Work package 4.2 - Scale-resolving simulation of reactive two-phase flows in monolith and solid foam reactors
Principal investigators: Dr. M. Wörner (KIT-IKFT), Dr. B. Dietrich (KIT-TVT)
PhD students: M.Sc. X. Cai (KIT-IKFT), Dipl.-Ing. S. Meinicke (KIT-TVT), M.Sc. M. Woo (KIT-IKFT)
Main scientific Goals:
The aim of the work package 4.2 is the development of numerical methods and computer programs for the scale-resolution simulation of chemically reacting two-phase flows and their application on monolith reactors and solid foam structures. The space and time resolved simulation data (phase distribution, velocity field, concentration fields, …) provide - in combination with data from experimental work packages (WP 3.1, 3.3, 5.2, 5.4) - the basis for understanding local flow and transport phenomena and for identifying reaction mechanisms within the aspired process windows ( WP 2.4, 2.5). In addition, they support the development of more simplifying engineering models (WP 4.3, 4.4).
Solid Foam Reactor (S. Meinicke and X. Cai)
This subtopic is devoted to CFD simulation of hydrodynamics, heat and mass transfer with chemical reaction in real solid sponge structures. The concerted approach is to develop a CFD code for simulation of both single-phase and two-phase flow through highly porous structures and to simultaneously process and prepare available real solid sponges structure data (CT, MRI) for following CFD investigations. CFD modeling shall include
- Hydrodynamics of liquid, gas and gas-liquid flows
- Heat transfer in both fluid and solid phase of the multi-phase system
- Mass transfer occurring e.g. in connection with chemical reactions at the surface of the possibly catalytically coated sponge surface
To carry out CFD simulations, open-source software OpenFOAM® is used.
Achievements up to now are:
- Successful structure determination and reconstruction as a CFD simulation geometry of various sponge types (Al2O3, SiSiC, varying ppi numbers (10 to 45 ppi) and porosities (75 to 90 %)) (see Figure 1)
- Mesh generation and CFD model set-up for single-phase flow through representative elementary volumes (REV’s) of the solid sponge structure (see Figure 2, ongoing)
- Experimentally validated results of CFD simulation on pressure drop and heat transfer coefficients in solid sponge structures (see Figure 3)
- Setting up a thermal CFD model for single-phase flow through solid sponge structures (ongoing)
- Successful implementation of the phase-field method in OpenFOAM®
- Verification and validation of the phase-field method for two-phase flows in contact with flat chemically-homogenous/heterogeneous surfaces (see Figure 4) against analytical and experimental data in literature
- Simulation of two-phase flows in representative sponge structure (see Figure 5, ongoing)
Figure 1: reconstrcution of Al2O3 sponge sample (20ppi, 80% porosity, left) and SiSiC sponge sample (20ppi,right) as a simulation geometry for further processing in OpenFOAM® (STL file format).
Figure 2: CFD model development for non-isothermal single-phase flow through reconstructed sponge REV’s.
|Fig. 3a: Single-phase pressure drop (CFD and experiment)||Fig. 3b: Heat transfer coefficient (CFD and Experiment)|
Figure 4: 3D simulation of anisotropic droplet spreading on chemically strip-patterned surface (red: hydrophilic strip; yellow: hydrophobic strip).
Figure 5: 3D simulation of two-phase gas-liquid flows in representative sponge structure (yellow: sponge structure; blue: liquid phase).
The next steps are:
CFD model refinements and generalization to further sponge types of interest
CFD simulation of two-phase hydrodynamics and heat transfer in solid sponge structures, using implemented phase-field method
- CFD simulation of two-phase hydrodynamics and mass transfer with sample chemical reaction in solid sponge structures, using implemented phase-field method
Monolith reactor (M. Woo)
The goal of the PhD project is the development and validation of a computational method and tool, which allows detailed numerical simulations of reactive gas-liquid two-phase flows within a single channel of a monolith reactor with a catalytic washcoat. This goal is achieved by coupling two well validated in-house codes for two-phase hydrodynamics (TURBIT-VOF) and chemical kinetics on catalytic surfaces (DETCHEM). The coupled codes shall be validated by experimental data (both, from literature and project partners within the Helmholtz Alliance) and shall be used to study the intrinsic coupling between two-phase flow, species and heat transport, and chemical reaction in heterogeneously catalyzed multiphase flows.
