The rising energy demand creates a huge need to explore and implement sustainable alternative fuels e.g., ammonia, hydrogen, methanol, ethanol, etc. to mitigate emission challenges and significantly lower CO emissions. Ammonia has gained much attention as promising alternative fuels for internal combustion engines due to its carbon-neutral nature, which can reduce the carbon footprint in transportation. The advantages of ammonia as a fuel includes carbon-free nature, high volumetric energy density compared to hydrogen, and renewable resource-based production. However, there is lack of the deep understanding of the ammonia spray characteristics and fuel-air mixing process, in particular, the superheated spray, which potentially improve the vaporization and fuel-air mixing. This study focused on investigating the impact of superheating on ammonia, methanol, ethanol, and gasoline fuel sprays by heating the fuel injector tip from non-evaporating to flash boiling temperatures. The fundamental spray parameters were investigated in a constant volume spray chamber using a multihole solenoid driven injector for 150 bar constant injection pressure under 10 bar and 30 bar chamber pressure conditions. To observe flash boiling and the dual-phase flow, a Z-type Schlieren imaging technique, known for its sensitivity to density gradients, was used. The experimental results indicated that ammonia spray behavior significantly differed from other tested fuels for both under cold and superheated conditions. The effect of superheating on methanol, ethanol, and gasoline sprays was very similar, resulting in the shrinkage of spray width and the merging of adjacent plumes into a single thick cloud of spray for elevated tip temperatures. However, ammonia sprays exhibited considerable differences in evaporative conditions, developing a more significant dual phase flow than other fuels upon increment in tip temperature. Overall, the results showed that the spray tip penetration and area for all tested fuels reduced upon heating.

中文翻译：

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过热燃料喷雾：用于多孔燃料喷射的闪蒸氨燃料喷雾与甲醇、乙醇和汽油的比较研究


不断增长的能源需求迫切需要探索和实施可持续替代燃料，例如氨、氢气、甲醇、乙醇等，以缓解排放挑战并显着降低二氧化碳排放。由于其碳中和性质，氨作为有前途的内燃机替代燃料而受到广泛关注，可以减少运输中的碳足迹。氨作为燃料的优点包括无碳、与氢相比体积能量密度高以及基于可再生资源的生产。然而，人们对氨喷雾特性和燃油-空气混合过程缺乏深入的了解，特别是过热喷雾，这可能会改善汽化和燃油-空气混合。本研究的重点是通过将燃油喷射器尖端从非蒸发温度加热到闪沸温度来研究过热对氨、甲醇、乙醇和汽油燃油喷雾的影响。在恒定体积喷雾室中研究基本喷雾参数，使用多孔螺线管驱动注射器，在 10 巴和 30 巴室压条件下实现 150 巴恒定注射压力。为了观察闪蒸和双相流，使用了因其对密度梯度的敏感性而闻名的 Z 型纹影成像技术。实验结果表明，在冷和过热条件下，氨喷雾行为与其他测试燃料显着不同。过热对甲醇、乙醇和汽油喷雾的影响非常相似，导致喷雾宽度收缩，相邻羽流合并成单一厚喷雾云，从而提高尖端温度。 然而，氨喷雾在蒸发条件方面表现出相当大的差异，随着尖端温度的增加，形成比其他燃料更显着的双相流。总体而言，结果表明所有测试燃料的喷嘴尖端穿透力和面积在加热时都会减少。