Experimental Investigation of Effects of Di-N-Butyl Ether Addition on Spray Macroscopic Characteristics of Diesel-Biodiesel Blends

Di-n-butyl ether (DBE) is one of the most promising alternative biofuels for vehicles due to its superior physicochemical properties and because it is a renewable resource. This study investigated the effects of DBE addition on the spray macroscopic characteristics of diesel-biodiesel blends under various injection and ambient conditions. Three kinds of ternary blended fuels were prepared-(1) 72% diesel, 18% biodiesel, 10% DBE by volume (D72B18DBE10); (2) 64% diesel, 16% biodiesel, 20% DBE by volume (D64B16DBE20); and (3) 56% diesel, 14% biodiesel, and 30% DBE by volume (D56B14DBE30)-in order to compare their spray characteristics with those of an 80% diesel-20% biodiesel mix (D80B20) and conventional diesel (D100). The experiments were conducted in a constant volume chamber with a high-pressure common rail injection system using a high-speed photography method. The results show that D80B20 gives the longest spray tip penetration and the smallest cone angle and projected area among the five test fuels. With increased DBE blending ratio, the spray penetration length decreases slightly, and spray cone angle and projected area increase. When the DBE volume fraction in the ternary blend is 20%, the spray tip penetration, cone angle, and projected area are comparable to those of diesel. In addition, air entrainment characteristics were analyzed with the quasi-steady jet theory. It was found that the addition of DBE can improve the air entrainment characteristics of diesel-biodiesel blends, and D64B16DBE20 results in fuel-air mixing similar to that of D100. (C) 2019 American Society of Civil Engineers.