The formation of NO and NO2 are sensitive indicators of both temperature and residence time. In this work, the NOx emission index is measured in an unsteady counterflow diffusion flame for methane, propane and ethylene, as a function of average strain rate and amplitude and frequency of imposed sinusoidal oscillation. The flames studied vary from non-sooting to high soot loading, and from low average strain rate to near extinction. Due to the relatively long time scales associated with NOx formation, the effect of unsteadiness on emission index is weaker than on either temperature or soot volume fraction. Time average global measurements were taken using a California Analytical Instruments Model 400 HCLD NO/NOx analyzer. Results are compared with unsteady calculations using a modified OPPDIF code included in the Chemkin package.

Keywords: Counterflow diffusion flames Nox.

Combustion technology has traditionally been dominated by air/fuel combustion. However, two developments have increased the significance of oxygen-enhanced combustion - new technology producing oxygen less expensively and the increased importance of environmental regulations. Advantages of oxygen-enhanced combustion include numerous environmental benefits as well as increased energy efficiency and productivity. The text compiles information about using oxygen to enhance high temperature industrial heating and melting processes - serving as a unique resource for specialists implementing the use of oxygen in combustion systems; combustion equipment and industrial gas suppliers; researchers; funding agencies for advanced combustion technologies; and agencies developing regulations for safe, efficient, and environmentally friendly combustion systems. Oxygen-Enhanced Combustion: Examines the fundamentals of using oxygen in combustion, pollutant emissions, oxygen production, and heat transfer Describes ferrous and nonferrous metals, glass, and incineration Discusses equipment, safety, design, and fuels Assesses recent trends including stricter environmental regulations, lower-cost methods of producing oxygen, improved burner designs, and increasing fuel costs Emphasizing applications and basic principles, this book will act as the primary resource for mechanical, chemical, aerospace, and environmental engineers and scientists; physical chemists; fuel technologists; fluid dynamists; and combustion design engineers. Topics include: General benefits Economics Potential problems Pollutant emissions Oxygen production Adsorption Air separation Heat transfer Ferrous metals Melting and refining processes Nonferrous metals Minerals Glass furnaces Incineration Safety Handling and storage Equipment design Flow controls Fuels