Analysis of soot formation and oxidation processes in the diesel engine fueled by n-octanol/biodiesel blends based on a detailed soot population balance model

Abstract

To gain in-depth knowledge of the effect of OCT (n-octanol) addition to biodiesel on the characteristics of soot formation and oxidation processes, a modeling study of the compression ignition engine fueled by OCT/biodiesel blends was carried out. The KIVA-CHEMKIN code was used in conjunction with a detailed soot population balance model solved using the advanced moment projection method. With this newly developed model, the soot formation processes including inception, coagulation, surface growth, and oxidation can be presented. During the study, the OCT/biodiesel blend ratio was changed from 0%/100% to 100%/0% with an interval of 10%. It was found that a higher ratio of OCT led to the formation of fuel-rich zones within the bowl of the cylinder due to the increased viscosity of the blends. This, in turn, resulted in the increased production of C2H2, which could lead to higher inception and coagulation rates. As a result, a greater number of soot particles were produced. In contrast, the soot mass was reduced when more OCT was blended, primarily due to the lowered soot surface growth rate and the expanded oxidation zone. In conclusion, a higher percentage of OCT in biodiesel contributed to a higher number of soot particles but a lower soot mass, suggesting that blending OCT in biodiesel could potentially reduce the size of soot particles.