Experimental evaluation of water-containing isopropanol-n-butanol-ethanol and gasoline blend as a fuel candidate in spark-ignition engine

Bio-n-butanol has attracted great attention as a potential alternative fuel in internal combustion engines (ICEs) due to its favorable physicochemical properties. However, the main issue impeding the use of bio-butanol in ICEs is its relatively high cost and energy consumption of dehydration and recovery processes in acetone-n-butanol-ethanol (ABE) or isopropanol-n-butanol-ethanol (IBE) fermentation technologies. Some researchers have proposed to use intermediate fermentation product, i.e. water-containing ABE or IBE, for clean combustion. Therefore, an experimental evaluation of spark-ignition (SI) engine fueled with water-containing IBE-gasoline blends was carried out in this study. Effects of IBE and water addition on combustion, performance, and emissions characteristics were first investigated at stoichiometric condition. Then, a “drop-in” fuel test was performed, i.e. IBE9W1 (9 vol.% IBE, 1 vol.% water and 90 vol.% gasoline) was compared with pure gasoline under various engine loads (3 and 5 bar BMEP) and equivalence ratios (Φ = 0.83-1.25). It was found that IBE9W1 showed a higher brake thermal efficiency, and a lower CO, NOx and BTX (benzene, toluene and xylene) emissions. The results indicate that water-containing IBE could be used as a fuel candidate in SI engine due to its eco-friendly production method and potential to improve energy efficiency and reduce emission pollutants.