Assessment of the operation of a pre-chamber marine engine fuelled by ammonia-hydrogen mixtures at full and partial load

Carbon-free fuels can play a crucial role in the decarbonization of the maritime sector. This research examines the operation of a pre-chamber marine engine fuelled with ammonia-hydrogen mixtures. The study is carried out by means of a previously validated three-dimensional computational fluid dynamics model. Both full and partial load conditions have been assessed. At full load with 15% hydrogen in the fuel mixture, a spark angle of 716° is necessary to avoid knocking. The engine can achieve an IMEPH of 29 bar, approximately 43% efficiency, and a gross power output of 1.1 MW per cylinder. In these conditions, unburned ammonia and NO2 emissions are relatively low, N2O emissions are zero, while NO remains the main pollutant. At partial load conditions, a fuel mixture that contains 15% hydrogen by volume does not enable acceptable engine operation, whereas a 30% hydrogen content results in suitable operating conditions.