Methodology for Chemical Characterization of Exhaust Emissions from Heavy Duty Trucks and Buses fueled by Diesel and CNG

摘要

A collaborative technology validation program was conducted for over a year (Fall 1999 -Spring 2001) to evaluate ultra-low sulfur diesel (ULSD) fuels and passive diesel particle filters (DPF) in several heavy-duty vehicle fleets in Southern California. Detailed description of the study design and results obtained to-date can be obtained at the study website: http://www.ecdiesel.com. In the second round of testing, a few of the vehicles were selected for chemical characterization of volatile, semi-volatile, and particle bound compounds. During the second round of testing, two transit buses, fueled by CNG, were added to the test matrix in addition to the diesel ones. This paper focuses on presenting the sampling and analysis methodology used for characterizing the exhaust emissions. It describes the lessons learned and highlights methodology issues. A small sample of the results is used to highlight issues of tunnel blanks and variability issues when characterizing exhaust emissions at very low concentrations.