NO_x Formation in H₂-CH₄ Blended Flame Under MILD Conditions

Abstract

In this article, NO production mechanisms for CH₄-H₂ combustion under MILD (moderate or intense low-oxygen dilution) conditions are studied using CDF and also zero-dimensional well stirred reactor (WSR) analysis. A H₂/CH₄ jet into a heated and diluted coflow is modeled in CFD analysis. The RANS equations with modified _k − ϵ equations are solved in an axisymmetric 2D computational domain. The GRI2.11 full mechanism is considered to represent the chemical reactions. The effects of oxidizer oxygen concentration, fuel hydrogen content, and fuel jet Reynolds number are studied on NO formation reactions. Results show that the measurements are predicted with an acceptable accuracy. The NNH and N₂O routes are the most important pathways in NO formation under MILD conditions. An increase in oxidizer O₂concentration or decrease in fuel hydrogen content addressesthe decrease in importance of the mentioned NO formation routes.

Keywords:

• CFD
• Hydrogen
• Methane
• MILD
• Non-premixed
• NO_x

Notes

Published as part of the Seventh Mediterranean Combustion Symposium Special Issue with Guest Editors Federico Beretta, Nevin Selçuk, Mohy S. Mansour, and Andrea D'Anna.