Influence of Temperature of Castor Oil Biodiesel in Blend with Ultralow Sulfur Diesel on Its Physical Properties and the Relationship of These with Spray Macroscopic Parameters.

内容摘要

Biodiesel is an alternative fuel to diesel, which can be derived from different feedstocks, and one of them is Ricinus communis L. oil (castor oil). Drawbacks of castor oil biodiesel are its high density, kinematic viscosity, and surface tension values, in comparison with those of diesel. The spray macroscopic characteristics of a fuel such as spray penetration and spray area are influenced mainly by fuel kinematic viscosity. A way to equate the physical properties of castor oil biodiesel (BH100) with those of diesel is by raising its temperature. The present study focused on analyzing the influence of castor oil biodiesel temperature in blend with ultralow sulfur diesel (ULSD) on its kinematic viscosity, and the relationship of this with spray macroscopic characteristics. To do so, a BH20 blend (20% of castor oil biodiesel and 80% of ultralow sulfur diesel) and ultralow sulfur diesel as the reference fuel were employed. In order to equate the density and kinematic viscosity values of BH20 with those of ultralow sulfur diesel at 40 °C, curves were determined in a temperature range of 15-75 °C. To evaluate the relationship between the physical properties of BH20 and its spray macroscopic characteristics and considering the physical properties of ULSD at 40 °C, three fuel temperature levels (40, 50, and 60 °C) were employed in the spray macroscopic characterization of BH20. All fuels were injected in a constant volume chamber under nonreactive and evaporative conditions and using three levels of rail pressure (Prail): 80, 100, and 120 MPa, and a level of back pressure (Pb) of 5 MPa. Among other results obtained, it can be highlighted that the spray cone angle exhibits no significant variations when changing both fuel kinematic viscosity and injection pressure. Meanwhile, the spray penetration and spray area of B20 at 60 °C exhibit a similar behavior to that of ULSD at all Prail levels analyzed. Therefore, BH20 injected at 60 °C could be an alternative fuel for diesel engines.