Jet penetration characteristics and NO combustion emission process of ammonia/methane fuel in a flue gas environment

Abstract

Ammonia is an alternative fuel that has potential in much industrial equipment such as internal combustion engines, gas turbines, and boilers. In the present study, the influence of flue gas on the injection process of ammonia fuel was analyzed for the first time, and the influences of ammonia/methane fuel ratio and equivalence ratio on the diffusion process were considered. A Schlieren system was used to characterize the characteristics of ammonia jet, including tip penetration and jet angle. Meanwhile, the NO emissions during this progress were calculated based on the GRI 3.0 combustion mechanism. The results showed that the penetration distance was affected by both the diffusion effect and the chemical effect. The time evolution of penetration has three stages. The second stage of penetration in the flue gas environment develops faster with the decrease in the equivalence ratio. The increase in jet angle is accelerated by the flue gas environment and a decrease in equivalence ratio. Furthermore, the theoretical results showed that the emission process of NO is mainly affected by the fuel ratio and equivalence ratio. When the equivalence ratio increased from 0.8 to 1.2, NO emissions decreased by 85.7%. The distribution of NO along the axis is also affected by the fuel ratio. When the volume ratio of NH3 to CH4 decreases from 1 to 0.5, the peak value of NO concentration decreases by 29.4%.