Study on spray and combustion of acetone-butanol-ethanol (ABE)/biodiesel blends in a constant volume chamber

Both acetone-butanol-ethanol (ABE) and biodiesel are promising biomass fuels. In this work, ABE was blended with biodiesel to decrease its viscosity and surface tension and improve its volatility. Spray and combustion characteristics of ABE/biodiesel blends (0 %, 10 %, 20 %, and 30 % ABE by vol.) were investigated in a constant volume combustion chamber. The experiments were conducted at 300K, 600K, and 900K for non-evaporating, evaporating, and combustion conditions. The results reveal that as the blending ratio of ABE increases, the spray tip penetration decreases, and the corresponding spray cone angle and projected area increases under both non-evaporating and evaporating conditions. This effect becomes even more pronounced under evaporating conditions. The spray cone angle and spray projected area of ABE30 are the largest. For the combustion process, with the increase in ABE blending ratio, the ignition delay and flame lift-off length increase, providing more time and space for fuel-air mixture formation. Meanwhile, a higher ABE blending ratio leads to a lower flame temperature, realizing low-temperature combustion. Lastly, both the natural flame luminosity and flame KL factor of ABE30 are the lowest, indicating the best effect in soot reduction. These findings show that the addition of ABE improves the spray and combustion characteristics compared to pure biodiesel, and provides a method for thoroughly substituting diesel with biomass fuels.