Fuel Design Concept for Low Emission in Engine Systems 3rd Report: Analysis of Spray Characteristics for Mixed Fuels

In this study, the novel fuel design concept has been proposed in order to realize the low emission and combustion control in engine systems. In the fuel design concept, the fuel mixed with high volatility fuel (gasoline or gaseous fuel components) and low volatility fuel (gas oil or fuel oil components) are used to improve the spray characteristics using flash boiling effect. The authors has addressed the combustion processes of the mixed fuel with n-pentane and n-tridecane (n-pentane/n-tridecane) using heat release analysis, shadow photography and two-color method in rapid compression and expansion machine (RCEM).

It has been reported the spray characteristics of single component fuel, but that of multicomponent fuels is almost unknown. In the present study, it is reported the results of spray experiments for mixed fuels conducted in RCEM. The liquid and vapor distributions of n-pentane/n-tridecane were analyzed by using Mie scattering and planar laser-induced fluorescence (PLIF). In addition, Mie scattering and laser-induced exciplex fluorescence (LIEF) were applied to investigate the effects of ambient pressure on the spray characteristics of propane/n-tridecane. In the case, pure n-pentane, which has the same transport properties as propane/n-tridecane has, was used to compare the mixture formation of pure n-pentane with that of propane/n-tridecane. From the results of these experiments, it was confirmed that vaporization characteristic of low volatility fuel was improved by mixing high volatility fuel and the effect of flash boiling on liquid-phase penetration and vapor distribution of propane/n-tridecane was obtained at low ambient pressure.