Research on the characteristics of real-world vehicle particle number and mass emissions

Abstract Plug-in hybrid electric vehicles (PHEVs) have been greatly promoted due to their advantages in both performance and energy saving. However, real-world particle emission measurements for PHEV are generally conducted by dilution system but rarely through the directly hot-sampling method. This study firstly employs a hot-sampling HT-ELPI+, the main component of a portable emission measurement system, to investigate the real-world emissions of particle matter (PM) and particle number (PN) from a Euro V PHEV. Obvious higher emission factors (EFs) of PN and PM occurred on the highway compared to those on other road types. However, the lowest EFs occurred on the urban road for PN, while on the rural road for PM. The average speed-bin EFs of PN and PM both exhibited increasing trends with the speed increase, especially when the speed exceeds 100 km/h. And the peak PN and PM emission rates in different speed ranges exhibit the highest in the high-speed range, while the lowest in the low-speed range. Furthermore, the particle number size distribution exhibited an obvious unimodal distribution (mode size: 9 nm) for the whole speed and the medium- and high-speed ranges, while a bimodal distribution (mode size: 9 nm and 30 nm) for the low-speed range.