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A. Matynia, J.-L. Delfau, L. Pillier and C. Vovelle
IIIInstitut de CCCCombustion AAAAérothermique RRRRéactivité EEEEnvironnement1C avenue de la recherche scientifique45071 Orléans Cedex 02 - France
EGR : most efficient technique to reduce NOx emissions
CH4/air Φ=1 P=1atm
In studies, exhaust gas are generally assimilated to N2 or N2/CO2 blend
� Only few studies exist on the effect of water on combustion
2222
Burnt gases
6th International Seminar on Flame Structure 14-17 Sept 2008
Experimental
- To analyse flame structures of methane/air + additives
Numerical
- To check the accuracy of the different mechanisms
- To study the influence of CO and H O additions on adiabatic- To study the influence of CO2 and H2O additions on adiabatictemperature 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
3333 6th International Seminar on Flame Structure 14-17 Sept 2008
Lean flamesLean flamesLean flamesLean flamesΦΦΦΦ=0.7=0.7=0.7=0.7
CHCHCHCH4444/air /air /air /air flame 1aflame 1aflame 1aflame 1a
CHCHCHCH4444/air + CO/air + CO/air + CO/air + CO2222 flame 1bflame 1bflame 1bflame 1b
CHCHCHCH4444/air + H/air + H/air + H/air + H2222OOOO flame 1cflame 1cflame 1cflame 1c
Rich flamesRich flamesRich flamesRich flamesCHCHCHCH4444/air /air /air /air flame 2aflame 2aflame 2aflame 2a
CHCHCHCH /air + CO/air + CO/air + CO/air + CO flame 2bflame 2bflame 2bflame 2b
4444 6th International Seminar on Flame Structure 14-17 Sept 2008
Rich flamesRich flamesRich flamesRich flamesΦΦΦΦ=1.4=1.4=1.4=1.4
CHCHCHCH4444/air + CO/air + CO/air + CO/air + CO2222 flame 2bflame 2bflame 2bflame 2b
CHCHCHCH4444/air + H/air + H/air + H/air + H2222OOOO flame 2cflame 2cflame 2cflame 2c
5555 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
� FTIR
CH2OCH2O
Temperature
Kaiser et al. methodJ. 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
6666 6th International Seminar on Flame Structure 14-17 Sept 2008
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
6th International Seminar on Flame Structure 14-17 Sept 20087777
BURN : burner-stabilized flame FREE : freely propagating flame
1 0001 0001 0001 000
1 5001 5001 5001 500
2 0002 0002 0002 000
Temperature
Temperature
Temperature
Temperature(K)
(K)
(K)
(K)
CH4/air Φ=0.7 P=1atmUCSD mechanism
BURN/FREE comparison
8888 6th International Seminar on Flame Structure 14-17 Sept 2008
0000
500500500500
1 0001 0001 0001 000
0000 0,10,10,10,1 0,20,20,20,2 0,30,30,30,3
Temperature
Temperature
Temperature
Temperature
Distance Distance Distance Distance fromfromfromfrom the the the the burnerburnerburnerburner surface (cm)surface (cm)surface (cm)surface (cm)
Calculated profile with "FREE" option
Experimental profile
0,040,040,040,04
0,060,060,060,06
0,080,080,080,08
Mole fraction
Mole fraction
Mole fraction
Mole fraction
BURN/FREE comparison
BURN : burner-stabilized flame FREE : freely propagating flame
CH4/air Φ=0.7 P=1atmUCSD mechanism
Similar results between BURN and FREE modelling� next calculations were performed with FREE option
9999 6th International Seminar on Flame Structure 14-17 Sept 2008
0,000,000,000,00
0,020,020,020,02
0,040,040,040,04
0000 0,10,10,10,1 0,20,20,20,2 0,30,30,30,3
Mole fraction
Mole fraction
Mole fraction
