Combustion of Premixed Ammonia and Air Initiated by Spark- ignited Micro-gasoline-jet in a Constant Volume Combustible Vessel

As an efficient hydrogen carrier, ammonia itself is also a promising zero-carbon fuel that is drawing more and more attention. As the combustion of pure ammonia is hard to achieve on SI engines, in this study, spark- ignited micro-gasoline-jet was utilized to ignite the premixed ammonia/air mixture in a constant volume combustible vessel at different premixed ammonia/air excess air coefficient and backpressure (represented by ammonia partial pressure). The flame image was captured by a high-speed camera and the transient pressure change in the vessel was measured by an engine cylinder pressure sensor. The experimental results at stoichiometric equivalence ratio show that the IDT (from 129.9-198.6ms to 58.7-72.6ms) and the main combustion durations (from 494.3-654.9ms to 164.7-286.2ms) of ammonia combustion are significantly shortened by the novel ignition method compared with the traditional spark ignition method, and the results of representative heat release rate and representative total heat release (from 0.15-0.48MPa to 0.89-1.51MPa) are enhanced by several times. Compared with the conditions of different excess air coefficient, the experimental results indicate that this new ignition method is more effective at high backpressure and ammonia-enriched conditions.