Development of two diesel surrogates focusing on the soot emission under engine-like conditions

Threshold sooting index (TSI) is one of the critical properties related to the soot emission of diesel. Investigating the effects of TSI on the prediction of soot emission and the response of the soot model to TSI may improve our understanding of the soot formation process and model establishment during the combustion of diesel under engine-like conditions. To meet this need, two different d.iesel surrogates, named S1 and S2 were developed. S1 comprised n-dodecane, iso-octane, methylcyclohexane, and 1-methylnaphthalene, while S2 replaced 1-methylnaphthalene with toluene. Both were adjusted for similar cetane numbers, H/C ratios, and heating values, differing in TSI to analyze sooting tendencies to ensure the S1 and S2 had different soot tendencies but close ignition quality. Then, the skeletal mechanism containing the kinetics of the components in S1 and S2 was developed and validated against ignition delay times, speciation, laminar flame speeds and the 3-D spray combustion with results agreeing well with predictions. Finally, the soot performances of S1 and S2 in different soot models were compared in the constant volume combustion chamber (CVCC). The results showed that the comparison of S1 and S2 in different soot models could promote the understanding of soot models.