Characterization Spray and Combustion Processes of Acetone-Butanol-Ethanol (ABE) in a Constant Volume Chamber

Recent research has shown that butanol, instead of ethanol, has the potential of introducing a more suitable blend in diesel engines. This is because butanol has properties similar to current transportation fuels in comparison to ethanol. However, the main downside is the high cost of the butanol production process. Acetone-butanol-ethanol (ABE) is an intermediate product of the fermentation process of butanol production. By eliminating the separation and purification processes, using ABE directly in diesel blends has the potential of greatly decreasing the overall cost for fuel production. This could lead to a vast commercial use of ABE-diesel blends on the market. Much research has been done in the past five years concerning spray and combustion processes of both neat ABE and ABE-diesel mixtures. Additionally, different compositions of ABE mixtures had been characterized with a similar experimental approach. This paper reviews the production of ABE and characterization of its spray and combustion processes. The results obtained by our research group during the recent four years will also be presented. The main focus of this paper is to review the efforts made in fundamental spray research under quasi-steady flow field environments provided by a high-pressure, high-temperature constant volume chamber. In-cylinder pressure traces were calculated to derive apparent heat release rates high-speed Mie-scattering images were acquired to characterize liquid spray penetration, and natural flame luminosity was also captured to depict spatial and temporal soot distribution. It is observed that the acetone content has a major influence in the combustion behavior of the ABE mixture. An increased content of acetone will lead to a significantly advanced combustion phasing. Butanol, as another important species in the ABE mixture, is able to compensate the advancing effect caused by acetone and ethanol. More importantly, butanol can increase the overall energy density of the mixture, which makes the property of the mixture closer to that of current transportation fuels. In addition, the underlying challenges faced in this area of research are described.