Search Results

The California Air Resources Board (CARB) examined the performance of a Partial Flow Sampling System (PFSS) against a reference Constant Volume Sampling (CVS) system in measuring emissions from a heavy-duty vehicle (HDV) during dynamometer testing at CARB's Stockton Heavy-Duty Emissions Laboratory (SL). The SL PFSS system is a Sierra BG-2 system that uses flow-based (rather than CO2-based) dilution. The CVS system uses the University of California, Riverside's (UCR) Mobile Emissions Laboratory (MEL). The test vehicle was a 2000 model-year HD tractor powered by a CAT C-15 engine. Exhaust samples were collected simultaneously with the SL and MEL systems and analyzed for total particulate matter (PM), oxides of nitrogen (NOx), carbon dioxide (CO2), carbon monoxide (CO), and total hydrocarbons (THC). The samples were taken during steady-state vehicle operation. Each test mode was repeated seven times in each of two patterns: consecutive and sequential.

The study was aimed at assessing in-use emissions of a USEPA 2010 emissions-compliant heavy-duty diesel vehicle powered by a model year (MY) 2011 engine using West Virginia University's Transportable Emissions Measurement System (TEMS). The TEMS houses full-scale CVS dilution tunnel and laboratory-grade emissions measurement systems, which are compliant with the Code of Federal Regulation (CFR), Title 40, Part 1065 [1] emissions measurement specifications. One of the specific objectives of the study, and the key topic of this paper, is the quantification of greenhouse gas (GHG) emissions (CO2, N2O and CH4) along with ammonia (NH3) and regulated emissions during real-world operation of a long-haul heavy-duty vehicle, equipped with a diesel particulate filter (DPF) and urea based selective catalytic reduction (SCR) aftertreatment system for PM and NOx reduction, respectively.