Determination of car on-road black carbon and particle number emission factors and comparison between mobile and stationary measurements

摘要

We have used two methods for measuring emission factors (EFs) in real drivingconditions on five cars in a controlled environment: the stationary method,where the investigated vehicle drives by the stationary measurement platformand the composition of the plume is measured, and the chasing method, wherea mobile measurement platform drives behind the investigated vehicle. Wemeasured EFs of black carbon and particle number concentration. Thestationary method was tested for repeatability at different speeds and on aslope. The chasing method was tested on a test track and compared to theportable emission measurement system. We further developed the dataprocessing algorithm for both methods, trying to improve consistency,determine the plume duration, limit the background influence and facilitateautomatic processing of measurements. The comparison of emission factorsdetermined by the two methods showed good agreement. EFs of a single carmeasured with either method have a specific distribution with acharacteristic value and a long tail of super emissions. Measuring EFs atdifferent speeds or slopes did not significantly influence the EFs ofdifferent cars; hence, we propose a new description of vehicle emissions thatis not related to kinematic or engine parameters, and we rather describe thevehicle EF with a characteristic value and a super emission tail.