3.1 Compositions and fuel properties of BWCO, DDCL, ET and BT
The total ion chromatogram and the fatty acid methyl ester (FAME) compositions of the neat BWCO are shown in Figure 1 and Table 1. The BWCO is composed of FAMEs with different carbon chains and saturated compositions. As shown in Figure 1 and Table 1, although the unsaturated FAMEs (73.41 wt.%) in the prepared BWCO are more than saturated FAMEs, the relatively higher content of saturated esters (25.77 wt.%) always resulted in the weaker low-temperature fluidity of BWCO. Table 3 shows that the PP, CFPP, and CP of BWCO are 4 °C, 5 °C, and 6 °C, respectively, and other fuel properties, such as acid value, oxidation stability, flash point, density, and kinematic viscosity are within the ASTM D6751 and EN 14214 limits.
The compositions and fuel properties of DDCL are differ from that of BWCO. Figure 2 and Table 2 show the total ion chromatogram and compositions of DDCL. DDCL is a liquid fuel direct obtained from solid coal liquefaction reaction and mainly consists of hydrocarbons, cycloalkanes, alkanes, and alkenes [15, 18]. Thus, DDCL exerted better low-temperature flow properties than biodiesel due to their lower melting points. The CP, CFPP and PP of DDCL reached −41 °C, −49 °C and −62 °C, respectively [15]. These results are well consistent with the results of previous reports [19, 20]. Similarly, the melting point of ethanol (ET) and 1-butanol (BT) had lower values of −114 °C and −89 °C, respectively. Therefore, blending ET, BT and DDCL with BWCO can potentially enhance the low-temperature flow properties of biodiesel.