*3.4. Fuel Consumption*

The fuel consumption is also an important parameter to commercialize a new (bio)fuel. Figure 6 shows the influence of the different EA/SVO and D/EA/SVO blends with SO (Figure 6a) and CO (Figure 6b), on consumed volume (in liters per hour) by a diesel engine at low (1000 W), medium (3000 W), and high engine loads (5000 W). As biofuel ratio added to blends is rising, from B20 to B100, the volume consumed by the engine is greater. This fact is attributed to the fact that ethyl acetate has a lower calorific value than diesel (Table 1), which results in a reduction in the energy content of the mixtures, and therefore it is necessary to introduce more fuel on the engine to reach the required output power. As all the studied mixtures have lower calorific values than those of diesel, the engine consumes more fuel. The presence of sunflower oil leads to slightly higher fuel consumption compared to the analogous mixture that it contains CO, probably due to the lower cetane number of sunflower oil that increases the ignition delay, which deteriorates combustion process and leads to a higher fuel consumption. Particularly, blends B20–B80 with SO consume between 14 and 24% more than diesel, whereas the consumption of same blends with CO is about 4–21% more than diesel. On the other hand, as it is expected, the B100 blends display the highest percentage of consumption, 33% and 29% for EA/SO and EA/CO, respectively. For all the blends tested, the highest consumption as compared to diesel is usually produced at the highest engine load (5000 W).

To sum up, blends with ethyl acetate as LVS of sunflower and castor oils here evaluated has showed a greater efficiency on C.I. diesel engine than analogous mixtures tested in previous researches [16,17]. Triple blends containing DEE as renewable solvent achieved the best result with a proportion 60/18/22 D/DEE/CO, which led to a maximum of 40% of diesel replacement, and up to 77% of smoke emissions reduction [16]. Likewise, the same ratio in a blend containing ACE [17] gave rise to an equal percentage of fossil fuel substitution, but with emissions slightly lower (82%). In these cases, the engine does not work with higher amounts of DEE and ACE due to knocking problems attributed to the low energetic content of blends. Herein, the use of ethyl acetate allows to replace up to 100% of fossil diesel, with up to 94% in soot reduction respect to diesel. This means that all blends proposed can run in a conventional diesel engine, although it should be taking into account that a loss in engine power is produced as the concentration of pure biofuel EA/SVO supplied to the engine is increased.
