Evaluation of Control Strategy on Operation Range Expansion of High-Pressure Ammonia Direct Injection Marine Dual-Fuel Engine

To compensate for the difficulty in directly applying ammonia to internal combustion engines, much research has been conducted to improve ignition characteristics by changing parts such as strengthening spark plugs, increasing compression ratio, or cofiring with other fuels. Ammonia engines are currently in the development stage as an eco-friendly alternative fuel for ships for decarbonization, and in this study, micropilot fuel was applied to compensate for the high spontaneous ignition temperature and slow combustion speed. In conditions of higher boosting pressure, power output and efficiency decrease and maximum power and efficiency are achieved under conditions where the injection timing of diesel fuel for ignition is advanced 5 crank angle degrees further than that for lower boosting pressure. Combustion stability and NOx emissions are predominantly affected by the combustion of ignition diesel, so they are not improved even if the ammonia supply flow rate is increased at the boosting pressure level of 0.3 MPa.