The Application of Nanoparticle Catalysts to Enhance Ammonia Reactivity and Improve Ammonia/Diesel Dual-Fuel Engine Performance

The combustion mode of high-activity fuel ignition remains the primary method for applying ammonia fuel in engines. To investigate the feasibility of improving ammonia reactivity and enhancing ammonia fuel engine performance by adding nanoparticle catalysts, this study conducted visualization analyses of the ammonia/nanofuel compound combustion flame development process. The results show that in the ammonia/nanofuel compound combustion mode, metal nanoparticles primarily improve the combustion process by promoting the premixed combustion of high-activity fuels. Metal oxide nanoparticles effectively enhance the ammonia reactivity through their relatively abundant ammonia decomposition sites. At 20 and 30% ammonia ratios, the compound combustion process is primarily influenced by combustion of the ignition fuel. The addition of α-Fe2O3 nanoparticles to the ignition fuel suppresses combustion, whereas the addition of Ag, Ni, and CeO2 nanoparticles promotes the combustion process, shortening the ignition delay (ID), advancing the combustion center (CA50), and increasing the indicated mean effective pressure (IMEP). When the ammonia ratio exceeds 50%, the ammonia/D0 compound combustion process deteriorates, with the ammonia reactivity becoming the dominant factor in the compound combustion process. Adding various metal and metal oxide nanoparticles to the ignition fuel effectively improves the combustion process, resulting in a shorter ID and combustion duration (CD), an advanced CA50, and an increased IMEP.