New EGR Technology Retains HD Diesel Economy with 21st Century Emissions 960848
An EGR system for turbocharged (and aftercooled) heavy-duty diesel engines has been demonstrated on a 12 litre 315 kW engine with 4 valves per cylinder head and high pressure injection system.
In the EGR system exhaust gas is tapped off before the turbine, run through a cooler and mixed with the intake air after the compressor and aftercooler. This is done with a minimum of disturbance to the pressure balance across the engine by combining a 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.
Optimization of EGR quantity and injection timing reduced the NOx emission over the European 13-mode test by almost 60% to 2.4 g/kWh. Particulate emissions were 0.107 g/kWh and the BSFC penalty 2.5%. Initial tests demonstrate acceptable transient behaviour when using a dedicated control strategy. The expected EURO4 emission requirements are 3 g/kWh NOx and 0.10 g/kWh particulates (approximate time of implementation is 2004).