Biodiesel has been paid more and more attention as a renewable fuel due to some excellent properties such as renewable, high cetane number, ultralow sulfur content, no aromatic hydrocarbon, high flash point, low CO2 emission when compared with diesel. While others physical properties like high viscosity, high surface tension, big density and bad volatility would spoil the spray characteristics of biodiesel fuel, which will affect the thermal efficiency when running in diesel engine.
Accompanied with constant volume vessel and high speed video camera system, a high pressure common rail system, which could provide an injection pressure of 180 MPa, is used to investigate the characteristics of jatropha curcas biodiesel, palm oil biodiesel and diesel fuel. The effects of injection pressures and ambient densities on spray characteristics of these fuels are studied.
The results show that: The spray penetrations of jatropha curcas biodiesel and palm oil biodiesel are larger than that of diesel, and the spray angles of biodiesel fuels are smaller than that of diesel. The spray penetrations of diesel, jatropha curcas biodiesel and palm oil biodiesel have the same exponential relationship between fuel spray penetration and injection pressure, fuel spray penetration and ambient density: S = P⁰\u.₂9, S = pa\u-⁰\u.₃⁶. It indicates that, based on the test results, the fuel physical properties have no effect on the exponential relationship between fuel spray penetration and injection pressure, ambient density.