Achievements upt to now:
- Merging the Fortran library of TURBIT-VOF and DETCHEM as a basis of the coupled solver
- Extension of species transport equation (TURBIT-VOF) from single species to multispecies and validation for multispecies diffusion with and without reactions in single phase condition
- Validation for multiphase and multispecies mass transport near the interface without flow
The next steps:
- Study for the chemical properties and reaction kinetics of the Nitrobenzene hydrogenation
- CFD-simulation for the multispecies mass transfer in the two phase flow conditions
- Prof. Michael Schlüter, Dipl.-Ing. Ole Möller, Institute of Multiphase Flows, TU Hamburg-Harburg: µPIV measurements of liquid single-phase flow through silica glass sponges (see Fig. 6).
|Figure 6: test setup for µPIV measurements of liquid single-phase flow through silica glass sponges(see left) and exemplary velocity field result for a 2.3mm x 1.7mm 2-D test section (see right)|
- Dr. Holger Marschall, Center of Smart Interfaces, TU Darmstadt: Optimization of the numerical implementation of phase field method in OpenFOAM®
- Prof. Pengtao Yue, Virginia Tech, Blacksburg, USA: Extension of the phase field method for more complex hydrodynamics in sponge structure
- Prof. Hocine Alla, Laboratoire de Physique des Matériaux et des Fluides, USTO, Oran, Algeria: Incorporation of surface roughness effect on wetting
- S. Meinicke, B. Dietrich, Th. Wetzel: Strukturdatenrekonstruktion und CFD-Simulation zur Charakterisierung fester Schwammstrukturen, ProcessNet-Jahrestagung und 31. DECHEMA-Jahrestagung der Biotechnologen, Sept. 30 – October 02, 2014, Aachen, Germany (Poster)
- X. Cai, H. Marschall, M. Wörner, O. Deutschmann: A Phase Field Method with Adaptive Mesh Refinement for Numerical Simulation of 3D Wetting Processes with OpenFOAM®, 2nd International Symposium on Multiscale Multiphase Process Engineering, Sept. 24-27, 2014, Hamburg, Germany (Presentation)
- M. Woo, M. Wörner, S. Tischer, O. Deutschmann: Development of a computer code for numerical simulation of reactive and catalytic two-phase flows with detailed chemistry, 2nd International Symposium on Multiscale Multiphase Process Engineering, Sept. 24-27, 2014, Hamburg, Germany (Poster)
- X. Cai, H. Marschall, M. Wörner, O. Deutschmann: Development of Phase Field Methods with OpenFOAM® and its Application to Dynamic Wetting Processes, 2nd International Conference on Numerical Methods in Multiphase Flows, June 30 — July 01, 2014, Darmstadt, Germany (Poster)
- X. Cai, H. Marschall, M. Wörner, D. Bothe, O. Deutschmann: Development of Phase Field Methods for Direct Numerical Simulation of Wetting Processes with OpenFOAM®, 9th International OpenFOAM® Workshop, June 23-26, 2014, Zagreb, Croatia (Presentation)
- X. Cai, M. Wörner, O. Deutschmann: A Phase Field Method for Numerical Simulation of Wetting and Spreading Processes with OpenFOAM®, Jahrestreffen der ProcessNet Fachgruppen Computational Fluid Dynamics, Mischvorgänge und Rheologie, February 24-26, 2014, Würzburg, Germany (Presentation)
- S. Meinicke, B. Dietrich, Th. Wetzel: CFD-Simulation der einphasigen Durchströmung fester Schwammstrukturen, Jahrestreffen der ProcessNet Fachgruppen Computational Fluid Dynamics, Mischvorgänge und Rheologie, February 24-26, 2014, Würzburg, Germany (Poster)
- X. Cai, M. Wörner, O. Deutschmann: Implementation of a Phase Field Method in OpenFOAM® for Simulation of Spreading Droplets and Verification by Test Problems, 7th Open Source CFD International Conference, October 24-25, 2013, Hamburg, Germany (Presentation + Proceeding Paper).
- X. Cai, H. Marschall, M. Wörner, O. Deutschmann, A Phase Field Method with Adaptive Mesh Refinement for Numerical Simulation of 3D Wetting Processes with OpenFOAM®, Chemical Engineering & Technology (Sonderband MMPE-Konferenz Hamburg 2014, auf Einladung), 2015, in preparation.