Performance of hydrous ethanol, butanol, and their blends in comparison to primary reference fuels on a spark-ignited engine

Global warming and pollutant emission concerns have been driving research towards cleaner and environmentally friendly fuels. Like ethanol, butanol is a promising biofuel with characteristics such as higher calorific value and lower latent heat of vaporization. Due to its similar properties to those of gasoline, butanol stands as a potential gasoline surrogate. Butanol can be produced from through the ABE (acetone–butanol–ethanol) fermentation process, which uses bacterial fermentation to produce acetone, n-Butanol, and ethanol from carbohydrates such as starch and glucose. This work presents the experimental results of a single-cylinder spark ignition research engine equipped with port fuel injection. Several compression ratios were compared via spacer rings. Fuels as n-butanol, hydrous ethanol (E95W05) and their blends were evaluated in comparison to primary reverence fuel (isooctane). Experimental tests were performed at stoichiometric air/fuel ratio, 9 bar IMEP load and 1800 rpm, while the combustion phasing was fixed at 10 CAD ATDC or maximum spark advance before knock. The combustion limits were explored regarding knock tendency and combustion stability. Heat release data, indicated efficiency, and several performance indicators were evaluated in order to assess the potential of neat butanol, B73E27 and E95W05 as a renewable fuel for internal combustion engines. The highest indicating efficiency was about 40% for E95W05 for a compression ratio of 12.5. B100 provided the worst performance for all tested conditions. The B73E27 blend showed the highest indicated efficiency when compared with isooctane and B100 because of the presence of ethanol, which increased the knock limit.