An experimental and simulative study for transient performance and emissions analysis of a marine engine fed with flex-fuel as methanol and ammonia blends

Transportation, being a significant contributor to rising global emissions, underscores the need for alternative fuels like ammonia, methanol, hydrogen, and others. Transient scenarios are crucial to study because they reflect real-world driving conditions where engines frequently transition between different loads and speeds, significantly impacting emissions and performance. There is a significant gap in research on using ammonia and methanol blended fuels in engines, particularly under transient conditions, due to the complexity and challenges in combustion control. This study aims to address this gap by conducting a comprehensive simulative investigation of ammonia-methanol flex-fuel blends for a transient marine engine. Utilizing an experimentally validated GT-Power model, the study evaluates three key characteristics: performance, combustion, and emissions, under various operating conditions involving parameters such as injection timing, spark timing, and different blend ratios of both fuels. The study reveals that increasing the ammonia content in methanol blends results in moderate changes to engine performance, with slight decreases in indicated mean effective pressure and indicated efficiency, despite maintaining constant energy input. These performance reductions are minor compared to pure methanol. However, the most significant advantages are seen in emissions, with carbon dioxide levels decreasing by up to 80% when comparing blends of 25% Methanol and 75% Ammonia to 100% Methanol, highlighting the potential of ammonia-methanol flex-fuels as environmentally friendly alternatives. Furthermore, the air-fuel ratio fluctuation was also observed to be reduced with methanol-ammonia blends, which can make the engine drivability smoother during transient operation with sudden load changes that will minimized the engine vibration during transition stage. This research positions ammonia-methanol blends as a 100% renewable fuel option for engines, offering significant potential for reducing emissions and improving environmental sustainability in the transportation sector.