Mole fraction
Distance from the burner surface (cm)Distance from the burner surface (cm)Distance from the burner surface (cm)Distance from the burner surface (cm)
CH4 profile calculated with "FREE" option
CH4 profile calculated with "BURN" option
Experimental
- To analyse flame structures of methane/air + additives
Numerical
---- To check the accuracy of the different mechanismsTo check the accuracy of the different mechanismsTo check the accuracy of the different mechanismsTo check the accuracy of the different mechanisms
- To study the influence of CO and H O additions on adiabatic- To study the influence of CO2 and H2O additions on adiabatictemperature 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
10101010 6th International Seminar on Flame Structure 14-17 Sept 2008
Experimental/modelling comparison
ΦΦΦΦ = 0.7= 0.7= 0.7= 0.7
0,000,000,000,00
0,020,020,020,02
0,040,040,040,04
0,060,060,060,06
0,080,080,080,08
Mole fraction
Mole fraction
Mole fraction
Mole fraction
CHCHCHCHCHCHCHCH44444444
CHCHCHCH4444/air/air/air/air
Experimental profile
UCSD
Dagaut
GRI-Mech 3.0
0,000,000,000,00
0,020,020,020,02
0,040,040,040,04
0,060,060,060,06
0,080,080,080,08
0,00,00,00,0 0,10,10,10,1 0,20,20,20,2 0,30,30,30,3
Mole fraction
Mole fraction
Mole fraction
Mole fraction
Distance Distance Distance Distance fromfromfromfrom the the the the burnerburnerburnerburner surface (cm)surface (cm)surface (cm)surface (cm)
0,000,000,000,00
0,00,00,00,0 0,10,10,10,1 0,20,20,20,2 0,30,30,30,3
Distance Distance Distance Distance fromfromfromfrom the the the the burnerburnerburnerburner surface (cm)surface (cm)surface (cm)surface (cm)
11111111 6th International Seminar on Flame Structure 14-17 Sept 2008
CHCHCHCH4444/CO/CO/CO/CO2222/air/air/air/air
CHCHCHCHCHCHCHCH44444444
GDFkin ® 3.0
0,000,000,000,00
0,020,020,020,02
0,040,040,040,04
0,060,060,060,06
0,080,080,080,08
0,00,00,00,0 0,10,10,10,1 0,20,20,20,2 0,30,30,30,3
Mole fraction
Mole fraction
Mole fraction
Mole fraction
Distance Distance Distance Distance fromfromfromfrom the the the the burnerburnerburnerburner surface (cm)surface (cm)surface (cm)surface (cm)
CHCHCHCH4444/H/H/H/H2222O/airO/airO/airO/air
CHCHCHCHCHCHCHCH44444444
0,000,000,000,00
0,010,010,010,01
0,020,020,020,02
Mole fraction
Mole fraction
Mole fraction
Mole fraction
CHCHCHCH4444/air/air/air/air
COCOCOCOCOCOCOCO
ΦΦΦΦ = 0.7= 0.7= 0.7= 0.7
Experimental/modelling comparison
Experimental profile
UCSD
Dagaut
GRI-Mech 3.0
0,00,00,00,0 0,10,10,10,1 0,20,20,20,2 0,30,30,30,3
Distance Distance Distance Distance fromfromfromfrom the the the the burnerburnerburnerburner surface (cm)surface (cm)surface (cm)surface (cm)
0,000,000,000,00
0,010,010,010,01
0,020,020,020,02
0,00,00,00,0 0,10,10,10,1 0,20,20,20,2 0,30,30,30,3
Mole fraction
Mole fraction
Mole fraction
Mole fraction
Distance Distance Distance Distance fromfromfromfrom the the the the burnerburnerburnerburner surface (cm)surface (cm)surface (cm)surface (cm)
12121212
CHCHCHCH4444/CO/CO/CO/CO2222/air/air/air/air
6th International Seminar on Flame Structure 14-17 Sept 2008
CHCHCHCH4444/H/H/H/H2222O/airO/airO/airO/air
COCOCOCOCOCOCOCO
0,000,000,000,00
0,010,010,010,01
0,020,020,020,02
0,00,00,00,0 0,10,10,10,1 0,20,20,20,2 0,30,30,30,3
Mole fraction
