Computational Investigation on Soot Mechanism of Diesel and Diesel/n-Butanol Blend in Constant Volume Chamber with Various Ambient Temperatures

Abstract

Computational investigation was carried out in an optical constant volume chamber to explore the combined effects of initial ambient temperatures (800, 900, and 1000 K) and n-butanol additive (20% volume fraction of n-butanol) on diesel combustion and soot characteristics. An improved phenomenological soot model integrated with a reduced n-heptane/n-butanol/polycyclic aromatic hydrocarbon (PAH) mechanism was developed and implemented into the KIVA-3V R2 code to study the soot formation and oxidation mechanism. The predicted chamber pressure and heat release rate as well as soot mass trace and distribution showed good agreements with the experimental data. Results indicated that the ignition delay was retarded and total soot mass was reduced with the decrease of initial ambient temperature and with the n-butanol additive. The heat release rate of pure diesel demonstrated a transition from diffusion-dominated combustion at 1000 K to premix-dominated combustion at 800 K. Diesel/n-butanol blend showed no obvi...