thermodynamic performance and exergy analysis of a four-cylinder gasoline engine fueled with gasoline-alcohol blends: the role of pentanol, butanol, ethanol, and propanol

This study examines the combustion behavior and exergy performance of a water-cooled, four-cylinder gasoline engine operating on pure gasoline and various gasoline–bio-alcohol blends, including those containing ethanol, butanol, propanol, and pentanol. experiments were conducted at engine speeds of 1,000, 1,500, and 2,000 rpm. exergy analysis was employed to assess the input fuel exergy, exergy losses, and exergy efficiency. increased engine speed was correlated with higher input exergy rates across all fuels, resulting from increased fuel consumption. among the fuel blends, higher pentanol content led to lower input exergy but enhanced exergy transfer through heat due to improved combustion characteristics. exhaust exergy rates were higher for alcohol-containing fuels, especially at elevated speeds, due to higher combustion temperatures. the exergy work rate increased with engine speed in all blends, with the g60pe10e10bu10pr10 blend achieving the highest work output (46.48 kw at 2000 rpm). however, exergy destruction also rose with speed and alcohol concentration, particularly in blends with 20% pentanol. overall, blends with moderate alcohol content (particularly pentanol) showed favorable exergy behavior compared to pure gasoline. this study confirms the potential of optimized alcohol–gasoline blends to enhance engine thermodynamic performance while reducing dependence on fossil fuels. among the alcohols, pentanol blends demonstrated the most favorable exergy performance at higher engine speeds.