Multivariate analysis between driving condition and vehicle emission for light duty gasoline vehicles during rush hours

Abstract

Fourteen light-duty gasoline vehicles were tested by an OBS-2200 portable emission measurement system (PEMS). Vehicle speed, acceleration and emission rates of HC, CO, NOx and CO2 were recorded during rush hours (7:00–9:00 and 16:30–18:30 local time) in Tianjin, China. The emission factors of HC, CO and NOx for carbureted vehicles were 10, 4, 3 times higher than those with MPI (multi-points injection) and TWC (three-way catalytic converter), respectively. The emission factors of CO2 for carburetor car were 29% lower than those with MPI and TWC. For both types of vehicles, the Pearson correlation coefficients, between speed and CO2 emission in the mode of accelerating as well as between VSP (vehicle specific power) and CO2 emission when VSP>0, remained relatively high (r > 0.5, p < 0.001) and stable. This high repeatability of correlation was also found for NOx in carburetor vehicles. Linear trends between emission rates and VSP (bin-averaged data) were observed for NOx and CO2 from MPI vehicles, and HC, NOx and CO2 from carburetor vehicles.