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Williams A.,National Renewable Energy Laboratory | McCormick R.,National Renewable Energy Laboratory | Luecke J.,National Renewable Energy Laboratory | Brezny R.,Manufacturers of Emission Controls Assoc | And 6 more authors.
SAE International Journal of Fuels and Lubricants | Year: 2011

It is estimated that operating continuously on a B20 fuel containing the current allowable ASTM specification limits for metal impurities in biodiesel could result in a doubling of ash exposure relative to lube-oil derived ash. The purpose of this study was to determine if a fuel containing metals at the ASTM limits could cause adverse impacts on the performance and durability of diesel emission control systems. An accelerated durability test method was developed to determine the potential impact of these biodiesel impurities. The test program included engine testing with multiple DPF substrate types as well as DOC and SCR catalysts. The results showed no significant degradation in the thermo-mechanical properties of cordierite, aluminum titanate, or silicon carbide DPFs after exposure to 150,000 mile equivalent biodiesel ash and thermal aging. However, exposure of a cordierite DPF to 435,000 mile equivalent aging resulted in a 69% decrease in the thermal shock resistance parameter. It is estimated that the additional ash from 150,000 miles of biodiesel use would also result in a moderate increases in exhaust backpressure for a DPF. A decrease in DOC activity was seen after exposure to 150,000 mile equivalent aging, resulting in higher HC slip and a reduction in NO 2 formation. The metal-zeolite SCR catalyst experienced a slight loss in activity after exposure to 435,000 mile equivalent aging. This catalyst, placed downstream of the DPF, showed a 5% reduction in overall NOx conversion activity over the HDDT test cycle. Source


Williams A.,National Renewable Energy Laboratory | McCormick R.,National Renewable Energy Laboratory | Lance M.,Oak Ridge National Laboratory | Xie C.,Oak Ridge National Laboratory | And 2 more authors.
SAE International Journal of Fuels and Lubricants | Year: 2014

Small impurities in the fuel can have a significant impact on the emissions control system performance over the lifetime of the vehicle. Of particular interest in recent studies has been the impact of sodium, potassium, and calcium that can be introduced either through fuel constituents, such as biodiesel, or as lubricant additives. In a collaboration between the National Renewable Energy Laboratory and the Oak Ridge National Laboratory, a series of accelerated aging studies have been performed to understand the potential impact of these metals on the emissions control system. This paper explores the effect of the rate of accelerated aging on the capture of fuel-borne metal impurities in the emission control devices and the subsequent impact on performance. Aging was accelerated by doping the fuel with high levels of the metals of interest. Three separate evaluations were performed, each with a different rate of accelerated aging. The aged emissions control systems were evaluated through vehicle testing and then dissected for a more complete analysis of the devices. Results from these experiments show that increasing the rate of acceleration impacts the amount of fuel-borne metals that are captured by the catalyst, which subsequently impacts the catalyst performance. Beyond a certain threshold, the acceleration rate creates an artificial mechanism for catalyst deactivation. In the range of acceleration rates that were examined in this study, these effects were primarily isolated to the inlet of the catalyst whereas performance further down the length of the catalyst was mostly unaffected. Source


Williams A.,National Renewable Energy Laboratory | Burton J.,National Renewable Energy Laboratory | McCormick R.L.,National Renewable Energy Laboratory | Toops T.,Oak Ridge National Laboratory | And 9 more authors.
SAE Technical Papers | Year: 2013

Alkali and alkaline earth metal impurities found in diesel fuels are potential poisons for diesel exhaust catalysts. Using an accelerated aging procedure, a set of production exhaust systems from a 2011 Ford F250 equipped with a 6.7L diesel engine have been aged to an equivalent of 150,000 miles of thermal aging and metal exposure. These exhaust systems included a diesel oxidation catalyst (DOC), selective catalytic reduction (SCR) catalyst, and diesel particulate filter (DPF). Four separate exhaust systems were aged, each with a different fuel: ULSD containing no measureable metals, B20 containing sodium, B20 containing potassium and B20 containing calcium. Metals levels were selected to simulate the maximum allowable levels in B100 according to the ASTM D6751 standard. Analysis of the aged catalysts included Federal Test Procedure emissions testing with the systems installed on a Ford F250 pickup, bench flow reactor testing of catalyst cores, and electron probe microanalysis (EPMA). The thermo-mechanical properties of the aged DPFs were also measured. EPMA imaging of aged catalyst parts found that both the Na and K penetrated into the washcoat of the DOC and SCR catalysts, while Ca remained on the surface of the washcoat. Bench flow reactor experiments were used to measure the standard NOx conversion, NH3 storage and NH3 oxidation for each of the aged SCR catalysts. Flow reactor results showed that the first inch of the SCR catalysts exposed to Na and K had reduced NOx conversion through a range of temperatures and also had reduced NH3 storage capacity. The SCR catalyst exposed to Ca had similar NOx conversion and NH3 storage performance compared to the catalyst aged with ULSD. Using a chassis dynamometer, vehicle emissions tests were conducted with each of the aged catalyst systems installed onto a Ford F250 pickup. Regardless of the evidence of catalyst deactivation seen in flow reactor experiments and EPMA imaging, the vehicle successfully passed the 0.2 gram/mile NOx emission standard with each of the four aged exhaust systems. This indicates that total catalyst volume is adequate to accommodate the catalyst activity loss observed in the flow reactor experiments. Source


