Low temperature spray combustion of acetone-butanol-ethanol (ABE) and diesel blends

The combustion characteristics of acetone-butanol-ethanol (ABE) and diesel blends were studied in a constant volume chamber under both conventional diesel combustion and low temperature combustion (LTC) conditions. In this work, 20. vol.% ABE without water (ABE20) was mixed with diesel and the vol.% of acetone, butanol and ethanol were kept at 30%, 60% and 10% respectively. The advantageous combustion characteristics of ABE-diesel include higher oxygen content which promotes soot oxidation compared to pure diesel; longer ignition delay and soot lift-off length allowing more air entrainment upstream of the spray jet thus providing better air-fuel mixing. Based on the analysis, it is found that at low ambient temperature of 800. K and ambient oxygen of 11%, ABE20 presented close-to-zero soot luminosity with better combustion efficiency compared to D100 suggesting that ABE, an intermediate product during ABE fermentation, is a very promising alternative fuel to be directly used in diesel engines especially under LTC conditions. Meanwhile, ABE-diesel blends contain multiple components possessing drastically different volatilities, which greatly favor the occurrence of micro-explosion. This feature may result in better atomization and air-fuel mixing enhancement, which all contribute to the better combustion performance of ABE20 at LTC conditions.