Investigation on spray and flame lift-off length of acetone-butanol-ethanol-diesel blend in a constant volume chamber

Acetone-butanol-ethanol (ABE), as the intermediate product during producing biobutanol by fermentation, is considered as a promising alternative fuel due to its advanced properties and lower recovery cost. The spray and combustion process of ABE20 (20% ABE and 80% diesel) and pure diesel was investigated in a constant volume chamber. The tested ambient environments were set at different temperatures (1100 K, 900 K, and 700 K) and oxygen contents (21%, 16%, and 11%) to cover conventional combustion and low temperature combustion (LTC) conditions of diesel engines. The results show that with the addition of 20% ABE, blends exhibit an improved spray characteristics, shorter and narrower spray due to the low viscosity and high volatility of ABE components, and the spray performance impacted much less by environmental condition than that of neat diesel. In addition to the shorter spray penetration, ABE20 also exhibits a much longer flame lift-off length (FLoL) than that of neat diesel, which forms a much bigger gap from spray tip to flame area for ABE20 that will effectively reduce equivalence ratio of combustion region. As a result, the natural flame luminosity which represents the soot emission level of ABE20 is significantly lower than that of pure diesel (D100) at all tested conditions.