A. Matynia, J.-L. Delfau, L. Pillier and C. Vovelle


Institut de Combustion Aérothermique Réactivité Environnement
      ...
EGR : most efficient technique to reduce NOx emissions


           CH4/air    Φ=1      P=1atm




           Burnt gases
...
Experimental
    - To analyse flame structures of methane/air + additives

    Numerical
    - To check the accuracy of th...
CH4/air            flame 1a
    Lean flames
                  CH4/air + CO2      flame 1b
      Φ=0.7
                  CH...
5   6th International Seminar on Flame Structure   14-17 Sept 2008
Species
       Gas Chromatography
        - FID : CH4, CH3CHO, C2 and C3
        - TCD : CO, CO2, H2O, H2, O2, N2
       F...
Flame structure simulated by using Chemkin II and Premix codes
    Four detailed combustion mechanisms were considered



...
BURN/FREE comparison

    BURN : burner-stabilized flame                                         FREE : freely propagating...
BURN/FREE comparison

    BURN : burner-stabilized flame                                       FREE : freely propagating f...
Experimental
     - To analyse flame structures of methane/air + additives

     Numerical
     - To check the accuracy of...
Experimental/modelling comparison
                      0,08
                                                           CH...
Experimental/modelling comparison

                                                             CH4/air                   ...
Experimental/modelling comparison

                                                                                       ...
Experimental/modelling comparison

                                                           CH4/air
                    ...
Experimental/modelling comparison
                     0,10
                                    CH4/air                   ...
Experimental/modelling comparison

                       3,0E-
                       3,0E-03
                           ...
Experimental
     - To analyse flame structures of methane/air + additives

     Numerical
     - To check the accuracy of...
Temperature profiles
                              Φ = 0.7                                                                ...
Flame velocity
 25
                   Φ = 0.7                                       Φ = 1.4
 20

                         ...
Experimental
     - To analyse flame structures of methane/air + additives

     Numerical
     - To check the accuracy of...
Chemical influence of CO2 and H2O

         Liu et al. method
         Liu, H. Guo, G.J. Smallwood, O.L. Gülder, Combust. ...
Chemical influence of CO2 and H2O


     Inhibiting effect of CO2 :
     CO2 + H   CO + OH
          reduces the rate of t...
Experimental
     - To analyse flame structures of methane/air + additives

     Numerical
     - To check the accuracy of...
Influence of CO2 and H2O additions in EGR


       Addition of N2, CO2/N2, H2O/N2, EGR


                      EGR composi...
Influence of CO2 and H2O additions in EGR


                                                                              ...
Influence of CO2 and H2O additions in EGR


                                                                              ...
Experimental study of lean and rich methane/air flames with
     addition of CO2 and H2O


       Chemical influence of CO...
Thank you
for your attention
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Séminaire bruxelles version blog

