A common reactor type in the chemical and process industry is the fixed-bed reactor. Accurate modeling can be achieved with particle-resolved computational fluid dynamic (CFD) simulations. However, the underlying bed morphology plays a paramount role. Synthetic bed-generation methods are much more flexible and faster than image-based approaches. In this study, we look critically at the two different bed generation methods: Discrete element method (DEM) (in the commercial software STAR-CCM+) and the rigid-body model (in the open-source software Blender). The two approaches are compared in terms of synthetically generated beds with experimental data of overall and radial porosity, particle orientation, as well as radial velocities. Both models show accurate agreement for the porosity. However, only Blender shows similar particle orientation than the experimental results. The main drawback of the DEM is the long calculation time and the shape approximation with composite particles.

Slender packed beds are widely used in the chemical and process industry for heterogeneous catalytic reactions in tube-bundle reactors. Under safety and reaction engineering aspects, good radial heat transfer is of outstanding importance. However, because of local wall effects, the radial heat transport in the vicinity of the reactor wall is hindered. Particle-resolved computational fluid dynamics (CFD) is used to investigate the impact of internal heat fins on the near wall radial heat transport in slender packed beds filled with spherical particles. The simulation results are validated against experimental measurements in terms of particle count and pressure drop. The simulation results show that internal heat fins increase the conductive portion of the radial heat transport close to the reactor wall, leading to an overall increased thermal performance of the system. In a wide flow range ($100<R{e}_{\mathrm{p}}<1000$), an increase of up to 35% in wall heat transfer coefficient and almost 90% in effective radial thermal conductivity is observed, respectively.

For slender fixed beds, the void fraction and flow properties are complex topics. Different factors can influence the local bed structure. For statistical analysis, 2800 fixed beds have been generated and the impact of friction factor and reactor‐to‐particle diameter ratio on the distribution has been shown. With particle‐resolved computational fluid dynamics, all local structure effects are taken into account for the flow simulations. Pressure drop measurements and simulations showed that these effects can lead to areas with low flow resistance, leading to overestimated pressure drop by typical correlations up to 85 %.

Different flow field designs are known for vanadium redox-flow batteries (VFB). The best possible design to fulfil a variety of target parameters depends on the boundary conditions. Starting from an exemplary interdigitated flow field design, its channel and land dimensions are varied to investigate the impact on pressure drop, channel volume, flow uniformity and limiting current density. To find a desirable compromise between these several partly contrary requirements, the total costs of the VFB system are evaluated in dependence of the flow field’s dimensions. The total costs are composed of the electrolyte, production and component costs. For those, the production technique (injection moulding or milling), the pump and nominal power density as well as depth of discharge are determined. Finally, flow field designs are achieved, which lead to significantly reduced costs. The presented method is applicable for the design process of other flow fields and types of flow batteries. Graphical abstract