Study on Combustion Characteristics of Hydrogen Addition on Ammonia Flame at a Porous Burner

Abstract

In this study, the effects of pure ammonia combustion and hydrogen addition on ammonia combustion in a porous burner were investigated by numerical simulation to realize the practical application of ammonia as a fuel. The effects of porous burner parameters, hydrogen addition ratio and equivalence ratio on ammonia flame characteristics, temperature distribution and NO formation characteristics have been evaluated. The results show that stable flames can be achieved when the inlet velocity varied from 3 to 7m / s and the equivalence ratio from 0.9 to 1.2 for pure ammonia flame. With the increase of thermal conductivity and pore density of porous media, the peak temperature of ammonia flame decreases and the flame position moves upstream. The combustion temperature of ammonia flame increases with the increase of hydrogen addition ratio. However, rarely N element in the fuel is converted to NO in pure ammonia and ammonia/hydrogen flames. The dominant N element in the fuel is converted to N 2 , and the conversion ratio is as high as 88.16% ~ 98.57%. The conversion ratio of N element in the fuel converted to NO is less than 0.05% at the equivalence ratio of 1.20.­­­­­

Keywords: Ammonia flame, hydrogen addition, porous burner, Equivalence ratio, NO emission