Effects of Coaxial Air on Nitrogen-Diluted Hydrogen Jet Diffusion Flame Length and NOx Emission

Conference · Mon Oct 01 04:00:00 EDT 2007

OSTI ID:933152

Weiland, N T; Chen, R -H; Strakey, P A

Turbulent nitrogen-diluted hydrogen jet diffusion flames with high velocity coaxial air flows are investigated for their NOx emission levels. This study is motivated by the DOE turbine program’s goal of achieving 2 ppm dry low NOx from turbine combustors running on nitrogen-diluted high-hydrogen fuels. In this study, effects of coaxial air velocity and momentum are varied while maintaining low overall equivalence ratios to eliminate the effects of recirculation of combustion products on flame lengths, flame temperatures, and resulting NOx emission levels. The nature of flame length and NOx emission scaling relationships are found to vary, depending on whether the combined fuel and coaxial air jet is fuel-rich or fuel-lean. In the absence of differential diffusion effects, flame lengths agree well with predicted trends, and NOx emissions levels are shown to decrease with increasing coaxial air velocity, as expected. Normalizing the NOx emission index with a flame residence time reveals some interesting trends, and indicates that a global flame strain based on the difference between the fuel and coaxial air velocities, as is traditionally used, is not a viable parameter for scaling the normalized NOx emissions of coaxial air jet diffusion flames.

• Research Organization: National Energy Technology Laboratory (NETL), Pittsburgh, PA, Morgantown, WV, and Albany, OR
• Sponsoring Organization: USDOE - Office of Fossil Energy (FE)
• OSTI ID: 933152
• Report Number(s): DOE/NETL-IR-2008-016; NETL-TPR-1926
• Country of Publication: United States
• Language: English

Related Subjects

08 HYDROGEN
AIR FLOW
COMBUSTION
COMBUSTION PRODUCTS
COMBUSTION PROPERTIES
COMBUSTORS
DIFFUSION
FLAMES
HYDROGEN
STRAINS
TURBINES
VELOCITY