  1. 1. A. Matynia, J.-L. Delfau, L. Pillier and C. Vovelle Institut de Combustion Aérothermique Réactivité Environnement 1C avenue de la recherche scientifique 45071 Orléans Cedex 02 - France
  2. 2. EGR : most efficient technique to reduce NOx emissions CH4/air Φ=1 P=1atm Burnt gases In studies, exhaust gas are generally assimilated to N2 or N2/CO2 blend Only few studies exist on the effect of water on combustion 2 6th International Seminar on Flame Structure 14-17 Sept 2008
  3. 3. Experimental - To analyse flame structures of methane/air + additives Numerical - To check the accuracy of the different mechanisms - To study the influence of CO2 and H2O additions on adiabatic temperature and flame velocity - To analyse the chemical effects of CO2 and H2O - To study the influence of CO2 and H2O contents in EGR for the determination of the flame velocity 3 6th International Seminar on Flame Structure 14-17 Sept 2008
  4. 4. CH4/air flame 1a Lean flames CH4/air + CO2 flame 1b Φ=0.7 CH4/air + H2O flame 1c CH4/air flame 2a Rich flames CH4/air + CO2 flame 2b Φ=1.4 CH4/air + H2O flame 2c 4 6th International Seminar on Flame Structure 14-17 Sept 2008
  5. 5. 5 6th International Seminar on Flame Structure 14-17 Sept 2008
  6. 6. Species Gas Chromatography - FID : CH4, CH3CHO, C2 and C3 - TCD : CO, CO2, H2O, H2, O2, N2 FTIR CH2O Temperature Kaiser et al. method J. Phys. Chem. A 2000, 104, 8194-8206 - Temperature profiles determined from measurements of the gas flow through the sampling probe - Tmax measured by a Pt/Pt 10% Rh thermocouple 6 6th International Seminar on Flame Structure 14-17 Sept 2008
  7. 7. Flame structure simulated by using Chemkin II and Premix codes Four detailed combustion mechanisms were considered Mech. Nr Nsp UCSD 175 40 Dagaut 281 54 GRI-Mech3.0 325 53 GDFkin® 3.0 884 121 7 6th International Seminar on Flame Structure 14-17 Sept 2008
  8. 8. BURN/FREE comparison BURN : burner-stabilized flame FREE : freely propagating flame Φ=0.7 2 000 CH4/air P=1atm Temperature (K) 1 500 UCSD mechanism 1 000 Experimental profile 500 Calculated profile with "FREE" option 0 0 0,1 0,2 0,3 Distance from the burner surface (cm) 8 6th International Seminar on Flame Structure 14-17 Sept 2008
  9. 9. BURN/FREE comparison BURN : burner-stabilized flame FREE : freely propagating flame 0,08 CH4/air Φ=0.7 P=1atm 0,06 UCSD mechanism Mole fraction 0,04 CH4 profile calculated with "FREE" option 0,02 CH4 profile calculated with "BURN" option 0,00 0 0,1 0,2 0,3 Distance from the burner surface (cm) Similar results between BURN and FREE modelling next calculations were performed with FREE option 9 6th International Seminar on Flame Structure 14-17 Sept 2008
  10. 10. Experimental - To analyse flame structures of methane/air + additives Numerical - To check the accuracy of the different mechanisms - To study the influence of CO2 and H2O additions on adiabatic temperature and flame velocity - To analyse the chemical effects of CO2 and H2O - To study the influence of CO2 and H2O contents in EGR for the determination of the flame velocity 10 6th International Seminar on Flame Structure 14-17 Sept 2008
  11. 11. Experimental/modelling comparison 0,08 CH4/air Φ = 0.7 Mole fraction 0,06 CH4 Experimental profile 0,04 UCSD 0,02 Dagaut GRI-Mech 3.0 0,00 0,0 0,1 0,2 0,3 GDFkin ® 3.0 Distance from the burner surface (cm) 0,08 0,08 CH4/CO2/air CH4/H2O/air Mole fraction 0,06 0,06 Mole fraction CH4 CH4 0,04 0,04 0,02 0,02 0,00 0,00 0,0 0,1 0,2 0,3 0,0 0,1 0,2 0,3 Distance from the burner surface (cm) Distance from the burner surface (cm) 11 6th International Seminar on Flame Structure 14-17 Sept 2008
