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Beginning with the interim Tier 4 legislation in the US, off-highway engines with 56 - 560 kW are required to reduce Particulate Matter (PM) emissions to less than 0.02 g/kWh. While this significant reduction in PM emissions represents a great new challenge for off-highway engines, it can be achieved with a combination of engine measures and PM aftertreatment technologies. An engine with high engine out PM emissions would require a wall flow filter which has to be frequently actively regenerated at temperatures above 600 degree C and requires measures to address ash collection. On the other hand, an engine with low to moderate engine out PM emissions could be fitted with a passively regenerated partial filter such as the PM-Metalit, with no need for frequent high temperature soot regeneration or ash removal maintenance [1, 2]. A PM-Metalit system is constructed solely from metal and thus is extremely robust against severe mechanical loads that are present in off-highway applications.

Optimizing non-road applications is an ongoing challenge with the increasingly stringent emissions legislations. TIER 4 final will be introduced in the US starting in 2013 and Stage IV in the EU one year later. India, China and Japan are moving towards implementing similar emissions levels. Rapid deployment of advanced technologies will be needed to achieve the emissions regulations with minimized fuel consumption as well as low system and development costs. The enormous diversification of engines within the different power classes requires specific solutions to meet the legislation limits. New technologies will be introduced such as electronic fuel injection, cooled EGR and exhaust aftertreatment systems like a PM filter and/or SCR. Off-road operation has specific requirements regarding duty cycles, exhaust temperatures, robustness and durability, therefore on-road emissions solutions are only transferable to a limited extent.

While emission standards are becoming more stringent with every new legislation level, the engineering of compact aftertreatment system is becoming extremely challenging. This paper outlines a road map for cost-effective, compact aftertreatment systems through use of catalysts with standard and structured foil substrates. The longitudinal-structure (LS) foil disrupts laminar flow regimes within channels enhancing mass transfer and gas reconditioning. The presented results were applied to DOC catalyst functionality including parameters such as cross-section, substrate type and substrate volume. The catalysts were degreend and tested on a production 15ltr ISX Cummins engine calibrated for US 1998 emissions. Various load points were selected to determine catalyst performance as a function of exhaust gas temperature, exhaust flow rate (space velocity) and exhaust gas composition. A HC injector system was used to characterize oxidation performance at various concentration levels.