Mixture condition, combustion and sooting characteristics of ethanol-diesel blends in diffusion flames under various injection and ambient conditions

The liquid-phase penetration of the ethanol-diesel blends was almost equivalent to that of diesel under diesel-like injection and ambient conditions. The ethanol-diesel blend (E30) showed longer ignition delay than diesel, but this difference became insignificant at high ambient temperatures over 1000 K. The flame lift-off length of the E30 was longer than that of diesel that formed less fuel-rich mixture of E30 at the flame lift-off location. The difference in mixture condition between E30 and diesel became larger with increase in injection pressure, but smaller with increase in ambient temperature. The E30 suppressed the soot formation near the flame lift-off location, and also promoted the soot oxidation process. This soot reduction potential of E30 became larger with increase in injection pressure, but insignificant at high ambient temperatures. Increasing ethanol blend ratio decreased the flame temperature slightly, but further enhanced the soot reduction potential.