  12. 12. Experimental/modelling comparison CH4/air Φ = 0.7 0,02 Mole fraction Experimental profile CO 0,01 UCSD Dagaut 0,00 GRI-Mech 3.0 0,0 0,1 0,2 0,3 GDFkin ® 3.0 Distance from the burner surface (cm) CH4/CO2/air CH4/H24/H2O/air CH O/air 0,02 0,02 Mole fraction Mole fraction CO CO 0,01 0,01 0,00 0,00 0,0 0,1 0,2 0,3 0,0 0,1 0,2 0,3 Distance from the burner surface (cm) Distance from the burner surface (cm) 12 6th International Seminar on Flame Structure 14-17 Sept 2008
  13. 13. Experimental/modelling comparison Φ = 0.7 8,E- 8,E-04 CH4/air Mole fraction 6,E- 6,E-04 Experimental profile C2H 4 4,E- 4,E-04 UCSD 2,E- 2,E-04 Dagaut GRI-Mech 3.0 0,E+00 0,0 0,1 0,2 0,3 GDFkin ® 3.0 Distance from the burner surface (cm) 8,E- 8,E-04 8,0E- 8,0E-04 CH4/CO2/air CH4/H2O/air 6,E- 6,E-04 6,0E- 6,0E-04 Mole fraction Mole fraction C2H 4 C2H 4 4,E- 4,E-04 4,0E- 4,0E-04 2,E- 2,E-04 2,0E- 2,0E-04 0,E+00 0,0E+00 0,0 0,1 0,2 0,3 0,0 0,1 0,2 0,3 Distance from the burner surface (cm) Distance from the burner surface (cm) 13 6th International Seminar on Flame Structure 14-17 Sept 2008
  14. 14. Experimental/modelling comparison CH4/air Φ = 1.4 0,12 Mole fraction CH4 Experimental profile 0,08 UCSD 0,04 Dagaut GRI-Mech 3.0 0,00 0,0 0,1 0,2 0,3 GDFkin ® 3.0 Distance from the burner surface (cm) 0,12 CH4/CO2/air 0,12 CH4/H2O/air Mole fraction Mole fraction CH4 CH4 0,08 0,08 0,04 0,04 0,00 0,00 0,0 0,1 0,2 0,3 0,0 0,1 0,2 0,3 Distance from the burner surface (cm) Distance from the burner surface (cm) 14 6th International Seminar on Flame Structure 14-17 Sept 2008
  15. 15. Experimental/modelling comparison 0,10 CH4/air Φ = 1.4 0,08 Mole fraction 0,06 Experimental profile CO UCSD 0,04 0,02 Dagaut 0,00 GRI-Mech 3.0 0,0 0,1 0,2 0,3 GDFkin ® 3.0 Distance from the burner surface (cm) 0,10 0,10 CH4/CO2/air CH4/H2O/air 0,08 0,08 Mole fraction Mole fraction 0,06 0,06 CO CO 0,04 0,04 0,02 0,02 0,00 0,00 0,0 0,1 0,2 0,3 0,0 0,1 0,2 0,3 Distance from the burner surface (cm) Distance from the burner surface (cm) 15 6th International Seminar on Flame Structure 14-17 Sept 2008
  16. 16. Experimental/modelling comparison 3,0E- 3,0E-03 CH4/air Φ = 1.4 Mole fraction C2H 4 Experimental profile 2,0E- 2,0E-03 UCSD 1,0E- 1,0E-03 Dagaut GRI-Mech 3.0 0,0E+00 0,0 0,1 0,2 0,3 GDFkin ® 3.0 Distance from the burner surface (cm) 3,0E- 3,0E-03 CH4/CO2/air 3,0E- 3,0E-03 CH4/H2O/air Mole fraction Mole fraction C2H 4 C2H 4 2,0E- 2,0E-03 2,0E- 2,0E-03 1,0E- 1,0E-03 1,0E- 1,0E-03 0,0E+00 0,0E+00 0,0 0,1 0,2 0,3 0,0 0,1 0,2 0,3 Distance from the burner surface (cm) Distance from the burner surface (cm) 16 6th International Seminar on Flame Structure 14-17 Sept 2008
  17. 17. Experimental - To analyse flame structures of methane/air + additives Numerical - To check the accuracy of the different mechanisms - To study the influence of CO2 and H2O additions on adiabatic temperature and flame velocity - To analyse the chemical effects of CO2 and H2O - To study the influence of CO2 and H2O contents in EGR for the determination of the flame velocity 17 6th International Seminar on Flame Structure 14-17 Sept 2008
  18. 18. Temperature profiles Φ = 0.7 Φ = 1.4 2000 2 000 Temperature (K) Temperature (K) 1500 1 500 1000 1 000 500 500 0 UCSD 0 UCSD 0 0,1 0,2 0,3 0 0,1 0,2 0,3 Distance from the burner surface (cm) Distance from the burner surface (cm) 1800 2 000 1775 1 950 Tmax Tmax 1750 CH4/air 1 900 CH4/air 1725 + H2O 1 850 + H2O 1700 + CO2 1 800 + CO2 CH4/air CH4/air +CO2 CH4/air +H2O Downward shift in diluted flames Burnt gases temperature decreases 18 6th International Seminar on Flame Structure 14-17 Sept 2008
