氢能源份额低的高效、低排放氨氢发动机有助于促进重型长途运输的碳中和转型。在这项研究中,对氢喷射点火(HJI)氨发动机进行了数值研究,以研究氨端口燃油喷射(PFI)和氨直接喷射(ADI)对发动机性能的影响,包括燃烧和排放特性,在= 3 %,不同火花正时 (ST)。结果表明,与PFI模式相比,ADI模式具有更高的容积效率、更低的缸内温度和更低的传热损失,并且更多的延迟喷射可以进一步提高容积效率并降低温度。 ADI 模式导致燃料分布更不均匀,局部当量比更低,氢气比氨更早消耗,可能导致早期燃烧更快。多次喷射的ADI模式比单次喷射更有利于发动机性能,并且可以实现比PFI模式更高的指示平均有效压力(IMEP)和指示热效率(ITE)。通过进一步优化 ST,在可接受的 NH 和 NO 排放条件下,ADI 模式较 PFI 模式将 ITE 提高了 2.8%,NO 排放量降低了 70%。
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Effect of injection and ignition strategy on an ammonia direct injection–Hydrogen jet ignition (ADI-HJI) engine
High-efficiency, low-emission ammonia-hydrogen engines with low hydrogen energy share () help promote a carbon-neutral transition in heavy-duty, long-distance transportation. In this study, numerical investigations were carried out on a hydrogen jet ignition (HJI) ammonia engine to study the effects of ammonia port fuel injection (PFI) and ammonia direct injection (ADI) on the engine performance, including combustion and emission characteristics, at = 3 % with varied spark timing (ST). The results show that the ADI mode has higher volumetric efficiency, lower in-cylinder temperature, and lower heat transfer loss compared with the PFI mode, and more retarded injection can further increase the volumetric efficiency and reduce the temperature. ADI mode results in a more inhomogeneous fuel distribution and a lower local equivalence ratio, with hydrogen consumed earlier than ammonia, potentially resulting in more rapid early-stage combustion. ADI mode with multiple injections is more conducive to engine performance than single injection and can achieve the higher indicated mean effective pressure (IMEP) and indicated thermal efficiency (ITE) than PFI mode. By further optimizing ST, the ADI mode improves ITE by 2.8 % and reduces NO emission by 70 % compared with the PFI mode under acceptable NH and NO emission conditions.