Experimental study on spray and combustion of gasoline/hydrogenated catalytic biodiesel blends in a constant volume combustion chamber aimed for GCI engines

GCI combustion mode has become an interesting topic for high thermal efficiency and low emissions, while ignition problem and knocking combustion limited its application. The blending fuel of gasoline/Hydrogenated Catalytic Biodiesel (HCB) can extend the working conditions for GCI engines because there is no mixed and ignited problem. In this paper, the spray liquid length, ignition delay and flame lift-off length of three gasoline/ HCB blends with different blending ratio are measured simultaneously in a constant volume combustion chamber for providing enough data to guide the gasoline/HCB blends used in GCI combustion mode. The experimental results show that the ignition delay and lift-off length decrease with increasing the proportion of HCB in blends, while the spray liquid length shows an opposite trend. Moreover, for gasoline/HCB blends, chemical ignition delay plays a leading role in the total ignition delay and the cycle-to-cycle variation will be decreased with increasing the blending ratio of HCB. On the other hand, the spray and combustion characteristics of G70H30 and G50H50 are compared with those of diesel for further applying the blended fuel in compression ignition engines. The natural luminosity intensity of diesel is higher than that of G50H50 and G70H30 even the injection pressure of diesel is higher than that of blending fuel, which means the blending fuels have relatively lower soot emission. Meanwhile, the ignition delay and flame lift-off length of G50H50 are getting close to the diesel results. Moreover, there is a big difference in ignition delay for these three fuels under low oxygen concentration, while the difference decreases with increasing the oxygen concentration.