Mole fraction
Mole fraction
Mole fraction
Distance Distance Distance Distance fromfromfromfrom the the the the burnerburnerburnerburner surface (cm)surface (cm)surface (cm)surface (cm)
COCOCOCOCOCOCOCO
CHCHCHCH4444/H/H/H/H2222O/airO/airO/airO/air
GDFkin ® 3.0
0,E+000,E+000,E+000,E+00
2,E2,E2,E2,E----04040404
4,E4,E4,E4,E----04040404
6,E6,E6,E6,E----04040404
8,E8,E8,E8,E----04040404
Mole fraction
Mole fraction
Mole fraction
Mole fraction
CHCHCHCH4444/air/air/air/air
CCCCCCCC22222222HHHHHHHH44444444
Experimental/modelling comparison
Experimental profile
UCSD
Dagaut
GRI-Mech 3.0
ΦΦΦΦ = 0.7= 0.7= 0.7= 0.7
0,E+000,E+000,E+000,E+00
0,00,00,00,0 0,10,10,10,1 0,20,20,20,2 0,30,30,30,3
Distance Distance Distance Distance fromfromfromfrom the the the the burnerburnerburnerburner surface (cm)surface (cm)surface (cm)surface (cm)
0,E+000,E+000,E+000,E+00
2,E2,E2,E2,E----04040404
4,E4,E4,E4,E----04040404
6,E6,E6,E6,E----04040404
8,E8,E8,E8,E----04040404
0,00,00,00,0 0,10,10,10,1 0,20,20,20,2 0,30,30,30,3
Mole fraction
Mole fraction
Mole fraction
Mole fraction
Distance Distance Distance Distance fromfromfromfrom the the the the burnerburnerburnerburner surface (cm)surface (cm)surface (cm)surface (cm)
13131313 6th International Seminar on Flame Structure 14-17 Sept 2008
CHCHCHCH4444/CO/CO/CO/CO2222/air/air/air/air
CCCCCCCC22222222HHHHHHHH44444444
GDFkin ® 3.0
0,0E+000,0E+000,0E+000,0E+00
2,0E2,0E2,0E2,0E----04040404
4,0E4,0E4,0E4,0E----04040404
6,0E6,0E6,0E6,0E----04040404
8,0E8,0E8,0E8,0E----04040404
0,00,00,00,0 0,10,10,10,1 0,20,20,20,2 0,30,30,30,3
Mole fraction
Mole fraction
Mole fraction
Mole fraction
Distance Distance Distance Distance fromfromfromfrom the the the the burnerburnerburnerburner surface (cm)surface (cm)surface (cm)surface (cm)
CHCHCHCH4444/H/H/H/H2222O/airO/airO/airO/air
CCCCCCCC22222222HHHHHHHH44444444
0,000,000,000,00
0,040,040,040,04
0,080,080,080,08
0,120,120,120,12
Mole fraction
Mole fraction
Mole fraction
Mole fraction
CHCHCHCH4444/air/air/air/airΦΦΦΦ = 1.4= 1.4= 1.4= 1.4
Experimental profile
UCSD
Dagaut
GRI-Mech 3.0
CHCHCHCHCHCHCHCH44444444
Experimental/modelling comparison
0,000,000,000,00
0,040,040,040,04
0,080,080,080,08
0,120,120,120,12
0,00,00,00,0 0,10,10,10,1 0,20,20,20,2 0,30,30,30,3
Mole fraction
Mole fraction
Mole fraction
Mole fraction
Distance Distance Distance Distance fromfromfromfrom the the the the burnerburnerburnerburner surface (cm)surface (cm)surface (cm)surface (cm)
0,000,000,000,00
0,040,040,040,04
0,080,080,080,08
0,120,120,120,12
0,00,00,00,0 0,10,10,10,1 0,20,20,20,2 0,30,30,30,3
Mole fraction
Mole fraction
Mole fraction
Mole fraction
Distance Distance Distance Distance fromfromfromfrom the the the the burnerburnerburnerburner surface (cm)surface (cm)surface (cm)surface (cm)
0,000,000,000,00
0,00,00,00,0 0,10,10,10,1 0,20,20,20,2 0,30,30,30,3
Distance Distance Distance Distance fromfromfromfrom the the the the burnerburnerburnerburner surface (cm)surface (cm)surface (cm)surface (cm)
14141414
CHCHCHCH4444/H/H/H/H2222O/airO/airO/airO/air
6th International Seminar on Flame Structure 14-17 Sept 2008
CHCHCHCH4444/CO/CO/CO/CO2222/air/air/air/air
GDFkin ® 3.0
CHCHCHCHCHCHCHCH44444444CHCHCHCHCHCHCHCH44444444
0,000,000,000,00
0,020,020,020,02
0,040,040,040,04