Chan T.W.,Environment Canada | Meloche E.,Environment Canada | Kubsh J.,Manufacturers of Emission Controls Assoc | Brezny R.,Manufacturers of Emission Controls Assoc | And 2 more authors.
SAE International Journal of Fuels and Lubricants | Year: 2013

Gaseous and particle emissions from a gasoline direct injection (GDI) and a port fuel injection (PFI) vehicle were measured at various ambient temperatures (22 ŶC, -7 ŶC, -18 ŶC). These vehicles were driven over the U.S. Federal Test Procedure 75 (FTP-75) and US06 Supplemental Federal Test Procedure (US06) on Tier 2 certification gasoline (E0) and 10% by volume ethanol (E10). Emissions were analyzed to determine the impact of ambient temperature on exhaust emissions over different driving conditions. Measurements on the GDI vehicle with a gasoline particulate filter (GPF) installed were also made to evaluate the GPF particle filtration efficiency at cold ambient temperatures. The GDI vehicle was found to have better fuel economy than the PFI vehicle at all test conditions. Reduction in ambient temperature increased the fuel consumption for both vehicles, with a much larger impact on the cold-start FTP-75 drive cycle observed than for the hot-start US06 drive cycle. Colder ambient temperatures were also found to increase CO, THC, and particle emissions over the FTP-75 drive cycle, with little impact on the emissions over the US06 drive cycle. E10 was found to decrease particle number emissions from the PFI vehicle over both test cycles and all ambient temperatures. E10 almost always led to higher particle emissions from the GDI vehicle, except over the FTP-75 drive cycle at standard temperature. Limited soot regeneration in the GPF was observed at cold ambient temperatures over the FTP-75 drive cycle. However, the particle filtration efficiency of the GPF did not significantly change during cold ambient testing. On average, the mass-based GPF filtration efficiency over the FTP-75 drive cycle was observed to vary from 62% at standard temperature to 92% at -18 ŶC. When based on particle number, the GPF filtration efficiency varied from 85% at standard temperature to 80% at -18 ŶC. Over the US06 drive cycle, multiple spontaneous soot regenerations were observed and led to lower particle filtration efficiency. Mass-based filtration efficiency of the GPF was found to vary from 36% at standard temperature to 52% at -18 ŶC. Number-based filtration efficiency varied from 83% at standard temperature to 60% at -18 ŶC. Copyright © 2013 SAE International. Source


Chan T.W.,Environment Canada | Meloche E.,Environment Canada | Kubsh J.,Manufacturers of Emission Controls Assoc | Rosenblatt D.,Environment Canada | And 2 more authors.
SAE International Journal of Fuels and Lubricants | Year: 2012

Gaseous compounds, particle number and size distribution measurements on a gasoline direct injection (GDI) vehicle and a port fuel injection (PFI) vehicle were conducted over the U.S. Federal Test Procedure 75 (FTP-75) and US06 Supplemental Federal Test Procedure (US06) on Tier 2 certification gasoline (E0) and a 10% by volume ethanol (E10). Overall the GDI test vehicle was observed to have lower fuel consumption than the PFI test vehicle by 6% and 3% for the FTP-75 and US06 drive cycles, respectively. When using E10, this GDI vehicle had a better fuel consumption than the PFI vehicle by 7% and 5% for the FTP-75 and US06 drive cycles, respectively. For particle emissions, the solid particle number emission rates for the GDI, equipped with a 3-way catalyst in its original equipment manufacturer configuration (i.e., stock GDI), were 10 and 31 times higher than the PFI vehicle for the FTP-75 and US06 drive cycles, respectively. However, when a non-catalyzed gasoline particulate filter (GPF) was installed, the solid particle number emission rates were only 2 and 8 times higher than that from the PFI vehicle. For the GDI vehicle, the number-weighted geometric mean particle diameters over both FTP-75 and US06 cycles were in the range of 50-70 nm. The situation was similar for the PFI vehicle over the FTP-75, however, over the US06, most of the emitted particles were ultrafine particles with a diameter of about 10 nm. E10 had little impact on particle diameter for both the GDI and PFI vehicles. The use of E10 fuel generally led to a reduction in particle number emissions on the PFI vehicle over both cycles. For the GDI vehicle, the use of E10 led to a reduction in particle emissions over the FTP-75 but the opposite was observed for the US06 drive cycle. Based on the test results, the unconditioned GPF had a particle filtration efficiency of 82 and 76% for the FTP-75 and US06 cycles, respectively. Results also revealed that the GPF filtration efficiency was strongly linked to the exhaust temperature and continued soot regenerations were the reason for the lower filtration efficiency being observed for the US06 drive cycle. © 2012 SAE International. Source

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