암모니아 질량분율에 따른 암모니아/디젤 이중 연료 엔진의 실린더 내 온도 및 화학종 변화

초록

This study numerically investigated the combustion and emission characteristics of an ammonia/diesel dual-fuel engine using three-dimensional computational fluid dynamics. Ammonia was premixed with air, while n-dodecane was directly injected as a diesel surrogate fuel. After validating the baseline model against measured in-cylinder pressure and heat release rate, the ammonia mass fraction was varied from 0% to 25% under a constant total fuel mass. Increasing the ammonia fraction reduced the peak pressure, heat release rate, and maximum mean temperature, while delaying combustion. The fuel-normalized CO2 mass decreased nearly in proportion to the reduction in carbon input, whereas residual NH3 at exhaust valve opening (EVO) increased with ammonia fraction and was concentrated near low-temperature wall and crevice regions. Despite the lower mean temperature, the peak fuel-normalized nitric oxide (NO) mass increased at higher ammonia fractions and subsequently decreased more strongly during the late combustion period. These findings demonstrate the potential of ammonia co-firing to reduce carbon-based emissions, while highlighting the need to control residual NH3 and NO through optimized combustion strategies.

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