Influenced by the concept of carbon neutrality, ammonia is gaining widespread attention in the transport sector as a zero-carbon fuel. Diesel/ammonia dual fuel engines can achieve stable combustion of ammonia and reduce carbon emissions. To further enhance the low load combustion performance of a diesel/ammonia dual fuel engine, the effect of ozone addition on in-cylinder combustion and flame development was investigated based on an optical engine. Beyond that, ozone addition on pure diesel was also tested to understand the effect of ozone addition on diesel combustion enhancement in diesel/ammonia reactivity controlled compression ignition (RCCI) mode. The results show that the addition of ozone significantly advances the ignition phase, increases the flame area and brightness, and results in a growth in flame luminescence intensity along the radial length and closer to the center of the view field for diesel/ammonia RCCI combustion. In addition, chemical kinetic analysis shows that diesel/ammonia combustion requires higher ozone concentrations to overcome the inhibitory effect of ammonia to reach the upper limit of the promotional effect on the ignition phase and indicated mean effective pressure (IMEP), due to the large amount of OH consumed by ammonia compared to pure diesel. The promotional effect of added ozone on IMEP is similar for different pilot injection ratios (PIRs). At a low PIR and high ozone concentration, the diesel/ammonia RCCI engine achieves the highest IMEP, indicating that ozone addition combined with optimization of diesel injection parameters contributes to improve the performance of the diesel/ammonia RCCI engine at low loads.

中文翻译：

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添加臭氧对引燃柴油/氨双燃料发动机影响的光学研究


受碳中和理念影响，氨作为零碳燃料在交通领域受到广泛关注。柴油/氨双燃料发动机可以实现氨的稳定燃烧，减少碳排放。为了进一步提高柴油/氨双燃料发动机的低负荷燃烧性能，基于光学发动机研究了臭氧添加对缸内燃烧和火焰发展的影响。除此之外，还对纯柴油中添加臭氧进行了测试，以了解添加臭氧对柴油/氨反应性控制压缩点火（RCCI）模式下柴油增强燃烧的影响。结果表明，臭氧的添加显着提前了点火阶段，增加了火焰面积和亮度，并导致柴油/氨 RCCI 燃烧沿径向长度和靠近视场中心的火焰发光强度增加。此外，化学动力学分析表明，柴油/氨燃烧需要较高的臭氧浓度来克服氨的抑制作用，以达到对着火阶段和指示平均有效压力（IMEP）的促进作用上限，由于用量较大与纯柴油相比，氨消耗的 OH。对于不同的引燃喷射比 (PIR)，添加臭氧对 IMEP 的促进作用相似。在低PIR和高臭氧浓度下，柴油/氨RCCI发动机达到了最高的IMEP，表明臭氧添加与柴油喷射参数优化相结合有助于提高柴油/氨RCCI发动机在低负荷下的性能。