Performance improvement, flame control, and NO emission reduction in MILD combustion: The role of magnetic fields in a Jet-Hot Coflow burner

Abstract

Controlling flame, hot reaction zone extension, and NO emission reduction are the main challenges to improve the Moderate or Intense Low oxygen Dilution (MILD) combustion performance. To achieve these challenges, this paper pioneers the investigation of the impact of magnetic fields, a novel and underexplored approach, on MILD combustion performance in a Jet-Hot Coflow burner with flux densities of 0.5T, 1.0T, and 2.0T. Unlike previous works, this study systematically explores the interplay between magnetism and MILD combustion, revealing new possibilities for flame stabilization and emission control. NO formation mechanisms are locally studied in unprecedented detail to discover the dominant mechanisms in critical points, offering new insights into pollutant reduction strategies. Model accuracy is demonstrated by validation with several experimental studies and LES study results. The findings indicate that using magnetic fields enhances MILD combustion performance, regarding the quantitative analysis of MILD quality criteria. Additionally, it forms a vortex by applying the Lorentz force and Joule heating rate to the domain. Consequently, the magnetic field aids in the cold jet length reduction, residence time increment, hot region extension by 178 %, and only a 5 % increment in the average temperature, resulting in decreased NO emission by 90 %. The significant role of temperature and oxygen is identified in the NO formation, as the thermal is the dominant mechanism. The results recommend the magnetic field application for flame control and reducing pollutant emissions in MILD combustion. Ultimately, this research addresses challenges in improving MILD combustion quality and offers strategies for optimizing burner performance.