Combustion and emission characteristics of marine Ammonia-Diesel dual fuel single-cylinder engine with MP injector change

Recently, as regulations on greenhouse gas emissions due to global warming have tightened, there has been growing interest in engines that use environmentally friendly fuels. In this context, ammonia is gaining attention as a potential alternative to fossil fuels in the future. However, due to the unique fuel characteristics of ammonia compared to traditional fuels, research is being conducted on using diesel as an ammonia ignition source. In this study, combustion and exhaust characteristics were compared according to the characteristics of micro-pilot diesel injectors in the marine ammonia-diesel dual fuel single-cylinder engine. Various injectors with different hole numbers and sizes were examined (Injector A: more holes and larger size, Injector B: fewer holes and smaller size). To maintain a constant energy ratio between ammonia and diesel at a steady load, the injection duration was adjusted, and the MP injection timing varied in 5 CAD intervals to evaluate performance and emission conditions. The experimental results showed that when the MP injection timing was relatively delayed, Injector A exhibited superior efficiency and exhaust gas characteristics compared to Injector B. Conversely, when the MP injection timing was relatively advanced, better characteristics were observed due to reduced interference between ammonia and MP injection compared to the conditions with delayed timing.