Ov Over ervie view of R of Reacting Flo acting Flows Outline - PowerPoint PPT Presentation

Ov Over ervie view of R of Reacting Flo acting Flows

Outline Outline Various Applications rious Applications Over Ov ervie view of a of available reacting flo ailable reacting flow models models Latest additions Lat st additions Exam Example Cases ple Cases Summar Summary

Reacting Flo acting Flows Applications in S s Applications in STAR-CCM+ AR-CCM+ – Chemical Process Industry (liquid-liquid reactions) • Finite-rate chemistry model with a flexibility to modify EOS • EMP inter/intra-phase reactions • Moment methods • Surface Chemistry – Rocket Engines (Solid, Liquid, and Hybrid) • Particle Reactions in Lagrangian • Real–Gas model with all Combustion Models • Coupled Solver – High-speed jet engines (Ramjet, Scramjet) • Coupled solver with combustion models – Oil and Gas • Multiple-Phase reactions (intraphase and interphase)

Reacting Flo acting Flows Applications in S s Applications in STAR-CCM+ AR-CCM+ Ever Ev er-Expanding application co -Expanding application coverage rage – Gas turbine, process heaters, burners, and furnaces • Partially-premixed combustion models • LES • Soot and Nox models – Chemical Vapor Deposition • Detailed/Global Surface chemistry • multi-component diffusion – Aftertreatment (Automotive) • Detailed/Global Surface chemistry • Coupled with liquid film and porous media – Energy Industry (Coal and Biomass combustion) • Multiple Coal Types and cofiring with gas-fuel

Reacting Flo acting Flow Models in S Models in STAR-CCM+ AR-CCM+ Non-Premix Non-P remixed Combustion d Combustion EBU – • Standard, Hybrid, Finite-Rate • User Defined PPDF (Multi-stream) – • Equilibrium • Flamelet PVM (Chemistry Table) – Premix Premixed Combustion ed Combustion CFM (Choice for Laminar flame speed) – PEBU – TFC – Partially Par ially-Premix -Premixed Combustion d Combustion PCFM – • Equilibrium • Flamelet EBU – PVM – PTFC – Finite-Rat Finit -Rate Chemistr e Chemistry Calculation using D y Calculation using DARS-CFD RS-CFD EDC – ISAT – Dynamic Load Balancing – Sur Surface R ace Reactions actions Soo Soot and No and Nox Emission Models mission Models

Lat Latest A st Additions (v 8/9) dditions (v 8/9) Micr Micromixing omixing Models odels Sur Surface Chemistr ace Chemistry – Global mechanisms Combustion M Models w with Re Real G Gases – SRK and Peng-Robinson EOS Soo Soot Model Model – MBH Model – Soot absorption properties Eulerian Eulerian Multi-phase R Multi-phase Reaction Model action Model – Flexibility to add user defined reactions Com Comple lex Chemist x Chemistry Model (D y Model (DAR ARS-C S-CFD) D) – ISAT – Analytical Jacobian – PaSR Pe Performance

Ne New Micr w Micromixing Model f omixing Model for Liq r Liquid R id Reactions in 9.02 actions in 9.02 Eddy Contact Micr Eddy Contact Micromixing omixing Model (based on F odel (based on Frone oney and and Naf Nafia, Chem a, Chem Eng ng Sc, 2000) f Sc, 2000) for Liq r Liquid-Liq id-Liquid R uid Reactions. actions. User Users will ha s will have choice of three mixing choice of three mixing scales scales - Kolmogor olmogorov (corresponds t v (corresponds to Engulfment type of mixing) Engulfment type of mixing) - Classical Scalar Mixing lassical Scalar Mixing (consider (considers high Sc s high Sc number) number) - User Def ser Defined (ability t ned (ability to do user def do user defined f ined ff) - Kine inetics Only (No tics Only (No Micr Micromixing) omixing) The abo The above f e four choices are a ur choices are available f ailable for each reaction r each reaction

Micr Micromixing Model – omixing Model – Eddy Contact Micr ddy Contact Micromixing omixing

Eddy Contact Eddy Contact Micr Micromixing omixing

Validation Case – lidation Case – Low Re Re flo flow in Coaxial Jet in Coaxial Jet The results com The results compared t ared to the numerical of the numerical of Forne rney and Naf and Nafia (2000) a (2000) and e and experimental data of perimental data of Li and T Li and Toor (1 oor (1986) at lo 986) at low high R w high Reynolds ynolds number number. R . Reactants A and B react in aq actants A and B react in aqueous solution ueous solution

Mass F Mass Fractions of A actions of A, B, R B, R (Desired) and S (Desired) and S

Results (% Yield of R) sults (% Yield of R) Comparison with Experimental Data 100 90 Experiment (Li & Toor, 1986) % Yield of R Hybrid EBU 80 Eddy Contact Micromxing (Kolmogorov) Eddy Contact Micromxing 70 (Classical Scalar Mixing) Froney & Nafia Paper, 2000 60 50 2000 3000 4000 5000 6000 Reynolds Number  Micromixing Models predictions are much better than EBU  Classical Scalar Mixing time scale appears to give best match

