10th International Aerosol Conference September 2 - September 7, 2018 America's Center Convention Complex St. Louis, Missouri, USA
Abstract View
A Comparison of Partial Flow to Full Flow Dilution Tunnel Sampling for Engine Exhaust PM Measurement
MATTI MARICQ, Ford Motor Company
Abstract Number: 1042 Working Group: Combustion
Abstract The recent CFR Part 1066 specifications ushered in as part of the US Environmental Protection Agency Tier 3 upgrades to motor vehicle emissions regulations allow the use of partial flow dilution for chassis dynamometer certification of light duty vehicle particulate matter (PM) emissions. This methodology was validated and has been allowed since 2007 for heavy duty vehicles emissions measurements, but data for light duty applications is scarce. Partial flow dilution offers a number of advantages over the traditional constant volume sampling (CVS) method, including lower cost, smaller footprint, less infrastructure, and provides an attractive pathway to upgrading vehicle emissions test cells. This methodology is not yet allowed under the new Worldwide Harmonized Light vehicles Test Procedure, being developed for use in Europe and Asia, which is one motivation for the present work.
Whereas the conventional CVS method dilutes the vehicle’s entire exhaust and then samples only a very small fraction for PM measurement, partial flow dilution samples only the amount of exhaust needed for filter based gravimetric measurement (and solid particle counting if needed). This substantially reduces the size of the dilution / sampling system, but at the expense of requiring the measurement of exhaust flow and extracting a sample proportional to that flow. The present work demonstrates that a commercially available partial flow dilution system provides equivalent PM emissions results versus the traditional full flow method.
This work also examines the so-called “single filter” method. US emissions regulations are based on the composite emissions from a three part test, the Federal Test Procedure. Traditionally, this is accomplished by three PM mass measurements. But higher sensitivity and lower cost are possible by sampling the diluted exhaust from the three phases onto a single filter. We show that partial flow dilution can implement this single filter approach with higher signal to noise than the full flow dilution method. While examined here for PM, this approach works more broadly and can be applied as well to gaseous emissions, for example, formaldehyde.