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The “Multiple Disc Converter” is an innovative concept. In comparison to conventional catalytic converters, it is significantly less expensive and more compact, at identical conversion efficiency and durability. The catalytic substrate consists of 4 to 5 cylindrical ceramic discs with 62 cells/cm2 (400 cells/inch2). These are assembled in a sheet metal casing, without gaps between the discs, and angularly offset to each other. The flow through the channels is interrupted at the contact surfaces of the individual discs. Hence, the restarted turbulent flow intensifies the transverse mass transfer. Further, the uniformity of the exhaust gas flow is improved, particularly in the first discs. Thus, the conversion of emissions is improved and the durability extended. When the conversion is maintained at the level of conventional converters, then the converter volume can be substantially reduced using the same specific catalyst loading.

The unsteady flow effects of a Close-Coupled Converter (CCC) are investigated. The aim is to improve the catalytic efficiency by uniformly utilizing the entire converter volume. Experimental and computational methods were used to evaluate the differences between unsteady and steady-state flow. Catalytic converters placed close to the engine have individual inflow pipes from each cylinder and suffer extreme filling and emptying processes. There is severe interaction of the pulsating exhaust flows. A wide range of engine operating points were studied at different engine speeds and load conditions. Also described is the influence of the gas pulsation on the conversion characteristics.