Conference report: SAE 2013 Congress

26 April 2013

This year’s SAE Congress, held on April 16-18, continued to use the new format adopted in 2010, with a three-day condensed schedule and 20-minute presentations. In addition to the technical paper presentations, there were numerous oral-only open forums, keynote talks and various “chats with experts”. While the technical level of the conference was high, many morning sessions ended before the 11:30 am break-for-lunch and afternoon sessions before 4:00 pm. The exhibition accompanying the Congress was much improved from the last couple of years with plenty of new technology exhibited.

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Aftertreatment. Tim Johnson of Corning provided his usual summary of vehicle emission controls [2013-01-0538]. While past reviews focused on diesel, they have now expanded to include gasoline controls as well. Many of the points raised in the presentation were supportive of the benefits of gasoline particle filters (GPFs). Corning has been a strong promoter of this technology. While European efforts to ensure emissions from new vehicles in real world driving (RDE) reflect the increasingly stringent Euro certification limits for light-duty vehicles were inspired by stagnant real world NOx emissions from diesel vehicles since about Euro 3, issues related to particle number (PN) emissions from gasoline fueled vehicles have also been raised recently. In late model PFI engines, although certification PN emissions where below the certification limit (6 × 10¹¹/km), elevated PN emissions were observed under unregulated conditions such as low temperature and aggressive acceleration when fuel enrichment was applied. Late model GDIs were found to be high PN-emitters under all driving conditions, especially stoichiometric GDIs during low temperature tests where PN increases up to 210% over the cold start NEDC were noted. While GDI engines can be designed to meet the 2017 Euro 6c PN emissions limit in type approval testing and real-world driving conditions, some of these approaches result in fuel consumption penalties up to 5%. Also, the robustness of these engine control approaches was questioned. Injector deposits can increase PN emissions by a factor of 2.5, variation in pump fuels can cause variations by a factor of 1.7 and prolonged idling can increase PN emissions by a factor of 10.

Environment Canada reported on measurements of gaseous and particle emissions from a gasoline direct injection (GDI) and a port fuel injection (PFI) vehicle fitted with a GPF at various ambient temperatures. Over the FTP-75 cycle, limited soot regeneration in the GPF was observed at low ambient temperatures, mass-based filtration efficiency varied from 62-92% and particle number based efficiency varied from 80-85%. Over the US06 cycle, multiple spontaneous soot regenerations were observed which led to lower particle filtration efficiency, mass-based filtration efficiency varied from 36-52% and number-based efficiency varied from 60-83%.

Fuels. A presentation by Sasol provided some insight into the behavior of Zn in different fuels and the relationship with injector deposit formation [2013-01-1697]. Zn is commonly added to the fuel in some engine based tests such as the DW10 test to measure the tendency of fuels to form injector deposits that lead to nozzle flow losses. Its use is controversial for several reasons: it isn’t clear that fuel contamination by Zn is widespread and whether or not Zn induced deposits are reflective of the types of deposits found in the field. Also, not all detergent additives designed to combat injector tip deposits are effective on Zn based deposits. However, tests such as DW10 require a baseline condition where deposits are formed in the injector nozzle to allow the cleaning ability of detergent additives to be demonstrated; without spiking the fuel with a deposit inducing contaminant such as Zn, it is difficult to reliably induce this deposit formation. Sasol found that the solvency of Zn in the fuel had an inverse correlation with the formation of injector deposits. Specifically with GTL for which the solvency of Zn is low, the formation of injector deposits in test where the fuel is spiked with Zn could be very high. However, tests that exposed the fuel to Zn powder, rods and a galvanized piping system and that were designed to quantify a fuel’s ability to pick-up Zn and hold it in solution could not detect any Zn in GTL even after 6 weeks exposure.

Conference website: sae.org/congress