Diesel Fuel Multiple Injection Effects on Emission Characteristics of Diesel Engine Mixed Ammonia Gas Into Intake Air

This study focuses NH₃ as an alternative fuel for internal combustion engines, because NH₃ is known as a H₂ carrier and its combustion does not produce CO₂ causing global warming. On the other hand, some reports show that unburned NH₃ and N₂O appear in exhaust gas, when NH₃ is used as fuel for compression ignition or spark ignition engines. NH₃ is toxic and N₂O is one of the greenhouse gases. These emissions should not be emitted. These reports point out that exhaust gas after treatments and/or injection strategies can be effective to reduce these emissions. From our previous investigations, it was confirmed that NH₃ and N₂O were contained in the exhaust gas of a conventional diesel engine with NH₃ gas mixed into the engine intake. In this study, NH₃ combustion processes in the diesel engine were investigated from the experimental results. Based on the investigations, a pilot or postinjection was conducted to reduce emissions of NH₃ and N₂O. In this paper, first the experimental results of the combustion and exhaust emission characteristics on the conventional diesel engine with NH₃ gas mixed into the engine intake are shown. NH₃ and N₂O emissions are then verified by analyzing the exhaust gas. Next, NH₃ combustion processes in the diesel engine are considered from the experimental results to report on the effects of a pilot and postdiesel fuel injection on NH₃ and N₂O production processes. The experimental results suggest that the multiple diesel fuel injections would be one of the effective measures to reduce N₂O and NH₃ emissions on NH₃ and diesel dual-fueled engine.