Development of a diesel/biodiesel/alcohol (up to n-pentanol) combined mechanism based on reaction pathways analysis methodology

Recently, diesel/biodiesel/alcohol blend fuels have attracted tremendous attention as a potential alternative fuel in internal combustion engines, because of their beneficial effects on pollution emission and engine performance. However, there are few chemical mechanisms to forecast combustion characteristics of the ternary blends, especially for those blending with long-chain alcohols, such as butanol and pentanol. The objective of this paper is to develop a combined reduced combustion mechanism for the combustion simulation of diesel/biodiesel/alcohol (up to n-pentanol). This new combined mechanism, consisting of 229 species and 902 elementary reactions, was constructed by integrating two separated reduced mechanisms; one is the PRF-alcohols' mechanism (Liu et al., 2016), and another is the biodiesel mechanism (Luo et al., 2012). The new combined mechanism reproduced well predictions of fuel ignition and flame speed compared with those obtained using the original ones. Extensive validations were performed against various experimental data for 0-D homogenous systems, 1-D freely propagating premixed flames and 3-D spray combustion flames. The proposed combined mechanism was shown to be versatile and robust, successfully integrating the biodiesel reaction mechanism and the long-chain alcohol reaction mechanisms into a single reaction scheme. Coupling with advanced simulation technology, it could be a powerful numerical tool in the design and optimization of new generation engines which are fueled with clean alternative fuels, especially when concerning long-chain alcohols. In addition, the effects of adding biodiesel and different kinds of alcohols on fundamental combustion characteristics of diesel/biodiesel/alcohol blend fuels were investigated using the proposed combined mechanism.