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Egr Technology for Lowest Emissions
Published June 24, 1996 by Institution of Mechanical Engineers in United Kingdom
Event: International Seminar on Application of Powertrain and Fuel Technologies to Meet Emissions Standards
An EGR system for turbocharged and aftercooled HD diesel engines has been demonstrated on a 12 liter 315 kW engine with 4 valves per cylinder and a high pressure injection system. In this system exhaust gas is tapped off before the turbine, run through a cooler and mixed with the intake air after the compressor and aftercooler. The EGR system combines a novel, very efficient venturi-mixer unit with a VGT turbocharger. The venturi-mixer is positioned between the aftercooler and the intake manifold and provides a suction power to the EGR gas.
A first report showed that optimization of EGR quantity and injection timing enabled emission levels in the ECE R49 test below 3 g/kWh for NOx and around 0.10 g/kWh for particulates without a substantial increase in fuel consumption. Since then tests have continued with different fuels and with different EGR hardware. This paper gives further and more detailed information on the venturi-mixer characteristics and on how its interaction with the turbocharger influences engine operation and EGR potential. It is also shown that especially with some oxygenated fuels increase of particulate emissions with EGR could be minimal.