Research on Injection Characteristics of Marine Ammonia Fuel Injector under Wide Temperature Range

Ammonia fuel is typically characterized by low viscosity, low flash point, and non-flammability. This means that fuel characteristics and operational requirements significantly deviate from those of conventional fuels, requiring a significant technical upgrade to the existing fuel supply and injection systems. This research involves a numerical analysis of ammonia utilization in high-pressure direct injection. Considering the non-isothermal compressibility of the fuel flow process, the fluid properties in the model are specifically defined based on the physical properties of the ammonia fuel. The injection performance of ammonia fuel was studied, including comparing the injection performance of ammonia fuel with conventional diesel fuel under typical operating conditions in the injector, and exploring the injection characteristics of ammonia fuel injector under a wide fuel temperature range. The results of ammonia injection indicate that the response characteristics of liquid ammonia and diesel are slightly different. In terms of pressure characteristics, the pressure fluctuation of liquid ammonia is significantly smaller than that of diesel, and the fluctuation is more uniform. As for temperature characteristics, the liquid ammonia oil chamber has a lower temperature than the diesel oil chamber and reaches a stable state faster. In addition, the operating conditions of the engine are prone to changes in the phase state of ammonia fuel. The transition from liquid to supercritical state of ammonia fuel at various temperatures and pressures reveals the corresponding relationship between the phase transition zone of ammonia fuel and fuel injection characteristics.