Simultaneous study on spray liquid length, ignition and combustion characteristics of diesel and hydrogenated catalytic biodiesel in a constant volume combustion chamber

Application of biodiesel is very important for reducing the consumption of fossil fuels and improving emissions performance of internal combustion engines in the transportation field. Hydrogenated catalytic biodiesel has attracted more attention due to the high quality and eco-friendly nature. Hence, in order to provide more fundamental data for applying this biodiesel in engines, the spray liquid length, ignition and combustion characteristics for both diesel and hydrogenated catalytic biodiesel has been researched in a constant volume combustion chamber to see their differences and similarities, which can be used for determination of the possible proportion of hydrogenated catalytic biodiesel in blends for further research in engines. The results show that the spray liquid length of hydrogenated catalytic biodiesel is shorter than that of diesel fuel, which indicates that hydrogenated catalytic biodiesel has better atomization and less chance for occurrence of wall-impingement. While a shorter ignition delay of hydrogenated catalytic biodiesel reveals that it cannot be applied in blends with a large proportion due to knocking combustion. However, a shorter ignition delay of hydrogenated catalytic biodiesel means that it is a highly active fuel which can be used to engines as a blend for new advanced combustion modes. The lift-off lengths were compared with different optical methodologies. Lift-off length is more sensitive to fuel properties rather than temperature under low ambient temperature conditions. The relationships between spray liquid length and lift-off length and between ignition delay and lift-off length were also compared.