Effect of Advanced Aftertreatment for PM and NO_x Control on Heavy-Duty Diesel Truck Emissions

Abstract

Emissions from four heavy-duty and medium-duty diesel vehicles were tested in six different aftertreatment configurations using a chassis dynamometer. The aftertreatment included four different diesel particle filters (DPF) and two prototype selective catalytic reduction (SCR) devices for NO(x) control. The goal of the project was to fully characterize emissions from various in-use vehicles meeting the 2007 particulate matter (PM) standard for the United States and California and to provide a snapshot of emissions from 2010 compliant vehicles. The aftertreatment devices all worked as designed, realizing significant reductions of PM and NO(x). The DPF realized > 95% PM reductions irrespective of cycle and the SCRs > 75% NO(x) reductions during cruise and transient modes, but no NO(x) reductions during idle. Because of the large test matrix of vehicles and aftertreatment devices, we were able to characterize effects on additional emission species (CO, organics, and nucleation mode particles) from these devices as a function of their individual characteristics. The two predicting parameters were found to be exhaust temperature and available catalytic surface in the aftertreatment, which combine to create varying degrees of oxidizing conditions. The aftertreatments were not found to incur a fuel penalty.

Emissions of polycyclic aromatic hydrocarbons (PAHs) and nitro-PAHs from heavy-duty diesel vehicles with DPF and SCR

“…The highest emission of total PAHs from Veh3-DPF3 could be attributed to its less efficient control of the gas-phase PAHs. During idle operation, the temperatures of the exhaust were too low ($100 C) (Table S.6, Supplemental Materials) to activate the catalyst (van Setten et al, 2001;Herner et al, 2009) and hence a negligible effect was expected from the DOC in reducing gas-phase PAHs via oxidation. Veh1-DPF1þSCR2 was the lowest emitter of gas-phase PAHs during cruise (0.001 mg/mile) and UDDS (0.06 mg/mile) cycles among all vehicles with aftertreatment.…”

“…Vehicle emission testing took place at the CARB Heavy-Duty Emissions Testing Laboratory (HDETL) in Los Angeles, CA (Ayala et al, 2002;Herner et al, 2009). The laboratory was equipped with a heavy-duty chassis dynamometer (SchenckPegasus) driven by a direct-current 675-hp motor that can absorb up to 660 hp.…”

“…Total PM in the exhaust was significantly reduced by the after-treatment (Heeb et al, 2008;Liu et al, 2008;Herner et al, 2009;Khalek et al, 2011). The PM emitted from the baseline vehicle mainly consisted of carbonaceous particles, accounting for more than 99% of total PM (Herner et al, 2011).…”

“…A diesel oxidation catalyst (DOC) is often added as a part of a DPF system to control the gaseous pollutants, such as hydrocarbons (HC) and carbon monoxide (CO) (van Setten et al, 2001), and also to generate NO 2 , which helps with regeneration (Cooper and Thoss, 1989). The after-treatment effectively reduces PM and NO X emissions from diesel exhaust, but also changes the physical and chemical properties of the diesel exhaust and even its toxicity (Burtscher, 2005;Maricq, 2007;Biswas et al, 2009a;Herner et al, 2009).…”

Effects of Selective Catalytic Reduction on the Emissions of Persistent Organic Pollutants from a Heavy-Duty Diesel Engine

“…They are also significant NO x and particulate matter (PM) sources (Herner et al, 2009;Ramadhas et al, 2016). The health risks of diesel particulate matter is associated with its chemical composition which includes heavy metals and toxic organic compounds e.g., PAHs (Jin et al, 2017).…”