DARS Digital Analysis of Reactive Systems

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Bartholomew Harrison
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1 DARS Digital Analysis of Reactive Systems

2 Introduction DARS is a complex chemical reaction analysis system, developed by DigAnaRS. Our latest version, DARS V2.0, was released in September 2008 and new releases are planned every 4 months. You ll find more details at The DARS suite consists of the following components» DARS Basic» DARS LGT» DARS CFD» DARS ESM

3 What DARS Basic can do Import Chemkin format mechanisms and view, analyze, reduce and export chemical kinetics for fluid and surface reactions. Simulate simple 0-D reactors, 0-D engine models and 1-D reaction fronts. Generate kinetic landscapes for ignition delays times; Looping is supported for pressure, temperature, fuel-air equivalence ratio and artificial EGR Kinetic mapping is accelerated through multiprocessor usage. Multiprocessor options are offered as beneficial HPC licenses. Simulate Stochastic Reactor engine models. HCCI, SI and DI models are available in DARS v Simulate simple reactor networks like 0-D models. Our first reactor networks are available as command line models. Analyse results with the Graph Comparator. Export validated and tested mechanisms for usage with CFD or ESM tools.

4 More information about DARS Basic Supports gas phase chemistry and surface chemistry Allows definition of up to 10 surfaces. Highly robust stiff solver Both time dependent and steady state solutions. Includes data bases of physical properties Thermophysical data (specific heat, enthalpy, entropy) Transport properties (viscosity, thermal conductivity, diffusivity) Includes sophisticated ideal flame models 1-D reactor: Flamelet, Opposed Flame, Premixed Burner Stabilized Flame and Freely Propagating Flame. Can perform analyses of reaction mechanisms Sensitivity analysis, Reaction flow analysis, Necessity analysis, and Life time analysis Has a highly efficient mechanism reduction module

Constant Pressure reactor, HCCI engine model, SI engine model.

5 More information about DARS Basic Includes sophisticated ideal reactor models 0-D reactor: Perfectly Stirred Reactor, Plug Flow Reactor, Constant Volume reactor, Constant Pressure reactor, HCCI engine model, SI engine model. Multiple reactor definitions possible for kinetic map generation. Can exports mechanism data to STAR-CD, GT-POWER and WAVE

6 The DARS Basic Interface is intuitive and user-friendly

7 The mechanism analyses in DARS Basic Sensitivity analysis Flow analysis Necessity analysis Lifetime analysis

8 DARS-Basic (Reduction)

9 Reducing mechanisms using DARS Basic The reduction module uses reactor calculations to optimize the mechanism Results can easily be compared with detailed or with other reduced chemistry calculations

10 Exporting mechanism using DARS Basic Mechanisms can be exported in several different formats, for instance: CHEMKIN TM format Fortran 95 modules Allows using the chemistry in any software Compiled.dll/.so files Allows using the chemistry in any software that is compatible with DARS

11 Future development plans for DARS Basic Extended engine models Multi zone models. Engine performance optimization. Usage of library based models (Flamelet, TPFM) Development of reactor networks Simple engine models (Inlet system, engine model, exhaust system, EGR system) Visual reduction, through the DARS reaction flux filter technique. Fully support looping for reaction front calculations. Full soot model support

12 Overview 1D-project Intake valve Exhaust valve DI-SRM Catalyst DPF 12

$1D- Mass fraction burned$ OUTPUT Flow Temperatures

13 Standard tools vs DARS-1D INPUT INPUT Engine Parameters Mixing time Deterministic Heat release 1D- Mass fraction burned CODE DARS- Predictive 1D OUTPUT Flow Temperatures Performance parameters OUTPUT Flow Temperatures Performance parameters Unburned hydrocarbons Soot NOx 13

14 Stochastic Reactor Model DI-SRM 14

$species mass fraction and enthalpy The SRM captures inhomogeneities in the$

15 Stochastic Reactor Model PDF = Probability Density Function The mixture is represented by a PDF in phase-space In-cylinder mass is divided into particles realizing the distributions Each particle represents a point in phase space for species mass fraction and enthalpy The SRM captures inhomogeneities in the cylinder 15

16 Stochastic Reactor Model Fuel mixes with cylinder gas at injection fuel air in cylinder EGR Fuel is injected into the cylinder Portions of the cylinder gas is taken for evaporation New particles containing fuel and cylinder gas are created The mixing is controlled by the τ curve 16

17 Pressure [MPa] Stochastic Reactor Model Pressure history variations Pasternak et al, SAE ,0 15,0 14,0 13,0 12,0 11,0 10,0 9,0 8,0 7,0 Exp Sim, Cycle Sim, Average 10 cycles Sim, Average 20 cycles Sim, Average 30 cycles Sim, Average 50 cycles 6, Crank Angle [deg ATDC] Average values from simulated cycles 17

18 Catalyst Catalyst 18

19 Catalyst Several problems need to be adressed when simulating a catalyst. Heat and mass transfer between bulk gas and surface Surface reactions Gas phase reactions Diffusion in pores Heat conduction in surface Heat conduction in substrate 19

Catalyst The solution procedure is split into three levels Heat conduction is calculated Reactor level Detailed or global chemistry Washcoat

