A Study for the High Efficiency and Low NOx Emission Potential of a High-pressure Direct-injection Hydrogen Engine

Abstract

Hydrogen engines are required to provide high thermal efficiency and low nitrogen oxide (NOx) emissions. Direct-injection hydrogen engines have a potential to provide higher thermal efficiency and specific power rather than port-injection hydrogen engines. There are many possible combinations of injection pressure, injection timing and ignition timing that can be used in a direct-injection system for achieving such performance. In this study, different combinations of injection and ignition timings were classified as three combustion regimes, and experiments were conducted to make clear the differences in combustion conditions attributable to the operating conditions.