Numerical simulation of premixed methanol combustion characteristics in a swirl burner

Burner pollutant emissions are a significant source of atmospheric nitrogen oxides (NO x ), posing an ongoing challenge for low-NO x design. This study uses Fluent software to numerically simulate a methanol sleeve-type swirl burner, employing the eddy-dissipation concept (EDC) combustion model and a detailed chemical reaction mechanism. This study examines the influence of swirl angle and excess air ratio on burner thermal performance, with particular emphasis on NO x /CO emissions and velocity–temperature field synergy angle within the burner through application of the field synergy principle. Our results show that the field synergy angle exhibits a nonmonotonic trend (initial decrease followed by an increase) as the swirl angle increases, a trend that strongly correlates with the observed variations in NO x and CO emissions. Furthermore, an increased swirl angle significantly improves exhaust gas temperature uniformity. While higher excess air in the premixed gas effectively reduces NO x , it concurrently increases CO emissions, lowers combustion efficiency, and has minimal impact on field synergy angle. Therefore, for an effective low-NO x burner design, optimizing the field synergy angle is crucial for controlling NO x formation rather than solely relying on increasing the excess air ratio. This study presents novel insights for the design and optimization of low-NO x methanol-air premixed gas burners. Result:Numerical results demonstrate that an optimal swirl angle of 35° minimizes NO x /CO emissions by achieving the best velocity-temperature field synergy, which promotes uniform combustion and inhibits high-temperature zones. Furthermore, while increasing the excess air ratio reduces NO x emissions, it concurrently raises CO levels due to suppressed combustion temperatures. The field synergy angle is primarily governed by the swirl angle and remains largely unaffected by the excess air ratio.