Spray and Combustion Characterizations of Acetone-Butanol-Ethanol (ABE) blend at High-Pressure and High-Temperature Conditions

Abstract

The intermediate fermentation mixture of butanol production, Acetone, Butanol and Ethanol (ABE), is increasingly considered as a new alternative fuel in CI engines due to its physical and chemical properties, which are similar to those of butanol, and its advantages of no additional cost or energy consumption due to butanol separation. In a previous study, the High-Pressure and High-Temperature (HPHT) chamber, called 'New One Shot Engine" (NOSE), was used to investigate macroscopic spray-combustion parameters by validating Spray-A conditions of the Engine Combustion Network. The present study concerns the spray-combustion characteristics of the ABE mixture (volume ratio 3:6:1), blended with n-dodecane at a volumetric ratio of 20% (ABE20), compared to n-dodecane as reference fuel. The macroscopic spray and combustion parameters were investigated, for non-reactive conditions, in pure Nitrogen and for reactive conditions, in 15% oxygen, at ambient pressure (60 bar), ambient density (22.8 kg/m 3 ) and different ambient temperatures (800 K, 850 K and 900 K). The liquid and vapor spray penetrations were investigated by the Diffused Back Illumination (DBI) and Schlieren techniques in non-reactive conditions. In reactive conditions, the lift-off length was measured by OH* chemiluminescence images at 310 nm. The Schlieren technique was also used to verify the choice of detection criterion. The ignition delay results of the two fuels were compared. It was found that the behavior of the two fuels as a function of temperature was similar even if the liquid length of ABE20 was shorter than that of n-dodecane at all ambient temperatures. On the other hand, no real difference in vapor spray penetration between the two fuels was observed. The vaporization properties and the lower autoignition ability of ABE20 led to longer ignition delays and lift-off length. KeywordsSpray and Combustion Characterizations, Acetone-Butanol-Ethanol (ABE), High-Pressure and High-Temperature Conditions. IntroductionDue to the increase in energy demand and the depletion of oil resources during the last few decades, butanol has become an alternative fuel, considered in the transportation sector as a sustainable energy and also a means to reduce greenhouse gases compared to conventional fuel [1], as it can be produced from renewable bioresources in the form of agricultural biomass and waste [2]. Moreover, butanol induces lower fuel consumption as its energy content is higher than ethanol, up to 30%, and its lower water solubility decreases the tendency to microbial-induced corrosion in fuel storage and pipelines during transportation [1]. The higher cetane number (CN) of butanol (CN = 25) compared to ethanol (CN = 8) leads to easier ignition in compression ignition (CI) engines [3]. It is suitable for diesel injection systems thanks to its high level of viscosity like diesel fuel and no water content, unlike ethanol. Finally, researchers have considered butanol as one means to reduce CO, HC, NOx, and Soot emissions [4] and also to improve comb...