The engine bench test was carried out on a 1.4L naturally aspirated dual fuel engine

and the particulate matter emission characteristics of two fuels

gasoline and compressed natural gas(CNG)

were sampled and analyzed by DMS500 fast particle analyzer under different inlet pressure conditions with engine speed of 4000r/min. The experimental results show that the total particle number(PN) and particle mass(PM) concentrations of the two kinds of fuel decrease first and then increase with the increase of inlet pressure. The PN and PM emission of CNG are relatively stable under different inlet pressures. The nuclear particles in the PN account for a relatively large amount. At a particle size of about 200nm

the particle surface area concentration appears a peak. The accumulation state of gasoline emission particulate matter is dominant

so its PM concentration is greater than that of CNG

and its particulate matter surface area concentration is also greater

with the maximum surface area concentration appearing at about the particle size of 100nm.