**Outlook for Direct Use of Sunflower and Castor Oils as Biofuels in Compression Ignition Diesel Engines, Being Part of Diesel**/**Ethyl Acetate**/**Straight Vegetable Oil Triple Blends**

**Laura Aguado-Deblas 1, Rafael Estevez 1,\*, Jesús Hidalgo-Carrillo 1, Felipa M. Bautista 1, Carlos Luna 1, Juan Calero 1, Alejandro Posadillo 2, Antonio A. Romero 1 and Diego Luna 1**


Received: 9 August 2020; Accepted: 7 September 2020; Published: 16 September 2020

**Abstract:** Today, biofuels are indispensable in the implementation of fossil fuels replacement processes. This study evaluates ethyl acetate (EA) as a solvent of two straight vegetable oils (SVOs), castor oil (CO), and sunflower oil (SO), in order to obtain EA/SVO double blends that can be used directly as biofuels, or along with fossil diesel (D), in the current compression-ignition (C.I.) engines. The interest of EA as oxygenated additive lies not only in its low price and renewable character, but also in its very attractive properties such as low kinematic viscosity, reasonable energy density, high oxygen content, and rich cold flow properties. Revelant fuel properties of EA/SVO double and D/EA/SVO triple blends have been object of study including kinematic viscosity, pour point (PP), cloud point (CP), calorific value (CV), and cetane number (CN). The suitability of using these blends as fuels has been tested by running them on a diesel engine electric generator, analyzing their effect on engine power output, fuel consumption, and smoke emissions. Results obtained indicate that the D/EA/SO and D/EA/CO triple blends, composed by up to 24% and 36% EA, respectively, allow a fossil diesel substitution up to 60–80% providing power values very similar to conventional diesel.In addition, in exchange of a slight fuel consumption, a very notable lessening in the emission of pollutants as well as a better behavior at low temperatures, as compared to diesel, are achieved.

**Keywords:** ethyl acetate; castor oil; sunflower oil; straight vegetable oils; vegetable oil blends; biofuels; diesel engine; soot emissions; engine power output
