Direct injection of hydrogen can be applied to early, mid or late-cycle injection timing approaches on engines to achieve higher power density, efficiency and lower emissions. Due to volumetric efficiency and combustion effects, H2 DI technology has significant power density advantages relative to the more conventional H2 port-injected approach. Early development activities on direct injection (DI) technology for hydrogen in internal combustion (IC) engines is described with discussion of the specific issues and design requirements for the injector. Since some of the base technology was originally designed for natural gas DI, application for hydrogen has presented unique challenges and opportunities. The background behind different concepts for injector geometry is described along with discussion on actuation techniques. Most of the data shown is from a recent version of H2 DI technology which utilizes piezoelectric direct actuation and has the capability to modulate the needle lift in real time. As well, multiple injection strategies similar to those used on advanced common rail diesel engines can be applied to control combustion noise and exhaust emissions. The technical discussion focuses on the challenges presented by the fact that hydrogen has very low mass / energy density, high sonic velocity and low viscosity. These physical attributes will directly affect component size, material choice and wear rates. Chemical effects due to hydrogen must also be considered as they directly affect component life. Initial efforts to address these technical hurdles through fundamental research are also briefly discussed.
Development of H2 direct injection technology for high efficiency / high BMEP engines
Entwicklung der H2-Direkteinspritztechnologie für Motoren mit hohem Wirkungsgrad und hohem mittlerem, effektivem Bremsdruck
2006
9 Seiten, 7 Bilder, 5 Quellen
Conference paper
English
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