Evaluation and Visualization of Surfactant Effect on Single Emulsified Fuel Droplet for Diesel Engine

<div class="section abstract"><div class="htmlview paragraph">The emulsified fuel is mixed base fuel with water and stabilized by surfactant. The advantage of emulsified fuel is the improvement of spray and mixture formation by the secondary atomization. The secondary atomization means that the sprayed fuel droplets in cylinder would occur the atomization because of the difference of boiling points between base fuel and water. It is expected improving combustion efficiency and suppressing toxic emissions such as NOx and PM in small diesel engine [<span class="xref">1</span>].</div><div class="htmlview paragraph">The behavior of an emulsified fuel droplet in heating process has 3 types, Namely the micro-explosion, the puffing and only vaporizing without atomization. Their timing and behavior are influenced on the concentration of surfactant within an emulsified fuel droplet. However, it is difficult to determine the concentration. This paper focuses on the determination of the concentration by engineering evaluation.</div><div class="htmlview paragraph">Our previous reports have reported that the evaluation for the atomization timing of an emulsified fuel droplet which was applied to reliability engineering was proposed [<span class="xref">2</span>, <span class="xref">3</span>]. It evaluated the optimum water content, the kinematic viscosity of the fuel and the chemical species of an emulsified fuel droplet.</div><div class="htmlview paragraph">The objective of this paper is to clear the effect of surfactant for atomization of an emulsified fuel droplet. Therefore, engineering evaluation is applied. Also, the behavior of a fuel droplet is confirmed by the visualization in heating process.</div><div class="htmlview paragraph">The engineering evaluation shows that the effect of surfactant differs on the border between 1.0×10<sup>-3</sup> [vol%] and 0.5 [vol%] concentration. Moreover, it is found that the photos show the effect of surfactant too. The effect of surfactant is explained rationally by engineering evaluation and visualization in this research.</div><div class="htmlview paragraph">In conclusion, the evaluation for the atomization timing of an emulsified fuel droplet which is applied to reliability engineering is able to clear the effect of surfactant.</div></div>