Experimental investigation of the strain rate field in stretched laminar H2/air diffusion flames

A numerical study was carried out to understand the effect of CO enrichment on flame temperature and NO formation in counterflow CH4/air diffusion flames. The results indicate that when CO is added to the fuel, both flame temperature and NO formation rate are changed due to the variations in adiabatic flame temperature, fuel Lewis number, and chemical reaction. At a low strain rate, the addition of carbon monoxide causes a monotonic decrease in flame temperature and peak NO concentration. However, NO emission index first slightly increases, and then decreases. At a moderate strain rate, the addition of CO has negligible effect on flame temperature and leads to a slight increase in both peak NO concentration and NO emission index, until the fraction of carbon monoxide reaches about 0.7. Then, with a further increase in the fraction of added carbon monoxide, all three quantities quickly decrease. At a high strain rate, the addition of carbon monoxide causes increase in flame temperature and NO formation rate, until a critical carbon monoxide fraction is reached. After the critical fraction, the further addition of carbon monoxide leads to decrease in both flame temperature and NO formation rate.

Download Full-text

00/00973 Chemical response of methane/air diffusion flames to unsteady strain rate

Fuel and Energy Abstracts ◽

10.1016/s0140-6701(00)90950-0 ◽

2000 ◽

Vol 41 (2) ◽

pp. 107

Keyword(s):

Strain Rate ◽

Diffusion Flames ◽

Air Diffusion ◽

Chemical Response

Download Full-text

Chemical response of methane/air diffusion flames to unsteady strain rate

10.2172/671890 ◽

1998 ◽

Author(s):

H.G. Im ◽

J.H. Chen ◽

J.Y. Chen

Keyword(s):

Strain Rate ◽

Diffusion Flames ◽

Air Diffusion ◽

Chemical Response

Download Full-text

Chemical response of methane/air diffusion flames to unsteady strain rate

Combustion and Flame ◽

10.1016/s0010-2180(98)00153-9 ◽

1999 ◽

Vol 118 (1-2) ◽

pp. 204-212 ◽

Cited By ~ 45

Author(s):

Hong G IM ◽

Jacqueline H Chen ◽

Jyh-Yuan Chen

Keyword(s):

Strain Rate ◽

Diffusion Flames ◽

Air Diffusion ◽

Chemical Response

Download Full-text

A Numerical Study on the Effect of CO Addition on Flame Temperature and NO Formation in Counterflow CH4/Air Diffusion Flames

Volume 6: Energy Systems: Analysis, Thermodynamics and Sustainability ◽

10.1115/imece2007-41438 ◽

2007 ◽

Author(s):

Hongsheng Guo ◽

W. Stuart Neill

Keyword(s):

Carbon Monoxide ◽

Strain Rate ◽

Diffusion Flames ◽

Numerical Study ◽

Formation Rate ◽

Flame Temperature ◽

No Emission ◽

No Formation ◽

Air Diffusion ◽

Emission Index

A numerical study was carried out to understand the effect of carbon monoxide enrichment on flame temperature and NO formation in counterflow methane/air diffusion flames. Detailed chemistry and complex thermal and transport properties were employed. The results indicate that when carbon monoxide is added to the fuel, both flame temperature and NO formation rate are changed due to the variations in adiabatic flame temperature, fuel Lewis number and chemical reaction. The combination effects of three factors result in the different characteristics of flame temperature and NO formation at various strain rates, when carbon monoxide is added. At a low strain rate, the addition of carbon monoxide causes a monotonic decrease in flame temperature and peak NO concentration. However, NO emission index first slightly increases, and then decreases. When the value of strain rate is moderate, the addition of carbon monoxide has negligible effect on flame temperature and leads to a slight increase in both peak NO concentration and NO emission index, until the fraction of carbon monoxide reaches about 0.7. Then with a further increase in the fraction of added carbon monoxide, all three quantities quickly decrease. When strain rate is increased to a value close to the strain extinction limit of pure methane/air diffusion flame, the addition of carbon monoxide causes increase in flame temperature and NO formation rate, until a critical carbon monoxide fraction is reached. After the critical fraction, the further addition of carbon monoxide leads to decrease in both flame temperature and NO formation rate. The paper also analyzed the variation in the mechanism of NO formation, when carbon monoxide is added.

Download Full-text