983732 - An Investigation Into the Particle Number (PN) and Particle Mass (PM) Reported From Different Emissions Measurement Systems During Chassis Dynamometer Testing of a GDI Vehicle

Accurate measurement of particulate emissions from vehicles is an important step toward the successful abatement of this pollutant from the atmospheric environment. Transient particle mass (PM) and particle number (PN) measurements from multiple measurement systems were compared using an E10 fuelled light-duty GDI vehicle with TWC, tested on a chassis dynamometer. The effects of drive cycle and sampling technique on the reported PN and PM values from different measurement systems was investigated. The drive cycles used included the US EPA’s FTP-75, the LA92, the US06, and the Highway Fuel Economy Test (HWFET) cycles. PM measurements were made at the tailpipe with a Dekati Mass Monitor (DMM), and from the constant volume sampling (CVS) system with a DMM and AVL Micro Soot Sensor (MSS). PN recorded at the CVS tunnel by the AVL Particle Counter (APC) is compared with that calculated from TSI Engine Exhaust Particle Sizer (EEPS) measured particle size distributions both at the tailpipe and from the CVS. The effects of different sample conditioning methods are also investigated. Results showed that higher PN and PM measurements can occur when sampling from the CSV system than the tailpipe. In addition, the PN size distribution is generally shifted to larger diameters, and shows more variability, when sampling from the CVS system than the tailpipe. The findings of this work are important to inform best practices for particulate emissions sampling.