Liquid Ammonia Direct Injection (LADI) fundamental physics and modelling of the aero-thermodynamic of transitional atomisation regime

该提案开发了用于直接喷射（DI）液氨（LNH 3）的知识和技术，作为用于发动机应用的绿色和无碳替代液体燃料。这是重型公路运输和电力生产部门脱碳的关键一步。根据国际能源协会的报告，LNH 3被认为是无碳氢替代能源载体的“低挂果实”，原因如下[1]。(1)由于LNH 3在化肥工业中的广泛应用，LNH 3的大规模生产和运输基础设施已经广泛可用;（2）大量LNH 3的储存比氢气更安全和更经济-与氢气或天然气（LNG）相比，氨在室温下在9.90 atm下液化（类似于丙烷，一种在家庭中广泛应用的燃料）;（3）LNH 3具有非常高的氢密度，每100升（甚至高于液态氢）kg H2，是主要的氢载体。LNH 3的热值低于化石燃料，例如，因此，柴油和汽油需要更多的燃料来产生相同的功率输出。DI技术的发展实现了先进的喷射策略，通过这种策略，在较长时间内的高精度和调制的多次喷射允许输送更多的燃料，同时通过增强蒸发和混合来改善混合物质量。特别强调了MAN和瓦锡兰最近开发的发动机，这些公司目前正在商业化氨往复式发动机用于船舶应用[2]。问题：从理论上讲，纯LNH 3 DI发动机作为电力和道路运输部门完全脱碳的可行解决方案是可以实现的。然而，目前存在技术障碍，阻碍了LNH 3的广泛使用，以零碳排放发动机完全取代化石燃料。这是因为：（1）氨/空气混合物的反应性很低，与发动机的工作条件非常不相容;（2）LNH 3喷雾不同于化石燃料，具有高度非线性和不稳定的特性，会引发严重的燃烧不稳定性和灾难性的发动机故障。

This proposal develops the knowledge and technology for direct injection (DI) of liquid ammonia (LNH3), as green and carbon-free alternative liquid fuel for engine applications. This is a critical step toward the decarbonisation of heavy road transportation and the power production sector. According to the International Energy Association report, LNH3 is considered as "the low hanging fruit" carbon-free hydrogen alternative energy carrier for the following reasons [1]. (1) Mass production and shipping infrastructure of LNH3 is already widely available thanks to its widespread applications in the fertiliser industry; (2) Storage of LNH3, in large quantity, is significantly safer and more economical than hydrogen-compared to hydrogen or natural gas (LNG), ammonia is liquefied at room temperature at 9.90 atm (similar to propane, a fuel with widespread domestic applications); (3) With a very high hydrogen density of kg H2 per 100 litres (even higher than liquid hydrogen), LNH3 is a prime hydrogen carrier. The heating value of LNH3 is lower than fossil fuels, e.g., diesel and gasoline, hence, more fuel is required to produce the same power out. The evolution in DI technology has enabled advanced injection strategies, by which highly precise and modulated multiple injections over an extended period of time allows delivering more fuels while improving the mixture quality by enhancing the evaporation and mixing. Especial emphasis is made on the recent engines developed at MAN and Wärtsilä, companies that are currently commercialising ammonia reciprocating engines for marine applications [2]. Problem: In theory, pure LNH3 DI-engines, as a viable solution for full decarbonisation of power and road transportation sectors, is achievable. However, there are currently technological barriers that prevent the widespread use of LNH3 to completely replace fossil fuels with zero-carbon emission engines. This lays in the following facts: (1) the reactivity of ammonia/air mixtures is very low and quite incompatible with the engine operating conditions; (2) spray of LNH3 is different from fossil fuels and exhibits a highly non-linear and unsteady behaviour which trigger significant combustion instabilities and catastrophic engine failure.In this project, we focus on the second issue by investigating LNH3 sprays in DI-engine applications.