Abstract
Recently, ammonia (NH(3)), which has a higher energy density than hydrogen, has gained attention for zero-carbon emission goals in the transportation sector. However, in a conventional internal combustion engine (ICE), NH(3) combustion mechanism is still under investigation. In this paper, to further expand the knowledge on the adoption of NH(3) in ICEs, authors conducted NH(3)/gasoline co-combustion experiments in a modified, 17.7:1 compression ratio, naturally aspirated spark-assisted CI engine with sub-chamber. The sub-chamber was chosen in order to enhance the combustion speed of NH(3). In addition, the sub-chamber was equipped with glow and spark plugs to overcome the high auto-ignition temperature of NH(3). Engine performance and NO(X) emissions were studied under three different intake air temperatures. During the experiments, NH(3) content was increased gradually where the engine was run under lean conditions. Although higher NH(3) content was achieved compared to our previous work, increasing the intake air temperature resulted in decreased charging efficiency. In addition, corrosion was found on the piston ring after 120 h of operation, negatively affecting the engine performance. Furthermore, NH(3)/gasoline co-combustion duration was shortened drastically with the influence of the sub-chamber, where the longest combustion duration under the present conditions was found to be 17°CA.