Experimental evaluation of hydrogen–ammonia binary fuel strategies for diesel engines under low-load conditions

In this study, the performance and emission characteristics of a diesel engine operating under diesel + hydrogen and diesel + ammonia dual-fuel modes were experimentally investigated. The experimental results indicate that the use of gaseous fuels leads to a decrease in exhaust gas temperature, CO emissions, and smoke opacity. However, ammonia utilization exhibited notable limitations, particularly under low-load conditions, due to its low reactivity and slower combustion characteristics. This resulted in increased HC emissions and less stable combustion behavior. In contrast, hydrogen addition improved combustion efficiency and contributed to a reduction in HC emissions. Regarding nitrogen oxides, hydrogen enrichment caused a substantial rise in NOx emissions, reaching nearly 90%, while ammonia displayed different NOx formation tendencies, especially at low loads. The outcomes of this study improve understanding of performance and emission trends in CI engines under low-load conditions using diesel–hydrogen and diesel–ammonia fueling, and provide insights for low-carbon combustion strategies.