  19. 19. Flame velocity 25 Φ = 0.7 Φ = 1.4 20 GRI- GRI-Mech 3.0 15 CH4 Dagaut CH4/H2O CH4 CH4/CO2 UCSD 10 -16% -20% CH4/H2O GDFkin® 3.0 CH4/CO2 -25% 5 Experimental -38% data 0 Experimental data : Stone et al. Combust. Flame 114:546-555 (1998) Some scatters observed especially in rich flames but same tendencies with both diluents Additive concentration higher in the rich flames 19 6th International Seminar on Flame Structure 14-17 Sept 2008
  20. 20. Experimental - To analyse flame structures of methane/air + additives Numerical - To check the accuracy of the different mechanisms - To study the influence of CO2 and H2O additions on adiabatic temperature and flame velocity - To analyse the chemical effects of CO2 and H2O - To study the influence of CO2 and H2O contents in EGR for the determination of the flame velocity 20 6th International Seminar on Flame Structure 14-17 Sept 2008
  21. 21. Chemical influence of CO2 and H2O Liu et al. method Liu, H. Guo, G.J. Smallwood, O.L. Gülder, Combust. Flame, 125 (2001) 778-787 CO2 and H2O replaced by FCO2 and FH2O same thermochemical and transport properties than CO2 and H2O but not included in the mechanism CH4 FCO2/CH4 CO2/CH4 FH2O/CH4 H2O/CH4 Flame velocity (cm/s) Φ=0.7 19.8 16.8 -0.3 16.5 17.6 +0.1 17.7 Flame velocity (cm/s) Φ=1.4 16.0 10.1 -0.4 9.7 10.5 +0.5 11.0 UCSD computation Small decrease with normal CO2 -> inhibiting effect Small increase with normal H2O -> promoting effect 21 6th International Seminar on Flame Structure 14-17 Sept 2008
  22. 22. Chemical influence of CO2 and H2O Inhibiting effect of CO2 : CO2 + H CO + OH reduces the rate of the branching reaction H+O2 OH+O Promoting effect of H2O : H2O + H H2 + OH converts H2O into H2 22 6th International Seminar on Flame Structure 14-17 Sept 2008
  23. 23. Experimental - To analyse flame structures of methane/air + additives Numerical - To check the accuracy of the different mechanisms - To study the influence of CO2 and H2O additions on adiabatic temperature and flame velocity - To analyse the chemical effects of CO2 and H2O - To study the influence of CO2 and H2O contents in EGR for the determination of the flame velocity 23 6th International Seminar on Flame Structure 14-17 Sept 2008
  24. 24. Influence of CO2 and H2O additions in EGR Addition of N2, CO2/N2, H2O/N2, EGR EGR composition : Lean flame stoechiometric and rich flames CO2 : 6.6% CO2 : 9.5% H2O : 13.4% H2O : 19% N2 : 74% N2 : 71.5% O2 : 6% 24 6th International Seminar on Flame Structure 14-17 Sept 2008
  25. 25. Influence of CO2 and H2O additions in EGR 40 EGR CO2-N2 H 2O- N 2 30 N2 Flame speed (cm/s) N2 CO2-N2 H2O-N2 EGR Φ=1.0 20 φ = 0.7 -42 -48 -45 -46 20% EGR φ = 1.0 -44 -55 -47 -50 10 φ = 1.4 -35 -42 -35 -37 8% EGR Φ=1.4 Φ=0.7 Flame speed decrease (%) 0 0 10 20 30 % additive Results computed with UCSD mechanism 25 6th International Seminar on Flame Structure 14-17 Sept 2008
  26. 26. Influence of CO2 and H2O additions in EGR 40 EGR CO2-N2 H 2O- N 2 30 N2 Flame speed (cm/s) N2 CO2-N2 H2O-N2 EGR Φ=1.0 20 φ = 0.7 -42 -48 -45 -46 20% EGR φ = 1.0 Presence of H2O in burnt gases must be taken into account -44 -55 -47 -50 for more accurate flame modelling with EGR 10 φ = 1.4 -35 -42 -35 -37 8% EGR Φ=1.4 Φ=0.7 Flame speed decrease (%) 0 0 10 20 30 % additive Results computed with UCSD mechanism 26 6th International Seminar on Flame Structure 14-17 Sept 2008
  27. 27. Experimental study of lean and rich methane/air flames with addition of CO2 and H2O Chemical influence of CO2 and H2O Chemical inhibition effect of CO2 Promoting effect of H2O Influence of CO2 and H2O additions in EGR For more accurate simulation of EGR, the presence of H2O in the burnt gases must be taken into consideration 27 6th International Seminar on Flame Structure 14-17 Sept 2008
  28. 28. Thank you for your attention

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