A simultaneous test study on the particle number emission of particles whose diameters are greater than 23nm and 10nm was conducted on a China-6 certified

turbocharged

direct-injection gasoline engine vehicle without particulate filter using the worldwide harmonized light vehicles test cycle(WLTC) and RTS95 test cycle at ambient temperature(23℃)

and real drive emission(RDE) test cycle at low temperature(0℃)

to research the emission characteristics of sub-23nm particles from turbocharged direct-injection gasoline engine vehicles. The results showed that the emissions of numbers of particles whose diameters are above 10nm were 32.4%

30.4% and 15.6% higher than those of China-6 standard required particles whose diameters are above 23nm in the ambient-temperature WLTC

ambient temperature RTS95 test cycle and low-temperature RDE cycle respectively. Without particulate filter

the percentage of sub-23nm particles in the total particle emissions increased significantly during harsh accelerations

decelerations

and idle conditions

but it was very low in the cold-start and warm-up stages. Sub-23nm particles mainly formed after the vehicle was fully warme-up and the three-way catalyst converter was fired. Lower ambient temperature was not beneficial to the formation of sub-23nm particles.