Experimental and Kinetical Study of Component Volumetric Effects on Laminar Flame Speed of Acetone–Butanol–Ethanol (ABE)

Abstract

Acetone–Butanol–Ethanol (ABE), as a clean and economical alternative transportation fuel, its component ratio has been reported to have a significant impact on spray combustion characteristics. To fundamentally clarify the interactions between components in ABE, the laminar flame speeds (LFS) and stretch effect of ABE mixtures with component ratios (6:3:1, 3:6:1, 1:6:3) and their individual components under a wide range of equivalence ratios (0.8–1.6) at 1 bar, 400 K, were measured, and the chemical kinetics were further analyzed. The results indicate that the LFSs of the three pure fuels follow the order of ethanol > n-butanol > acetone, while ethanol only propagates marginally faster than n-butanol. The LFSs of the three ternary mixtures distribute in between that of the ethanol and acetone. In addition, their LFSs follow the order of ABE631 < ABE361 < ABE163. The comparison among all the tested fuels shows that the addition of ethanol or n-butanol improves burning velocity, while acetone suppresses it. It is noteworthy that ABE163 exhibits nearly the same LFS as pure n-butanol does, but with a lower Markstein length. The reason is that the Markstein lengths of acetone flames are the lowest among the three pure fuels at all equivalence ratios. The sensitivity analysis shows that, in addition to the commonly important methyl radical (CH3), the kinetics of the ketenyl radical (HCCO) also plays an indispensable role in reducing the global reaction rate of acetone and ABE631. Judging from the sensitivity coefficients and the concentration distribution of key species, the combustion characteristics of the three ternary mixtures are the combinations of that of the three individual components, moreover, determined by the dominant component.