Evaluation of the Stability and Ignition Quality of Diesel-Biodiesel-Butanol Blends 2017-01-2320
FAME is the most common renewable component of conventional automotive diesel. Despite the advantages, biodiesel is more susceptible to oxidative deterioration and due to its chemical composition as well as its higher affinity to water, is considered to be a favorable substrate for microorganisms. On the other hand, apart from biodiesel, alcohols are considered to be promising substitutes to conventional diesel fuel because they can offer higher oxygen concentration leading to better combustion characteristics and lower exhaust emissions. More specifically, n-butanol is a renewable alcohol demonstrating better blending capabilities and properties when it is added to diesel fuel, as its composition is closer to conventional fuel, when compared ethanol to for example. Taking into consideration the alleged disinfectant properties of alcohols, it would be interesting to examine also the microbial stability of blends containing n-butanol in various concentrations. Based on the aforementioned, the aim of this study is to investigate the effect of n-butanol in diesel/ biodiesel blends on fuel quality characteristics (ignition quality, lubricity) while the oxidation and microbial stability is also assessed. Blends of automotive diesel with a commercial FAME up to 20% v/v and n-butanol at concentrations of 5% and 10% v/v were prepared. The microbial stability of diesel/biodiesel/n-butanol blends was assessed and compared to diesel-biodiesel ones by preparing and storing laboratory-scale contaminated microcosms. Overall, ULSD/FAME/n-butanol ternary blends demonstrated high blending stability while density, viscosity, CFPP and sulfur content have not been substantially affected. The poor lubricity of n-butanol and ULSD was compensated by the presence of FAME. N-butanol contributed in increasing the stability - either oxidation or microbial - of the ternary blends compared to the respective binary B7 and B20 blends. Nevertheless, FAME and n-butanol have poor ignition quality characteristics, which resulted in a significant decrease of the DCN of the base fuel.