Combustion Characteristics of Diesel/Butanol Blends Within a Constant Volume Combustion Chamber

In this paper, the spray and combustion characteristics of diesel/butanol-blended fuels were studied within a high-temperature and high-pressure constant volume chamber equipped with a single-hole injector. Two blends with 80% diesel/20% butanol and 60% diesel/40% butanol mixed by volume were tested in this study. The pure diesel B0 was also tested here as a reference. The spray penetration, flame lift-off length, and soot optical thickness were obtained through high-speed schlieren imaging, OH* chemiluminescence, and diffused back-illumination extinction imaging technique, respectively. The thermogravimetric curves of different fuels were obtained through a thermogravimetric analyzer. The results showed that butanol/diesel blends presented a longer ignition delay (ID) and flame lift-off length compared with pure diesel, and such finding was mainly caused by the lower cetane number and higher latent heat of vaporization of n-butanol. With the increase in the n-butanol ratio, soot production in the combustion process decreased significantly. Given the shorter ID period, the soot distribution of pure diesel reached a steady state earlier than the blends.