest maldistribution factor, liquid and gas distribution inside the column are measured using MRI, assuming stationary flow. The size and vertical orientation of the 3 Tesla MRI system used enables the measurements of sample heights spanning several meters, allowing structured packing heights of one meter or more. The MRI non-invasive measurements enable the estimation of the interfacial area between the phases, as they allow for differentiation between the liquid, gas, and packing material. This contribution aims to show the potential and limitations of MRI in investigating processes in chemical engineering.Publicationtype: Conference Presentation47 - Some of the metrics are blocked by yourconsent settings
Item type:Publication, Access status: without files , Magnetic resonance imaging for 3D-printed structured packingsStructured packings are introduced as column internals for gas-liquid contacting to improve mass transfer and hydraulic parameters. The flow conditions within the column strongly depend on the design of the structured packings and correlate directly with the liquid holdup, mass-transfer rates, capacity, and pressure drop. The usually opaque columns prevent the direct optical measurement of parameters, such as the spatial distribution of the involved phases, thus impeding an evaluation and exploitation for the optimization of the design. To overcome this limitation, tomographic techniques can be utilized, which enable non-intrusive, temporally and spatially resolved measurements. In this study, we use magnetic resonance imaging (MRI) to measure the flow and the spatial distribution of water and air in a column with structured packings. The measurements are performed with a novel and worldwide unique vertical MRI scanner at Hamburg University of Technology. Structured packings with a diameter of 54 mm and a total height of 1 m are studied. Several 3D-printed packing designs, optimized with CFD simulations are measured with varying gas and liquid velocities. The detailed measurements of gas-liquid hydrodynamics within structured packings might enable the validation of numerical simulations and provide a comparison to established X-ray tomography data.Publicationtype: Conference Presentation99 - Some of the metrics are blocked by yourconsent settings
Item type:Publication, Access status: without files , The TUHH process imaging system(2024-08-26); ; ; 76