Improved SI engine efficiency using Acetone–Butanol–Ethanol (ABE)

• Acetone–Butanol–Ethanol (ABE) (6:3:1, 3:6:1 and 5:14:1 vol.% ratio) blends were combusted in an SI engine.
• ABE(6:3:1) showed combustion phasing closest to gasoline, accompanied by an improved brake thermal efficiency.
• Increasing n-butanol content increased HC emissions and CO emissions, due to incomplete combustion. On the other hand, ABE(6:3:1) showed reduced HC emissions.
• Under the tested conditions, fermentation products with higher acetone content, such as ABE(6:3:1) would be much better suited as alternative fuels for SI engines.

Alcohols, especially n-butanol, have received a lot of attention as potential fuels and have shown to be a possible alternative to pure gasoline. The main issue preventing butanol’s use in modern engines is its relatively high cost of production. ABE, the intermediate product in the ABE fermentation process for producing bio-butanol, is being studied as an alternative fuel because it not only preserves the advantages of oxygenated fuels, but also lowers the cost of fuel recovery for individual component during fermentation. With the development of advanced ABE fermentation technology, the volumetric percentage of acetone, butanol and ethanol in the bio-solvents can be precisely controlled. In this respect, it is desirable to estimate the performance of different ABE blends to determine the best blend and optimize the production process accordingly. In this paper, pure ABE fuels with different component volumetric ratio, (A:B:E of 3:6:1, 6:3:1 and 5:14:1), were combusted in a naturally aspirated, port-fuel injected spark ignited engine. The performance of these blends was evaluated through measurements of in-cylinder pressure, and various exhaust emissions. In addition, pure gasoline and neat n-butanol were also tested as baselines for comparison of ABE fuels. The tests were conducted at an engine speed of 1200 RPM and loads of 3 and 5 bar brake mean effective pressure (BMEP) under different equivalence ratios. On the basis of the experimental data, the combustion characteristics and emission behavior of these fuels have been presented and discussed. It was found that in terms of thermal efficiency, ABE(6:3:1) might be much better suited for use as an alternative fuel, relative to ABE(3:6:1) or n-butanol.