Greenhouse Gas Emissions of MY 2010 Advanced Heavy Duty Diesel Engine Measured Over a Cross-Continental Trip of USA 2013-24-0170

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.

The TEMS was additionally outfitted with an MKS MultiGas® 2030-HS high-speed FTIR to quantify NH₃ and N₂O, along with other compounds of interest, at a frequency of 5 Hz. One of the salient features of the study is the continuous measurement of N₂O and NH₃ concentrations at high temporal resolution while driving across the US.

A Mack heavy-duty Class8 tractor, powered by a MY 2011, 12.8 liter diesel engine, equipped with a DOC-DPF and a urea-SCR NOx aftertreatment system was used to transport the TEMS, and ancillary measurement systems. The study was conducted over a total distance of 2,450 miles driven between Morgantown, WV and Riverside, CA, with a gross vehicle weight (GVW) of 67,000 lbs. The chosen route represented varying topography and driving conditions that included the Appalachian Mountains, flat regions of the mid-west, high altitudes of the Rocky Mountains and the busy highways of Southern California.

Results show the effect of road grade, ambient operating conditions, and on-board diagnostics (OBD) related to DPF and SCR aftertreatment systems on the GHG emissions and regulated constituents. Specifically, the results show the measured payload-distance specific CO₂ emissions of a USEPA 2010 emissions-compliant Class 8 heavy-duty engine is higher than MY 2014 vehicle standards by 11% over the entire trip. The brake specific GHG emissions were lower than MY 2017 & later engine standards by a wide margin. However, the simulation tool (GEM) resulted in 13% higher CO₂ emissions than measured over the entire trip. The brake specific NOx emissions were an order of magnitude higher when the engine was operating at altitudes greater than 5,500 ft.