Using STAR-CCM+ for Research and Teaching at the Chair of Chemical & Process Engineering

Transcription

1 Using STAR-CCM+ for Research and Teaching at the PROF. DR.-ING. M. KRAUME, G. WEHINGER, T. EPPINGER Technische Universität Berlin (March 17-19), Vienna

2 Content 1. Introducing the chair of chemical & process engineering at TU Berlin 2. Single-phase research 3. Multi-phase research 4. Teaching CFD Slide 2

3 TU Berlin Chair of chemical & process engineering Slide 3

4 SINGLE-PHASE RESEARCH Slide 4

5 Single-phase stirrer vessels Enzymatic membrane reactor 70 mm x 40 mm 90 ml Volume H/D 1,8 Stirrer with d/d 0,9 Membrane at bottom Temperature control ph control Adapter Single-phase CFD simulations: Membrane fouling characteristics Stirrer momentum Mixing time Inlet Shaft Membrane Stirrer Outlet Lyagin et al. (2012). Chemical Engineering, 27 Slide 5

6 Membrane fouling and shear stress Shear stress [PA] Enzyme: Acylase from Aspergillus Melleus Lyagin et al. (2012) Procedia Engineering, 44, Slide 6

7 Spatially resolved catalytic fixed-bed reactors DEM (discrete element method) Generation of a random packing DARS Calculation of detailed homogeneous and heterogeneous reaction mechanism Spatially Resolved Simulation of Fixed-Bed Reactors CFD - STAR-CCM+ Calculation of fluid dynamics, temperature and species concentration Pore model Calculation of processes within pores Slide 7

8 Fixed bed generation using DEM simulations Filling by DEM-simulation Fixed-bed geometry Meshing CFD simulation Spherical particles Non-spherical particles Eppinger et al. (2011). Chemical Engineering Journal, 166(1), Slide 8

9 Work flow non-spherical particles Cylinders Raschig rings one hole Raschig rings four hole D/d = 8.8 D = 0.22m d = h = 0.025m H = 0.55m Slide 9

10 Catalytic fixed-bed reactors Coupling spatially complex geometries with detailed surface reactions Heterogeneous dry reforming of methane (42 irreversible reactions) Re p = v d p ν = 28, T wall = 700 C See the presentation by Gregor Wehinger: Spatially Resolved Simulations of Heterogeneous Dry Reforming of Methane in Fixed-Bed Reactors from 2:00 pm to 2:25 pm, Klimt I. Slide 10

11 Mixing in biogas plants Challenges: Shear thinning and viscoelastic fluids multi-phase systems: solid, liquid and gaseous Biogas plant: substrate: corn silage 2 submersible mixers volume: 2500m³ Requirement: Correspondence of the agitators S = 39 [Pa s 0.12 ] (0.12-1) 0 = 1000 Pa s = 0.34 Pa s Slide 11

12 Mixing in biogas plants Cavern forming in high viscous, shear thinning fluids the correspondence of the agitators breaks down Slide 12

13 Permeation through a semipermeable membrane Feed Membrane Feed side: c F (x,y,z) M Permeate side: c P (x,y,z) Retentate Mass transfer M as concentration dependent boundary condition Permeate For each component i: M i x, z = L A c i F c i P x,z,y=0 Mass flow Permeance Area Concentration difference between feed and permeate side on membrane surface Implementation as user function Slide 13

14 Application Details Gas permeation test cell Cross section Fluid volume Mesh Input Parameters Methane and n-butane mixture p Feed, p Perm, VFeed Permeance L of membrane material Trimmed Mesh Slide 14

15 Results Velocity profile Concentration profile Transmembrane mass transfer of n-butane: -6,3*10-5 kg/m² s bar -6,6*10-5 kg/m² s bar Slide 15

16 MULTI-PHASE RESEARCH Slide 16

17 Multi-phase slim stirrer reactors Combining CFD simulations and population balance equation drop size and power consumption Slide 17

18 Power number and Sauter mean diameter Slide 18

19 VOF-simulation of a silicon oil liquid film 0 cm Film with constant height 4 cm Regular beads Irregular beads due to coalescence 20cm Fewer but higher and faster beads 28 cm Wehinger et al. Chemical Engineering Science 104 (2013): Slide 19

20 Mass transfer at vertical liquid film Specific interfacial area depending on gas load Mean gas-side Sherwood number depending on Reynolds number Slide 20

21 TEACHING CFD Slide 21

22 Teaching Students are CFD users, not programmers Theory: as much as necessary Focus: solving engineering problems Advantages of STAR-CCM+: CAD modeler CAD mostly simple geometries GUI Hierarchical model selection Postprocessing Reports, Monitors, Animations Slide 22

23 Example: Hippopotamus pool in the zoo of Berlin Three hippopotami in the pool Water turbidity in the pool due to biomass disposal Pool: 600 m³ and 160 m³/h Velocity distribution and residence time Simplified geometric model Slide 23

24 Water turbidity by evaluating velocities Velocity distribution at different levels in the hippopotamus pool Dead zones indicates water turbidity Velocity inlet Pressure outlets Slide 24

25 Conclusion We are applying computational fluid dynamics regularly. Special objections need special solutions, e.g., user defined subroutines. CFD accompanies and/or enriches specific experiments at different length and time scales. CFD references and is likewise referenced by experiments. Slide 25

26 Thank you for your attention. Prof. Dr.-Ing. M. Kraume, G. Wehinger, T. Eppinger Technische Universität Berlin (March 17-19), Vienna