Final Report Summary - CUTTINGBUBBLES (Bubbles on the Cutting Edge) Bubbles on the Cutting EdgeMany processes in the chemical, petrochemical and/or biological industries involve three phase gas-liquid-solid flows, where the solid material acts as a catalyst carrier, the gas phase supplies the reactants for the (bio-)chemical transformations and the liquid phase carries the product. In these processes the performance and operation of the reactor is mostly constrained by the interfacial mass transfer rate and the achievable in-situ heat removal rate. A micro-structured bubble column reactor that significantly improves these crucial properties was developed in this project. This novel type of reactor takes advantage of micro-structuring of the catalyst carrier in the form of a wire-mesh.The aim of the wire-mesh is i) to cut bubbles into smaller pieces leading to a larger interfacial area, ii) to enhance the bubble interface dynamics and mass transfer due to the interaction between the bubbles and the wires, and iii) to save costs in practical operation due to the smaller required reactor volume and the fact that there is no need for an external filtration unit.In this project, the team of Dr. Deen and his co-workers developed cutting edge three-phase direct numerical simulation (DNS) tools and novel non-invasive optical (high-speed camera) techniques. These techniques were used to study the micro-scale interaction between bubbles and a wire-mesh to gain understanding of the splitting and merging of bubbles and associated mass transfer characteristics. Furthermore, a proof-of-principle of the micro-structured reactor was given through lab-scale experiments and macroscopic Euler-Lagrange numerical simulations, employing bubble-wire interaction closures based on the DNS simulations. With this proof-of-principle it was shown that the micro-structured bubble column significantly improves the gas-liquid contacting and hence that this novel reactor type is a promising alternative for gas-liquid contact equipment.In addition to the novel reactor type, the project generated a broad set of fundamental numerical and experimental research tools that can be used for the improvement of various gas-liquid-solid processes. In particular the improved surface tension model in the volume of fluid method and the second order accurate implicit immersed boundary method form important building blocks for the study of various multiphase systems.
