Comparative Analysis of Ethanol and Fusel Oil Blends on SI Engine Performance at Varying Speeds

Abstract

The increasing demand for sustainable energy sources has led to significant interest in biofuels as alternatives to fossil-based fuels in spark-ignition (SI) engines. This study investigates the comparative effects of ethanol and fusel oil blends on the performance and combustion characteristics of an SI engine at three different engine speeds: 1000, 2000, and 3000 RPM. The objective is to evaluate and compare the thermal efficiency, mean adequate pressure, and in-cylinder combustion behaviour of RON95 gasoline, ethanol blends (E10, E20, E30), and fusel oil blends (F10, F20, F30). Experimental tests were conducted under varying engine load conditions, and the data were analysed using performance metrics such as Brake Thermal Efficiency (BTE), Brake Mean Effective Pressure (BMEP), and in-cylinder pressure versus crank angle profiles. The results showed that ethanol blends, particularly E30, delivered the highest BTE of 54.6% and peak in-cylinder pressure of 8.30 MPa at 3000 RPM, while E10 performed optimally at 1000 RPM with a BTE of 27.4%. Fusel oil blends, although having lower calorific value, showed promising performance at higher speeds, with F10 reaching a BMEP of 7.76 bar at 3000 RPM. The novelty of this research lies in its integrated evaluation of two different biofuels across multiple engine speeds and loads, providing comprehensive insights into their real-world application potential. In conclusion, ethanol blends are most effective at enhancing SI engine performance at high speeds, while fuel oil blends show viable potential when properly blended and operated under optimised conditions. This study supports the strategic use of renewable fuels to reduce dependency on fossil energy sources.