Effect of Ammonia Energy Substitution Ratio on Combustion and Emission Performance of Ammonia and Diesel Dual-Fuel Engine at Different Loads

Ammonia (NH3), both as a hydrogen carrier and a carbon-neutral fuel, has garnered heightened interest in mitigating carbon emissions from transportation. The ammonia/diesel dual-fuel mode can proficiently address the ignition challenges of ammonia in the engine and serves as an excellent strategy to enhance ammonia combustion. This study uses both experiments and computer models to observe how the ammonia energy substitution ratio (AER) affects the combustion and emission characteristics of a diesel-and-ammonia engine running at different loads. The findings indicated that both in-cylinder pressure and in-cylinder temperature diminished with an increase in the AER across all loads. Furthermore, the standstill time (SOI-CA10) was extended, whereas the peak exothermic rate diminished with the increase in the AER. Regarding emission characteristics, CO2 emissions decreased by 54.4%, 46.9%, and 46.82% at light, medium, and heavy loads, respectively, while NOx emissions were lowered by 78%, 64.3%, and 63.7%, respectively, in comparison to the diesel mode. However, the N2O produced during combustion offsets the effect of greenhouse gas emission reduction brought about by the decrease in CO2. Future research can further optimize the engine’s combustion strategy by changing the fuel injection strategy and boundary conditions.