Droplet Combustion Behavior of Methyl Oleate-Methyl Palmitate Fuel Blend as The Surrogate Compounds of Palm Oil Biodiesel

Biodiesel feedstock has a few main constituents with different concentrations. The physicochemical properties of its constituents determine the biodiesel quality. This study investigates the single and binary droplet combustion of methyl oleate and methyl palmitate as the major constituents in palm oil biodiesel. An isolated droplet combustion experiment with the suspended droplet method and self-illuminated direct imaging technique was conducted at atmospheric pressure and room temperature under normal gravity. The thermal expansion during the heating phase is closely related to the viscosity and boiling point of the fuel droplet, which then determines the duration of ignition delay. The droplet lifetime in the subsequent stages also depends on the ignition delay time since the combustion is separated into two different combustion modes. The additional transition phase and a typical flame extinction mode were observed in methyl oleate combustion. In the fuel blends, methyl palmitate reduces the soot accumulation at the flame tip of methyl oleate combustion.