Experimental and kinetic studies on laminar flame characteristics of acetone-butanol-ethanol (ABE) and toluene reference fuel (TRF) blends at atmospheric pressure

Acetone–Butanol–Ethanol (ABE), as an alternative for butanol, can be used either in neat form or in blends with fossil fuels. Yet the flame characteristics of ABE blending gasolines have not been reported to date. To explore the effects of ABE addition on the laminar flame speed of gasoline, the spherical propagating flames of ABE, gasoline (represented by toluene reference fuel, TRF), as well as ABE-TRF mixture were measured at an initial condition of 1 bar, 400 K, and an equivalence ranging from 0.8 to 1.6. The results indicated that with an addition of 20% ABE fuel, the laminar flame speeds of ABE-TRF flame showed apparent increments at stoichiometric and ϕ=1.2 flames. The normalized increment of laminar burning velocity I_v raised monotonically with the increase of equivalence ratio. The three ABE-TRF mixtures showed small increment of laminar burning velocity than TRF flame in the order of u_n.ABE20631<u_n.ABE20361<u_n.ABE20163, suggesting a suppressing effect of acetone addition on the mixture burning velocity of ABE-TRF mixtures. ABE fuel with more alcohol contents extended the range of stable flame while acetone addition diminished the flame diffusional thermal stability. The kinetic analysis showed that the rate-limiting reactions shifted from heavier molecular reactions to lighter ones by blending the ABE fuel into TRF, as well as the rate of production (ROP) of OH radical increased by 5.5%. The sensitivity reactions for rich ABE-TRF flames are also more dependent on light fractions compared to lean flames.