Experimental study of soot particles characteristics for hydrous ethanol diesel emulsified fuel under diesel-like conditions

The emulsified fuel of the commercial diesel fuel and 20 wt% water-containing ethanol with 30% volume fraction of hydrous ethanol was burned in a constant-volume combustion chamber (CVCC). At varying sampling locations along the axis of jet flame, soot particles are thermophoretically sampled and analyzed using high resolution transmission electron microscopy (HRTEM). Many small inception particles bulging from the surface of large liquid-like particles are observed at the upstream of jet flames. As these particles move toward the downstream, many growing immature primary particles gradually appear on those large liquid-like particles' surfaces, then carbonized particles fuse together and form larger soot aggregates, the large soot aggregates finally crack to generate many smaller particles. During this process, the diameters and the radius of gyration of soot particles decrease steadily, while the fractal dimensions have the opposite trend. The chaotic inner structure of primary particles progressively becomes an ordered structure. These results possibly indicate a new formation mechanism of soot particles; Compared to diesel fuel, soot particles derived from emulsified fuel are much immature with higher oxidation reactivity. The two-color images indicate the potential of reducing soot emissions by using hydrous ethanol diesel emulsified fuel increases the flexibility in controlling engine emissions.

Automated summary

This study uses high resolution transmission electron microscopy to analyze the formation mechanism of soot particles during the combustion of commercial diesel fuel and emulsified fuel with water-containing ethanol. The results indicate that the soot particles derived from emulsified fuel are less mature but have higher oxidation reactivity compared to diesel fuel.