Characteristics of Nitrogen Oxide Produced in Counterflow Non-Premixed Flames of Diesel Fuel Surrogate and Ammonia Mixture

Numerical analysis was performed on the production of nitrogen oxides in a counter-flow non-premixed flame of fuel in which a diesel fuel surrogate and ammonia were mixed. Addition of ammonia, which has a lower calorific value than that of diesel fuel surrogate, lowers the flame temperature and narrows the flame width. The oxygen enrichment rate on the oxidizer side changes the rate of ammonia addition on the fuel side. However, it has little effect on the NO emission index. In flames containing ammonia, an increase in strain rate decreases the flame temperature. This results in a high NO emission index. Therefore, in the combustion of ammonia with fuel-origin NO production, the strain rate becomes an important factor in NO production.