To meet the requirement of reducing greenhouse gas (GHG) emissions, the application of carbon-free fuel ammonia in marine engines has gained importance. However, the use of ammonia as fuel leads to low thermal efficiency and high emissions of pollutants in engines. Increasing the rate of combustion of the fuel mixture in the engine helps to solve this problem. Therefore, the influence of hydrogen volume fraction (XH2) and oxygen volume fraction (XO2) in the main chamber, via numerical simulations, on the combustion and emission characteristics of a marine ammonia engine featuring a pre-chamber. Further analysis was conducted via adjustments in the start of ignition (SOI) to optimize both engine performance and emissions. The results showed that the increase of both XH2 and XO2 contributed to the improvement of indicated thermal efficiency (ITE) and the reduction of N2O emissions. However, this is usually accompanied by higher NOx emissions, especially in the case of high XO2. In addition, adjusting the SOI resulted in the engine ITE is greater than 47.6% in each case and reduces GHG emissions by about 80% (<40 ppm N2O). Finally, chemical kinetic analysis showed that oxygen-enriched or hydrogen-enriched conditions did not change the main reaction pathway.

中文翻译：

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应用强化燃烧策略和优化点火正时实现船用氨发动机满负荷工况高热效率和低N2O排放

为了满足减少温室气体（GHG）排放的要求，无碳燃料氨在船用发动机中的应用越来越重要。然而，使用氨作为燃料导致发动机热效率低、污染物排放高。提高发动机中燃料混合物的燃烧速率有助于解决这个问题。因此，氢气体积分数（X氢2) 和氧气体积分数 (X氧气）在主室中，通过数值模拟，研究具有预燃室的船用氨发动机的燃烧和排放特性。通过调整点火启动 (SOI) 进行进一步分析，以优化发动机性能和排放。结果表明，X 值均增加氢2和 X氧气有助于提高指示热效率 (ITE) 并减少 N2氧气排放。然而，这通常伴随着更高的NOX排放，特别是在高 X 的情况下氧气。此外，调整 SOI 可使发动机 ITE 在每种情况下均大于 47.6%，并减少约 80% 的温室气体排放（<40 ppm N2O）。最后，化学动力学分析表明富氧或富氢条件并没有改变主要反应途径。