0,060,060,060,06
0,080,080,080,08
0,100,100,100,10
Mole fraction
Mole fraction
Mole fraction
Mole fraction
CHCHCHCH4444/air/air/air/air ΦΦΦΦ = 1.4= 1.4= 1.4= 1.4
Experimental profile
UCSD
Dagaut
GRI-Mech 3.0
COCOCOCOCOCOCOCO
Experimental/modelling comparison
0,000,000,000,00
0,00,00,00,0 0,10,10,10,1 0,20,20,20,2 0,30,30,30,3
Distance Distance Distance Distance fromfromfromfrom the the the the burnerburnerburnerburner surface (cm)surface (cm)surface (cm)surface (cm)
0,000,000,000,00
0,020,020,020,02
0,040,040,040,04
0,060,060,060,06
0,080,080,080,08
0,100,100,100,10
0,00,00,00,0 0,10,10,10,1 0,20,20,20,2 0,30,30,30,3
Mole fraction
Mole fraction
Mole fraction
Mole fraction
Distance Distance Distance Distance fromfromfromfrom the the the the burnerburnerburnerburner surface (cm)surface (cm)surface (cm)surface (cm)
0,000,000,000,00
0,020,020,020,02
0,040,040,040,04
0,060,060,060,06
0,080,080,080,08
0,100,100,100,10
0,00,00,00,0 0,10,10,10,1 0,20,20,20,2 0,30,30,30,3
Mole fraction
Mole fraction
Mole fraction
Mole fraction
Distance Distance Distance Distance fromfromfromfrom the the the the burnerburnerburnerburner surface (cm)surface (cm)surface (cm)surface (cm)
15151515 6th International Seminar on Flame Structure 14-17 Sept 2008
CHCHCHCH4444/H/H/H/H2222O/airO/airO/airO/airCHCHCHCH4444/CO/CO/CO/CO2222/air/air/air/air
GDFkin ® 3.0
COCOCOCOCOCOCOCO COCOCOCOCOCOCOCO
0,0E+000,0E+000,0E+000,0E+00
1,0E1,0E1,0E1,0E----03030303
2,0E2,0E2,0E2,0E----03030303
3,0E3,0E3,0E3,0E----03030303
Mole fraction
Mole fraction
Mole fraction
Mole fraction
CHCHCHCH4444/air/air/air/air ΦΦΦΦ = 1.4= 1.4= 1.4= 1.4
Experimental profile
UCSD
Dagaut
GRI-Mech 3.0
CCCCCCCC22222222HHHHHHHH44444444
Experimental/modelling comparison
0,0E+000,0E+000,0E+000,0E+00
0,00,00,00,0 0,10,10,10,1 0,20,20,20,2 0,30,30,30,3
Distance Distance Distance Distance fromfromfromfrom the the the the burnerburnerburnerburner surface (cm)surface (cm)surface (cm)surface (cm)
0,0E+000,0E+000,0E+000,0E+00
1,0E1,0E1,0E1,0E----03030303
2,0E2,0E2,0E2,0E----03030303
3,0E3,0E3,0E3,0E----03030303
0,00,00,00,0 0,10,10,10,1 0,20,20,20,2 0,30,30,30,3
Mole fraction
Mole fraction
Mole fraction
Mole fraction
Distance Distance Distance Distance fromfromfromfrom the the the the burnerburnerburnerburner surface (cm)surface (cm)surface (cm)surface (cm)
0,0E+000,0E+000,0E+000,0E+00
1,0E1,0E1,0E1,0E----03030303
2,0E2,0E2,0E2,0E----03030303
3,0E3,0E3,0E3,0E----03030303
0,00,00,00,0 0,10,10,10,1 0,20,20,20,2 0,30,30,30,3
Mole fraction
Mole fraction
Mole fraction
Mole fraction
Distance Distance Distance Distance fromfromfromfrom the the the the burnerburnerburnerburner surface (cm)surface (cm)surface (cm)surface (cm)
16161616 6th International Seminar on Flame Structure 14-17 Sept 2008
CHCHCHCH4444/H/H/H/H2222O/airO/airO/airO/airCHCHCHCH4444/CO/CO/CO/CO2222/air/air/air/air
GDFkin ® 3.0
CCCCCCCC22222222HHHHHHHH44444444 CCCCCCCC22222222HHHHHHHH44444444
Experimental
- To analyse flame structures of methane/air + additives
Numerical
- To check the accuracy of the different mechanisms
