Experimental and analytical study on capture spray liquid penetration and combustion characteristics simultaneously with Hydrogenated Catalytic Biodiesel/Diesel blended fuel

Abstract

Hydrogenated Catalytic Biodiesel (HCB), with excellent volatility and cetane number while without contain oxygen and aromatic hydrocarbons, have great potential to improve engine performance and emission characteristics. In this study, the effect of HCB/Diesel blended fuels properties (by mass fraction of biodiesel in diesel) on spray combustion characteristics was investigated at inert and reacting conditions in a constant volume combustion chamber. Laser (532 nm) Mie-scattering, OH∗ chemiluminescence and high-temperature luminosity were used to capture the spray liquid length, flame lift-off length and ignition delay simultaneously with the help of two intensifier charge coupled device cameras and a high speed Complementary Metal Oxide Semiconductor camera. Encouraging results were obtained at different ambient conditions (temperatures, densities, oxygen concentration) and injection pressures. The results showed that fuels with high cetane number generate shorter ignition delay, and faster auto-ignition results in a shorter flame lift-off length. A new theory was used to interpret the effect of cetane number on lift-off length. Under reacting conditions, the combustion heat release shorten spray liquid length apparently as compared with the results under inert conditions. The liquid length was slightly affected by the injection pressure and oxygen concentrations under both reacting and inert conditions, while the flame lift-off length is significantly influenced by ambient parameters and injection pressure.