Development of combustion strategy for the internal combustion engine fueled by ammonia and its operating characteristics

Focusing on the possibility of using ammonia as a hydrogen carrier, a combustion strategy for pure ammonia as an engine fuel to convert the stored energy into a usable form has been proposed, which uses ammonia itself as a combustion promotor. Under this strategy, the conditions of sufficiently high temperature and pressure to cause the spray combustion of ammonia are obtained by the auto-ignition of a mixture of pilot-injected ammonia and air. To confirm the feasibility and the operating characteristics of an engine with the proposed ammonia combustion strategy, engine modeling has been conducted, the combustion strategy has been simulated, and a parametric study has been performed. To analyze the NO production mechanisms in an engine with the proposed combustion strategy, the NO production process has been classified into four phases, and the NO production in each phase has been analyzed under various start of injection timing and fuel amounts.