20 Catalyst The solution procedure is split into three levels Heat conduction is calculated Reactor level Detailed or global chemistry Washcoat level Washcoat Monolith wall Several representative channels are selected for solving of chemistry Channel level flow heat transport mass transport 20

21 Catalyst Channels are discretized into a number of cells C i,p, Γ m, Ѳ m,j,t w washcoat p, v, Y i, k-1 hk k+1 k+2 g n-2 Monolith wall n-1 n n+1 Flow and chemistry calculations are decoupled Chemistry calculations are performed in two subsections: Bulk gas Boundary layer (pores and wall surface) 21

22 Catalyst Chemistry calculation Series of perfectly stirred reactors Heat and mass transfer between bulk gas and thin film layer are modeled using heat and mass transfer coefficients Detailed chemistry or global gas phase chemistry can be used Gas phase chemistry in bulk gas can be modeled Assumption made for the flow Steady state solution for the flow calculated in each time step 22

23 Catalyst Validation against Koop, J., Deutschmann, O., Applied Catalysis B: Environmental 91 (2009)

24 DPF DPF 24

cake level Soot cake Porous wall washcoat Several representative channels are

25 DPF The solution procedure is split into three levels Heat conduction is calculated Reactor level Detailed or global chemistry Porous media and soot cake level Soot cake Porous wall washcoat Several representative channels are selected for solving of chemistry Channel flow level heat transport mass transport 25

26 DPF Soot cake Porous wall washcoat Flow between inlet and outlet channels are modeled using Darcy s law calculating pressure drop 26

27 DARS Library Generation Tool (LGT) DARS LGT contains the following features: Library Generation Tool for zero-dimensional ignition timing (ECFM) and progress variable based models. Looping can be performed together with DARS Basic. Library generation tool for one-dimensional stationary and transient flamelets (TFLM). Library generation tool for flame velocities. Future development of DARS LGT includes: Library generation tool for flame velocities.

28 DARS Computational Fluid Dynamics (CFD) DARS CFD contains the following features: Fast coupled ODE and algebraic chemistry solver. Coupling of detailed/reduced chemistry models with a CFD program. Multiprocessor options are offered as beneficial HPC licenses. Future development of DARS CFD: Full particle model support. Inclusion of monitoring cells for reaction flow and sensitivity analysis.

29 DARS-CFD STAR-CD coupling STAR-CD: Species Y i 0 Enthalpy h Species Y i * Transport data D ij, l, n DARS-CFD

30 STAR-CD TIF coupling STAR-CD Transport of Z, Z 2, h, I Z, Z 2 T, W q Update h and Get cell local T and W q Perform species pdf integration Y i (Z) TIF 2 Yi Yi 2 iwi t 2 Z

31 Flamelet library based emission models Soot Method of Moments Sectional Method NOx 31

denox, desox on catalyst Chemical vapor deposition Silicon epitaxial film Metal Organic

32 Application of DARS-CFD to reacting-flow Reduction of pollutant species NOx, SOx, Soot, Unburned Hydrocarbon in flames Catalyst reaction Catalyst combustion Fuell cell reformer denox, desox on catalyst Chemical vapor deposition Silicon epitaxial film Metal Organic Compound Other important process Partially oxidation of hydrocarbon Pyrolysis of hydrocarbon

33 Three way catalyst Problem description: X(CO) = 0.1 O2/CO = 0.5 u = 0.5 m/s, 1m/s T = 420K P = 1 atm. (k = A T**b exp(-e/rt)) SURFACE REACTIONS CONSIDERED A b E 1. O2+2PT(S)=>2O(S) 7.00E Coefficients are sticking parameters O(S)=>O2+2PT(S) 9.25E Coverage parameters for species O(S): 0.000E E E CO+PT(S)=>CO(S) 8.40E Coefficients are sticking parameters CO(S)=>CO+PT(S) 2.50E Coverage parameters for species CO(S): 0.000E E E CO2(S)=>CO2+PT(S) 2.50E CO(S)+O(S)=>CO2(S)+PT(S) 9.25E Coverage parameters for species CO(S): 0.000E E E+04 NOTE: E units Joules/mol, A units mole-cm-sec-k Monolith single channel 10 mm 1 mm

34 Gas Inlet X(CO) = 0.1mol% O2/CO = 0.5 u = 0.5 m/s T = 420K P = 1 atm.

35 Summary NOx Results Experiment Lib-NOx E0 E1 F0 F1 F2 35

36 Summary Soot Results Experiment SCt = 0.5 SCt = E0 E1 F0 F1 F2 36

37 Secondary Air Combustion (DARS-CFD)

38 DARS Summary DARS includes capabilities for chemistry development: Mechanism analysis via several 0-D and 1-D models Mechanism reduction Mechanism optimization DARS facilitates use of chemical models in: 1-D engine simulation software (HCCI, SI, Diesel) 3-D computational fluid dynamics software» Fast solver for 0-D treatment of chemistry» Flamelet libraries» Transient interactive flamelets The DARS team can quickly respond to customer requests and format needs!

DARS overview, IISc Bangalore 18/03/2014

www.cd-adapco.com CH2O Temperatur e Air C2H4 Air DARS overview, IISc Bangalore 18/03/2014 Outline Introduction Modeling reactions in CFD CFD to DARS Introduction to DARS DARS capabilities and applications