Thermodynamic Evaluation of Using Ethanol-Gasoline Blends in Spark Ignition Engine

Resumo

The present investigation was developed in the Engines Laboratory that belongs to the Faculty of Technical Sciences, in the Agrarian University of the Havana (UNAH). For its development a spark ignition engine, Jacto model, was used. The objective of this investigation was to evaluate thermodynamically the use of blends ethanol-gasoline. To achieve the outlined objective, different percentages of ethanol were added to the gasoline (E-10%; E-15%; E-20%; E-25%), to carry out an incomplete combustion with coefficient of excess of air ∝=0,85 and an complete combustion with coefficient of excess of air ∝=1,5, for the different percentages of ethanol. Among the main results obtained it was evidenced that when using pure gasoline, the necessary air-fuel rate to achieve the combustion, is bigger than when blends are used with ethanol, because ethanol contains oxygen, and that impoverishes the blend and guarantees a better quality in the combustion process. On the other hand, it was verified that for E-10 and E-15 blends, a better environmental and energy behaviour was obtained due to the increment of the octane rating or antiexplosive capacity of the fuel blends used which improves the quality of the combustion, although decreases the energy power during the explosion (detonation).