Surface R Sur ace Reactions actions No DARS-CFD licenses are req No D RS-CFD licenses are required ired Users can User s can add their o add their own reactions n reactions Same interface f Same int ace for adding r adding reactions as reactions as gas-phase reactions gas-phase reactions

Applications Applications Tools ools – Porous chemistry – Global Surface chemistry – Detailed Surface Chemistry CVD R CVD React actors rs Af After-treatment de treatment devices: vices: - Three-Way Catalytic Converters (TWC) - Diesel Oxidation Catalyst (DOC) - Diesel Particulate Filter (DPF) - Selective Catalytic Reduction (SCR)

Results – sults – NOx R Ox Reduction Com duction Comparison arison Two-Step Model Detailed Surface Chemistry

Real Fluid Modeling in STAR-CCM+ - Real Fluid Physics in STAR-CCM+ - Van der Waals - Redlich-Kwong (RK) - Peng-Robinson (PR) - Soave-Redlich-Kwong (SRK, available in 8.02) - Modified Soave-Redlich-Kwong (MSRK, available in 8.02) - All above Equation of Sates are Cubic

Real Fluid Thermodynamic Departures Enthalpy : Enthalpy : Specific Heat Specific Heat : Entropy : Entropy : Speed of Speed of Sound Sound :

Results (Density Comparison) PR PR SRK SRK Ideal Ideal Gas Gas

Soot modeling Two-Equation Soot Model Transport equations are solved for two soot variables – Transport equations are solved for two soot variables – Soot oot number density (N) and Soot Mass density (M) number density (N) and Soot Mass density (M) Key ph y physical pr ysical processes are : ocesses are : – Nucleation cleation – Coagul Coagulati ation – Soo Soot gr growth th – Soo Soot o oxidati idation

Nucleation Acetylene PAH inception inception C 2 H 2 C 2 H 2 , C , C 6 H 6 , C , C 6 H 5 , H , H 2 Compute from: Compute from: 1. Species list 1. Species list 2. Empirical (non- 2. Empirical (non- premixed) premixed)

Available Soot Models

Two-equation model Two-equation model without radiation without radiation All the All the scaling scaling facto factors fo rs for r source terms source terms are 1.0 are 1.0 Two-equation model Two-equation model with radiation with radiation Moments model with radiation Moments model with radiation

Int Inter-Phase R Phase Reactions with EMP actions with EMP Following Options are • Provided First-order combined rate • Half-order combined rate • Second-order combined • rate User reaction rate • 23

Gas phase reaction setup in S Gas phase reaction setup in STAR-CCM+ AR-CCM+ When using the built-in • reaction rate expression, input the temperature exponent • activation energy • pre-exponent, and • the diffusion coefficient. • 24

General Ov General Over ervie view of F of Furnace Flo rnace Flow Fe 2 O 3 Ore / Coke Layer Ore / Coke Layer Fe 3 O 4 - Falls lls d down n very s ry slowly. owly. FeO Fe Gas Gas Cohesive Zone Cohesive Zone - Hot gas in gas inject jection ion - Flow upward t upward through rough ore / ore / - Ore la e layer temper erat atur ure e coke coke l laye yers rs increases inc eases - Lost of heat i Lost of heat into ore to ore / coke / coke - Bloc Blocked gas passage ked gas passage due due la layers rs to m melted or lted ore - Chemic Chemical r al reactions wit eactions with - Cohesive z Cohesive zone of ne of lar large e ore / coke ore / coke vol volume me

Eulerian por Eulerian porous media appr us media approach oach Gas Phase •  Three components: CO/CO2/N2 Porous media •  Three components: Fe/Ore/Coke Boundary conditions: •  Outlet boundary: Pressure outlet  Inlet boundary: Mass fraction of the gas phase: CO/N2= 0.8/0.2.  Velocity = 15 m/s, Temperature = 2000K  26 26

Chemical reactions Chemical reactions Two reactions •  C + CO2 -> 2CO  Fe2O3 + 3CO -> 2Fe + 3CO2  Time step: 1 sec  The model is stable and fast:  32 processors, one hour, simulated around 3000 seconds in the physical time. 27 27

Cok Coke and Ore par and Ore particle icle area area 28 28

Con Conver ersion of Ore sion of Ore int into F Fe 29 29

Eulerian multiphase: 2-phase model Eulerian multiphase: 2-phase model Full size furnace: • 25m height • 7.2m hearth diameter • 2D axisymmetric model • M ulti-component Eulerian phases: •  Gas phase: CO, CO2, N2  Solid phase: Ore, Coke, Fe, Fe2O3, C Two reactions: •  Fe2O3 + 3CO -> 2Fe + 3CO2  C + CO2 -> 2CO 30 30