Evolution of Tailpipe Particulate Emissions from a GTDI Mild-Hybrid SUV with a Gasoline Particulate Filter 2021-01-0582

The ceramic wall-flow filter has now been globally commercialized for aftertreatment systems in light-duty gasoline engine powered vehicles. This technology, known as the gasoline particulate filter (GPF), represents a durable solution for particulate emissions control. The goal of this study was to track the evolution of tailpipe particulate and gaseous emissions of a 4-cylinder gasoline turbocharged direct injected (GTDI) 2018 North American (NA) mild-hybrid light-duty SUV, from a fresh state to the 4,000-mile, EPA certification mileage level. For this purpose, a production TWC + GPF aftertreatment system designed for a China 6b-compliant variant of this test vehicle was retrofitted in place of the North American Tier 3 Bin 85 TWC-only system. Chassis dyno emissions testing was performed at predetermined mileage points with real-world, on-road driving conducted for the necessary mileage accumulation. The vehicle was tested at 0, 500, 1000, 1800, 3000, and 4000-mile points in order to characterize the evolution of tailpipe particulate emissions: particulate mass (PM), particulate number (PN), and particulate size distribution (PSD). Industry standard methods were applied throughout this study to align with future NA particulate measurements under CARB LEV III and US EPA Tier 3 standards. Correlations are presented, specific to the nature of FTP chassis testing strategy. The impact of drive cycle during the mileage accumulation for soot particulate emission capture within the GPF aftertreatment of new mild-hybrid GTDI powered vehicles is also evaluated. Tailpipe emission results showed a decrease in PM along with shifts in the particle count and size range as the vehicle accumulated mileage. Turbo out and TP gaseous emissions demonstrated trends consistent with engine and aftertreatment system break-in throughout the 4,000-mile period.