Workflow for computational fluid dynamics modeling of fixed‐bed reactors packed with metal foam pellets: Hydrodynamics

Abstract

In recent years, the catalyst pellets made of open‐cell metallic foams have been identified as a promising alternative in fixed‐bed reactors. A reliable modeling tool is necessary to investigate the suitability of different foam properties and the shapes of foam pellets. In this article, a workflow for a detailed computational fluid dynamics (CFD) model is presented, which aims to study the flow characteristics in the slender packed beds made of metal foam pellets. The CFD model accounts for the actual random packing structure and the fluid flow throughout the interstitial regions is fully resolved, whereas flow through the porous foam pellets is represented by the closure equations for the porous media model. The bed structure is generated using rigid body dynamics (RBD) and the influence of the catalyst loading method is also considered. The mean bed voidage and the pressure drop predicted by the simulations show good agreement with the experimental data.

Influence of Foam Morphology on Flow and Heat Transport in a Random Packed Bed with Metallic Foam Pellets—An Investigation Using CFD

“…The application of Blender in packing generation has been discussed in many recent works [ 26 , 27 , 28 ]. In a previous work [ 20 ], we have verified the impact of RBD parameters such as friction factor and restitution coefficient as well as different catalyst loading methods on the generated packing structures. Blender settings identified as suitable for creating a packing of cylindrical particles were used in this study.…”

“…However, applying such a detailed PRCFD approach in a foam-packed bed is computationally intensive, when resolving flow through the fine inner geometries of foam pellets, i.e., on the strut level. In prior works [ 20 , 21 ], we have introduced a modified version of PRCFD, in which the foam pellets are considered as porous media, and appropriate closure equations are used to account for the pressure loss and energy transport inside the pellets, i.e., flow along inter-particle spaces are considered as they are, whereas inner foam geometric features are not physically resolved. The Rigid Body Dynamics (RBD) method was used to generate the packing structure.…”

“…The Rigid Body Dynamics (RBD) method was used to generate the packing structure. The CFD model has been validated with experimental data for pressure drop and axial bed temperature, with excellent agreement [ 20 , 21 ]. Although the proposed PRCFD workflow can reduce the computation effort relatively, it is not very efficient for simulations like parametric analysis, since it takes from several hours to days for a bed containing more than 1000 particles (computed by 1 CPU—intel Core i7-8700K).…”

Review on Additive Manufacturing of Catalysts and Sorbents and the Potential for Process Intensification

“…Pellets are incorporated in the reactor similarly to particles: by random packing. However, since pellets are often nonsymmetrical structures, packing requires more careful attention and the quality of packing affects the reactor performance to a high degree (Cheng et al, 2010;Moghaddam et al, 2019;George et al, 2021).…”

Young Scientists – Juniorprofessor Gregor D. Wehinger stellt sich vor

“…Ein interessanter Ansatz, um synthetische Schaumstrukturen zu erzeugen und mit anschließenden CFD-Simulationen zu untersuchten, wurde anhand der Partialoxidation von Methan vorgestellt [21]. In Zusammenarbeit mit der Firma Alantum wird in meiner Arbeitsgruppe in einem ZIM-Projekt der Einsatz von Schaumpellets in Festbettreaktoren mit CFD-Simulationen untersucht [22,23] (s. Abb. 5).…”