Operable Range Extension of Ammonia Direct Injection Spark Ignition Engine by Hydrogen Addition

Ammonia is gaining attention as a non-carbon environmental-friendly fuel due to its superior storage capability compared to hydrogen. However, its high minimum ignition energy and slow laminar flame speed make it unsuitable for application in combustion-based energy conversion devices. In particular, when applied to internal combustion engines, issues such as combustion instability and limitations in operational range exist. Therefore, the intention is to address these issues by adding hydrogen, which has a wider flammable range and a faster laminar flame speed, to ammonia. In this study, the extension of the operable range of ammonia-fueled spark ignition engine by hydrogen addition was mainly discussed. Ammonia was injected directly in the cylinder and hydrogen was supplied into the intake port. The result showed that operable range of ammonia fueled combustion with hydrogen addition could be extended from 0.2 to 1.4 MPa with relatively stable combustion, i.e. CoV of gIMEP