Numerical study on effect of CO2 addition in flame structure and NOx formation of CH4-air counterflow diffusion flames

2001 ◽  
Vol 25 (4) ◽  
pp. 343-354 ◽  
Author(s):  
C. E. Lee ◽  
S. R. Lee ◽  
J. W. Han ◽  
J. Park
Keyword(s):  
Diffusion Flames ◽  
Numerical Study ◽  
Flame Structure ◽  
Nox Formation ◽  
Counterflow Diffusion Flames ◽  
Co2 Addition

Chemical effects of CO2 addition to oxidizer and fuel streams on flame structure in H2-O2 counterflow diffusion flames

2003 ◽  
Vol 27 (13) ◽  
pp. 1205-1220 ◽  
Author(s):  
Jeong Park ◽  
Dong-Jin Hwang ◽  
Jong-Geun Choi ◽  
Kee-Man Lee ◽  
Sang-In Keel ◽  
...  
Keyword(s):  
Diffusion Flames ◽  
Flame Structure ◽  
Counterflow Diffusion Flames ◽  
Chemical Effects ◽  
Co2 Addition

scholarly journals A Numerical Investigation of NOx Formation in Counterflow CH4/H2/Air Diffusion Flames

2006 ◽  
Author(s):  
Hongsheng Guo ◽  
Stuart W. Neill ◽  
Gregory J. Smallwood
Keyword(s):  
Diffusion Flames ◽  
Numerical Study ◽  
Flame Structure ◽  
Pure Hydrogen ◽  
No Emission ◽  
Nox Formation ◽  
No Formation ◽  
Hydrogen Enrichment ◽  
Air Diffusion ◽  
Emission Index

A detailed numerical study was carried out for the effect of hydrogen enrichment on flame structure and NOx formation in counterflow CH4/air diffusion flames. Detailed chemistry and complex thermal and transport properties were employed. The enrichment fraction was changed from 0 (pure CH4) to 1.0 (pure H2). The result indicates that for flames with low to moderate stretch rates, with the increase of the enrichment fraction from 0 to 0.5~0.6, NO emission index keeps almost constant or only slightly increases. When the enrichment fraction is increased from 0.5~0.6 to about 0.9, NO emission index quickly increases, and finally NO formation decreases again when pure hydrogen flame condition is approached. However, for flames with higher stretch rates, with the increase of hydrogen enrichment fraction from 0 to 1.0, the formation of NO first quickly increases, then slightly decreases and finally increases again. Detailed analysis suggests that the variation of the characteristics in NO formation in stretched CH4/air diffusion flames is caused by the change of flame structure and NO formation mechanism, when the enrichment fraction and stretch rate are changed.

scholarly journals A computational study of soot formation and flame structure of coflow laminar methane/air diffusion flames under microgravity and normal gravity

2021 ◽  
Author(s):  
Armin Veshkini ◽  
Seth B. Dworkin
Keyword(s):  
Normal Gravity ◽  
Volume Fraction ◽  
Diffusion Flames ◽  
Soot Formation ◽  
Numerical Study ◽  
Computational Study ◽  
Flame Structure ◽  
Chemical Kinetic ◽  
Surface Growth ◽  
Rate Of Increase

A numerical study is conducted of methane-air coflow diffusion flames at microgravity (μg) and normal gravity (lg), and comparisons are made with experimental data in the literature. The model employed uses a detailed gas phase chemical kinetic mechanism that includes PAH formation and growth, and is coupled to a sectional soot particle dynamics model. The model is able to accurately predict the trends observed experimentally with reduction of gravity without any tuning of the model for different flames. The microgravity sooting flames were found to have lower temperatures and higher volume fraction than their normal gravity counterparts. In the absence of gravity, the flame radii increase due to elimination of buoyance forces and reduction of flow velocity, which is consistent with experimental observations. Soot formation along the wings is seen to be surface growth dominated, while PAH condensation plays a more major role on centerline soot formation. Surface growth and PAH growth increase in microgravity primarily due to increases in the residence time inside the flame. The rate of increase of surface growth is more significant compared to PAH growth, which causes soot distribution to shift from the centerline of the flame to the wings in microgravity. Keywords: laminar diffusion flame,methane-air,microgravity, soot formation, numerical modelling

Experimental and numerical study of transient laminar counterflow diffusion flames

1993 ◽  
Vol 29 (3) ◽  
pp. 311-315 ◽  
Author(s):  
F. Aguerre ◽  
N. Darabiha ◽  
J. C. Rolon ◽  
S. Candel
Keyword(s):  
Diffusion Flames ◽  
Numerical Study ◽  
Counterflow Diffusion Flames

Numerical study of the effects of radiative heat losses on diffusion flames

2006 ◽  
Vol 220 (8) ◽  
pp. 1189-1199
Author(s):  
M D Gaustad ◽  
T Shamim
Keyword(s):  
Radiation Effects ◽  
Diffusion Flames ◽  
Numerical Study ◽  
Flame Structure ◽  
Combustion Products ◽  
Chemical Mechanism ◽  
Strain Rates ◽  
Detailed Chemistry ◽  
Extinction Limit ◽  
Radiative Losses

The effects of thermal radiation are numerically investigated for a methane-air counterflow diffusion flame, using ‘detailed’ chemistry. The radiative losses from combustion products (CO2 and H2O) were considered by using a thin gas approximation. The results show a significant effect of radiative losses causing extinction at low strain rates. On the basis of the radiative losses from gaseous combustion products, an extinction limit was found to be 0.7 s−1. The presence of soot will move this limit to higher strain rates. The radiation effects are relatively less at moderate and high strain rates, where they may cause a reduction in the peak temperatures by ∼ 10 per cent. In addition to decreasing peak temperatures and combustion products, the radiative losses also reduce the flame width. The results show the importance of including detailed chemical mechanism in correctly predicting the extinction limit and the influence of radiative losses on flame structure.

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