Energies, Vol. 18, Pages 4841: Numerical Study and Optimization of Combustion and Emissions of Ammonia/Diesel Dual-Fuel Engines Under Heavy Load

Energies, Vol. 18, Pages 4841: Numerical Study and Optimization of Combustion and Emissions of Ammonia/Diesel Dual-Fuel Engines Under Heavy Load

Energies doi: 10.3390/en18184841

Authors:
Shikai Xing
Xianglong Li
Juxia Li
Jianbing Gao
Qiang Lu
Xiaochen Wang
Yunge Zhao
Sunchu Wu
Zhonghui Fu

Ammonia fuel is expected to emerge as an effective alternative to fossil fuels due to its zero-carbon nature, high-efficiency storage and transportation advantages, and extensive industrial manufacturing infrastructure. This study discussed the impacts of compression ratio and injection timing on combustion and emission characteristics of an ammonia/diesel dual-fuel (ADDF) engine using numerical simulation. Results indicated that the corresponding optimal indicated thermal efficiency (ITE) continuously increases with an increasing compression ratio. When the compression ratio is 15:1, the injection timing corresponding to the maximum indicated thermal efficiency is −18 °CA after top dead center (ATDC). When the compression ratio ranged from 16:1 to 19:1, the corresponding optimal ITE was achieved at a retarded injection timing of −12 °CA ATDC. At a compression ratio of 19:1, the optimal ITE reached 47.9%. The in-cylinder formation regions of nitrous oxide (N2O) are closely correlated with NH3, NO, and temperature distributions, being primarily located at the interface between high-concentration regions of unburned NH3 and NO. Under the comprehensive impact of increased compression ratio and advanced injection timing, both N2O and unburned NH3 emissions show a tendency of increasing first and then decreasing, while NOx emissions demonstrated a monotonically increasing behavior.