Comparative Analysis of the Engine Performance and Emissions Characteristics Powered by Various Ethanol-Butanol-Gasoline Blends

Although many biofuel blends have been proposed recently, comparisons of such blends are rarely investigated. Currently, it is extremely difficult to recommend one biofuel blend over another since comparisons are not carried out under the same engine conditions. In the current study, different biofuel blends in dual and ternary issues are compared together, as well as with conventional gasoline under the same engine conditions. Five different biofuel blends are considered, i-butanol (iB), n-butanol (nB), bio-ethanol (E), n-butanol-bio-ethanol (nBE), and i-butanol-bio-ethanol-gasoline (iBE) blends, at two different engine speeds (2500 and 3500 rpm/min). Additionally, the blends are compared in the average bases through wide engine speeds. The comparisons of blends are carried out via engine performance and emissions. The performance includes engine power, torque, and volumetric efficiency, while the emissions include CO, CO2, and UHC. Results showed that the E blends presented higher performance than the pure/neat gasoline by about 6.5%, 1.5%, and 25% for engine power, torque, and volumetric efficiency, respectively. Nevertheless the other four blended fuels (nB, iB, nBE, and iBE) presented lower levels of engine performance than the pure gasoline by about -3.4%, -2.6%, -5.2%, and -2.3% for engine power, -1.48%, -0.9%, -1.9%, and -1.7% for torque, and -3.3%, -3%, -2.4%, and -2.7% for volumetric efficiency, respectively. Regarding emissions, the E blends presented the highest CO2 (by about 4.6%) and the lowest CO (by about -20%), while both nB and iB showed the lowest CO2 (by about -35% and -36%, respectively) and the highest CO emissions (by about -10% and -11.6%, respectively). Lastly, iB and nBE introduced, respectively, the highest and the lowest UHC emissions (by about -6.8% and -17%, respectively) among all blends.