Thermodynamic and economic analyses of a spark-ignition engine operating with bioethanol-gasoline blends

The problems associated with the use of fossil energy sources, as well as the constant rise in energy demand, have increased the importance of biofuels. In this study, the use of gasoline/bioethanol dual fuel blend as an alternative fuel in an SI engine was investigated by experiments and thermodynamic analysis. In experimental studies, performance and emission tests were performed at three different bioethanol ratios (10%-30%) at five different engine speeds (1200-1600 rpm). Thermodynamic and economic analyses were accomplished considering fuel consumption, torque, temperatures of cooling water and exhaust gases, and emissions obtained from these tests. Besides that, the sustainability index value of the fuel blends was taken into account. The augmentation of bioethanol fraction in the mixtures leads to a decline in thermal and exergy efficiencies. When the speed is 1600 rpm, the thermal and exergetic efficiencies of B0 fuel are 2.66% and 3.73% higher than those of B30 fuel, respectively. When the bioethanol concentration in the blends increased, the destroyed exergy increased. The exergy lost for G100, B10, B20, and B30 fuel blends were calculated as 6.822, 6.985, 6.908, and 7.017 respectively when the speed was adjusted to be 1200 rpm. The exergetic efficiency values for G100 and B30 at 1200 rpm were observed to be 36.82% and 35.39%, respectively. Based on the exergoeconomic analysis, the rise in the concentration of bioethanol in the blends increases the fuel cost rate, and accordingly, the unit cost of engine power exergy increases. The unit cost of engine power exergy in B30 fuel is approximately 50% higher than that of G100 fuel. The exergoeconomic factor was found to be 2.52 for G100, 1.893 for B10, 1.511 for B20, and 1.217 for B30 at the speed of 1200 rpm. The minimum sustainability index in all engine speeds in bioethanol fuel blends was calculated as 1.548.

Automated summary

The use of gasoline/bioethanol blend as an alternative fuel in SI engines was investigated through experiments and thermodynamic analysis. The study found that as the bioethanol fraction increased, the thermal and exergetic efficiencies declined, along with an increase in fuel cost and unit cost of engine power exergy. The sustainability index of the fuel blends also needed to be taken into account.