Investigation of intake air temperature effect on co-combustion characteristics of NH 3 /gasoline in naturally aspirated high compression ratio engine with sub-chamber

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.