Enhanced ignition possibilities of ammonia by the prechamber fueled methanol: Rich, stoichiometric and lean combustion evaluations

Ammonia is a zero-carbon fuel, being better transportable than hydrogen. However, ammonia engines have problems with the low ignition and combustion behaviors of ammonia. Prechamber ignition is therefore seen as option, which in this work is fed with a small amount of methanol (2.5 %). The prechamber generates a stable jet flame with high energy to ignite and induce a fast ammonia combustion process even for lean conditions. In this study, the methanol jet induced ammonia combustion was assessed within a constant volume combustion chamber and investigated with the time-dependent shadow method. Several jet hole diameters of a single channel setup between 3 mm and 6 mm were compared. The lean combustion limit was extended up to an equivalence ratio of 0.5 for an increased jet hole diameter of 6 mm., which successfully realized ultra-lean combustion of ammonia (Ф≤0.5). The ignition delay and the reduced combustion speed of the lean ammonia combustion will be regarded in future studies.