Theoretical analysis of the spray characteristics of ternary blends of diesel, biodiesel, and long-chain alcohols inside a combustion chamber

Abstract

The diesel and alcohol blends are potential alternatives to biogenic fuels to reduce biodiesel consumption, which might help reduce toxic emissions. Due to the high-quality requirements for engines, the fuel fundaments in the fluid properties and its impact on the macroscopic spray characteristics. Herein, a study proposed the experimental determination of density, viscosity, and surface tension for ternary mixtures of diesel (D) + biodiesel (B) + 1-hexanol (H) and + 1-octanol (O) at 298.15 K. These properties comply with the limits established by the EN 14214 and ASTM D975 standards. Thus, to extend the impact of these results, a theoretical analysis via CFD is carried out in ANSYS FLUENT ® by considering a macroscopic and isothermal system, which involved the independence tests of meshing and turbulence modeling. The numerical results evaluated the spray tip penetration, spray angle, spray morphology, eddy turbulence, and relation of spray volume and surface spray area at the injection pressure of 90 MPa using the Large Eddy Simulation (LES) model. The behavior of the spray tip penetration and spray angle agree with experimental values reported in the literature for diesel fuel. This condition validates our simulations for biodiesel and ternary blends. Therefore, the use of alcohols and biodiesel as new additives to diesel improves the macroscopic spray characteristics, and some ternary mixtures showed similar behavior to conventional diesel: spray tip penetration (70D5B25O, 70D25B5H, and 70D25B5O) and spray angle (70D25B5H, 70D15B15H, 80D5B15O, and 80D15B5). The mixture of 70D25B5H agrees with both spray characteristics; therefore, this mixture could be considered an alternative fuel to conventional diesel. Hence, this analysis presents the essential elements to visualize the macroscopic spray characteristics and the fluid properties. This knowledge serves as a foundation for elucidating the intricate dynamics of spray during combustion processes and the development of complementary studies aimed at optimizing engine performance.