Realization and analysis of jet-based direct mixing gas phase agglomeration for the formation of hetero-agglomerates with new properties

• Applicants: Professor Dr.-Ing. Harald Kruggel-Emden; Professor Dr.-Ing. Eberhard Schmidt
• Subject Area: Mechanical Process Engineering
• Term: since 2021
• Project identifier: Deutsche Forschungsgemeinschaft (DFG) - Project number 462460600

The overall objective of the proposed research work is to contribute to the development of new particulate products based on hetero-agglomerates / hetero-aggregates formed in the gas phase providing new emerging properties. To achieve this goal, gas phase-based processes must be established that enable the controlled formation of the agglomerates / aggregates in sufficient quantity and quality. A jet-based hetero-agglomeration process was first developed and investigated by the groups of Kruggel-Emden at Technische Universität Berlin and Schmidt at Bergische Universität Wuppertal as part of the first funding period of PP. This comprises three steps. In the first step, the various primary particles are dispersed and dosed in a carrier gas stream. In a second step, the jets formed out of the carrier gas streams with the different primary particles interact with each other, contact occurs, which enables the formation of hetero-agglomerates. In a third step, the formed products are removed from the agglomeration zone in a controlled manner. In the second funding phase, this process is further developed and the link between process parameters, agglomerate structure and properties / material functions is elaborated. To do so it is focused on all-solid-state battery materials as an example for a certain type of hetero-agglomerates. Thereby the cathode materials to be focused on consist of three substances, which not only extends the gas phase process dealing with a multicomponent system, but also places additional demands on dispersion and mixing. Therefore, in the second funding phase, the aim is to investigate the process parameters of the described process and the three sub-processes with regard to the quality and functionality of the composites formed. For this purpose, the samples are investigated for their electrochemical properties and the structure of the hetero-agglomerates they contain is assessed in order to relate them to the aforementioned properties. Thereby a process intensification is aimed for by realizing an electrostatic separation of unwanted homo-agglomerates by means of targeted triboelectric charging of the primary particle systems and generation of an electric field. The gas phase based hetero-agglomeration process is mapped and analyzed in parallel with the experimental investigation using a DEM/CFD approach for modelling agglomeration in inhomogeneous, isotropic turbulence while also the process intensification basing on charging and electrostatic separation is modelled for. Furthermore, the analysis of the electrochemical properties of the produced hetero-agglomerates is also reflected simulatively using a voxel-based 3D microstructure model to link process parameters in the simulations with the associated material functions and the agglomerate structure. Thereby a direct comparison between experiment and simulation is aimed for.

• DFG Programme: Priority Programmes
• Subproject of: SPP 2289: Creation of synergies in tailor-made mixtures of heterogeneous powders: Hetero aggregations of particulate systems and their properties
• International Connection: USA
• Cooperation Partner: Professor Jeffrey Marshall, Ph.D.