Simulation Study of Diesel Spray Tilt Angle and Ammonia Energy Ratio Effect on Ammonia-Diesel Dual-Fuel Engine Performance.

Ammonia-diesel dual fuel (ADDF) engines for transportation applications are an important way to reduce carbon emissions. In order to achieve better combustion of ammonia in diesel engines. A small-bore single-cylinder engine was converted into an ADDF engine with the help of mature computational fluid dynamics (CFD) simulation software to investigate the performance of an engine with a high ammonia energy ratio (AER), and to study the effect of spray tilt angle on ADDF engine. The results showed that the increase in AER reduced nitric oxide (NO) and nitrogen dioxide (NO) emissions but increased nitrous oxide (NO) and unburned ammonia emissions. AER in the range of 50%–70% achieved lower greenhouse gases (GHG) emissions than the pure diesel mode. Relative to the pure diesel mode, when the AER was 60%, the indicated thermal efficiency (ITE) was increased by 0.2% and the GHG emissions were decreased by 22.3%, but carbon monoxide (CO) and Hydrocarbon (HC) emissions were increased. Increasing the in-cylinder combustion temperature or high-temperature region range of the ADDF engine could reduce GHG emissions. At an AER of 60%, an increase in the spray tilt angle helped the ammonia combustion in the residual gap to reduce the unburned ammonia emissions. Compared to the pure diesel mode with a spray tilt angle of 75°, an AER of 60% with a spray tilt angle of 77.5° improved the ITE by 1.5%, and reduced the GHG emissions by 25.7%. Adjusting the spray tilt angle of the ADDF engine also reduced CO and HC emissions. This is an effective way to improve ADDF engine performance by adjusting the spray tilt angle. [ABSTRACT FROM AUTHOR]