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Diesel particulate filters are expected to be used on most passenger car applications designed to meet coming European emission standards, EU5 and EU6. Similar expectations hold for systems designed to meet US Tier 2 Bin 5 standards. Among the various products oxide filter materials, such as cordierite and aluminum titanate, are gaining growing interest due to their unique properties. Besides the intrinsic robustness of the filter products a well designed operating strategy is required for the successful use of filters. The operating strategy is comprised of two elements: the soot estimation and the regeneration strategy. In this paper the second element is discussed in detail by means of theoretical considerations as well as dedicated engine bench experiments. The impact the key operating variables, soot load, exhaust mass flow, oxygen content and temperature, have on the conditions inside the filter are discussed.

Diesel particulate filters are becoming a standard for most light duty diesel applications designed for European EU5 and EU6 regulations. Oxide based filter materials are continuing to gain significant interest and have been in high volume serial application since 2005. Compared to carbide materials they show some unique properties. With respect to the design, the length of a filter is a key variable. Usually the prime design consideration is the desired filter volume. The diameter or frontal area is then usually defined by packaging constraints. Finally, the length is adapted. The paper provides experimental data on the impact this key design parameter has on the pressure drop and the thermal behavior under “worst case” regeneration conditions. A wide range of soot loads (from 4 g/dm3 to 9 g/dm3) as well as filter lengths from 6″ to 12″ is considered and evaluated under comparable experimental conditions.

India is the world’s largest two-wheeler (2Wh) market. With the proportion of its middle class rapidly rising, 2Wh sales and the resulting emissions, are expected to grow exponentially. The decision to leap-frog from BSIV to BSVI emission norms shows India’s commitment to clean up its atmosphere. As of now, the regulation mandates Gaseous Pollutant (CO, HC, NOx) emission limits for all 2Whs and a particulate limit (PM & PN) for 2Whs powered by Direct Injection (DI) engines. Most of the 2Whs manufactured in India are powered by gasoline engines using the Port Fuel Injection (PFI) technology, and hence by definition particulate emission limits do not apply to them. Particulates when inhaled - especially of the ultrafine sizes capable of entering the blood stream - pose a serious health risk. This was the primary motivation to investigate the particulate emission levels of the 2Whs, which as on date, do not come under the purview of BSVI regulation.

Increasingly stringent vehicle emissions legislation is being introduced throughout the world, regulating the allowed levels of particulate matter emitted from vehicle tailpipes. The regulation may prove challenging for gasoline vehicles equipped with modern gasoline direct injection (GDI) technology, owing to their increased levels of particulate matter production. It is expected that gasoline particulate filters (GPFs) will soon be fitted to most vehicles sold in China and Europe, allowing for carbonaceous particulate matter to be effectively captured. However, GPFs will also capture and accumulate non-combustible inorganic ash within them, mainly derived from engine oil. Studies exist to demonstrate the impact of such ash on GPF and vehicle performance, but these commonly make use of accelerated ash loading methods, which themselves introduce significant variation.