Numerical investigation of component coupling effect on soot forming under low temperature condition

The chemical reactions of each component of hydrocarbon fuels at low temperatures become more complex and the interactions become stronger, which is considered to potentially affect the soot formation characteristics. A 0-dimensional simulation was applied to analysis the component coupling effect on polycyclic aromatic hydrocarbon(PAH) forming process for diesel surrogate fuel, n-heptane/cyclohexane/toluene. The results show that, for the single component, the low temperature reaction of cyclohexane could contribute to the PAH formation while n-heptane inhibit it, and toluene is hardly involved in the soot generation at low temperature. Due to the component coupling effect of multi-component diesel surrogate fuels, the soot generation is significantly reduced at low temperatures, and the pyrene(A4) generation is reduced by 3 orders of magnitude compared to individual components weighted fuels. The generation of O radicals from n-heptane rapidly consumes C₆H₅O, which replaces its original reaction road to naphthalene(A2). As a result, the reaction time of A2 is shortened by 2 orders of magnitude, then, the generation of A4 and soot are reduced due to the reduction of A2. Therefore, the competition and consumption between the low temperature reaction products and the core radicals of soot generation are the key to reducing soot accumulation.