Real-Time Black Carbon Emissions from Light-Duty Passenger Vehicles Using a Portable Emissions Measurement System

Black carbon (BC) is considered the second largest anthropogenic climate forcer, but the radiative effects of BC are highly correlated with its combustion sources. On-road vehicles are an important source of anthropogenic BC. However, there are major uncertainties in the estimates of the BC emissions from on-road light-duty passenger vehicles (LDPVs), and results obtained with the portable emissions mea-surement system (PEMS) method are particularly lacking. We developed a PEMS platform and evaluated the on-road BC emissions from ten in-use LDPVs. We demonstrated that the BC emission factors (EFs) of gasoline direction injection (GDI) engine vehicles range from 1.10 to 1.56 mg.km(-1), which are higher than the EFs of port fuel injection (PFI) engine vehicles (0.10-0.17 mg.km(-1)) by a factor of 11. The BC emissions during the cold-start phase contributed 2%-33% to the total emissions. A strong correlation (R-2 = 0.70) was observed between the relative BC EFs and average vehicle speed, indicating that traffic congestion alleviation could effectively mitigate BC emissions. Moreover, BC and particle number (PN) emissions were linearly correlated (R-2 = 0.90), and compared to PFI engine vehicles, the instantaneous PN-to-BC emission rates of GDI engine vehicles were less sensitive to vehicle specific power-to-velocity (VSPV) increase in all speed ranges. (C) 2022 THE AUTHORS. Published by Elsevier LTD on behalf of Chinese Academy of Engineering and Higher Education Press Limited Company.

Automated summary

This study evaluated the on-road BC emissions from ten in-use light-duty passenger vehicles (LDPVs) using a portable emissions measurement system (PEMS) platform. The emission factors (EFs) of vehicles with gasoline direct injection (GDI) engines were found to be higher than those with port fuel injection (PFI) engines. A strong correlation was observed between vehicle speed and BC emissions, and BC emissions were linearly correlated with particle number (PN) emissions.