Hydrogen-diesel dual-fuel direct-injection (H2DDI) combustion under compression-ignition engine conditions

Abstract

<p>This study investigates the ignition and combustion characteristics of interacting diesel-pilot and hydrogen (H₂) jets under simulated compression-ignition engine conditions. Two converging single-hole injectors were used to inject H₂ and diesel-pilot jets into an optically accessible constant-volume combustion chamber (CVCC). The parameters varied include fuel injection sequence, timing between injections, and ambient temperature (780–890 K). The results indicate that when diesel-pilot is injected before H₂, with increasing time separation, the burnt diesel products mix and cool down, requiring longer jet-jet interaction to ignite the H₂ jet. When H₂ is injected before diesel-pilot, the H₂-air mixing amount prior to pilot-fuel igniting impacts the combustion spreading through the H₂ jet. If ignition of the H2 jet occurs beyond its end-of-injection (EOI), the H₂ mixture zone where the pilot-diesel interacts with becomes too lean for combustion. At lower ambient temperatures, the combustion variability increases, attributed to the diesel-pilot lean out.<br></p>