Characteristics of NO/NO 2 /N 2 O Formation and Distribution in Ammonia/ n -Heptane Dual-Fuel Spray Combustion under Different Ammonia Concentrations

作者：Weiping Yu, Yi Wei, Dongsheng Dong, Mengni Zhou, Xiaoxiong Mi, Zunhua Zhang, Jiajia Hu, Xiangjie Zhang, Gesheng Li · 发表于：Energy & Fuels · 年份：2024 · DOI：10.1021/acs.energyfuels.4c02035 · 被引用次数：10 · 研究领域：Advanced Combustion Engine Technologies、Catalytic Processes in Materials Science、Combustion and flame dynamics

Ammonia, a zero-carbon fuel, shows promise for replacing fossil fuels in internal combustion engines to reduce the level of CO 2 emissions. Using a dual-fuel model with a pilot diesel spray igniting the ammonia/air mixture is a practical approach for engine applications. However, adding ammonia leads to nitrogen pollutants like NO, NO 2, and N 2 O. This study uses a validated large-eddy simulation model in OpenFOAM to examine ignition and pollutant formation in ammonia/ n -heptane dual-fuel spray combustion at various ammonia concentrations (ϕ NH 3 ). First, the effects of ϕ NH 3 on the ignition of the n -heptane spray are investigated. Competition between ammonia and n -heptane for the OH radical leads to a nonlinear delay in n -heptane spray ignition with rising ϕ NH 3 . This prolonged delay increases the NH 3 mixing time duri n g n -heptane spray combustion, affecting pollutant formation. The total masses of NO, NO 2, and N 2 O increase with the increase of ϕ NH 3 . Furthermore, pollutants presented notable characteristics in spatiotemporal distribution with the effects of turbulence and multistage ignition in the n -heptane spray. NO 2 is concentrated in the n -heptane spray zone of ϕ > 1 and 900–1150 K, followed by N 2 O in the zone of ϕ > 1 and 1150–1500 K. NO distributes on the tip of the n -heptane spray, where the temperature and ϕ are around 2500 K and 1, respectively. Finally, chemical kinetic analyses for NH 3 consumption present intricate interconversion pathways...