Entrainment effects on combustion and emission characteristics of turbulent non-premixed ammonia/air and methane/air swirl flames through a developed perforated burner

Abstract

A fuel/oxidizer mixture can be burned using a colourless distributed combustion (CDC) process to obtain low emissions and homogeneous combustion. As an alternative way, a perforated burner can be designed to achieve homogeneous combustion and low emissions without changing the combustion performance by having entrainment effects on the combustion chamber. In this study, computational fluid dynamics (CFD) 3D modelling was performed in a perforated burner for ammonia/methane fuels in order to obtain the distributed regime and focus on the entrainment effects. In numerical analysis, the eddy break-up was used as combustion model, k-Ɛ as turbulence model, and P-1 as radiation model. In this study, 10% and 20% entrainment rates were provided from the flame holder wall of the perforated burner. The effects of entrainment rates on temperature, velocity, and NOX emission values were examined. According to the results, when the entrainment rate was increased from 10% to 20%, the overall temperature values of ammonia and methane combustion slightly increased by approximately 1.0%, while on the other hand the maximum temperature levels in the near burner zone decreased by about 5.0%. The findings demonstrated that temperature and velocity distributions got more uniform and the flame zones became thinner. This provided a more colourless and invisible flame appearance. In this way, an improvement in the thermal field has been achieved. In conclusion, when the effect of the distributed regime on NOX emission levels was examined, it has been noted that entrainment effects enable the achievement of low emission levels (approximately 9.0%).