---- To study the influence of COTo study the influence of COTo study the influence of COTo study the influence of CO and Hand Hand Hand H O additions on adiabaticO additions on adiabaticO additions on adiabaticO additions on adiabatic---- To study the influence of COTo study the influence of COTo study the influence of COTo study the influence of CO2222 and Hand Hand Hand H2222O additions on adiabaticO additions on adiabaticO additions on adiabaticO additions on adiabatictemperature and flame velocity temperature and flame velocity temperature and flame velocity 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
17171717 6th International Seminar on Flame Structure 14-17 Sept 2008
Temperature profiles
Φ = 0.7
0000
500500500500
1 0001 0001 0001 000
1 5001 5001 5001 500
2 0002 0002 0002 000
Temperature
Temperature
Temperature
Temperature(K)
(K)
(K)
(K)
Φ = 1.4
0000
500500500500
1000100010001000
1500150015001500
2000200020002000
Temperature
Temperature
Temperature
Temperature(K)
(K)
(K)
(K)
UCSD UCSD
0000 0,10,10,10,1 0,20,20,20,2 0,30,30,30,3
Distance Distance Distance Distance fromfromfromfrom the the the the burnerburnerburnerburner surface (cm)surface (cm)surface (cm)surface (cm)
18181818
Burnt gases temperature decreases
Downward shift in diluted flames
6th International Seminar on Flame Structure 14-17 Sept 2008
0000 0,10,10,10,1 0,20,20,20,2 0,30,30,30,3
Distance from the burner surface (cm)Distance from the burner surface (cm)Distance from the burner surface (cm)Distance from the burner surface (cm)
CH4/air CH4/air +CO2 CH4/air +H2O
1700
1725
1750
1775
1800
TT TTmax
max
max
max
CH4/air
+ CO2
+ H2O1 800
1 850
1 900
1 950
2 000
TT TTmax
max
max
max
CH4/air
+ CO2
+ H2O
Flame velocity
10
15
20
25
GRIGRIGRIGRI----Mech 3.0Mech 3.0Mech 3.0Mech 3.0
DagautDagautDagautDagaut
UCSDUCSDUCSDUCSD
GDFkin® 3.0GDFkin® 3.0GDFkin® 3.0GDFkin® 3.0
Φ = 0.7 Φ = 1.4
CH4
CH4/CO2CH4/H2O CH4
CH /COCH4/H2O
-16%-20%
19191919
Some scatters observed especially in rich flames but same tendencies with both diluents
Additive concentration higher in the rich flames
6th International Seminar on Flame Structure 14-17 Sept 2008
0
5-38%
CH4/CO2
CH4/H2O
-25%Experimental Experimental Experimental Experimental datadatadatadata
Experimental data : Stone et al. Combust. Flame 114:546-555 (1998)
Experimental
- To analyse flame structures of methane/air + additives
Numerical
- To check the accuracy of the different mechanisms
- To study the influence of CO and H O additions on adiabatic- To study the influence of CO2 and H2O additions on adiabatictemperature and flame velocity
---- To analyse the chemical effects of COTo analyse the chemical effects of COTo analyse the chemical effects of COTo analyse the chemical effects of CO2222 and Hand Hand Hand H2222OOOO
- To study the influence of CO2 and H2O contents in EGR for the determination of the flame velocity
20202020 6th International Seminar on Flame Structure 14-17 Sept 2008
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 thanCO2 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 16.5 17.6 17.7
Flame velocity (cm/s) Φ=1.4 16.0 10.1 9.7 10.5 11.0
21212121
� Small decrease with normal CO2 -> inhibiting effectSmall increase with normal H2O -> promoting effect
----0.30.30.30.3
----0.40.40.40.4
+0.1+0.1+0.1+0.1
+0.5+0.5+0.5+0.5
6th International Seminar on Flame Structure 14-17 Sept 2008
2 2
UCSD computation
Inhibiting effect of CO2 :
