**2. Materials and Methods**

Table 1 shows the main physicochemical properties of diesel, sunflower oil, castor oil, and ethyl acetate.

**Table 1.** Physicochemical properties of fossil diesel, sunflower oil, castor oil, and ethyl acetate [22,23,27,29,30]. Kinematic viscosity values have been experimentally measured in the present work.


*2.1. Ethyl Acetate*/*Vegetable Oil Double Blends and Diesel*/*Ethyl Acetate*/*Vegetable Oil Triple Blends*

Sunflower oil was supplied by a local market, castor oil was purchased from Panreac Company (Castellar Del Vallès, Spain), and ethyl acetate was acquired from Sigma-Aldrich Chemical Company (St. Louis, MO, USA, ≥99.8% purity). Fossil diesel, used as reference fuel, was purchased from local Repsol service station. The experimental methodology is shown in Figure 1. The EA/SO and EA/CO double blends, and D/EA/SO and D/EA/CO triple blends were prepared by manual mixing of the

different components at room temperature. The mixtures were designated as B20, B40, B60, B80, and B100, where 100% fossil diesel is indicated as B0 and EA/SVO blend is B100, Table 2.

**Figure 1.** Scheme of experimental methodology.

**Table 2.** Diesel/ethyl acetate/sunflower oil blends containing 40% ethyl acetate, and diesel/ethyl acetate/castor oil blends containing 45% ethyl acetate.


#### *2.2. Characterization of the (Bio)fuel Blends*

A fuel is defined by a series of properties that determine its performance in the engine, and consequently, its commercialization. Blends properties, including kinematic viscosity, pour point, cloud point, calorific value and cetane number, were determined through predictive equationsor experimental methodology described below.
