Performance and Emission Characteristics of Gasoline–Isoamyl Alcohol Blends in a Variable Compression Ratio Spark-Ignition Engine under Partial and Full Throttle Conditions
Alcohol fuels are better than alternative fuels for a few reasons: they can be used in engines that are already there, and they help cut down on greenhouse emissions. This study used neat gasoline (G100) as the reference fuel to examine the performance and emission characteristics of isoamyl alcohol–gasoline blends in a single-cylinder spark ignition (SI) engine. Three blends—G90IA10, G80IA20, and G70IA30—were tested at 100% and 75% TPS between 1200 and 1800 rpm. Along with controlled exhaust emissions, performance metrics such as brake power (BP), torque, brake mean effective pressure (BMEP), brake thermal efficiency (BTE), brake specific fuel consumption (BSFC), and mechanical efficiency (ME) were assessed. The G70IA30 outperformed the G100 at full load, increasing BP and brake torque by 9.8%, improving BTE by 56.9%, and lowering BSFC by 35.9%. NOx emissions were roughly three times higher than gasoline, but HC emissions dropped by about one-third and CO emissions by 33%. G70IA30 decreased BSEC by 38–41%, increased CO2 by 26%, and increased O2 by 4-6% at 100% TPS. G70IA30 increased BP by 8.3%, BTE by 8.1%, and decreased BSFC by 9.3% under part-load (75% TPS), while NOx increased by more than three times while HC decreased to a tenth of baseline. BSEC dropped by 7-9%, CO2 rose by 20.5%, and O2 fell by 5-7%. With lower NOx but marginally higher HC emissions, G80IA20 demonstrated moderate improvements (BP +5.3%, BTE +5.0%). Every test was carried out without VCR optimization at a fixed compression ratio of 8.5:1.
