Study of NO _x Emissions Reduction Strategy for a Naturally Aspirated 4-Cylinder Direct Injection Hydrogen ICE

Hydrogen engines are required to provide high thermal efficiency and low nitrogen oxide (NO_X) emissions. There are many possible combinations of injection timing, ignition timing, lambda and EGR rate that can be used in a direct-injection system for achieving such performance. In this study, NO_X emissions of natural aspirated 4 cylinders engine with management strategies involving the injection timing, ignition timing, lambda and the EGR rate were evaluated under a Japanese JE05 emissions test cycle. Finally, the paper projects the potential of direct injection hydrogen engine for obtaining high output power and attaining low NO_X emissions of 0.7 g/kWh under the emission test cycle.