Spray and Combustion Characteristics of Butanol-Biodiesel-Diesel in a Constant Volume Combustion Chamber

Abstract

The spray and combustion characteristics of ternary blends of butanol-biodiesel-diesel fuel were experimentally investigated in a constant volume combustion chamber under various ambient temperatures. The blends were mixed in three different volumetric ratios and the biofuels additive is lower than 20% in volume. The results indicate that the spray tip penetration reduced with the increase of ambient temperature and n-butanol volume percentage. A sudden drop of the spray tip penetration was observed in the spray evolution at ambient temperature of 800 K and 900 K for the fuel with a certain blending ratio which might be related to micro-explosion. The heat release rate demonstrated the transition from total mixing controlled combustion at high ambient temperature to premixed combustion mode at low ambient temperature. At lower ambient temperature, the increasing of n-butanol volume in blends resulted in longer ignition delay while virtually no difference was observed at high ambient temperature condition. Also, the total soot emissions increased as ambient temperatures went up. By adding n-butanol, soot emissions were remarkably reduced for the entire tested ambient temperatures range, though the n-butanol additive reduced soot emissions more effectively at higher ambient temperature. The flame behavior and the corresponding soot distribution under various ambient temperatures were also presented.

Keywords:

• n-Butanol
• Soybean biodiesel
• Spray
• Natural flame luminosity
• Soot emission

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