Study on the influence of methanol on the precursor of soot and particulate matter of diesel engine fueled with F-T diesel

Methanol is a high-quality alternative fuel for diesel engines and mainly used for methanol intake injection (MII) and methanol mixing direct injection (MMDI) modes. The methanol injection mode influences the formation of soot precursors and particulate matter (PM). This paper carried out a methanol/F-T diesel engine bench test at 2400 r/min, 100% load with two methanol injection modes. And the effects of methanol injection mode on the soot precursor were investigated by establishing an in-cylinder working process simulation. Research has shown that when the methanol blending ratio is 30%, the smoke emissions of MMDI and MII were reduced by 25.3% and 30.2% compared to F-T diesel. Moreover, the MII mode was more conducive to improving the agglomeration degree of particulate matter. MII mode formed a uniform methanol mixture earlier than MMDI mode at the same crankshaft angle in the cylinder. Benzene (A1) is the first ring of aromatic hydrocarbons and the most important precursor of soot. When the methanol blending ratio was 30%, compared with MMDI, the peak concentration of A1 was reduced by 17.2% and appeared earlier by 14.3% in MII mode. C3H3 was the main intermediate product of aromatic hydrocarbons formation. Compared with the MMDI mode, the peak concentration of C3H3 in the MII mode was reduced by 51.6%, effectively suppressing the generation of benzene.