Ring Catalyst Turbocharger Increases Engine Efficiency in Hybrids

In an attempt to increase the efficiency of engines in hybrids, Continental has combined a turbocharger and a ring catalyst to further reduce emissions and fuel consumption. 

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Automotive supplier Continental has debuted its ring catalyst turbocharger at the 40th International Vienna Motor Symposium 2019. This highly integrated combination of a turbocharger and a catalytic converter is intended to offer additional advantages over separate installation of the individual components.

The ring catalyst turbocharger is an evolved version of Continental's Raax turbocharger and ring catalyst technology. Continental explains the operating principle as follows: After passing through the turbine, the exhaust gas coming from the turbocharger flows into a conical mixing pipe. At the end of this pipe, the exhaust mass flow is redirected and passed through the ring-shaped 3-way catalyst that surrounds the mixing pipe.

The catalyst becomes more efficient

In conventional turbochargers, the exhaust gases quickly expand as they leave the turbine, which causes fluid dynamic losses and impacts efficiency. The ring catalyst turbocharger works differently: the conical mixing pipe permits controlled expansion. In addition, the exhaust gas from the wastegate is fed through an annular gap around the mixing pipe, facilitating low-loss mixing with the exhaust gas flow leaving the turbine impeller. According to Continental, the exhaust gas temperature distribution is homogeneous on reaching the catalyst, increasing its efficiency and extending its service life. It also means that λ=1 operation can be extended. Consequently, this ring catalyst turbocharger is exceptionally economical. "If we combine it in hybrid vehicles with Emicat electrical heating technology, then we're rolling together fuel saving and minimised emissions even during cold starts and after prolonged engine-off phases," says Rolf Brück, head of Catalysts and Filters at the Powertrain Components business unit.

The electric power for heating the catalyst can be provided by an efficient 48 V hybrid solution. Continental tested its Super Clean Electrified Diesel prototype on a dynamometer to demonstrate that the electrically heatable catalyst makes it possible to comply even with the demanding London Traffic Cycle: NO_x output during this short cycle with many idle times (jams), low engine load and repeated moving off from standstill was below 27 mg/km. At the same time, CO₂ output dropped by 4 g/km.