CO2 + H � CO + OH� reduces the rate of the branching reaction H+O2 � OH+O
Chemical influence of CO2 and H2O
Promoting effect of H O :
22222222 6th International Seminar on Flame Structure 14-17 Sept 2008
Promoting effect of H2O :
H2O + H � H2 + OH� converts H2O into H2
Experimental
- To analyse flame structures of methane/air + additives
Numerical
- To check the accuracy of the different mechanisms
- To study the influence of CO and H O additions on adiabatic- To study the influence of CO2 and H2O additions on adiabatictemperature and flame velocity
- To analyse the chemical effects of CO2 and H2O
---- To study the influence of COTo study the influence of COTo study the influence of COTo study the influence of CO2222 and Hand Hand Hand H2222O contents in EGR for the O contents in EGR for the O contents in EGR for the O contents in EGR for the determination of the flame velocitydetermination of the flame velocitydetermination of the flame velocitydetermination of the flame velocity
23232323 6th International Seminar on Flame Structure 14-17 Sept 2008
� Addition of N2, CO2/N2, H2O/N2, EGR
Lean flame
Influence of CO2 and H2O additions in EGR
stoechiometric and rich flames
EGR composition :
24242424
CO2 : 6.6%H2O : 13.4%N2 : 74%O2 : 6%
6th International Seminar on Flame Structure 14-17 Sept 2008
CO2 : 9.5% H2O : 19%N2 : 71.5%
Influence of CO2 and H2O additions in EGR
30303030
40404040
speed (cm/s)
speed (cm/s)
speed (cm/s)
speed (cm/s)
EGREGREGREGR
COCOCOCO2222----NNNN2222
HHHH2222OOOO----NNNN2222
NNNN2222
ΦΦΦΦ=1.0=1.0=1.0=1.0N2 CO2-N2 H2O-N2 EGR
25252525 6th International Seminar on Flame Structure 14-17 Sept 2008
0000
10101010
20202020
0000 10101010 20202020 30303030
Flame
Flame
Flame
Flamespeed (cm/s)
speed (cm/s)
speed (cm/s)
speed (cm/s)
% % % % additiveadditiveadditiveadditive
ΦΦΦΦ=1.0=1.0=1.0=1.0
ΦΦΦΦ=0.7=0.7=0.7=0.7ΦΦΦΦ=1.4=1.4=1.4=1.4
N2 CO2-N2 H2O-N2 EGR
φ = 0.7 -42 -48 -45 -4620% EGR
φ = 1.0 -44 -55 -47 -50
φ = 1.4 -35 -42 -35 -37 8% EGR
Flame speed decrease (%)
Results computed with UCSD mechanism
Influence of CO2 and H2O additions in EGR
30303030
40404040
speed (cm/s)
speed (cm/s)
speed (cm/s)
speed (cm/s)
EGREGREGREGR
COCOCOCO2222----NNNN2222
HHHH2222OOOO----NNNN2222
NNNN2222
ΦΦΦΦ=1.0=1.0=1.0=1.0N2 CO2-N2 H2O-N2 EGR
26262626 6th International Seminar on Flame Structure 14-17 Sept 2008
0000
10101010
20202020
0000 10101010 20202020 30303030
Flame
Flame
Flame
Flamespeed (cm/s)
speed (cm/s)
speed (cm/s)
speed (cm/s)
% % % % additiveadditiveadditiveadditive
ΦΦΦΦ=1.0=1.0=1.0=1.0
ΦΦΦΦ=0.7=0.7=0.7=0.7ΦΦΦΦ=1.4=1.4=1.4=1.4
N2 CO2-N2 H2O-N2 EGR
φ = 0.7 -42 -48 -45 -4620% EGR
φ = 1.0 -44 -55 -47 -50
φ = 1.4 -35 -42 -35 -37 8% EGR
Flame speed decrease (%)
Results computed with UCSD mechanism
Presence of H2O in burnt gases must be taken into account for more accurate flame modelling with EGR
Chemical influence of CO2 and H2O
Chemical inhibition effect of CO2
Promoting effect of H O
Experimental study of lean and rich methane/air flames with addition of CO2 and H2O
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2
Promoting effect of H2O
6th International Seminar on Flame Structure 14-17 Sept 2008
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
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